A further bird monitoring transect has been added to our Farmland and Coastland Bird Monitoring Project. This transect, a second in the Sorel Point to Mourier Valley area, is the 16th that we are counting birds along. As with the other transects (15 at 14 sites), this 1,070m path will be visited once every two weeks from January 2013 and all birds present recorded. The new transect runs along the National Trust for Jersey land on the south of Le Don Paton. This land will be farmed in a rotation that will be beneficial to wildlife with some of the fields providing food for birds each year. In December 2012 there are over 200 linnets feeding in these fields with good numbers of chaffinches and meadow pipits present. Up to three marsh harriers are regularly present and migrant birds such as swallows and winter thrushes will no doubt be recorded at the right time of year. The new transect compliments the existing Sorel to Mourier Valley transect that runs along the cliff path.
The project’s monitoring guidelines are available for download here
With obvious concerns about how Jersey’s choughs may contend with the potential threats in their environment, it is reassuring to hear these thoughts on the birds that naturally recolonised Cornwall.
Cornish Choughs note that choughs are really feisty, they certainly punch above their weight using their feet and talons as weapons, often tackling birds much bigger than themselves. Sometimes they make contact in mid-air, it is nail-biting watching a male chough attempt to grapple with a peregrine and the famous Lizard male sustained a serious injury to a leg a few years ago after fighting off a herring gull. Choughs often walk along with a pronounced limp and can have slightly deformed legs where they have broken and healed wonkily! These images by Colin Seager show immature choughs practice fighting – all good preparation for defending a territory in later life.
Claire Mucklow from the RSPB’s Cornish Chough project personally adds that from her experience choughs think they are invincible – and mostly they are!
Tori Orchard at BBC Radio Jersey is now recording weekly updates on the BIRDS ON THE EDGE project. Tori will keep listeners informed on progress of the key elements on the project and even the choughs themselves. Listen live each week to Tori’s interviews with all the key players in the project and, if they are in the mood, the choughs. The exact day that Tori’s interviews will go out can change through other news events but will be during the Carrie and Sara show on each weekday 1200-1500.
If you miss Tori’s updates on the radio, listen to them all in our audio libraryhere.
Update from Regis Perdriat LPO Station at Île Grande in Brittany
There has been much interest in Jersey with the three choughs that appear to be setting up home in the Sept Îles Reserve. As potential colonists at the reserve, their choice of feeding habitat is interesting and is being monitored closely. The three birds move between two of the islands, Bono and Île aux Moines and feed mainly in the areas of maritime grassland or “silene maritima” lawn. There are still good areas of this habitat in patches along the Jersey coastline so it will be interesting to see if birds prefer this habitat in Jersey or whether they prefer something more agricultural. There are particularly obvious similarities between the photographs taken at the Sept Îles and Les Landes and Petit Plémont.
On the 7th Gianna was taken from quarantine to the vets to be x-rayed under anaesthetic and then moved to the shut-off cage in the Display Aviary to join the two breeding pairs. She weighed 294g on leaving quarantine which is an average weight for our adult females.
When she first went into the new aviary, Gianna was greeted by Tristan and Issy who sat on top of the cage and took a great interest in her. However, this interest was short lived and they did not really bother with her after that. Gianna was let out of the cage after a week so she could acclimatise to the new surroundings and the birds got to know each other. For the first fifteen minutes she quietly walked up and down the shelving at the back weighing up her options. The pairs were perched high preening each other and paid no attention. However, as soon as she vocalised, Tristan and Issy flew straight down and Tristan started fighting with Gianna. The contact only lasted a few seconds until Gianna flew up and circled the aviary a couple of times. Whenever she flew near Arthur and Gwinny they would display to her and sometimes chase her but it was only half-hearted. Once the hierarchy was explained, Gianna was left alone. She spends a lot of the time on the ground or on the rocks at the back left corner of the aviary.
With Gianna now in the display aviary and getting attention from the keepers, the other choughs perch lower and come down to the ground when the keepers are present, making the exhibit a lot more interesting for the public.
After a few days of being mixed, Gianna was seen to be holding up her left leg quite a bit. Often birds do this to thermo-regulate but they usually swap between legs. The fact that she was using the same leg became a concern and the problem became more pronounced so on the 27th she was caught up to be seen by the vet. She can grip with her left foot but doesn’t want to put any weight on it. The left leg felt slightly warmer than the right which could suggest an infection. She was put on a five day course of antibiotic but showed no improvement. The course has been extended to see if that makes any difference before opting for more invasive measures. Gianna remains in the Display Aviary but is temporarily separated from the other birds.
It is interesting to note that Gianna has a higher pitch call than the other choughs. This could be a consequence of something she picked up whilst being isolated in captivity when young. Maybe it’s the Italian in her!
