Report by Liz Corry

Choughs at Sorel

At the start of April the juveniles at Durrell nominated for release were transported to Sorel. Catching them up out of the main display aviary proved a little trickier than first thought!

Having witnessed the breeding pairs being trapped and having vague flashbacks to the year before (if birds indeed do that) the juveniles were apprehensive to say the least. Keeper sat with baited trap and baited breath waiting to catch up four out of the seven birds in the aviary. Day 1 was fruitless. Day 2 saw B6974 and B6978 caught up (technically B6973 was also in the shut-off but evaded capture). Finally – Day 7, albeit with a two day break, saw the last two captured; B6973 and B6977.

All four juveniles had to undergo visual health checks by the vets before moving to Sorel. Three had already been fitted with radio transmitters so this was an opportunity to check attachment and the birds’ feather condition. B6977 was fitted with a radio transmitter and all four had Channel Islands metal rings attached to their right legs. Two of the birds had their existing plastic rings swapped for a different colour to avoid duplication with choughs already at Sorel.

During the catch-up process it was noticed that B6975 had lost her dummy radio transmitter. From previous observations we think the transmitter had fallen off in the past couple of weeks. On examining the bird there was a new feather growing where the transmitter would have been glued on. The adjacent feather, which would have been tied to the antennae, showed signs that the tag, once unstuck, moved down the feather shaft and fell off. This transmitter had been attached for over five months, so it is not a grave concern, but is of interest. The birds with the real transmitters attached will naturally moult within this time period anyway.

When the Durrell birds were moved into Sorel there was a lot of interest from the other, Paradise Park, birds. No aggression was observed just lots of vocalising. This was a positive sign that the two groups would get on once mixed. After a few days living next to each other and adjusting, the hatches between 1A & 1B were opened to allow the groups to mix.

The Durrell birds seemed more interested in their new surroundings than in interacting with the Paradise Park birds. The Durrell male (green) was seen to order around a few individuals at the start, but no one was chased or blocked from getting to food. This may have had a lot to do with them being juveniles and not breeding pairs.

However, we did notice male and female ‘pairings’ even at this early age. Black and Orange from Paradise Park hang out together and Green and Mauve from Durrell do likewise. We have also seen them pick up and carry around twig-like vegetation. One bird has gone a step further and carried material up to the top of a shelter box. A fruitless task since the wind clears anything within seconds, but at least it keeps them occupied!

Durrell vets have visited the aviary on a couple of occasions this month. On the 10^th the Paradise Park group had to be caught up to be given Ivermectin injections. They also had blood samples taken whilst in the hand. All juveniles had put on approximately 20g in weight since arriving in Jersey. Weight gain was expected but needs to be monitored if the training is to be successful.

George, the tame adult, had not put on any weight and started to become more of a concern towards the end of the month. He was spending more time lying down even when the keeper was present. It was difficult to know whether he was depressed from being alone (he still hadn’t ventured into the polytunnel with the others) or through a physical illness. When the hatches between 1A and 1B were opened he became a little perkier since he could mix with the Durrell juveniles next door to him. However, as the juveniles became braver and spent more time in the tunnel George was back to being alone again except at feed times or when sheltering from bad weather.

George’s mobility looked to be declining and he was immediately put on a course of an anti-inflammatory drug given to him in his insect feeds. This made a brief improvement until the course finished. On two occasions after that he grazed his toe on the left foot. Fear of infection and further decline in condition meant that George had to be moved back to Durrell to be housed in the Veterinary Centre.

Under anaesthetic, several X-rays were taken and George’s feet were examined. He came to Jersey with bumblefoot on his right foot. This is a bacterial infection and inflammatory reaction affecting feet. George’s rotated left leg means that he will load more on his right and has probably aggravated if not caused this issue. A swab was taken from the site of the bumblefoot. In house Lab analysis identified the bacteria present and George was put on a course of antibiotics as well as the anti-inflammatory medication. Bio-security legislation requires George to undergo a quarantine period whilst with the vets before he can be moved into one of Durrell’s aviaries. He gets a lot more attention in the Vet Centre than at Sorel so his mood quickly improved although his physical condition is still a struggle. We will review his situation once the antibiotics have finished.

