Last month we gave you an insight into Cornish choughs and what people are doing there to help them. This month we continue our travels and will take you north across the border to Wales. Known for its lush valleys and majestic mountains, Wales is also home to about three-quarter’s of the UK’s choughs.
The Welsh name for a chough is brân goesgoch meaning ‘red-legged crow’.
Wales is broadly categorised into four regions; north, mid, west, and south. Choughs can be found more or less along the entire Welsh coastline from the Gower Peninsula in the south to the isle of Anglesey in the north.
They can also be found inland from the coast nesting in abandoned quarries or mineshafts. Most famously at the Llechwedd slate caverns , North Wales, where a pair are known to nest much to the delight of the tourists deep underground. A video made by the RSPB gives you more of an insight and can be viewed here.
Over the past two decades researchers working with these choughs have seen more and more inland nests becoming abandoned and breeding pairs disappearing. Ceredigion had five breeding sites in the late 1980s. Ten years later it was down to one. Montgomeryshire has seen a complete loss. It is believed that the boom in natural predator numbers, namely peregrine and goshawk, has not helped matters.
Silurian shale coastline in Mid Wales.
Coastal nest sites are also under threat, but in this case it is due to natural erosion. A lot of the coast is limestone, sandstone, or shale and easily erodes. Looking at the photo on the right you wouldn’t think a bird would chose to build a nest on these cliffs. Yet they do, often with success, although a few years down the line the ledge might give way falling into the sea and a new nest will need to be built.
Nest-site availability is a very strong limiting factor in population expansion. In the late 1980s Scottish researchers had already shown the effectiveness of providing choughs with artificial nest-sites. Wales took on board this advice and started providing nest-boxes or ledge supports at various coastal sites. Within a few years just over two thirds of the artificial sites were being used. As of 2008 choughs at 22 artificial nest-sites successfully raised a total of 335 fledglings!
On a recent holiday to Wales I had the privilege of meeting Tony Cross, a champion chough supporter and the person responsible for designing the artificial nest-boxes (which we use at the Wildlife Park). Tony very kindly spared time to show me around some of the sites and teach me more about the Welsh choughs. Having ringed over 4,000 choughs and followed many individuals for several years there is a lot we can learn from him.
This area was once used by choughs to raise chicks, but has now been abandoned.
An abandoned mine shaft once used by nesting choughs.
The first stop was at an abandoned mining area where a pair of choughs used to nest. It is hard to see from the photos, but they chose a spot down a deep shaft which kept them fairly well protected from nest predators.
The land around looks quite healthy in terms of insect availability with cattle grazing pastures and its away from built up areas.
This is probably one of those sites which ‘suffered at the talons’ of the goshawk (although great news for the goshawk I guess).
As it was outside of the breeding season we didn’t disturb any nesting choughs. Tony is a licensed ringer and licenced to approach nests. I would not have been able to do this without him.
We then drove to the coast to take a look at some of the nest-boxes Tony and his colleagues have fitted to the cliffs. It is quite a challenge as they have to find a site that they can access, but at the same time deter egg collectors and the like from reaching it. In recent years Tony has sadly found activity at boxes suggestive of human raids rather than natural predators (and we thought those days were over). One clue being that ravens don’t need to use ropes!
Nest-boxes are positioned away from potential land predators in areas where choughs are trying to breed naturally but fail.
Tony Cross indicating how far back the nest-box reaches. This one is unusual in that it is positioned on top of the cliff.
The front of the box has and overhang which, apart from acting as a deterrent to something trying to reach in, makes it feel a bit more enclosed and sheltered for the birds.
An chough nest-box facing the sea (the black dot in the sea is a seal, trust me)
One factor Tony did not consider when first designing these boxes was how badger-proof they would need to be. Don’t be alarmed, Welsh badgers have not adapted to have opposable thumbs and learn rope skills. They do, however, burrow and at one particular sight they have given the nest-box a bit of a battering pushing it out of place.
One nest-box needs re-positioning after a run in with badgers.
The boxes need to be checked each year as they do suffer from being exposed to the sea air. As long as the roof remains dry and there is no risk of collapse the boxes can be used for several years. It normally takes a year before a breeding pair move in to a new box. Lots of HSE forms to fill in, quality control tests, and the long wait for the Royal Court date (Jersey in-joke sorry).
It is clear that the work Tony and his colleagues are doing has made a great difference to the Welsh chough population. Jersey’s choughs may well benefit from the same practices as these birds have no experience of wild nest sites and will need some encouragement.
They steal, raid nests, and keep the company of witches. But the unpopular crow may not be the menace people think.
A new study, published in the BOU’s journal IBIS (here), has found that crows – along with their cousins the magpie and the raven – have surprisingly little impact on the abundance of other bird species.
Collectively known as corvids (a group that includes choughs, jackdaws and even jays), these birds are in fact being menaced by mankind in the mistaken belief that removing them is good for conservation. This new study found that in the vast majority of cases (82%), corvids had no impact at all on their potential prey species.
“Many nature lovers have been distressed to witness a crow or magpie raiding the nests of their beloved garden songbirds, stealing their eggs or eating their defenceless chicks,” said study co-author Dr Arjun Amar from the Percy FitzPatrick Institute for Ornithology. “Although this predation is entirely natural, these observations can be upsetting to witness and often leave people wondering if these predators might be reducing bird numbers.”
“However, our global review suggests that we should be cautious before jumping to conclusions over the impacts these species may have. Just because a predator eats something occasionally does not always mean that they have an impact,” Dr Amar said.