Trial of new ID rings for released choughs
When the choughs are finally released into Jersey and free to roam, we need to be able to follow them around and differentiate between individuals. There is always the possibility too that they may fly off the Island and head elsewhere. If they do, then people away from Jersey need to be able to identify that they are ‘Jersey’ choughs. For this reason we have been investigating the best possible ID ringing programme that will not conflict with UK or France ringing schemes.
We plan to attach a standard issue metal ring to one leg of the bird which will have the Jersey Museum address stamped on it. The address will only be visible if the bird is in the hand, e.g. caught in a mist-net, found injured/dead, or the observer is extremely lucky with their binoculars. A colour plastic ring will be also be used to identify individuals. All birds within the Durrell collection are fitted with plastic and metal rings so they are quite used to wearing them.
After discussions with Tony Cross, who is responsible for ringing Cornish and Welsh choughs, we have decided to try a new type of ring with the choughs. Darvic style incoloy (nickel-chromium alloy) rings are hard wearing rings used for coastal birds. They can be made the same diameter as standard chough rings, but are much longer allowing for a number to be engraved along the length. Paul Veron in Guernsey kindly supplied us with some perfect rings originally made for black-headed gulls.
On the 8th we caught up one of the juveniles not being released (B6977) and attached the new ring. She is now identified by “2A01” on her left leg and white on her right. After twenty days she was caught up again to check the fitting and make sure there was no rubbing or injury to the leg. The ring is free to rotate and so far no rubbing can be seen and she doesn’t show any particular interest in the tag which is also a good sign. She has put on 25g in weight since the tag was attached. This could simply be due to eating more as the temperature has dropped.
This month, video cameras were placed in the two aviaries housing the juveniles during feeding time. One aviary houses the birds with dummy radio transmitters and the other aviary has the candidates for release, i.e. with no dummy transmitters. The aim of this was to see if there were any behavioural differences between the two groups. The weather restricted the number of days this could be done since the cameras are outside and not waterproof. However, we were able to get footage of the birds which is still being reviewed. At present there seems to be no significant difference between the groups. All birds forage and fly with no restrictions.
B6975 and B6976 were caught up on the 28th to check on the condition of the dummy radio transmitters and the birds themselves. The birds appear fine with minimal disturbance to the tail feathers. There was no further damage to the glued areas although it does look like one of the threads is looser than when first attached. An order has now been placed for the real transmitters to be built with delivery expected in January.
An interesting note is that the three birds under various trials in one aviary (SF2) are spending less time hiding in the nest-box when keepers are present. The other group (in SF3), chosen for release because they were more confident, still hide every time.
Progress of the release aviary
Planning permission for building a release aviary at Sorel was granted on the 13th. After preliminary meetings with the National Trust for Jersey and Aaron Le Couteur, the shepherd, groundwork began on the aviary.
The field where the aviary is being built will also be used to graze sheep in the spring. For this reason there needs to be a sheep-proof fence erected not just around the field but also the aviary itself. Hopefully, this will also act as a deterrent for the public getting too close to the birds. During the time we have been present at the site there have been dog walkers every day either next to or in the same field and often with their dogs off the leads. Whilst we do not want to discourage dog walkers in the area we do need to ensure that the birds in the aviary do not suffer any stress related to this. There will be publicity including messaging boards around the site to inform people of the project and ask for their support.
Trevor Smith from Durrell’s Maintenance Department is leading the build onsite with assistance from staff and volunteers. The first post went in in the ground on Friday 23rd and so far, despite battling the elements, Trevor has made great progress. Aaron Le Couteur has kindly loaned the team the use of his lockable trailer for equipment and water tank for the duration of the build. The weather will be the deciding factor on when the building can be completed, but we hope to finish by Christmas.
Five young marsh harriers hatched on Sculthorpe Moor Reserve in Norfolk, UK have had wing tags fitted as part of a long-term study to see where the species travels to once the young birds leave the area where they were hatched.
This year’s birds join a total of 27 young marsh harriers hatched from other Norfolk sites in the same season and 14 from the 2011 generation, making a total to date of 46 birds carrying distinctive lime green wing tags.
Tags are visible to the naked eye from a distance, and the individual codes can be read with binoculars or telescopes.
Older birds can be distinguished from this year’s because the 2011 harriers’ tags carried white letters and numbers, while the 2012 birds have black codes.
The fitting of the wing tags is done by bird ringers, who have a wealth of experience and knowledge in handling birds of all species. It is a painless experience for the birds. Data is being analysed by students at Leicester University, but little is known about the birds’ movements once they leave the nest, where they go in winter and where they return to nest in the spring. Marsh harriers are migratory and are expected to fly south. However, in recent years many marsh harriers have been stayed within the UK and Channel Islands.
