In January, Birds On The Edge reported on an exciting project to remove rats from St Agnes and Gugh in the Isles of Scilly in order to safeguard important numbers of nesting seabirds (see the article here). Since then the project has progressed nicely:
•To reverse recent declines in seabird populations on the Isles of Scilly through removal of a non-native species (brown rat) from the islands of St Agnes and Gugh;
•To enable people living in and visiting the Isles of Scilly to learn about, take pride in, and play an active role in celebrating and conserving their seabird and wider natural heritage;
•To train and support island communities to embrace the benefits of seabird recovery, including the removal of rats, and continue to protect their heritage once the project has ended.
The islands, which are located off Cornwall, are home to breeding populations of 14 seabird species and approximately 20,000 birds. Eradication experts from the UK and New Zealand’s Wildlife Management International Limited (WMIL) will manage the poisoning of several thousand rats.
“Among many challenges our seabirds face, the greatest threat on land is predation of eggs and chicks by brown rats,” said Jaclyn Pearson, Project Manager of the Isles of Scilly Seabird Recovery Project.
Elizabeth Bell, from WMIL said (see BBC Cornwall): “A period of intensive baiting will start from 8th November and most of the rats will be dead by the end of November. We’ll then target the surviving rats.”
A long-term monitoring programme will start at the beginning of 2014 to check the rodents have been eradicated from the islands. Ms Bell said all the bait stations were enclosed, tied down and were designed not to kill any other species, such as rabbits.
Ms Pearson said: “The project is 25 years in length, although the project team will disband after five years, for the remaining 20 years the community will continue to protect their seabird heritage, by keeping the islands ‘rat-free’. This includes correct waste management, ensuring bio-security on boats and freight to the islands, and of course, educating all visitors to the islands to be vigilant and ‘rat on a rat'”.
“This is the largest community-based island restoration project attempted in the world to date, with 85 residents living here year round.”
The project has recruited a team of ‘seabird task force volunteers’ and the first arrived on the islands in early November of the start of the delivery phase. They will be on St Agnes and Gugh baiting and monitoring rats for the next six months. After their induction to the project and the team, they were straight out to collect windfall apples (removing this food source away from the rats) and on to meet the community as part of an evening community talk ahead of the baiting starting. Safety protocols around the bait stations were reiterated and the WMIL team will be on call 24 hours a day.
On 12th November the local news ‘ ITV West-Country’ came to report on the first day of baiting. They flew to the islands on the first flight of the day to capture the excitement on this important day in the project (see the video here).
Jaclyn Pearson spent this first important week of baiting with the WMIL team and the volunteers, and has been interviewing the volunteers for the local radio station to find out why they have volunteered for the project and what it means to them. Volunteer Lyndsey Death says “I am so happy to be spending the winter on the islands gaining skills and learning about island restoration projects. The project is so well organised, I am really enjoying it.”.
Many thanks to Jaclyn Pearson for help in compiling this report. See the project’s poster here, read regular updates and sign up for the newsletter.
The ‘early bird’ strategy has been revealed by a team studying the winter foraging behaviour of birds in Wytham Woods, Oxfordshire. The researchers fitted over 2,000 birds with tiny PIT radio tags. They then used 101 feeders which detected these tags and captured the exact time individual birds found each feeder. By moving 36 of these feeders around the forest throughout the day, and recording the results, the team showed that birds gathered information about new food sources during the morning so that they can then eat it later in the day.
The birds studied were a mixture of great tits, blue tits, marsh tits, coal tits and nuthatches. The full report, published this week, can be downloaded here
Damien Farine of Oxford University, who led the research, says that ‘birds have to store body-fat to avoid starving during the cold winter nights, but this can make them slower and less manoeuvrable so that they are more likely to be caught by predators’. ‘So there is a trade-off, where birds need to remain lean enough in order to ‘outrun’ their predators, or at least the next slowest bird, during the day but also store enough fat to survive each night.’
The team knew from previous studies at Wytham Woods that, when the predation risk appears high, birds delay putting on fat until late in the day. The researchers wanted to test the idea that, instead of simply ‘idly waiting’ until the afternoon, birds were actively seeking out new sources of food to work out where their next meal was coming from.