The study reviewed all published evidence on whether predation by corvids actually reduces the overall breeding performance of birds or, more importantly from a conservation perspective, reduces their numbers. Data were collated from 42 studies of corvid predation conducted across the globe over the last 60 years.
Not only were corvids unlikely to have any impact on their potential prey species, if there was an impact it most often affected the breeding success of the prey species rather than their subsequent numbers. Half of cases found that corvids reduced breeding success whereas less than 10% of cases found that they reduced prey numbers in the long term.
“These results have big implications for the likely benefits of corvid control,” Dr Amar said. “They suggest that killing corvids will be of most benefit to those interested in gamebird shooting rather than conservationists.” He added: “Bird hunters are usually most interested in increasing numbers of birds available to shoot immediately after the breeding season and this appears to be where corvids have most impact”. “Conservationists on the other hand, are usually interested in increasing a species population size and our results suggest that only in a very few cases did corvids have an influence on this aspect of their prey,” Dr Amar said.
The review analysed the impact of six corvid species on a variety of prey species including gamebirds, songbirds, waders, herons, cranes, sea birds, wildfowl and raptors. The 42 studies incorporated into the review included 326 cases of corvid – bird prey interaction Most of the data stemmed from field research in the UK, France and the United States. The impacts were determined partly by comparing bird counts before and after corvids were either removed or their numbers reduced.
The review also found large differences between the impacts of crows, historically considered the most ‘cunning’ corvid, and magpies which are sometimes killed by home owners hoping to protect songbirds in their gardens. Crow species were six times more likely to have an impact on bird prey species than Magpies.
Mistaken assumptions about corvid predation were possibly explained by the birds’ diurnal nature and the fact that they are conspicuous nest predators: “Their importance in prey population regulation is often assumed prior to any assessment of the evidence,” the study warned.
Chrissie Madden, the lead author on the paper, hoped that the review would challenge the perception that all corvids were bad, thereby preventing needless killing: “Our results suggest that this is a mistaken belief and that generally speaking people would be wasting their time killing corvids to increase bird numbers”.
“Overall therefore, our study points to the fact that we are often too quick to jump to the conclusion that crows and magpies may be the cause of bird population declines,” she said.
You can download A review of the impacts of corvids on bird productivity and abundancehere
Careful planning measures must be put into place to ensure small wind turbine developments (such as those that fit on house roofs or in the garden) do not cause bat and bird population decline, according to research from University of Stirling.
Small domestic wind turbines or ‘microturbines’, which can kill bats and birds, are becoming an increasingly popular means to generate clean energy for home owners.
The Stirling team, whose research was published in Biodiversity and Conservation, found that the careful positioning of these turbines – and the avoidance of installing them in areas where bird or bat activity is likely to be high – is vital to ensure rare species of wildlife are not forced to abandon their homes in search of safer habitats.
Although previous research has shown that birds and bats may be killed in significant numbers by colliding with turbines in large wind farms, the Stirling research – carried out in collaboration with the British Trust for Ornithology – is the first study to examine whether small wind turbines could have a similar impact on wildlife.
The study looked at data, questionnaires from turbine owners and computer modelling, to assess the likely levels of bird and bat deaths caused by all small wind turbines across the UK. Results showed that between 1,567–5,510 birds and 161–3,363 bats may be killed per year by small wind turbines in the UK.
Dr Jeroen Minderman from the University’s School of Natural Sciences said: “Bird and bat deaths are a reality at small wind turbine sites.
“Whilst our findings show the relative extent of this problem is much smaller than other causes of wildlife deaths, such as cats or road collisions, our previous work has shown that bats avoid microturbine development areas – which may explain the relatively lower number of bat deaths estimated.”
Dr Kirsty Park, who led the Stirling research team said: “While our estimates of bird and bat deaths may seem high, it is important to realise that this is across a range of species and across more than 19,000 small wind turbines currently installed in the UK. Moreover, such estimates are several orders of magnitude lower than estimated numbers of deaths due to other human-related causes.
“However, this avoidance of microturbine sites by wildlife might have an adverse impact on rare or sensitive species if it causes bats to abandon what would otherwise be suitable feeding areas.”
She stressed: “Appropriate siting decisions that avoid such effects are therefore very important, and our work can help inform this.”
Microturbines are much smaller than their large wind farm counterparts and used mainly in domestic and farmland settings. Normally they are installed individually and can make a substantial contribution to household energy needs.
The increase in installation of such turbines is due to rapid technological developments and the introduction of financial incentives in the form of feed-in tariffs: schemes which pay people for creating their own ‘green’ electricity and offer additional bonuses for exporting electricity into the grid.
Abstract of the paper Estimates and correlates of bird and bat mortality at small wind turbine sites can be read here
Research published by the Stirling team in 2012 (full paper here) suggested that, while further research was needed, turbines should be sited at least 20 metres away from potentially valuable bat habitat. This will help to maximise the benefits of renewable energy generation whilst minimising potentially adverse effects on wildlife.
Thanks to the blanket fog, gales, and torrential rain we have been experiencing, plus the reduced daylight hours, November’s report is probably the shortest on record. Both the chough team and the equipment have taken a bit of a battering. A few tracking sessions have been cancelled whilst we shelter in cars or with the choughs in the aviary.
To be fair the start of the month was fairly pleasant. A bit bracing in the wind, but the sun was out and the chicks were on the move. Considering how much of the Island a chough can cover in just a few minutes the tracking team tried to be cunning and set up at three strategic vantage points; Sorel, Devil’s Hole/Crabbe, and Grantez.
