Report from Liz Corry

Captive choughs at Durrell

On the 7^th 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 27^th 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 8^th 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.

Radio-transmitter trials

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 28^th 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 13^th. 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 23^rd 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.

Report from Liz Corry

Captive choughs at Durrell

The two breeding pairs now in the display aviary appear to have settled in well. Arthur and Gwinny still come down for insects before the other two birds when keepers are present, but Tristan and Issy are by no means going without. There are four food bowls distributed around the aviary so everyone gets a chance to eat and enrichment food is also spread out.

During the heavy rains at the start of the month it was noted that Arthur and Gwinny were roosting out in the open. There is a large area of shelter at the back of the aviary, but the concern was that Tristan and Issy might have been defending the entire shelter. With that in mind keepers built two small shelters that were positioned either side at the front of the aviary. Food bowls were placed inside to encourage the birds to use the new areas. Occasionally keepers observe chasing between the pairs but this is to be expected.

Benvenuto Gianna

The start of the month was an exciting time for Durrell staff as a new addition to the chough cohort arrived all the way from Italy. Staff at the University of Turin’s Faculty of Veterinary Medicine contacted Durrell during the summer regarding a juvenile chough they had hospitalised and wanted to re-home. They believed, through her very tame nature, that she had been taken from the wild as a young chick and kept in captivity and for this reason they could not release her back into the wild. They had, however, heard about Durrell’s captive breeding programme for choughs and wondered if she could be of use to the re-introduction project whilst also gaining a better quality of life.

Gianna, named by the staff in Turin, arrived on the 1^st of October and stayed in the Les Noyers quarantine facilities until she had cleared her quarantine period. She weighed 260g upon arrival, slightly low for a female but expected after an overnight journey all the way from Italy. She was eating and drinking immediately and showed no signs of stress.

The Durrell Veterinary Department took blood samples and conducted a general health check during the first week in quarantine followed by weekly faecal screening. Once Gianna has cleared quarantine she will be moved to the display aviary to join the other choughs

NOTE it is presumed that Gianna is a different subspecies (P. p. erythrorhamphus) to the other birds (P. p. pyrrhocorax) and will not be allowed to breed with them. She will, however, be an invaluable asset to the flock.

Radio-transmitter trials

All of the choughs being released on the north coast this year will have radio-transmitters attached so their movements can be closely monitored. Standard tail-mounted tags supplied by Biotrack will be fitted to each bird once they move up to the release aviary. Tail feather attachment means that the tags will fall off naturally when the birds moult, thus reducing stress. In order to assess if the tags have any impact on the birds’ health and/or behaviour once attached we are trialling dummy tags on two choughs in the Wildlife Park. This trial also allows us to test the durability of the tags, especially important considering the inquisitive nature of the choughs!

B6975 (♀) and B6976 (♂) were taken to the vets to have the tags attached and then released straight back into their aviary. Upon release, B6975 was observed preening and taking an interest in the antennae of the tag, but soon lost interest. She was caught up four days later to check her health and the condition of the tag. The tag was still intact although there had been extensive pecking at the glue used to attach the tag to the feathers. Her health and that of the other bird seem at present to be unaffected by the tag.

Update by Régis Perdriat of the LPO Station at l’Île Grande

Regis reports that in August and September this year there have been 2-3 red-billed choughs visiting the vicinity of the Station and Brittany’s Sept Îles Reserve. With 50+ pairs of choughs breeding in Brittany, the species’ nearest stronghold is Ile Ouessant (Ushant), the island at the western end of the Brest Peninsula.  

These sightings are not the first as in recent years there have been several choughs recorded in the reserve and in the vicinity of the Île Grande station:

• 1-2 birds were seen at the LPO Station between 18^th October and 6^th December 1987;
• 1 bird seen at the LPO Station 31^st October and 2^nd November 1994;
• 1 bird seen in August 1997 on Île Rouzic (the island of the Sept Îles with the gannet colony);
• 3 birds seen between the 8th and 20th August 2005 (one bird had been ringed on Ouessant in May of the same year and was back on Ouessant two months later);
• 7 birds were seen at the LPO Station on 3^rd October 2007 and 2 on the 17^th October;
• 2-3 birds seen regularly between the 20th August and the 17th of September 2012.

Interestingly there have been sightings of choughs even further north including birds at Cap Fréhel, Calais and even a juvenile at the Antifer nature reserve (Seine Maritime).

These records from l’Île Grande and the Sept Îles Reserve on Bittany’s north coast well show how much these birds may roam along the coast to the south of Jersey.

Report from Liz Corry

Captive choughs at Durrell

In the wild at this time of the year breeding pairs, juveniles, and non-breeding adults are coming together to form their winter flocking groups. In captivity this is replicated by moving all the birds into our large display aviary. However, due to the imminent re-introduction plans we are keeping the potential release candidates separate from the other choughs. So Operation chough-fle shuffle was put into place by the keepers this month.

The shuffle began with the breeding pairs being moved out from their aviaries to off-show holding facilities (LNQ). The non-breeding birds (release candidates) in the display aviary were moved down to the breeding aviaries. Then, finally, the breeding pairs could be moved into the display aviary.

To avoid any negative associations with their keepers the non-breeding birds were netted by non-uniformed staff and handled by different species’ keepers. Once in the hand all birds were weighed, had a general health check, and had blood samples taken by the vet for disease screening. A group faecal sample was taken prior to the catch-up for disease screening, which was also submitted as part of Durrell’s bi-annual screening process.  It took two days to catch up all six birds because they first needed to be lured into the shut-off cage before netting. After the first two birds were trapped the others became understandably wary of going in the shut-off, hence the two days.

