Local birds increasingly likely to stay at home this winter

Robin (3). Photo by Mick Dryden

Two technical reports just published confirm what local birdwatchers have long known: some of our migratory birds are staying much closer to home in winter these days.

Climate warming and other environmental changes seem to be causing a shift in the wintering grounds of European birds northwards. This was tested in two studies, one looking at numbers of some common northern-European songbirds including robins, chaffinches and wagtails that winter in Spain and one looking more specifically at robins. These birds are partial migrants, species where parts of the overall population are migratory while others remain in place, not like swallows or redstarts whose whole population migrates south. The studies looked at annual numbers reaching Spain using data from recoveries of ringed birds.

White wagtail. Photo by Regis PerdriatResults showed that the numbers of the study species from outside of Spain reaching there in winter has decreased since the 1980s and probably well before. This tendency had to be checked against the species’ overall population numbers in northern Europe to make sure the birds weren’t just getting rarer anyway, and, as they weren’t, this confirmed that these birds are moving less. An understanding of the species’ preferred diet did show some likely patterns since frugivorous (fruit-eating) birds, a group well adapted to tracking changes in food availability, showed sharper reductions in numbers reaching Spain in winter than the more insectivorous species. In addition, larger birds, such as thrushes, less affected by problems of winter temperatures, reduced their migratory movements to the south more than small birds. The results suggest a long-term rearrangement of migratory movements of European birds in which the Mediterranean basin is losing its traditional role as primary wintering ground for many of our birds.

Blackcap. Photo by Mick Dryden

The reduction in numbers of wintering migrant birds in Spain appears to have been taking place since at least the 1970s. However, this reduction may have been in progress earlier, since several partially migratory songbirds began to winter in northern Europe in the mid-twentieth century and earlier. The ability of wintering blackcaps, thrushes and, to a lesser extent, robins to move according to fruit resources is most often observed in their wintering grounds, where their abundances are regulated by the annual availability of fruits. The reported changes in the migratory behaviour of the blackcap, one frugivorous species for which foreign recoveries in Spain has declined despite the sharp increase in the European population, support this interpretation. This change of migratory schedules in blackcaps has been related to this species’ ability to adapt its migratory journeys to increasing food availability offered by urban areas in central Europe and warmer coastal areas like the Channel Islands. Why fly all the way to Spain if you can stay at home or move to someone’s garden?

Partial migratory birds possess the genetic variation required to change from partially migratory to resident in just a few generations, suggesting that, according to current predictions of global warming, such trends will continue to increase the number of sedentary populations in Europe and to reduce the number of overwintering birds in the Barn swallow in Jersey. 16 December 2014 (2). Photo by Mick DrydenMediterranean. In the Channel Islands we have seen big changes in our wintering birds over the last 25 or so years. Fieldfares hardly bother to come here now unless the weather turns really cold whereas the UK is full of them. In their place (but not necessarily in the same habitat) we see lots of chiffchaffs and blackcaps. Interestingly, as reported elsewhere in Europe, our wintering blackcaps are very much a bird of the garden where they hog the feeders rather than out in the wider countryside where they’ll later breed.

What of the true migrants? Well, although this winter we have had several swallows and a wheatear sticking around, these species are unlikely to change their habits very soon.

Read the paper abstracts:

Are European birds leaving traditional wintering grounds in the Mediterranean?

Has the Number of European Robins Erithacus rubecula Wintering in Spain Decreased?

Robin (4). Photo by Mick Dryden



Chough report: December 2014

Bean 2By Harriet Clark

December was another quiet month for the choughs, and it seems, for now at least, their exploratory days are over. The birds rarely ventured further than half a kilometre from the aviary, apparently content probing for insects in the grazed fields near the aviary. The ten juveniles were at least a little more adventurous than the older six birds however, and for the first few weeks in December, could faithfully be found every morning, perched on the muddy cliffs at the mouth of Mourier Valley, digging furiously, doing what looked like some impressive excavation work!