Dawn tracking at Grantez.
Without sounding too bitter our plan failed on all but one occasion. Since I returned from holiday on the 8th the chicks have only flown south once…on my weekend (there is probably opportunity for a research paper into that correlation).
They decided to start exploring the north-west corner of the Island. Only ever seen flying, never touching down to feed, and only really on a few occasions. As the weather started to turn they hunkered down in Mourier Valley and haven’t really left since.
Juvenile choughs probing for food on the cliffs at Mourier Valley. Photo by Liz Corry
Thanks again to everyone who sent in sightings this month. They have definitely helped to solve one mystery disappearance and have now made it onto five of 22 bird monitoring transects in Jersey.
To distract from the lack of content this month here are some photos and a video of what the choughs have been up to….
Seconds before the shutter clicked three choughs had been perched with the kestrel, exchanging daily gossip perhaps.
Cauvette and Dingle having a squabble over a prize insect Cauvette had dug up.
Dingle begging for food from Bean (she wasn’t too impressed).
Further evidence of the importance to birds and farmers of hedges in agricultural land comes to us from a rather unlikely source. Studies from Akot, Maharashtra State in central India revealed how strong the difference in bird numbers and diversity between different farmland sites with and without hedges can be. Hedges in the study area were shown to provide important nesting, feeding and sheltering sites for birds in agricultural areas with highest numbers of birds in those fields with hedges.
During the Indian study, 64 bird species from 34 families were observed. Most of the birds were recorded actually in or very near hedges. An earlier study (here) in Germany reported that increasing hedge length enhanced significantly the number of bird species and that adding hedges or introducing organic farming practices should be primarily promoted in simple landscapes, where it really makes a difference for biodiversity.
These studies show that hedge length has a stronger effect on bird richness than management and that the increasing length of hedges enhances birds in conventional, non-organic, fields too. Bird conservation even in intensively used agricultural landscapes should concentrate on hedges or green lanes.
Providing more hedgerows and carefully managing them, can significantly contribute to the conservation of declining farmland birds. Birds forage in the agricultural fields, using the hedges for resting and breeding. Highest diversity of birds was also directly connected to diversity of plants as the greatest number of plant types gave more choice of food for the bird species. High numbers of bushes and plants at the boundary of agricultural land will benefit the largest numbers of birds. Thus planting trees in agricultural lands and well managed hedges can increase the bird diversity and large scale cutting of hedges should be avoided.
Not only will populations of birds benefit from increased hedges but the birds can themselves benefit the farmer. Insectivorous and predatory birds play a very useful role in controlling insect and rodent pests of crops. Presence of healthy numbers of birds in the farm fields is an eco-friendly and useful way of controlling the pests on the crop so, hedgerows must be saved to conserve farmland bird diversity. Hedges should, however, be maintained properly and not allowed to become invasive and reduce the utilizable area of the field.
Studies on farmland avian diversity with special reference to importance of hedges in conserving farmland bird diversity can be downloaded here.
This summer we travelled to Cornwall to collect six chough chicks from Paradise Park. Whilst we were there we took the opportunity to meet up with Claire Mucklow, RSPB Cornwall chough project manager, and Nicola Shanks, RSPB chough project officer. They very kindly drove myself and Harriet around the picturesque countryside in the hunt for the Cornish legend that is the red-billed chough.
Choughs have a long standing history with Cornwall dating back to the 13th Century and even feature on its coat of arms. In the 19th Century the population of Cornish choughs came under immense pressures from egg collectors, people shooting for fun or misidentifying them as pests, and people taking chicks to tame as house pets.
All that on top of the continually degrading habitat in which livestock were being moved inland for easier farming leaving once grazed cliff top pastures to become overgrown and unmanaged.
By the 1950s choughs were failing to breed in Cornwall and by 1974 the population was no more. Throughout the 1970s and right up until the Millenium Cornwall would only be visited by outsiders passing through. It was not until 2001 when three of these ‘tourist’ choughs (from Ireland) decided conditions were favourable enough to stay. In 2002 two of the birds nested and for the first time in over fifty years Cornwall once again had its own wild chough chicks. Now, twelve years later, there are seven pairs of chough nesting in Cornwall (or should I say ‘attempting’ since one is a male-male pairing). Check up on Cornwall’s choughs through their own website
A view from Lizard Point where choughs returned to breed in 2001. Photo by Liz Corry
The three birds who returned in 2001 chose Lizard Point on the south coast of Cornwall to become their new home. With suitable grazing and dramatic cliff tops it is easy to see why. As part of their conservation management Claire organises volunteer nest watches each year so the eggs and subsequent chicks can receive round-the-clock protection. Sadly, egg-collecting still threatens choughs and many other species today. In 2006 police seized a collection of over 7,000 wild bird eggs including chough, the largest case to date. For more information on this case click here.
A volunteer chough watch point at The Lizard this year manned by National Trust (in red). Photo by Liz Corry.
Choughs are protected by UK law to the extent that a licence is needed in order to photograph and access nests. The volunteers watch from a distance and gauge breeding activity according to what the parents are doing. With an incubation period of around three weeks and a further six to seven weeks before the chicks leave the nest, the volunteers are often in for a long wait to see the chicks fledge. Happily the breeding success and survival of these Cornish birds is very good.
It doesn’t have to be the breeding season for you to see choughs at Lizard Point (although from personal experience it helps!). And don’t be put off by the thought of standing out in blustery, icy winds at this time of year. The Polpeor Café has a great view and heating. You can get even ‘warmer’ by stopping off at The Witchball in the village and sampling the delights of the Cornish Chough Brewery.