‘We used new tracking technologies to investigate how great tits, blue tits, and other common garden birds, balance the competing risks of predation and starvation’. ‘Our results show that these birds display very different patterns of food discovery in the morning and afternoon; very few new food sources were found during the afternoon, whereas nearly every new food source that we put out during the morning was quickly discovered. It supports the idea of an ‘early bird’ strategy of scouting for food early on so that they can return to feast a couple of hours before dusk in preparation for a long winter’s night.’
Winter is a tough time for small garden birds as not only is there less natural food available but their predators, such as the sparrowhawk, are keen to stock up their own fat reserves and so are hunting every day. The short days and long cold nights mean that small birds can lose around 10% of their body weight over a single night so that individuals failing to pile on the grams on even one day can starve and won’t be around to pass on their genes the next summer.
‘Because small birds can’t reproduce without surviving the winter they have evolved a complex set of behaviours that enables them to maximise their chance of both surviving predators and avoiding starvation,’ said Damien Farine ‘It’s a good example of how animals alter their behaviour to respond to constantly changing environmental conditions. It also shows how new technologies, like tiny PIT tags, are enabling us to explore questions about animal survival strategies at an unprecedented scale.’
Anglo-Scottish rivalry takes a completely new turn. In a surprising story of contrasting wildlife fortunes, southern England is rapidly losing some of its most attractive summer birds, from swallows to willow warblers, while at the same time, Scotland is gaining them.
It’s not that birds are quitting the South of Britain to go and nest in the North. Rather, the southern populations of several species of summer visitors are rapidly declining, while their northern populations are expanding substantially. The striking and so far unexplained divergence has been revealed by the magnificent new atlas of British and Irish (and Channel Islands) birds, all 700 pages of it, which has been six years in the making and is published next week. See a taster of the new atlas here
It displays a growing North-South contrast in abundance, over the past two decades, in at least eight species – swallow, house martin and sand martin, willow warbler, garden warbler and grasshopper warbler, plus tree pipit and cuckoo. (Other species are showing signs of this, but it is in these eight that the shift is clear).
Scotland, long seen in bird terms as the grandiose home of the golden eagle, is now a much better place than the Home Counties to hear two of spring’s most delicate sounds – the musical double note of the cuckoo and the silvery cascade of the willow warbler – and to witness the exhilarating springtime sight of swallow acrobatics.
The population of the willow warbler, for example, has declined by 28 per cent in England since the early 1990s but in Scotland it increased by 33 per cent over the same period. Willow warbler was lost too as a Jersey breeding species. Over the same period, the cuckoo declined in England by no less than 63 per cent and it is missing now across much of the South (it too no longer breeds in Jersey). But over Scotland as a whole, while there was a total decline of 5 per cent, in some areas such as the Highlands and Islands there was a notable growth in numbers.
Swallows too are increasingly thin on the ground in the South-East of England but increasing north of the border, and the same can be seen for house martin and sand martin.
These shifts are vividly displayed, with green for losses and red for gains, in the maps of Bird Atlas 2007-2011 (see willow warbler here) – the most complete overview of bird distribution and change in Britain, Ireland, Channel Islands and Isle of Man ever put together. Produced by the British Trust for Ornithology with BirdWatch Ireland and the Scottish Ornithologists’ Club, the atlas examines the breeding and wintering fortunes of nearly 300 species over the 2007 to 2011 period, as noted down by 40,000 volunteer observers who between them contributed 19 million records. More than 99 per cent of the land surface of the British Isles has been covered.
The resultant snapshot of the present is engrossing, but the real value is in the contrasts the atlas affords with the two previous bird atlases of the British Isles, done for the periods 1968-1972 and 1988-91. What results, says the BTO’s director, Andy Clements, is “a 40-year story of change”.
There are changes in all directions. An arresting one is the spread eastwards of a pair of species once persecuted by gamekeepers – the buzzard and the raven. Two decades ago they were largely confined to the west of a line drawn from the Pennines to Southampton; now (perhaps because persecution has ended) both birds have spread all over England. During this period the buzzard has also colonised Jersey.