This study will allow the scientists to understand the following questions:
1. Where do these birds go once they are independent of their parents? Are they a long distant migrant, travelling into Europe and beyond, or do they stay in the local area for the winter?
2. Once mature, do they return to the area where they were hatched, or do they breed at completely different sites?
3. Once they start to breed, do they breed in their traditional reed bed habitat or in other crops?”
None of Jersey’s marsh harriers have been given wing tags but several have been given numbered metal leg rings in common with other bird species ringed locally and elsewhere.
Please report any sightings of wing-tagged harriers if they come to Jersey or pass through the Island. Sightings should be reported to the Hawk and Owl Trust here but please also let the Société Jersiaise Ornithology Section know too. All records are valuable even if details of the wing codes are not clear to the observer. Look out too for any birds with coloured plastic leg rings that might be obvious – these might be birds from other study programmes.
Bird populations have long been considered by scientists to provide a good indication of the broad state of wildlife because birds occupy a wide range of habitats, they tend to be near or at the top of food chains and there are considerable long-term data on changes in bird populations from a range of national surveys and monitoring schemes coordinated by expert organisations. Birds also have huge cultural importance and are viewed as a highly valued part of the UK’s natural environment by the general public.
The latest annual statistics present trends up to 2011 in wild bird populations in the UK and highlight that:
When viewed together, the status of common native breeding bird species in UK appear to have changed little compared with 40 years ago. However, there has been considerable variation between individual bird species and groups of species that share the same broad habitats, and there have been some large losses in once abundant species, particularly house sparrow and starling. The all-species index showed a small but significant decline of 2% from 2005 to 2010;
Although the largest decreases in farmland bird populations occurred between the late seventies and the early nineties, there has been a pronounced recent decline of 13% since 2003. Historically, the decrease has been driven mainly by species that are restricted to, or highly dependent, on farmland habitats (the ‘specialists’). However, there has also been a decline in species that are associated with a wider range of habitats (the ‘generalists’) following a peak in 2003;
There has been little recent change in UK woodland bird populations, with the greatest decline occurring from the late eighties until the mid nineties. In the late nineties, populations of generalist species started to increase but the populations of specialist species continued to decline;
In 2011 breeding water and wetland bird populations in the UK were at around the same level as they were in 1975, although there has been a decline of 14%since 2000;
Seabird populations in the UK have fallen by 12% since a peak in 1999; however, they remain 27% higher than when data collection began in 1970;
In the winter of 2010-11 populations of wintering waterbirds in the UK were 93% higher than in the winter of 1975-6, although there has been a 7% decline in numbers since their peak in 1996-7.
The bird population indices have been compiled in conjunction with the Royal Society for the Protection of Birds (RSPB), the British Trust for Ornithology (BTO) and the Joint Nature Conservation Committee (JNCC).
The BTO publishes preliminary results each Autumn to provide an initial assessment on the UK’s bird breeding season prior to the publication of the annual BirdTrends Report the following year. Producing results so soon after the breeding season is only possible thanks to NRS participants’ speedy submission of data.
To say it was a wet spring and summer this year is an understatement. UK Met Office rainfall totals for England & Wales in two months were the highest on record, with four times the average falling in April and twice the average falling in June. If the adverse weather affected nesting birds, it also made life difficult for volunteers, resulting in many cancelled field sessions and missed nest visits. However, thanks to the dedication of the nest recorders, over 25,000 records were submitted in time for the preliminary report and 2012 breeding performance figures have been produced for 25 species.
Early breeders advance, late breeders delay
Conditions in February and March were actually warmer and drier than average, and many of the early resident breeders, including tawny owl, song thrush and long-tailed tit, commenced nesting significantly earlier than the five-year average. In contrast, long-distance migrants travelling northwards from their African wintering quarters the following month had to contend with a succession of severe weather systems across Europe and were greeted by cold, wet weather when they finally returned to their breeding grounds. As a result, laying dates of all six species for which preliminary results are produced were significantly delayed relative to the average for the preceding five years. Laying dates of short-distance migrants, blackcap and chiffchaff, which winter in the Mediterranean and therefore return to breed earlier, were no later than average.
Caterpillar-dependent residents struggle
Feedback from lepidopterists suggest that 2012 was a very poor year for moths and species that rely heavily on caterpillars as a source of food for their nestlings experienced a sharp drop in productivity. The average number of fledglings produced per breeding attempt for both blue and great tit was significantly below average, the latter experiencing the second worst season on record. This poor performance was influenced by small clutches and high failure rates during incubation, as well as by a reduction in brood sizes, suggesting that adults were in poor condition when breeding commenced. The number of chaffinch fledglings per nest was at its lowest level since records began in 1966, by some margin. Losses during incubation were high and heavy rainfall may have had a direct impact, wetting the eggs when the female left the nest to feed.