Cornish Chough Brewery ales on tap at The Witchball.
Just north of Lizard Point is Kynance Cove a very popular destination in summer for both people and choughs. People are attracted to the turquoise water, white sands, and café cream teas.
Chough habitat at Kynance, Cornwall. Photo by Liz Corry
The choughs…cow pats. In 2010 local farmer Roland Hill, in partnership with Nature England and the National Trust, started grazing ruby red cattle (sometimes, and whisper this, called North Devons) at Kynance and Lizard Downs in order to restore the coastal grassland including rare plants such as spring sandwort. Of course they also benefit the choughs by allowing insect communities to thrive in the grazed land and their dung provides an almost endless supply of beetle larvae. Ruby reds happen to be one of the most docile and prettiest breeds of cattle, Jerseys aside of course, which make them quite an attraction in their own right at Kynance.
Ruby red cattle grazing the cliff tops at Kynance Cove. Photo by Liz Corry.
Ruby reds grazing in amongst the visitors to Kynance Cove. Photo by Liz Corry.
As chough numbers started to increase the birds began slowly dispersing further along the coastline. An hour’s drive west of Lizard Point is Cape Cornwall and where we based ourselves for the two day trip. We asked Nicola to recommend accommodation in the area with a tongue in cheek challenge to find somewhere we could photograph a Cornish chough with the sun setting in the background over picture perfect calm seas. Hats of to her she did it, but I don’t think Nicola expected us to be quite so lucky (Claire says she did. It was test to see if we were going to put beer or choughs first that evening!).
Cape Cornwall and a view of the Heniz Monument. Photo by Liz Corry.
After checking in at the hotel on the first evening we walked down to the end of the headland to Heniz Monument. Very soon we heard the unmistakeable call of a chough and, on following the sound, spotted three birds coming in to land. Oblivious to the two over-excited, binocular clad, girls jumping up and down twenty five metres away, the choughs went about their business foraging in the grass around the headland and preening on the wall surrounding the pubic car park.
One of three choughs spotted feeding around Cape Cornwall. Photo by Liz Corry
After a while the choughs took to the air and flew off north. As we watched the birds disappear into the distance we began to make out tiny black specks on the slopes below Kenidjack. Following the footpath around to get closer the tiny specks began to take shape and we soon realised we were looking at choughs. Not just dirt on the lens or rabbit holes (trust me it happens).
Choughs gathering near a communal roost site. Photo by Liz Corry.
Pre-roost preening ritual. Photo by Liz Corry
In total we counted fourteen choughs scattered across the rocks on the other side of the valley. We sat and watched them until the sun had set. Clearly we had found a communal roost site and had been fortunate enough to watch them all bed down for the night.
Sunset at Cape Cornwall. Photo by Liz Corry
The next morning when we met Claire we worked out that we had been observing two family groups and the all male pairing. During the breeding season these three groups tend to keep their distance from one another. Once breeding is over groups will flock together sharing roosts and feeding sites.
Coastal farmland grazed by longhorn cattle to improve chough feeding sites. Photo by Liz Corry
To help us learn more about the habitat preferences of the choughs Claire and Nicola drove us to sites either side of Cape Cornwall. Our first stop was an area called Nanjulian where longhorn cattle are being used to graze the headland. The farmer here is so pleased with the way things have gone he is looking to expand is herd although as with many projects of this kind he is limited by time and resources.
Slightly less huggable in appearance than ruby reds, yet just as likeable and important, the longhorns keep the grasses short, scrub at bay, and allow the insect comminuties to thrive.
Longhorn cattle graze land as part of chough conservation measures in Cornwall. Photo by Liz Corry.
With food supplies in check, chough parents-to-be need secure nest sites. Generally these are in caves or deep crevices along the cliffs. Cornwall’s coastline is abound with such features and the choughs often choose the most dramatic of sites, many of which cannot be accessed on foot by people providing the birds with a certain amount of security. We were taken to see a few such sites and marvelled at how Claire spotted the site in the first place, followed by how the licensed ringer accesses the nests in order to collect data on the chicks.
Abandoed tin mines, such as Botallack, are a common feature of the Cornish coastline. Photo by Liz Corry.
Choughs are quite resourceful and take advantage of Cornwall’s other offering of nest sites in the form of abandoned mines, adits, and other stone buildings. Our final stop on the guided tour was the Botallack Mine complex north of St. Just. These are abandoned tin mines built in the 1860s which run about 400m into the Atlantic Ocean. The area is now managed by the National Trust and home to Cornish choughs. The National Trust have secured all the old mineshafts, but it always pays to be careful where you walk in old mining areas. The deepest shaft at Botallack runs about 500m down into the ground. It is advisable to stick to designated footpaths. Choughs rarely like to abide by rules and where they nest in this area is certainly off the beaten track, barely accessible by humans. A perfect spot to safely raise chicks.
Before heading home we couldn’t resist one final check of Cape Cornwall’s offerings. We only counted twelve choughs that evening as they dropped off the cliff edge out of sight down to the roost below.
Choughs flying along the Cornish coast. Photo by Liz Corry.
Whether one, twelve, or twenty-two it was amazing to see a bird that has been able to return home and breed once again. The population is nowhere near the numbers it used to be. However, thanks to the conservation efforts of the RSPB, National Trust, Nature England, the farmers and the people of Cornwall the number of choughs has gone from three to thirty-three in little more than a decade.