Chickay, Bean and co digging on their “favourite” cliff. Photo by Harriet Clark

Chickay, Bean and co digging on their “favourite” cliff. Photo by Harriet Clark

Quite what the birds were finding there is unclear, but our pitfall trapping showed that there were still plenty of insects about, including rove beetles, ground beetles, minotaur beetles, earthworms and leatherjackets. Leatherjackets (crane fly larvae) are known to be a favourite food item for choughs, and this is certainly evident with our birds as they excitedly, and rather comically, chase each other when one chances upon the prized invertebrate prey.

Unsurprisingly December brought more downpours, fog, gale force winds and hail, but I am thrilled to say that the choughs have battled through, all in good health. We only had one morning of heavy frost, and interestingly, early that day the birds were nowhere to be seen in the usual grazed fields.

Handfuls of leatherjackets to be found! Photo by Harriet Clark

Handfuls of leatherjackets to be found! Photo by Harriet Clark

We eventually tracked the flock to Mourier Valley, and found them foraging amongst the dead stands of bracken. We hadn’t observed the birds foraging there before, but closer inspection revealed the soil was very soft, and presumably easier to probe for insects in than the harder ground of the grazed fields. Will, Jennifer and I also adapted to the windier, wetter weather and located several “good” gorse bushes to huddle beneath or, in Jennifer’s case, lie flat on her back underneath, just to have a bit of a break from the pounding, relentless wind!

The flock flying over a frosty Mourier Valley. Photo by Will Campbell

The choughs weighing themselves in the aviary. Photo by Harriet Clark

The choughs weighing themselves in the aviary. Photo by Harriet Clark

December marked seven months of living free for the older birds, and three months for the juveniles. Faecal samples were submitted to the laboratory at Durrell as part of our continuous post-release health screening. The results were very encouraging and showed that the birds’ parasite load has decreased since their last screening in October. We also monitor their health by weighing them, and we now have a second set of scales so that when the weather allows we can weigh as many individuals as possible. Despite halving the quantity of dry mix and insects that we feed the choughs in October, regular weighing shows that the birds definitely aren’t suffering from lack of food, with several even putting on weight. This and their low levels of parasites, indicates the birds are clearly maintaining good body condition and are acclimatising well to their environment.


Sorel is ideal habitat for minotaur beetles, which prefer short grazed turf and plenty of sheep dung for the larvae to feed on. Photo by Harriet Clark

The older choughs developed a new habit this month; during feeds they would collect several mealworms or a “beakful” of dry mix and fly out of the aviary, disappearing out of sight to a nearby field. At first we wondered whether they were simply taking their food away from the group to eat it in peace, but careful observation revealed that although sometimes they were eating it, other times they were digging a hole and hiding the food in there. Choughs caching mealworms has previously been observed by Eric Bignal in his study of supplementary feeding wild choughs in Islay (report published in British Wildlife), and the birds there were seen marking their caches with different objects such as feathers, to aid finding them later. Although we feed our choughs twice a day, they don’t receive a huge amount and it is quickly consumed, so perhaps the adults are caching food so that they have access to it later in the day.

Evidence of choughs at work. Photo by Will Campbell.

Evidence of choughs at work. Photo by Will Campbell.

At the beginning of the month we started to notice several muddy patches scattered randomly across the sheep grazed fields. We quickly discovered the culprits- the choughs of course. They seem to have developed a penchant for tearing up the grass, and we’ve observed the group many times this month energetically flinging clumps of grass into the air, no doubt searching for soil invertebrates to feed on.

Icho and three of the adults tearing up the grass in search of insects. Photo by Harriet Clark

Icho and three of the adults tearing up the grass in search of insects. Photo by Harriet Clark

The adult female Mauve, finally gave up pursuing her previous partner Green this month, focussing her attention instead on the two-year-old male White. We monitor the location and activity of the birds hourly throughout the day, and White and Mauve are almost always found foraging close together, often separate from the rest of the group. During supplementary feeds the pair also feed from the same dish, and regular roost checks throughout the month revealed that rather than returning to the aviary with the rest of the group at sunset, they roost together in the quarry. Fingers crossed we may now have two potential breeding pairs to keep an eye on in 2015!