There are many such: the hobby, the dashing summer falcon, is moving steadily northwards in distribution, while the nightingale is shrinking back remorselessly towards South-East England and its stronghold in Essex, Kent and Sussex. In terms of sheer increase, the prize is taken by the little egret, which at the time of the last atlas did not breed in Britain; now there are about 700 breeding pairs (with around four small colonies in Jersey). But it is the English-Scottish shift of the willow warbler et al. which is most remarkable. All eight birds concerned winter in sub-Saharan Africa, and it is very probable that this offers a clue to what is happening, although it has not been teased out yet. Climate change, affecting the hatching of their caterpillar food, may also be playing a role.
Yet whatever the cause, there it is in the maps. “We have removed observer bias and we are sure this is a real phenomenon, and a notable one,” said co-author Dr Simon Gillings. Have a look for yourself from next week. It is the most riveting bird book produced in Britain for years.
4thInternational Workshop on the Conservation of the Red-billed Chough, Portugal
Glyn Young and I attended the 4th International Workshop on the Conservation of the Red-billed Chough in the second week of October (see earlier announcement here). It was held at the Universidade de Trás-os-Montes e Alto Douro, in Villa Real. The conference was well attended with representatives from Wales, Cornwall, Isle of Man, Spain, Portugal, and of course Jersey. Glyn gave a presentation on the Birds On The Edge project and why the chough is being used as the flagship species. Whist I talked about the reintroduction plans and results to date.
All the talks were fairly balanced between field updates since the last, 2010, conference and post graduate research based around genetics and sex determination. There were no major revelations as most of the work has already been published and every population is suffering the same problems….habitat loss and low genetic diversity.
Welsh chough populations face an extra challenge when it comes to habitat loss. They have to deal with continuing erosion of limestone cliffs. Workers here have used artificial nest-boxes for choughs because of this, but have lost one through continued erosion.
Unfortunately with low population numbers, choughs in the UK have very little genetic diversity and most likely already do or will in future suffer from inbreeding. Across Spain their numbers are in the hundreds and thousands yet they are still on the decline. Choughs from Ireland across to Spain share the same genetic makeup and are, therefore, considered the same race (research presented at conference). This opens up the possibilities for sourcing donor stock for our reintroduction and any possible translocation projects in the UK.
However, the different ‘nationalities’ (of choughs) display cultural differences in nest-site selection, roosting, food choice and dispersal. This needs to be taken into consideration when discussing donor stock.
Choughs on mainland Spain are swapping their natural nest and roost sites in the canyons and cliff tops for manmade structures. The research team were very keen to show a photo of choughs roosting on quarry building roof after they had seen the Jersey presentation. Quarries it seems are not an unusual choice for a chough to make. Palm trees, car parks, and a wardrobe in a disused apartment are definitely not what you would expect if you had only seen Cornish choughs.
Field trip: Douro Valley and the International Douro Natural Park
Portugal has only five locations for choughs, mostly in the north. Their main threat is change in land use and, most recently, the introduction of wind turbines (although their true impact is under question).
Intensive agriculture has removed forest and created a landscape prone to natural fires further destroying habitat.
The workshop delegates were taken around the Douro Valley region, home to vineyards, olive groves, and sweet chestnut (see more here). All of which were traditionally farmed by families but now mass produced by corporates. Of course, as a result, the loss of forest increases the risk of wildfire. As we were driving along we could see at least one hillside ablaze.
I would like to tell you great things about the choughs we saw on the field trip on the last day to visit the birds’ feeding and breeding sites. However, since we spent eight hours on a coach, ended up at the Spanish border (intentionally), and didn’t see a single chough I can’t! If I could use Photoshop I would just to pretend we saw them.
What we saw instead were loads (scientific term) of vultures, falcons, and the odd golden eagle…and Glyn’s ‘lifer’, the azure-winged magpie. In a last ditch attempt our patient hosts took us to a known roost site. Unfortunately the choughs chose a different spot that night!
At least its gives us an excuse to go back! We can’t thank our hosts enough and are proud to join this international chough ‘family’. There are more photos from the workshop and field trip here
Inter-island Environmental Meeting 2013
From Portugal to Guernsey. This year’s inter-island environmental meeting was held in Guernsey at the Société Guernesiase. The theme for this year’s meeting was engaging the community to promote biodiversity and cooperation for action. Glyn Young presented on behalf of BOTE explaining how local volunteers have been involved in habitat management and the chough reintroduction. The talk also highlighted the involvement of Jersey schools and how the children have been engaged.