Brent geese must be amongst the best known birds in the Channel Islands. Up to 1,500 may winter in Jersey with smaller numbers in Guernsey, Herm and Alderney each year. The main reason that these geese come to our shores is because there are beds of the highly vulnerable eel-grass, one of the birds’ most important food sources here. However, despite spending around eight months with us, how much do we really know about these little, approachable geese? For one thing, how many Channel Islanders actually know that our islands are almost unique in annually hosting populations of two very distinctly different brent geese?
Dark-bellied brent geese (Branta bernicla bernicla) return to us each year in September from the Russian arctic. They breed up in the wilds of the Asian tundra but spend their winter in much tamer environments of British and French beaches, harbours and, at times, farmers’ fields and even golf courses. It is often hard to imagine that the calm little geese we see in winter are the same birds that disperse across a hostile arctic wilderness each spring.
Earlier in the 20th Century, dark-bellied brent geese were quiet rare. The numbers we see now (over 200,000 worldwide) are testament to a successful global conservation campaign. The population began to rise when UK and France banned hunting in 1954 and 1966 respectively. However, things really changed when the flocks migrating through Denmark were given legal protection in 1972. Safe in their breeding grounds, their wintering areas and on their migration stopovers in between, this endearing little goose quickly recovered.
In winter, we see these Russian visitors collecting in our quiet bays and beaches or flocking inland on the high tide in a handful of places (most still roost out to sea). Over recent years, many geese have been given coloured plastic rings by researchers that are easy for birdwatchers to see allowing us to keep an eye on the birds’ activities. These ringing studies, some geese have been caught locally, some in the Netherlands and some in the arctic, show us how long the birds might live, how productive their breeding seasons are (did you know their breeding success is linked to the abundance of lemmings?) and, most importantly, how they distribute themselves along our coastline. Perhaps the most important discovery has been that individual geese return to the same bay or stretch of beach each year and don’t visit other bays. This means that loss of one site might mean the total loss of that site’s geese. They won’t just go to another bay. Put simply, they’ll probably die.
Pale-bellied brent geese (Branta bernicla hrota), the other brent goose present in the Channel Islands over the winter, arrive rather later, in November each year, and are much less numerous. These, as their name suggests, and as can be seen in the photographs, have much paler bellies than their Russian counterparts. Juvenile upper-wings have a barred appearance when the bird is at rest, compared with the more uniform back of adults. Up to 150 can be observed in Jersey, concentrated in St. Aubin’s Bay (look out for them at West Park or by St Aubin’s Harbour), but only a handful has been recorded in the other islands.
Similar ringing studies to those for the dark-bellied brent geese have shown that there are two distinct flyway populations of pale-bellied brent geese, one which breeds in Svalbard and North-eastern Greenland, the other in arctic Canada. The latter population, to which our birds have been shown to belong, currently numbers around 40,000 birds, and has been subject to intensive study by the Irish Brent Goose Research Group and their Icelandic collaborators. When they arrive in Jersey, the geese have undertaken an amazing annual migration, travelling from the breeding grounds over the Greenland Ice-cap, then staging in western Iceland before an onward flight to Ireland, where an amazing 75% of birds gather initially at a single site, Strangford Lough in Northern Ireland. Peak numbers generally occur there in early October, following which the geese move on, as the eel-grass which attracts them there gets depleted. About 90% of these pale-bellied brent geese will disperse to within the bays all around Ireland for the rest of the winter, but others will travel further, to spend the rest of the winter in Western Britain, Normandy, and here in Jersey. Jersey is, therefore, particularly special as it is near the southern limit of the flyway range, as shown by the re-sighting of marked birds.
The resightings of the pale-bellieds further demonstrate just how site-faithful these geese can be. An example is 3XYY (see photo), which was ringed near Reykjavik in Iceland in May 2006 and has appeared at St. Aubin’s Bay every winter since then. Another is PUWR, seen every winter but one since being ringed in west Iceland in May 2010, passing through Jersey en route to Régnéville in Normandy.
Both these geese are back this winter.
Whilst the numbers of geese in this population have approximately doubled over the past 10-15 years, they can experience low reproduction in years when conditions in the arctic are inclement, as the suitable weather window of time for successful breeding can be very narrow. This was particularly evident after summer 2013, when birds returned to the wintering areas with virtually no young. Birds are highly dispersed whilst breeding, and nests are liable to predation. Brent geese tend to congregate, often in very large flocks, during passage and the winter. The fact that such a high proportion of the flyway population gathers together at a single site in autumn also renders the geese potentially significantly vulnerable to a major problem with their main food source there (eel-grass), and to contagious disease. This year again, very few young birds have been seen in Jersey while, in contrast, the dark-bellied birds appear to have had a very good year.
So, next time you see a flock of this most maritime species of goose, take a good look and see whether you can spot any of these amazing little pale-bellied brent geese, and marvel.
Interestingly, to complete the record, a third brent goose, the black brant (Branta bernicla nigricans) lives in the Pacific. This goose too occasionally, but not annually, visits the Channel Islands usually in the flocks of dark-bellied brent, presumably having joined them in the Russian far east.
Read Graham McElwaine’s blog on monitoring brent geese from their breeding grounds (watch out for those polar bears), to the winter beaches here.
October marked six months since the release hatches were first opened in 2014 and five months of living free for the six older choughs. I am, therefore, delighted to report that they are doing amazingly well. Even more pleasing is their decision to return to the aviary to roost with the juveniles each night.
They are behaving exactly the same as any wild chough. Foraging for insects, sheltering on cliff ledges, and fully aware of potential predators. The only difference being that they return for extra food at the aviary when we call them in. Although if you are a Scottish chough living in Islay this isn’t that unusual. Eric Bignal’s work with supplementary feeding is once again being highlighted in the UK media.
