By Liz Corry

On 3rd October the choughs inside the release aviary were given access outside to join the free-living flock. Chick S is still missing presumed dead so the radio-tracking study will focus on the eleven remaining captive-bred juveniles of 2016. This includes Trevor, Durrell’s parent-reared male, already at liberty with the older birds. However, our primary concern during the first week of the October release was ‘simply’ making sure the six Paradise Park birds survived.

Table 1: The identities of the radio-tracked choughs for the 2016 release.

The four foster chicks knew what to expect due to their summer outing shortly after fledging. The six birds from Paradise Park had to take a leap of faith. For a few it was obvious that the situation was overwhelming. The physical stress of flying outside of the aviary parameters started to show quite quickly.

Earl took to the air after a period of contemplation on the outer shelf. His flight was quite laboured compared to the birds with several months flying experience. He flew continuously making several loops high above the aviary and started flying open-mouthed implying shortness of breath. When he finally landed back at the aviary it took him several minutes to compose himself, standing on the shelf, mouth wide open, before venturing back inside to feed.

One of the females, Yarila, acted in a similar fashion. She flew non-stop for almost an hour flapping back and forth between Sorel Farm and Mourier Valley whilst the other 34 choughs paid her no attention. Almost certainly peregrine fodder, fortunately for her they were occupied elsewhere. Yarila is the name of a Russian deity symbolising spring (and an anagram of Ali and Ray). Fingers crossed she makes it through to the spring if she keeps up antics like that.

Earl (on the rock) returned to the aviary after his first flight looking visibly stressed. After taking several minutes to compose himself he went back inside to feed. Photo by Liz Corry.

The foster chicks also appeared to have had a hectic first half hour. Hopefully more out of excitement than stress. Very quickly they settled back into life outside the aviary, foraging together or joining the adults in flight around Sorel. They chose to roost back at the aviary which helped calm the nerves of the tracking team.

Two of the foster chicks, Wally and Ube, quickly settled back into their old ways having already experienced life outside the aviary for two months back in summer. Photo by Liz Corry.

Trevor (red over orange leg ring) foraging alongside one of the older birds. Photo by Liz Corry.

Dingle, seen here preening his partner Red, demonstrating just how interested the older choughs were in the new additions to the flock. Photo by Liz Corry.

Duke and Earl are two males from Paradise Park and very important for the future of the wild population. No surprises then that these two deviated from the plan. After recuperating in the aviary, Earl took flight again following a group leaving the aviary towards the quarry. Radio signals suggested he was with the group flying around the quarry which put the tracking team at ease and allowed the focus to shift to Duke who had wandered off to the cliffs.

Student Simon ready and waiting with the tracking gear in case the released choughs disappear out of sight. Photo by Liz Corry.

The radio signal for Duke suggested he was part of a trio hanging around the top of Sorel Point. As the team crept closer with binoculars primed, the choughs took flight and dropped behind the point. Half an hour before sunset Duke reappeared, alone, on the cliff-top near the aviary. We know from previous releases, that if the bird is not at the aviary as the sun is setting on their first night out they start to panic. They look for an alternative roost site within their immediate vicinity which might not be appropriate, but it is the only option they see. Duke had settled in an area where we have a nest box secured on the cliff face. When his signal disappeared at sunset we had to hope he had found the box and was sheltering at the back.

Sunrise from Le Marionneux. Photo by Liz Corry.

Returning at sunrise we found that Duke‘s signal was coming from the same area. We tried to scour the area as best as possible, bearing in mind sections of shear cliff and thick vegetation physically blocking areas and the cliff structure bouncing/blocking radio waves. We started to fear the worse after two hours of the signal behaving as if the bird (or transmitter) was stationary. Suddenly a chough flew up out of nowhere, called, then disappeared. Was this Duke or one of the others who had been foraging nearby? At 10:30 the student went off to prepare the dishes for the morning feed at the aviary. Much to everyone’s surprise Duke was at the aviary flanked by the other Paradise Park chicks. He didn’t seem quite at ease, but must have been as relieved to be back as were we.

At the same time as searching for Duke we had to find out what had happened to Earl. His signal was still at the quarry despite all the other quarry roosting choughs dispersing at dawn. Trevor and sixteen other choughs had entirely vanished. No sign of them at Devils Hole or Crabbé. The three breeding pairs and their chicks were foraging with the newbies at Sorel. Earl was alone. As with Duke his signal was not changing location but it was behaving as if he was moving. Possibly short flights back and forth. Yet not a single chough in sight. The good news was that he had gone to the side of the quarry where others have in the past and we can get supplemental food to them (via a catapult). The bad news was that it was also the same place where Ronez perished last year.

As the sun was setting 24 hours after Earl had first arrived at the quarry, a large group of choughs flew into the quarry. They started foraging for food in the same area where Earl‘s signal was coming from. A total of 27 choughs were there including the foster chicks. He had to be in that group. Surely this meant he would roost with either the quarry group or follow the foster chicks when they headed back to the aviary to roost.