Regular visitors to Sorel will undoubtedly have noticed significantly fewer sheep out and about on the north coast towards the end of the month. Unfortunately several young sheep were taken ill and because it was not clear at first what the problem was, the flock was moved into the fenced-off aviary field for close monitoring and care by their shepherd Aaron Le Couteur (CS Conservation). Test results revealed the sheep had a gastro-intestinal problem, and, being a primitive breed, they have physiological differences so often respond differently to parasites compared to commercial sheep breeds. The flock has now been treated with a novel drug and are fortunately well on the road to recovery.

Choughs foraging alongside the sheep in the aviary field; wherever the sheep go, the choughs go too! Photo by Harriet Clark

We sadly said goodbye to Will at the end of December, after four months on the project. He started volunteering one week after the juveniles were released and has been following their progress ever since, spending many hours radio tracking the birds across the island and observing their antics on the cliff tops at Sorel. Will has been a huge help both in the field and in developing our invertebrate monitoring project. We wish him every success as he moves to England to pursue a career in wildlife conservation. You can read his brilliant piece about his time on the project here

Will recording the location of a foraging site commonly used by the juveniles. Photo by Harriet Clark

My time with the choughs – it’s not all sunshine on Jersey’s north coast


By Will Campbell

In October Adam wrote about his time with the choughs on the sunny north coast of Jersey. However, it’s not all sunshine and calm days on our coastline and here Will recounts his time following the choughs into a Jersey winter.

My toes are numb as I squeeze my way past gorse bushes and through muddy fields, arm and radio antenna outstretched, feverishly waiting for the reassuring ‘pip’ from the SIKA that indicates a nearby chough. Because, once you have found one chough (the ‘Judas chough’ as fellow volunteer Jenny calls them), you can be pretty sure that the others are nearby.

Radio receiver in fog. Photo by Liz CorryI trudge, stooping into the wind, to a high point and wave the antenna in every direction for what seems like the hundredth time. At last a faint ‘pip’ comes through the SIKA slung over my shoulder. I look anxiously ahead into the wind and rain but instead of the familiar acrobatics of a chough I see nothing but a thick sea mist. Dejectedly I trudge on, in the vague direction of the ‘pip’ in order to pinpoint their location.

It’s at times like these when some people might ask, ‘Why?’ And I tell them that although data collection isn’t easy, no matter how minute and irrelevant it may seem, it is absolutely necessary to build the bigger picture. A big part of my time with the choughs was spent radio tracking them – essentially finding out where they were and how far they were from their mates. Doing this up to eight times every day allows you to amass a huge amount of data, which can in turn help answer loads of questions in matters such as social sub-groups, home range, and even potential breeding pairs and nest sites come the spring.

IMG_5200Although I’ve painted a pretty grim picture at the start of this piece, I did in fact experience all four seasons in my four months up on the north coast, sometimes, it seemed, in the space of one day. At 8am I might be huddled with the sheep in what little shelter there was from the wind and rain, and by 11am I could be sunbathing in a field, cursing myself for forgetting my sun cream.

The most extreme weather I faced up at Sorel was during gale force 8/9 winds where simply walking from A to B was a challenge. Even the choughs were wisely sheltering in the aviary from the onslaught. Harriet and I noticed an upturned kayak in the sea and, fearing the worst, she called the Coastguard. It didn’t take long for a search plane to arrive and start scouring the sea. Luckily, it turned out the kayak had never been occupied and the plane turned back to what must have been a very bumpy landing.


It was during the warmer half of my placement that the choughs decided to clock some air miles and check out what the rest of the Island had to offer. This left us frantically driving around the west of Island, but ‘as the chough flies’ is a much quicker way of getting around than ‘as the Skoda drives’. It was only due to the very welcome tip-offs from local bird-watchers that we were able to find the choughs down at Beauport probing amongst the cliffs; apparently oblivious to the panic and excitement they caused us. It was incredibly rewarding to see the previously captive birds exploring the island and always making it back to the aviary with impeccable timing to demand their lunch.


The choughs seem to have an uncanny ‘spider sense’ when it comes to feeding time. The idea is that, once you have put out the dishes, you give a tinnitus-inducing blow of a whistle and the choughs appear in unison to merrily scoff all the food. The birds have been trained to the whistle to try and give us an element of control, for example if they need to be shut in the aviary. In practice, however, the choughs are canny little birds and seem to react to the subtlest of cues such as the gentle clinking of dishes, the opening of a door or even a Durrell jumper walking towards the aviary. The result is always the same. By the time you have put the dishes out and raised the whistle to your lips all 16 birds will be lined up along the exterior aviary shelf, begging with their wings open and squawking to express their irritation at having to wait for their dinner. During the afternoon feed, when insects are scattered and hidden in pine cones and under logs, you have the delight of witnessing an ‘Easter Egg Hunt’ as the birds frantically waddle around the aviary trying to be the first to find the delectable wax moth larvae.