Supplementary feeding study of wild choughs living in Islay showed an increase in juvenile survival rates over-winter. Bignal, E., & Bignal, C. Supplementary feeding of sub-adult choughs. British Wildlife 2011: 315-319.
Eric and the Scottish Chough Study Group started a programme of controlled supplementary feeds providing wild choughs with a daily ‘top up’ of mealworms. Survival rates in juvenile choughs during their first winter are very low due to limited availibility of insects at that time of year; insect numbers are lower, ground frosts block access to the soil. After several years of supplementary feeding, the choughs on Islay have increased in breeding pairs from 39 in 2013 to 46 this year (report published in British Wildlife). Still a long way to go to get back up to the 95 they had in 1986, but evidence that this sort of management in the wild can work. Click here to learn more.
This work has been critical in how we planned the Jersey project and we fully expect to continue with some form of supplmentary feeding in the future. At present the Jersey choughs are receiving two feeds a day from staff. Without knowing exactly how many calories each of our choughs are getting from the wild it is difficult to quantify how much extra to give them.
Bean’s bill a tell tale sign that the choughs are probing for insects, but are they finding enough? Photo by Liz Corry
We tried reducing the quantity of insects and drymix per feed by half this month. We gave them a week to adjust, continued to monitor their body weights, and their general behaviour. Constant hounding of staff by the choughs suggested that they weren’t finding enough in the wild. We tried to leave it long enough in order to rule out complaicancy of not getting an easy meal. I’m still not convinced, but don’t have enough will-power to crack the whip just yet.
Invertebrate sampling at Sorel
To try and get a handle on what the choughs are eating out in the wild we have set out pitfall traps and randomly selected sites within the choughs’ current foraging area. These will be checked once a day for five days and repeated every month. This will allow us to assess seasonal variations and help us to indentify the insects we found in the faecal samples that we have collected. This month we are starting to see a lot more beetles in the feacals and pellets as opposed to ants and hawthorn seeds back in September.
Pitfall traps in the ground at chough feeding sites to study insect abundance. Photo by Liz Corry.
Will and our new student, Jennifer, have been creating an identification guide for the invertebrates we are likely to find based on existing studies and what is found in the traps. For image copyright reasons this report will only be for internal use for the time being. However, we would be very keen to see this developed into a much wider available publication for Jersey.
New six-month student placement
New student Jennifer began her six month placement studying the choughs…not the sheep! Photo by Harriet Clark.
Jennifer Garbutt joined the chough team this month for a six month placement on the project. Jennifer has just finished her Master’s Degree at Bristol and hopes to further develop her research skills for a career in conservation.
As a new arrival to Jersey the first few weeks of driving green lanes to follow choughs has been quite daunting, but a welcome challenge.
Jennifer is our first student who has been able to commit to longer than the minimum three-month requirement.
Often by the time you have learnt the ropes it is time to leave. By committing longer term there is undoubtedly a greater benefit for all. We will be inviting people to apply for our student positions in the New Year. The placements are currently full until March 2015. For more information and how to apply please click here or phone 01534 860045.
Maladies, mysteries, and muck
Faecal samples were submitted to Durrell’s lab this month as part of our post-release health monitoring. This coincided with the Wildlife Park’s bi-annual screening programme in which every animal at Durrell is sampled. To save Ann’s, our lab technician’s, sanity we treated the post-release samples as their bi-annual check as well so she only had to do half the amount of testing. Thankfully nothing came back on the results to cause Ann even more stress and the birds seem happy. That said, we did have two veterinary cases this month which have left us all somewhat baffled.
Egg, a five month old female chough. Photo by Liz Cory
On the last Saturday of the month at a supplementary feed Egg (red leg ring) seemed a little off colour. When the rest of the group had eaten and flown off to play on the cliff tops she stayed in the aviary. Her body weight was average and she showed no external signs of injury. She was observed closely for the rest of the day but showed no improvement and was not eating.
Egg was locked into section 1A of the release aviary and the vet was called up to examine her. Both vet and keepers drew a blank. Egg’s faeces showed no sign of infection and there were no other clues to suggest a reason for her depression. She was kept in the aviary for the next two nights with the other chicks roosting next door, and monitored closely. Egg started to eat and her mood had picked up. On the Monday morning she was released back out of the aviary and joined the others straight away. Egg’s condition will remain a mystery. We just hope this is a one off for her.
Our most alarming mystery this month, however, involved Jean (white leg ring). On the morning of the 11th they was no sign of her at Devil’s Hole foraging with the others. We found her perched alone in a roost box in the aviary at 08:20. She flew out in alarm when we approached and joined the others who had also flown over to Sorel by that point. When they were all back in the aviary for lunch Jean’s left eye was closed. When the others had finished eating and flown out she remained perched. We shut the aviary hatches so we could get a closer look without her flying away. It was clear that something was up with her eye and on the vet’s recommendations she was caught up and examined.