Pre-release training

The choughs are being trained to fly in and out of the release hatches (within the aviary)on a whistle command and rewarded with food. This is to ensure that during the early stages of the soft-release the birds will come back to the aviary and that they can be safely locked in overnight. They will learn that the aviary is a safe shelter and holds food resources if they struggle to locate any in their first few months exploring the coast. In the long term this should also help with monitoring their condition after release.

To achieve this, the aviary has been designed to let keepers train the choughs to go through an internal set of hatches before attempting the external release hatch. There are large target boards on the food stands and two tables in the polytunnel (kindly donated by Tony Pirozzolo at Café Firefly). Hopefully the birds will start to associate these boards with food and will easily spot them when flying around after their release.

The birds responded well when they had access to the first half of the polytunnel. Whilst still nervous of the keepers they would fly in for food once the keeper had blown the whistle and left. When they were given access to the entire polytunnel they started to become less responsive.

Radio-tracking and behavioural studies

There have been several practice sessions this month on how to radio-track choughs. More importantly, learning how the Jersey landscape affects radio frequencies and discovering the practicalities involved. Initially this involved checking that the transmitters on the birds were working and seeing how far the signal will travel. When feeling a bit more adventurous this progressed to seeing if keepers could track down a live moving target. Durrell staff, with transmitter in hand, kindly volunteered to be ‘choughs’ and hide somewhere between Sorel point and Devil’s Hole. They took the role to heart by belly-crawling through gorse bushes and sitting on cliff tops. Despite all their efforts to deceive the radio-trackers they were all found and pretty quickly. Next test….paragliding volunteers!

Jess Maxwell, a Durrell intern student, is assisting with the field project and undertaking a behavioural study for her degree. Her observations started this month and will continue post-release. These studies involve Jess sitting in a field for two hours each day which is why Jess is very grateful for the recent weather improvements. She is studying the group dynamics to see if they behave the same pre- and post-release and try to assess what is the ideal cohort size for release. Hopefully this work will be replicated with future releases and the data can be used to evaluate the ongoing project.

Choughs at Durrell

With the last of the release birds being moved out of the display aviary we are now left with three birds in there including Gianna. These choughs have been joined by a pair of breeding toads who have decided to spawn in the choughs’ ‘pond’! Keepers have provided the choughs with water bowls to deter them from going near the pond. At the time of writing we now have tadpoles.

Our two breeding pairs of choughs have been very busy off show. Keepers provided nesting material in the appropriate stages; large twigs, heather thatch and finer twigs, wool and horse hair. Both pairs set to work building nests and completed them relatively quickly. Keepers never witnessed any copulation, but on the morning of the 22^nd they did see their first egg. Unfortunately this was when Issy got off her nest, walked along the shelf and laid the egg there much to the dismay and confusion of the keeper watching. On inspection of the nest camera it looked like there was an egg in the nest too (although the wool can be deceptive) so the shelf egg could be the second egg not the first. On the 25^th, keepers thought they could see three eggs in the nest and by the 26^th Issy was sitting tightly on them. If all goes to plan these eggs should hatch towards the end of May.

Keepers are not sure if Arthur and Gwinny are up to anything. We do know that they have a nest. Somehow the camera lens moved position so we do not have a clear view of the nest but from their behaviour it doesn’t appear that Gwinny is sitting on eggs. We don’t want to disturb them so will continue as normal and monitor them as closely as we can.

Keepers have also been kept busy at the display aviary after members of the public reported seeing the choughs “trying to escape”. Being inquisitive birds they investigate everything including broken threads in aviary netting. It wasn’t an escape attempt more a quality assurance test. The height of the aviary makes it very difficult to repair holes in the netting with just a ladder and a good head for heights. Jono le Maistre, tree surgeon, kindly offered his assistance and with harnesses firmly attached climbed the poles to fix the netting.

Report by Liz Corry

Captive choughs at Durrell

The breeding pairs were caught up out of the display aviary at the start of the month and moved down to their breeding aviaries. It took three days to get them all. By the second day they were all wary of the catch-up cage and it took Tristan three days before he summoned up the courage and/or his hunger got the better of him.