Another ongoing study that I was involved with was a pitfall-trapping survey in order to gather information about the choughs’ available food sources. Unfortunately I didn’t have the chance to look into the other end (literally) and sift through chough poo to see what they were actually eating. As I have a weird fascination with invertebrates and had gained some experience in stream-dwelling bugs during my degree, I was appointed the authority on all things creepy and crawly and was instructed to create a pictorial guide to the invertebrates previously found at Sorel. This soon turned into an 80+-page monstrosity that I sincerely hope will be of use to the other volunteers and staff (other than to prop up their computer screens).

It was a challenge at first to identify the unique coloured rings around the legs of each bird, let alone remember which bird the rings belonged to. But after a while you can even guess which birds hang out together and, at the risk of anthropomorphizing our feathered friends, understand their individual characters. The love triangle between Dingle, Chickay and Caûvette (and Caûvette’s incessant whining) wouldn’t be out of place in an episode of EastEnders.

Although you shouldn’t choose amongst your children, Chickay is definitely my favourite. When you watch the choughs for as many hours as I have you see them do some pretty bizarre things. It always seemed to be Chickay that would hang upside-down from the aviary netting like a bat, groom a sheep or chase butterflies with her peculiar waddle.

Chickay. Photo by Liz Corry

Reluctantly, my time with the choughs has come to an end. It has been a great experience working on the reintroduction project, and to be part of such an important and exciting project in its infancy. All that is left to say is a big thank you to Liz, Harriet, Glyn, Jenny and everyone at Durrell for making my placement unforgettable. And, of course, thank you to the 16 choughs (you know who you are) that kept me company up on the cliffs. Oh, and thanks of course to the sheep for sharing their best spots to shelter from the rain. I sincerely hope that all the hard work, dedication and frostbite bears fruit once it comes to the breeding season!

Keep up the great work!

Red-billed chough and common buzzard. Sorel, Jersey. October 2014. Photo by Nick Parlett  (4)

Effects of the 2014 storms becoming apparent in Wales

Puffin 2 low res. Photo by Paul MarshallFrom BirdGuides

As we begin to see the first serious winter storms of the year around the British coastline, research in Wales is revealing the full consequences of last winter’s exceptional storm activity amongst our seabird populations. Dr Matt Wood, from the University of Gloucestershire, is helping to uncover the consequences for the thousands of puffins on Skomer Island, in Wales.

Around 50,000 dead seabirds, including puffins, guillemots and razorbills, were washed ashore in a severely emaciated state — they’d essentially starved as storm after storm prevented them from catching enough fish to eat. With unknown numbers dying out at sea, this was the biggest seabird wreck recorded in Europe. By the end of 2014’s breeding season, the numbers of adult puffins returning breed was down by 25% on the previous year: a quarter of the birds on Skomer and Skokholm islands in Pembrokeshire may have died before the season started, totalling around 5,000 individuals. Three guillemots ringed in Skomer were picked up dead on Jersey beaches.

Razorbill (2). Photo by Mick Dryden

Dr Wood commented: “Puffins typically live in large island colonies, seabird cities if you like. Now take a city like Cardiff and imagine what would happen if a quarter of people didn’t come back after the Christmas holidays; by mid-January things would be going seriously wrong, and it looks like that’s what happened to the puffins”.

Field assistant Ros Green found that Skomer puffins bred unusually late, their chicks hatching two weeks later than usual and being fed at only a third of the rate in 2013. As a result, breeding success dropped markedly by 25%, with only just over half of pairs raising a chick. It proved the worst year on record for puffins on Skomer, in the 43 years of the study (since 1972).

Dr Wood added: “The long-term seabird studies on Skomer are an amazing resource. One of the puffins that was still around until recently was first seen in 1973, the year I was born.