Staff noticed something wrong with Jean’ eye so she was isolated for veterinrary care. Photo by Liz Corry
The surface of the eye was very cloudy suggesting severe inflammation and no menace reflex was observed which indicated that Jean could not see with the left eye. Thankfully there was still perfect vision in the right eye. No signs of ulcers in the surface of the eye were noted and no conjunctivitis was observed. Additionally she was not showing any signs of pain and discomfort at this point. Medications were administered topically and orally given in insects, in order to decrease the inflammation to allow a more detailed examination of the eye. This meant that she had to be confined to the aviary for at least five days. Photos were sent off to a veterinary ophthalmologist for a second opinion. Five days later the eye was examined again in more detail as most of the inflammation was resolved. Jean was still unable to see and an opacity was noted in the lens inside of the eye, suggesting the formation of a cataract. The posterior portion of the eye was still not visible and an ultrasound of the eye was performed to evaluate this area – having a portable ultrasound machine allowed the veterinary team to perform this examination at the Sorel aviary after applying a topical anaesthesia on the eye. No problems were noted in this section of the eye and we decided that the cataract formation was the result of trauma to the eye.
Ocular opacity in left eye covering entire lens (left) began clearing up after five days of treatment (right). Photos by Harriet Clark.
Jean continued to be confined to the aviary and given anti-inflammatory drugs for the next three days. Weighing up the options with careful consideration for Jean’s welfare we decided it would be in her best interest to release her again. We would continue to monitor her closely and if we felt there was a concern over her mobility due to the loss of binocular vision we would consider confining her to an aviary permanently. Follow up examinations have showed a decrease in the size of the cataract so there is the possibility that Jean will regain some vision in the future but it is very early to say.
Durrell vet, Alberto Barbon, performing an ultrasound on a Jean’s eye. Photo by Harriet Clark
Having seen her response to a peregrine the day she was initially confined to the aviary we had faith that she would stand a good chance of survival if the choughs continued to act as a group. Choughs are a social animal and remain in continuous contact with each other whether by calling or by displaying a flick of a wing feather. They show each other where to feed and when to stop feeding if a potential threat is approaching be it peregrine or person. She had already gained enough experience to know the lay of the land around the release site and would still roost in the relative saftey of the aviary. If she had a been a bird of prey who is reliant on pin-point 20:20 vision to hunt or a solitary species left to fend for herself our decision would have been different.
We are pleased to say that Jean was released back out to Sorel on the 20th, joined the flock straight away, and has been with them ever since. She has shown no concern when flying or feeding. At first, and with strong winds, she found it difficult to judge distance going through the hatches to get to food inside the aviary. Very quickly she learned to adapt and flew in sideways using her good eye for judgement. I hasten to add that we provide food dishes outside as well as in the aviary, she was just greedy and wanted to go to all the dishes. It is clear that she is an intelligent bird and has the ability to learn to adapt qucikly. Only time will tell if the damage is permanent and we may never know what caused it in the first place. This was a huge learning experience for us, the vets, and avian husbandary in general. Let us hope that November has fewer surprises in store!
Juveniles reunited after Egg and Jean’s mystery illnesses (Cauvette is a little camera shy). Photo by Liz Corry
We have had to add more food shelters to the aviary to protect the choughs from the driving rain which hits in all directions. The roof alone does not provide sufficient protection and, with twice as many birds as last winter, we need extra spaces. Will and Harriet fitted the plywood shelters and watched contently as the choughs put them to good use.
Juvenile choughs on a windy day in Jersey.
Trick or Treat: Juvenile dispersal
The choughs now seem very settled at Sorel. They have been bathing in the stream at the mouth of Mourier Valley, sheltering on the cliff when it rains, and probing in the Conservation Fields. All of which are new sites for both the juveniles and adults.
Choughs at Devil’s Hole rock face. Photo by Liz Corry
The biggest change came at the end of the month. At 07:30 on the 27th the team went to Sorel and counted 16 choughs. They continued to observe the choughs playing, feeding, preening, until 08:45 when nine juveniles took to the air and flew out of sight over Devil’s Hole (nb: Egg was still confined to the aviary at this stage due to her malaise).
In the last few weeks when they have flown beyond Devil’s Hole we have been able to watch them fly over Crabbé, maybe dip out of sight behind the gun range, then reappear. This time they never reappeared!
The radio trackers set off the best they could trying to follow signals. However, it appears that motorised vehicles and Jersey’s 15mph, winding, green lanes are no match for a chough. Thanks to reports from members of the public, the team were informed that the choughs had reached the south-west of the Island within fifteen minutes of ‘dropping off the radar’. Sticking rigidly to Jersey’s speed limits Harriet made her way down only to find the choughs had gone….back to the aviary.
By 10:50 the nine juveniles were visible flying in west along the coast from Devil’s Hole towards the aviary. They joined back with the adults, who had stayed around the release site, and all came down for their lunchtime feed a few minutes later. Egg was released back into the group at this point. The group spent the afternoon around the aviary, although four adults left for the quarry at 16:30. All the juveniles roosted in the aviary.
The next morning there was not a single chough in sight at Sorel. Phone calls and text messages came in from the public once again, placing the adults around St Ouen’s Bay (perhaps checking out the best spot for breakfast) and the chicks even further south. This time the chicks were not just flying but foraging on the ground around Beauport and Ficquet Bay. This is a really interesting development as this part of the coast was the last known breeding location for Jersey’s choughs over 100 years ago.
Choughs return for supplementary food twice a day. Photo by Liz Corry.
The chicks didn’t stay long, returning to the aviary by 11:00. The adults had returned ninety minutes earlier. They spent the rest of the afternoon around Sorel and roosted in the aviary again.
We think that five of the adults might have spent the night in the quarry. One was spotted flying back from the quarry to the aviary at 16:45, but after sunset it was hard to tell if others had followed suit.