Nesting material was added to the breeding aviaries almost straight away, but the record-breaking snow blizzard deterred the birds from doing anything. As soon as this past and the weather ‘improved’ they began taking the material into the boxes.

The choughs in the display aviary braved the elements at the start of the blizzard. By the end of the first day the snow had settled on the netting and transformed the aviary into an igloo. They were probably warmer than their keepers.

Thanks to the generosity of Paradise Park we have been given two brand new Sony 700 line nest cameras. With weather disrupting breeding behaviour we took the opportunity to install one of the new cameras. The existing camera in SF3, whilst showing a clear picture, was not suitable in design, size, and position and was removed.

Gianna has started to be a bit more forthcoming towards keepers now she has settled in to the main display aviary. She has started conditional behaviour training and is learning to fly on command. Once this is mastered she will begin learning to weigh herself on scales and enter/exit carrying crates without being handled. Hopefully the other choughs in the aviary will follow suit in the near future

Arrival of Paradise Park’s 2012 juveniles

Three juvenile choughs, hatched in 2012, and the trained adult male, George, were scheduled to arrive by plane in Jersey on the 12^th March. Lee Durrell had kindly loaned her Navajo plane for the collection of the choughs from Paradise Park. Colin Stevenson was going to be the pilot.

However, with the unprecedented snow blizzards this plan was thrown into mild chaos. By hook or by crook the birds had to arrive by the end of that week. If not, the next import date would be in mid-April. Having been ‘snowed in’ for two days at the Wildlife Park, keepers were far from optimistic that the birds would arrive.

A decision was needed by the 13^th in order for the airport authorities to sign off on the paperwork for a flight on the 14^th. Despite the 9ft snow drifts that lined the roads the route to the Sorel aviary was still accessible. The next task was making sure that Lee’s plane could get onto the runway on the 14th, let alone be able to fly. Colin, the pilot, reported that:

“Steve Driscoll, the Ports of Jersey Group Operations Director and André Rabet, the Airport Engineering Director made a significant intervention by diverting their very stretched crews to clear our taxiway.

The Airport snow clearing team themselves, once detached from their normal duties, cheerfully made short work of clearing the snow from our taxiway and had us operational by Wednesday night…..Eric, the digger driver, worked at the hangar for four and a half hours, until half past seven in the evening – after starting to clear snow at the airport at 5am that morning.”

After, what we were told were near perfect flying conditions, Colin, co-pilot Gregory Guida and the choughs touched down in the early afternoon. The choughs were accompanied by David Woolcock, Curator at Paradise Park, who had kindly volunteered his time to stay at Durrell for two days to help settle the birds in and discuss training protocols.

Once the birds arrived at Durrell they were swiftly whisked away to the Vet Centre under quarantine conditions. There the birds had a general health check, blood samples taken, ID rings attached, and radio transmitters attached where appropriate.

On inspection of two of the juveniles it was noted that some of their tail feathers had ‘fret lines’. The central tail feather, where the radio transmitter is attached, had broken off quite close to the base. It meant it was not possible to attach radio transmitters to these two birds. After careful consideration of the options it was decided that these two would not be used in the trial release. Their feathers will be allowed to moult through naturally at the end of the breeding season and we would consider them for a second release if planned.

The two birds involved were still given Jersey addressed metal ID rings in case they accidentally escape over the next few months. It will not make them easier to find but if recovered it will make it easier to identify where they came from. The only one who has not been given a Jersey ring is George due to his leg deformity. All the choughs at Durrell and now at Sorel have transponders implanted under their skin as another means of identification if recovered. These tiny ‘microchips’ were fitted by Paradise Park staff prior to the birds departure for Jersey.

After what must have seemed like a lifetime for the birds they finally got to leave the Durrell Vet Centre and be transported by car to the release aviary at Sorel. Andrew Terry volunteered his time and more importantly his 4WD to transport the birds. Unfortunately the last 100m of track leading up to the field site had not been cleared and the driver faced a 6ft wall of snow. The last leg of the journey had to be done on foot from Sorel car park, but finally with the sun setting the choughs made it to the aviary. They were released into the back half of the enclosure (Sorel1A) where they will stay until the Durrell group get moved up and then mixed together. For the next thirty days quarantine restrictions will apply and only designated staff can access the aviary.