A poor vole year
Many of the lowland owls and raptors feed primarily on volves, which anecdotal evidence suggests were in short supply during 2012, although the extent to which this paucity was influenced by the adverse weather conditions is not yet clear. However, heavy rainfall almost certainly affects the accessibility of these prey items, making it difficult for birds to hunt. Fledgling numbers of all three species for which preliminary trends are produced (kestrel, tawny owl and barn owl) were below average, although this difference was significant only for kestrel.
Flooding and water-logging
Exceptionally high levels of rainfall directly impacted on those species whose nests are vulnerable to flooding. Reed warbler is the most obvious example, demonstrating a significant reduction in every aspect of its breeding success as a result of rising water levels in ponds and lakes, leading to a fall in fledgling production of almost 36%. Increased river flow may also have contributed to the increase in failure rates of dipper nests during incubation.
Poor prospects for fledglings?
The results of the preliminary NRS analyses are broadly consistent with those of the BTO’s Constant Effort Scheme (CES), which calculates breeding success by comparing the numbers of adult and juvenile birds ringed each year at 120 sites across Britain & Ireland. However, there are some species (long-tailed tit, willow warbler) for which CES records a much more marked reduction in productivity during 2012. This difference suggests that young birds may have continued to struggle after leaving the nest, their lack of experience and relatively poor quality plumage making it much harder for them to cope with extreme weather conditions, leading to a drop in survival rates post-fledging.
Many of the species for which preliminary trends have been calculated are capable of producing large numbers of offspring each year, and so have the potential to bounce back rapidly following a poor breeding season provided conditions improve. However, the extreme conditions in 2012 resulted from a shift in the jet stream and it is difficult to predict how its position may be influenced by future climatic warming and the melting of the Arctic icecaps. If wet summers become more frequent, then we may witness long-term changes in the numbers of some bird species.
A new report published this week online in PLOS ONE reports on the impact that avian pox is having on great tit populations. Avian pox has been recorded in British bird species such as house sparrows, blackbirds, dunnocks and wood pigeons for a number of years. However, the emergence of a new strain of this viral disease in great tits is causing concern amongst vets and ornithologists.
Wildlife vet Dr Becki Lawson from ZSL says: “Infection leads to warty, tumour-like growths on different parts of a bird’s body, particularly on the head around the eyes and beak. Although the disease can be relatively mild in some species, great tits suffer severe growths that can prevent them from feeding and increase their susceptibility to predation. Whilst a range of tit species are susceptible to this novel form of the disease, detailed monitoring of birds in Wytham Woods by scientists at the University of Oxford show that great tits are by far the most susceptible.”
“Although recovery from infection can occur, our results show that this new strain of avian poxvirus significantly reduces the survival of wild great tits and has particularly large effects on the survival of juvenile birds. Based on the numbers of affected great tits that we have observed at Wytham Woods, our models do not predict that this new disease will cause an overall population decline of the species. However, pox-affected populations have lower yearly growth rates. Hence, they are likely to have greater difficulty in recovering from other environmental factors that might reduce their numbers,” says Dr Shelly Lachish of the Edward Grey Institute at Oxford University.
With help from the public, scientists at the RSPB and ZSL have tracked the disease, which has spread rapidly in five years from southeast England to central England and into Wales. The annual seasonal peak of observed cases occurs in the early autumn months and incidents continue to be reported at this time of year. Genetic studies on the virus show that it appears to be the same strain seen previously in Scandinavia and more recently in central Europe, and is unlikely to have originated within Great Britain. BTO data on bird movements confirms that great tits rarely migrate outside the country. The spread of the virus to Britain is, therefore, thought to have occurred through the arrival of an infected vector, such as a mosquito.
Great tits are a particularly obvious bird at this time of year as many of them visit bird feeders. Numbers of great tits and blue tits do migrate into the Channel Islands in winter, especially during very cold weather on the continent. Please look out for any with obvious raw looking lesions and abscess-like growths often on the legs and face. There may be obvious lumps too under the feathers. If you see any birds that are affected please let the Société Jersiaise Ornithology Section know and information will be sent on to the authorities. It is unlikely that anything can be done for individual birds but it will be useful to monitor the disease’s progress in Jersey.
Two separate reports are available as downloads from PLOS ONE
Emergence of a novel avian pox disease in British tit species download here
Epidemiology of the emergent disease Paridae pox in an intensively studied wild bird population download here