For the next few days leading up to the 31st, the chicks would follow a pattern of leaving Sorel first thing after sunrise, heading to Beauport to explore the headland, then return to the aviary in time for the lunch feed and weigh-in. The adults showed no further interest in leaving stretch of coast between Sorel and Devil’s Hole. See report here
We will have to wait to see if this is going to become a permanent pattern of dispersal with the chicks or whether they were just tricking us. Well it was Halloween after all.
Speaking of which, an interesting article about Channel Island folklore was sent to the chough team recently. It turns out that we might be dabbling in the dark arts! In the Nineteenth Century when choughs were found across the Channel Islands people were very superstitious about the red-legged bird. Why? Witches wore red stockings as a means of identification and, therefore, in the days when logical thought was questionable, choughs were also, by association, witches. The infamous Guernsey witch Marie Pipet, was even said to be able to turn herself into a chough.
Witch burning. Image taken from www.theislandwiki.org
Georges Métvier explained the link in the Dictionnaire Anglo-Normand translated in a Guernsey magazine in April 1883 (de Garis – Folklore): ‘… a certain Sieur Job, the venerable owner of the property found some Marie or Judith in his cow house in the shape of one of these birds, which he wounded in the leg with a pitchfork. Soon after the good woman sent for the doctor, who was called upon to tend exactly the same wound which had been inflicted on the bird, and so ill was she that for 6 months she was confined to her bed.‘
Scientific proof if ever one needed it! Thank you to Sarah Nugent for sending this our way and to Guernsey Birds for reference material regarding the choughs.
Many thousands of seabirds including grebes, divers, ducks, auks, gulls, cormorants and shags spend the winter at sea in the Channel Islands. Even in a good year it is possible that some of these birds may be found dead on our coastline. However, in periods of extremely bad weather or during pollution incidents many hundreds of birds may wash up on the beaches.
Earlier this year over 1,000 dead birds were found on our beaches following a period of extreme weather in the area. In 2013 we had the tragic experience of PIBs being discharged in the Channel and killing many seabirds.
The sight of dead birds like these is never pleasant but it is very important that we record the numbers of birds and their species in order to understand the extent of the incident and to predict what impacts there may be on already threatened seabird populations.
The birds may have rings or other identification devices and reporting these will increase our knowledge of the birds’ ecology as we can map where different species spend the winter or chose to moult and understand how long they can live.
If you find a dead seabird please report it immediately to Birds On The Edge at email@example.com or phone Glyn Young at 01534 860032 or Cris Sellarés at 07700 337077 with the following important information:
1)The species of bird or size, colour of the head, body, beak and feet if species is unknown;
2) The date that you found the bird and your contact details if you are happy to share them;
3) Information on its location (e.g. which beach and nearest landmark such as slipway or café);
4) A picture taken from your phone or camera, if you can;
5) Any rings or other tags that it might have. If ringed, please write down the ring number and address.
Gulls tucking in to discarded food or flocking around landfills has become a familiar sight. Now data from the Pacific north-west of Canada spanning 149 years has shown that substituting fish with less nutritious food is linked to population declines and lower fertility in glaucous-winged gulls (Larus glaucescens) a close relative of the herring and lesser black-backed gull.
Louise Blight from the University of British Columbia and her colleagues looked at 270 gulls’ feather samples from museums, taken between 1860 and 2009. Using the ratios of heavy isotopes of carbon and nitrogen, the team pieced together the dietary habits of these seabirds, all of which had lived in the Salish Sea region off the coast of south-western Canada and the north-western USA.
They found a decline in heavier carbon isotopes, indicating that the gulls shifted from a fishy source of carbon to a terrestrial source. A decline in heavier nitrogen isotopes implied that their diets had also shifted to a less nutritious staple; most likely lower marine invertebrates and corn-based organic food waste.
This change in diet coincided with over-fishing in the region in the early 1900s, after which the gull population dropped.
“The stable isotope work shows a decrease of fish in diet over the time frame where forage fishes have declined”, says Blight.
Fish or chips
Overfishing has meant that one of the gulls’ favourite fish species, the highly nutritious eulachon (a smelt species), is now considered threatened in the Salish Sea area. Another former staple, the Pacific herring, no longer forms the large aggregations that gulls once feasted on.
But between 1960 and 1986, the gull population increased, perhaps because more readily available rubbish, although less nutritious than fish, was helping to support the population. “Our field observations show that many pairs are feeding their chicks on sand lance and herring, and that some pairs feed their chicks on things like chicken or French fries,” says Blight.
This shift to a poor-quality, low-protein diet could be linked to reduced reproductive success in the gulls. A previous study by Blight showed that gulls have been producing smaller and fewer eggs over the last few decades, which she believes is consistent with a decline in diet quality around egg production time in the early spring.
“Rarely will you visit these garbage dumps without seeing multiple gull species. You will even see them at transfer stations or intermediate garbage staging areas,” says Joe Gaydos, Director and Chief Scientist at the SeaDoc Society, a Salish Sea research organisation based in Eastsound, Washington.
The glaucous-winged gull is a generalist feeder, meaning it can survive on a wide range of different food sources. While there is some evidence that switching to a trashy diet has helped gulls through tough times, overall, the data reveals a worrying decline in numbers. “Their populations should not decline as quickly as specialist feeders. The fact that generalists like gulls could be in decline is definitely worrisome,” says Gaydos.
This research will be published in Global Change Biology and the abstract can be read here
Paul Veron heads a Guernsey-based project (website and Birds On The Edge report) looking at long-term ecology of gulls in the Channel Islands. Paul is particularly looking at what will happen when the Chouet Landfill site is closed and the gulls across our Islands lose access to a major part of their food supply now that there are so few fish available to them.