“With studies like this, with birds we know and study as individuals, we can understand how populations work in the detail we need to face the challenges of the future. Will more storms impact seabird populations? I’d say ‘probably, yes’, but it’ll take us years to get a true picture of what happened in 2014, and only long-term monitoring at key sites like Skomer can provide reliable answers to questions like that.”

Long-lived seabirds like puffins can take a gap year if times are tough, but Dr Wood believes that the numbers of birds washed up dead on beaches last winter are little cause for optimism. He concluded: “Seabird wrecks are not unprecedented, these are tough little birds that can usually cope with a storm, but forecasts of global climate change predict that these extreme storms will become bigger and more frequent. The effects of the recent seabird wreck will only become clear over the next five to ten years: long-term studies are vital to understand how the populations will cope in the future.”

The Skomer and Skokholm seabird reports are published online here

Puffin. Photo by Regis Perdriat

Trends in numbers and breeding success of UK breeding birds now online

Mistle thrush. Photo by Mick DrydenFrom British Birds and the BTO

The BTO’s latest BirdTrends report published online, summarises the population trends for 120 breeding bird species across the UK using data collected by volunteers including those in the Channel Islands. For the first time, this year’s report provides habitat-specific trends for many species, highlighting those habitats where species are in trouble. As is becoming all too familiar, while intensive conservation efforts and targeted habitat management have benefited some rarer UK bird species, many widespread and formerly common birds are experiencing severe declines. Some 28 species, almost a quarter of those included in the BirdTrends report, have exhibited falls in numbers greater than 50% over the last 35–45 years.House sparrow (3). Photo by Mick Dryden


House sparrow population in England 1976-2013. From BTO http://blx1.bto.org/birdtrends/species.jsp?s=housp&year=2014

‘National declines in farmland birds are well-documented and these latest figures show that this decrease is continuing,’ explains the report’s lead author, Senior Research Fellow Stephen Baillie. ‘The results of BTO surveys show that many familiar garden birds are also experiencing problems. House sparrow numbers have dropped by almost 70% since the 1960s and the data suggest that sparrows occupying urban and suburban habitats are faring worst.’

‘The range of garden birds experiencing population declines appears to be increasing,’ explains report co-author John Marchant. ‘While many will be familiar with the disappearance of house sparrow, starling and spotted flycatcher, it may surprise people to know that house martin, mistle thrush and greenfinch are heading in the same direction. Again, there is evidence that house martin and mistle thrush declines are most pronounced around human habitation; the BTO will be launching a volunteer house martin survey in spring 2015 to find out more about the current distribution of breeding populations in order to identify and inform conservation measures.’


Turtle dove population in UK 1966-2013. From BTO http://blx1.bto.org/birdtrends/species.jsp?year=2014&s=turdo

So what can be done to reverse these declines? ‘We urgently need more data to answer that question, and volunteer surveyors can provide it,” explains Dave Leech, a Senior Research Ecologist at BTO. ‘Information generated by ringing birds and monitoring their nests proved that the majority of farmland bird declines were driven by a reduction in food availability during the winter. Drivers of garden bird declines are more variable; reduced winter food availability and disease appear to have caused a fall in starling and greenfinch numbers respectively, whilst house sparrows seem to be struggling to rear enough chicks. Data gathered by BTO ringers and nest recorders will help us to identify the mechanisms underlying declines of other species.’

There is, however, far more to the BirdTrends report besides the species pages! Supporting pages describe the field and analytical methods that were used to produce the results for each species and to identify alerts. Overall patterns of trends in abundance and breeding success are discussed, and compared with the latest trend information and alerts with the Birds of Conservation Concern list. Summary tables list alerts and population changes by scheme, and there is also a facility to select and display your own tables of population change. A detailed References section lists more than 700 of the most relevant recent publications, with onward links to abstracts or to full text where freely available, and is a valuable key to recent scientific work by BTO and other researchers. The Key findings page provides a brief overview of our main findings this year.

Text, tables, graphs and presentation for each species are updated annually to include the latest results and interpretative material from the literature. Information on demographic trends and on the causes of change is gradually being expanded. There are new pages this year for gadwall, little egret and common tern.Gadwall. Photo by Mick Dryden