With the display aviary empty and cleaned both breeding pairs were caught up once again and moved down into the display aviary. They were released at the same time to avoid one pair establishing a territory before the other. Observations were made by keepers for the first two hours after mixing and continued intermittently over the next few days to make sure everyone was harmonious.

As expected, last year’s dominant pair, Tristan and Issy, made their presence known and repeatedly flew around the aviary vocalising. This was matched by Arthur and Gwinny although they preferred to stay perched high. There were a couple of mid-air scuffles in which Tristan brought one of the other birds to the ground but these only lasted a few seconds. The birds are more confident in the aviary than they were last year and are more tolerant of the keepers being in the aviary. Arthur and Gwinny are always first down for insects: this could be seen as a positive thing if the birds are more confident. However, it might be that the other pair is stopping them from getting to the main food dishes when the keepers are not there. This behaviour is being closely monitored by the keepers.

As we prepare to return the red-billed chough to Jersey this recent summary of the bird’s disappearance from Cornwall and its successful return is very timely. See Cornish Choughs for the whole story.

Key dates

1800s: A marked decline in numbers of choughs in Cornwall due to persecution and habitat decline
1930s: Probably only half a dozen breeding pairs remain in Cornwall
1947: Last successful breeding recorded in Cornwall
1967: One of the last pair found dead
1973: Last chough in Cornwall seen in February 1973

1973-2000: A handful of records of choughs passing through, two birds arrived at Rame Head in 1996 and stayed for 6 months
2001: Choughs return naturally to Cornwall – a small influx of birds recorded and three birds settle at the tip of the Lizard peninsula
2002: Choughs successfully breed in Cornwall again
2006: Two pairs of choughs raise young in Cornwall. Also first documented record of colour-ringed Welsh choughs in England (seen in Somerset and north Devon)
2008: First chough chicks born in West Penwith, Cornwall, for 150 years
2011: Six pairs nest in Cornwall
2012: Seven pairs nest in Cornwall.

Has that natural recolonisation been successful?  These figures show the slow but steady increase in the number of breeding pairs and youngsters fledged from Cornish nests. Not all young choughs are expected to survive, these are long-lived birds with a high mortality rate, especially in their first year, but the survival rates of Cornish birds are very good compared to other UK populations.

Year    Pairs     Young fledged
2002   1            3
2003   1            3
2004   1            4
2005   1            5
2006   2            8
2007   2            9
2008   2            6
2009   5            8     Two pairs successful, two young pairs attempt to breed
2010   6            9     Three pairs successful, two attempt and one male pair
2011   6            15   Four pairs successful, one pair’s eggs predated, plus one male pair
2012   7            18   Five pairs productive, plus one young pair and one male pair

Reports from Liz Corry

JULY 2012

Captive breeding at Durrell

All of the choughs have started to moult: juveniles around the 11^th whilst the breeding pairs started a few days later.

Captive breeding at Paradise Park

The sexes of the three chicks bred this year have been confirmed as 1 male and 2 female.

AUGUST 2012

Captive breeding at Durrell

All the choughs are now being given their non-breeding/winter diet whereby the protein levels are reduced, i.e. the ox heart has been removed and less insects are given. In past years we have given mixed corn in winter as wild choughs are known to forage in cereal fields when insect numbers are low. However, the choughs in captivity at Paradise Park and at Durrell rarely touch the corn so it has been removed from the diet completely.

The breeding pairs have now finished for the season. Normally they would be integrated back into the display flock; however, due to the release planned for this autumn/winter we will keep the breeding birds separated from the potential release birds for now.

Display flock

The low productivity of chough chicks this year means that the trial release cohort will consist of the three chicks hatched at Paradise Park this year and another three selected from the older juveniles in the display aviary at Durrell. In preparation for their release these birds will be trained to fly to target boards for food as this will help with the supplementary feeding once in the wild and allow the keepers to call the birds back if they need to be shut away in the release aviary.

Training began at the end of July and looked promising at the start of August. The birds are accustomed to flying down for food, but they need to learn to respond to their cue for food. Working with a large group rather than training on an individual basis has proved challenging. We increased the number of target boards so that each bird has a chance of getting to food which in turn strengthens the learned behaviour. However, there are still a couple of individuals who hang back whilst the dominant birds fly down first and take all the food. We will continue with the training and looking at ways to improve the birds’ success.

Notes 

All the juvenile choughs have somehow managed to lose an ID ring. Five have lost their metal rings and the sixth has lost its plastic ring. One metal ring has been recovered and it looks as if it has been prised open. All six birds can still be identified but new (and improved) rings will be added before any release.

An application for planning permission to construct the chough release aviary was submitted to States of Jersey on 13th August. Application P/2012/1033 and all supporting documents can be viewed in full on the States of Jersey website.

The aviary will be constructed in Field 6, La Rue de Sorel, St John. This field belongs to the National Trust for Jersey and is adjacent to Le Don Paton. The aviary will house the choughs for at least six weeks before they are released into the wild. The birds will be fed in the aviary while acclimatising to their new environment before being allowed to fly free. After release the birds will still be fed in the vicinity of the aviary and may even return to roost inside at night. If any of the birds have difficulty acclimatising to their new life, or if weather conditions become difficult for them, they may be returned to the aviary.  

We are extremely grateful to Naish Waddington Architects who produced all the plans for the aviary and have provided support throughout the planning process. Please check the BIRDS ON THE EDGE website for updates on the aviary and the release programme. Details on the choughs and their management can be found here.