Choughs at Sorel

The first quarantine faecal sample was submitted to the lab on the 18^th. For the choughs (and their keepers) to be ‘released’ from their quarantine period a minimum of three pooled faecal samples need to be taken on a weekly basis. Analysis of these samples will determine whether more are needed and/or if treatment is required.

The first faecal sample showed positive for nematodes and coccidians, albeit at low levels. It was decided to not move the Durrell choughs until a second faecal sample could be analysed and a decision made about treatment. The second faecal showed low levels of coccidians and nematodes, but since this would be typical for wild birds as well it was not deemed significant. However, as a standard of good practice we will treat George’s group with a single injection of Ivermectin (anti-parasitic drug) prior to release.

A Bushnell trail camera was installed in the aviary when the choughs moved in. This will act as a security camera as well as documenting the birds’ behaviour when keepers are not present. It has proven very useful so far and we have been able to see how the birds react when dogs, people, and heavy machinery are around. It has shown that like most other corvids, choughs can be active from 05.00 onwards.

The camera has also recorded a surprising, and unprovoked, attack on George by the other male in the group. This might be expected since George has been kept separate from the group over the last 5-6 weeks. From the keeper’s point of view, whenever they enter the aviary, the juveniles hide or are too busy eating to show any animosity towards George. Most squabbles seem to be between the juvenile male and the female without the radio transmitter so it was interesting to be able to remotely observe this behaviour.

Pre-release training

George, having been trained prior to arriving in Jersey, will be the role model for the other choughs when they start their conditional behaviour training. However, it is not a role he can easily jump into. First he needs to adjust to his new surroundings, the new weather conditions (gale force winds are not a common occurrence in Hayle) and, even more challenging, adjust to his new keepers.

Whilst George settled in very quickly (eating straight away) it took him a few days to be confident enough to perch close to the keepers. He will now fly to the keeper when called and can jump onto the scales to be weighed. This last task is quite a challenge in his new surroundings. For a start, on certain days he has to battle against the wind. The scales are a slightly different design to what he is used to which will make him insecure. We have ordered the same scales as Paradise Park, but they have to be delivered from the manufacturer in Germany.

For the keeper to reach the shelving and be at a comfortable height with George a ladder is required. At first George was scared of the long ladder, so they were swapped for a small pair of steps. Gradually he warmed to the ladder, mainly due to the keeper using it a lot to carry out DIY work inside the aviary.

The biggest challenge was in keeper and bird trying to understand each other. George knows the command for “please jump on the scale” and he knows that he will be rewarded with insects. The keeper knows the correct command and the correct reward. But when the bird doesn’t want to jump up in the wind onto a strange object it is very hard for it to convey this. It is a lot easier to hop along to the keeper, look doe-eyed (trust me they can do this) and ‘guilt’ the keeper into giving them insects!

Report from Liz Corry

Captive choughs at Durrell

With the breeding season looming, staff at Durrell have been working hard this month to set up the breeding aviaries and move the birds around accordingly. Gianna was moved out of her off-show holding into the main display aviary. She was kept in the shut-off for two days as a way of re-introducing her to the group. She received a very uneventful welcome: Gwinny was the only one to fly down to her and that was only because she was looking for food.

On the 19^th the three juveniles in SF3 were caught up and moved to the display aviary. These three birds will make up half of the release cohort. Before being released into the main flight all three birds were fitted with active radio-transmitters and an incoloy leg ring. The battery life on the radio transmitters is such that it should not run out before the birds moult tail feathers in autumn.

When the three juveniles were released into the main flight the other juveniles paid them a lot of attention. There was a lot of squabbling and defending of roost sites but no real aggression observed. The breeding pairs have stayed together throughout this which is looking positive for the new breeding season.

Once the juveniles had been moved out of the off show aviaries work could begin to prepare them for the breeding season. Apart from the obvious spring clean a few modifications were needed to improve our chances of a successful breeding season. Plywood has been added to a part of SF3 aviary to ensure a complete visual barrier between the choughs and any disturbance at the back of the aviary. The Orang-utan House kitchen and maintenance area is located behind the aviaries as well as other breeding bird enclosures. Daily disturbance should now be limited.