Green and Mauve’s ventures into the quarry came to a temporary close this month after a mysterious turn of events. Ronez Quarry personnel phoned the team to report sightings of the pair in their machinery rooms at the bottom of the quarry. In itself, this was not unusual but, as it was during the day and the workers were testing out equipment, there were concerns for the birds’ safety. From the reports it seemed that the birds were actually quite calm, perched in the roof space watching the workers below. The real concern was raised when Mauve returned to the aviary minus her partner and minus her radio transmitter.
It is not possible to say how she lost the transmitter. In flight it was clear to see she was missing the two central tail feathers that would have been attached to the transmitter and closer examination showed they had come straight out at the base rather than having snapped off. Maybe she got them caught or something tried to grab her by the tail. Other than the absent tail feathers she was in good health and her body weight was fine.
Meanwhile, Green’s signal had not moved from the building. A site visit was arranged in the afternoon thanks to Ronez to see conditions inside the building and to try to locate Green. His signal was loud and clear but he was not visible. With a bit of detective work he was finally located outside the building on the lower bank. Mauve’s signal (from her missing transmitter) could not be picked up in the area or along the coast. A quarry worker reported seeing one of the choughs with missing tail feathers whilst in the building earlier so we assume she lost them in the quarry, and the transmitter has been broken or the signal is being blocked.
When Green finally made an appearance he was looking a little subdued. Maybe confused as to where Mauve had gone and stressed at being by himself. Fortunately for him, Black was close by and excitedly calling for food when we appeared. This caught the attention of Green who flew closer to Black. After lots of frantic displaying/flirting by Black, Green joined her and then joined her in the supplementary feed.
The next day saw both Green and Black appearing for food each time the we called them. Until that is they flew back to the aviary on their own accord at the end of the day. We tried to get them back inside the aviary, but the onset of thunder and lightning spooked the pair off the aviary roof and back to the safety of the quarry.
In the morning, Green and Black were back at their normal spot in the quarry. An all-day motocross event at Ronez Point, however, meant an alternative supplementary feeding site had to be found. Luckily with the team having access to the upper level of the quarry they could go in and approach from a different angle. Green was spooked by the use of the catapult, having never seen it before, and flew off across the quarry. Black followed but for some reason turned back halfway and returned to feed. Green continued to fly over the 4 X 4 race day going on at Sorel below him and on to the aviary.
Green’s return was certainly welcomed by Mauve and the others, but the whole atmosphere seemed a little subdued. From observing him over the afternoon it was clear that he was not himself. His feathers on his front and the skin on his feet were grey and ‘muddy’. Presumably this was a result from being in the quarry buildings where rock dust settles in thick layers.
Not having the ability to ask your ‘patient’ what the problem is makes it difficult to know how to treat. The additional problem is that any manhandling and catching of these choughs will stress them which may lead to negative associations. Much like dogs when they hear the v.e.t. word, we don’t want the choughs fearing the a.v.i.a.r.y.
After a day in the aviary, Green’s feathers were clean but the feet were still grey. At training he was eating with the group when called although he wasn’t as quick to get to the food as the rest. This was put down to stress but with a mind that if things didn’t improve there might be an underlying health issue. Observations on the second day showed that he was not strong when flying and often couldn’t make it from one end of the tunnel to the other without losing height and landing on the netting or the ground.
The decision was made to catch him up and upon weighing it was found that he was a good 30-40g underweight. This explained part of the weakness when flying.
Looking at his feet it was clear that the grey was not washable, it was necrotic skin most likely a result of a chemical burn. He had also suffered a chest wound at some point as there was a large scab forming.
Green was immediately put on a treatment of antibiotics to fight any infection. Medication is injected into insects which the chough will then eat. In order to ensure he would get exactly the right dose he had to be housed separate to the others for the duration of the course. He was locked into one of the sheds and given access to part of the poly-tunnel during the day.