The nest box in SF2 has been relocated to the other side of the aviary to increase the distance between the two nests. We are not sure how much this influenced last year’s breeding, but the two pairs were very aware of each other and were almost synchronous in nesting behaviour, for example they kicked eggs out of the nest on the same days.

Another major difference compared to last season is in how we house the nest box cameras and what type of camera is used. We have tried to ensure the birds cannot tamper with the position of the lens. We are using different cameras and will not really know how effective they are until the birds are in the enclosure. No pun intended, but we will monitor closely!

Progress of the release aviary

The release aviary is now nearing completion. The major building tasks have been completed and the focus now is on making sure that the release hatches operate smoothly and all the necessary interior fixtures and fittings are in place. Work will begin on signage for the site when the choughs move into the aviary.

There were several visitors to the aviary in February including Mike Stentiford, Professor Carl Jones, Dr Richard Young and Paul Buckley. Each guest was shown around the aviary and went away suitably impressed.

Other news

On the 10^th, Sally Dalman from the National Trust for Jersey volunteered her time to shadow Liz for half a day in the Bird department. Unfortunately she picked a day where it persistently tipped it down with rain. However, it was still beneficial and both parties gained a greater understanding of what each other’s jobs involve.

On the 23^rd a group of Durrell’s volunteer guides were shown around the chough enclosures and updated on the progress of the release project and BOTE. They will hopefully be able to incorporate this information into their talks at the Wildlife Park and answer any questions posed by the public.

Biannual faecal samples were required from all the birds at Durrell this month; awaiting final results for choughs.

Report from Liz Corry

Captive choughs at Durrell

Gianna continued visiting the vets at the start of the year to have her bandage changed until the 9^th when it was removed. Another x-ray showed improvement, but she was put on a five-day course of anti-inflammatory pain killers as a precaution. It took her some time to get used to not having the ball bandage on and to realise she could use her foot again.

Gianna was caught up and moved to an off-show enclosure (X1B) on the 11^th so we could provide her with more flight space whilst her condition improved. She weighed 275g on moving her.

On the 26^th we moved the three juveniles not marked for release up to the display aviary. They were kept in the shut-off area for two days before being released to allow them to acclimatise to the new surroundings and for the breeding pairs to get used to them. Typically, upon release, Tristan and Issy were the first ones to swoop down and check out the new arrivals. Arthur and Gwinny showed some interest, but on the whole left them alone.

The three juveniles are the birds we have been testing with dummy radio tags and incoloy gull rings. We fitted B6976 ♂ with an incoloy ring using a new pair of ringing pliers specially adapted for the job. Thanks go to our Maintenance Department volunteer for his impressive metal work skills. There seems to be no further damage to the dummy tags or birds and no abrasions etc from the ring. All positive signs for the release birds.

Work began on fitting nest-box cameras at the end of the month. We will be using a different type of camera this year with a much better resolution. The camera is a different size and style so the existing nest-boxes have had to be modified. This year we have worked on making them tamper proof so the parents can’t move the lens off the nest. However, these cameras have a lot more infra-red lights on them (improving dusk/dawn image quality) which could create a distraction or the birds could ignore them completely. Either way we will be watching closely to see how the birds behave in the box. If we think the new cameras are not working out we will have to modify.

Progress of the release aviary

Work on the release aviary started again after the winter festivities. Aaron kindly loaned us his lockable trailer once again so materials could be stored on site. The shed end is looking more like a shed and the netting is finally on the polytunnel.

However, yet again Trevor and his team had to battle the elements and the day snow came to Jersey was the day they finally had to down tools. One ongoing issue is the strong winds which puts a stop to any work involving a ladder. The other growing worry was that the snow and non-stop rain have completely saturated the fields and the truck was starting to churn up the ground beyond repair.

Once these issues can be resolved work will continue, but it now means that the completion date will be nearer the end of February. On the plus side it has freed up Trevor to come back to the Wildlife Park and fit the new nest box cameras.