Faecal samples were submitted to Durrell’s lab including a group sample from the females. Although with no recent clinical signs, both samples tested positive for gapeworm. This parasite is not unusual in captive birds and can also be found in the natural environment. However, the situation the Sorel choughs are in will mean their stress levels are raised and are, consequently, more susceptible to the effects of gapeworm. All the choughs immediately started a two week course of ivermectin. Unfortunately this meant catching them up to inject them and repeating it two weeks later. In turn this meant no releases could happen until the medication was finished.
Whilst this was going on Black made a surprising yet welcomed return to the aviary. She came back the day after Green had returned. In an attempt to coax her out of the quarry we had shifted the feeding site further west around the edge of the quarry. By the afternoon she had decided to return to the aviary taking a direct route along the cliff-path. Once again her body weight had changed little from when she first left.
Since re-joining the other four choughs the group dynamics have subtly changed. Without anthropomorphising too much this is no doubt related to Green’s time spent with Black as well as the loss of Orange and White. Immediately upon returning to the aviary Black stayed back from the group eating and preening and doing her own thing. Every now and then Mauve would leave Green’s side, fly at Black chasing her from her perch, then return right back to Green and preen him (a sign of pairing). With Green, now the only male, locked away, the competition for his attention has become a bit of a free-for-all.
A veterinary check-up after Green’s medication ended showed that whilst his feet were healing there was still some way to go. The most damage is around the ends of the digits leading to a small risk of losing one or two claws. A new discovery of a puncture wound on the right hock meant that the vet wanted to extend the antibiotic treatment. From assessing the scab and injury site this wound must too have occurred whilst out and about in the quarry. The next physical check-up for Green will be after the treatment has finished on 1st November. Until then he will be monitored continuously to watch how much he is eating and if he is in any discomfort.
Choughs at Durrell
This month has seen changes afoot within the breeding pairs. Arthur has taken a fancy to the juvenile female who is now coming of age. This was somewhat predictable since Arthur and Guinevere didn’t progress past nest-building this season and failed to produce a clutch last year. ‘Gwinny’ is now perching and feeding with Tristan the male who we originally paired her with in 2010. The switch to Arthur came about when the two females fought over Tristan in 2012 and Gwinny lost out to Iseult. Keepers will be observing Iseult closely now as the breeding season approaches. Along with Tristan and Arthur there is a single juvenile male in the display aviary with a claim to stake.
George, the hand-reared chough flown over in March to assist with the reintroduction, bid his farewells this month and returned to Paradise Park. With the breeding season approaching he needed to move out of the breeding aviary he was being held in. With no alternative and no possibility of using him at Sorel, Paradise Park were asked if they could take him back. George is quite the character and will be missed by all and no doubt there will be a few holidays booked to Cornwall in the near future!
The Bird Department recently purchased new weighing scales, the same model as used at Sorel. The scales’ design makes it easier for certain species to walk or land on them. Bird staff have started training some of the captive choughs as in this way we can monitor weights and infer general body condition, without having to catch the individual and cause unnecessary stress. George was eager to show off his skills when it came to jumping on the scales. It will require a little more work with novices like Arthur and Gwinny.
Nutritional research on captive diets
Earlier this year, Iona Mucherek-Parramore spent time on the Bird Department collecting data for her MSc in Endangered Species and Conservation. Durrell has developed a close relationship over the years with Nottingham Trent University who send students here for various degree programmes. Iona’s study was looking at the nutrient profile of the chough diets at Durrell and relating it to reproductive parameters.
Choughs in captivity are provided with a breeding diet from January to August and then a general maintenance diet for the rest of the year. Birds require more protein in their diet during egg-production and chick-rearing. We cannot provide the diversity and quantity of insects choughs would need, so finely chopped ox heart is added in January to replicate this.
Iona spent eight days at Durrell collecting food samples and analysing reproductive data. On returning to Nottingham Trent she then had several weeks of lab analysis and the daunting task of dissertation writing. Her final thesis was submitted in October, a copy of which will be kept at Durrell.
The analysis brought to light a few interesting points that need addressing before the next breeding season as they may be influencing egg productivity and survival rates. For example there appears to be no difference in calcium provision between the two diets. Extra calcium is added for the breeding season using grated cuttlefish bone. However, other ingredients are reduced which also contain calcium thereby negating the impact of the cuttlefish bone. Also, the fat content year-round is much higher than one would expect for birds. It should be noted though that there is no published data available for choughs to allow a definitive comparison.