Earl spent his first day outside of the aviary alone on the east side of the quarry. Photo by Liz Corry.

A group of twenty-seven choughs including Earl foraging in the quarry shortly before roost. Photo by Liz Corry.

Nope. Day 2 began like groundhog day. Earl alone in the quarry, Trevor and a large group off travelling the Island, and the remainder at the aviary. The major difference was at 9am when suddenly Earl appeared, sat on a rock. Jumping into action, chough food was catapulted over the fence towards Earl. Initially he seemed oblivious, then noticed the food and started eating.

Earl made an appearance after a day of hiding in the quarry. Photo by Liz Corry.

Staff managed to catapult in food for Earl to boost his energy levels. Photo by Liz Corry.

We paid him another two visits making sure he kept his energy levels up throughout the day. Then at 3pm a group of 19 choughs flew in from the direction of the quarry and landed at the aviary. One of which was Earl. Unfamiliar with the concept of walking on netting he edged his way slowly across the roof to re-join the Paradise Park chicks.

Earl cautiously walking across the netting for the first time to get back into the safety of the aviary. Photo by Liz Corry.

The rest of the first week outside was relatively uneventful. The newbies stayed around Sorel along with the breeding pairs with occasional visits to the quarry or Devil’s Hole. It was Trevor and other choughs who caused fun and games for the tracking team. We knew the older birds had been visiting other areas along the north coast thanks to a couple of public sightings. Once we started radio-tracking again from dawn until dusk it was evident the visits were common place.

Even before the sun had risen over the horizon a group had set off to find breakfast at Les Landes. They visited the race course at Les Landes last autumn. This time round there are more of them and the consistency of their visits is fairly promising. They are expanding their range and who can blame them with managed grassland potentially rich in invertebrates thanks to the dung produced from the resident cows in the middle of the track and the visiting horses.

Sunrise at Les Landes where the choughs were having breakfast. Photo by Liz Corry.

Choughs foraging in the middle of the race track which just happens to double up as cattle pasture. Photo by Liz Corry.

The track at Les Landes proving popular with the choughs out of the horse racing season. Photo by Liz Corry.

It is a difficult area to keep track of exactly how many choughs are present. It may look flat, but there are plenty of dips, dents, and barriers to visibility. The most challenging being when they land in amongst the heather as you can see below.

Can you spot the TWO choughs in amongst the heather at Les Landes. Photo by Liz Corry.

Public sightings of choughs

Other areas regularly visited by the choughs this month have been Crabbé shooting range, L’Etacq just south of the race course and the Model Aircraft Field. There is a prize up for grabs to the first person to get a photo of a chough taking off from that runway! They have also been seen flying over Plémont to get to or from Les Landes. No one has yet reported seeing a chough feeding at Plémont. The habitat restoration work carried out at Plémont  by the National Trust for Jersey should make it more attractive to the choughs over the next few years. If not sooner.

We are starting to collect a few intriguing sightings in areas where we wouldn’t typically expect to see the choughs, but not impossible considering the size of the Island. They tend to be a single bird flying overhead, making it impossible to identify the individual. It also means we cannot be certain if they are using that area or just flying over en route to another location. Either way we are urging Islanders to keep an eye out in St Lawrence and Trinity!

Transmitter tales

Of course it doesn’t help matters when the birds you are tracking drop their radio-transmitters. After only two weeks Zennor lost her radio-transmitter. It dropped close to the aviary with the feather still attached. The quill was damaged. This could be an indication of why the feather came out before their natural moult. Equally the damage could have occurred after it dropped by feet (or hooves!) unknowingly trampling the feather.

Zennor tends to stay close to the other juveniles which means her movements should be relatively easy to follow. Hopefully this is a one off and the others stay attached until the birds moult naturally in May/June.

Patience is a virtue

We finally succeeded in trapping the sick wild chick, PP003, in the aviary towards the end of the month. Her condition had not worsened, but it certainly wasn’t improving. After an injection of wormer and visual inspection by Durrell’s vet nurse she was released and re-joined the group. We have noticed a considerable improvement and will continue to monitor in case a second dose of wormer is required.

PP003 the sick wild chick pictured here with her sibling was caught up this month and treated for syngamus. Photo by Liz Corry

Daylight savings

The end of British Summertime saw a shift in daylight hours and has meant that the supplemental feed in the afternoon has been brought forward to 15:00 from 30th October. Our roost checks will now occur daily at a more amenable time as sunset becomes earlier and earlier.

And relax!

With the choughs successfully released and settling down into their new lives in the wild it was time for a day off. What better way of relaxing than taking a boat trip with Jersey Seafaris to see….the choughs.

To be fair, the two hour trip along the north coast from St Catherine’s Breakwater to L’Île Agois promised sea caves and dolphins and nothing (strictly) to do with choughs.

That being said it did provide a unique opportunity to scour the coastline thinking about future breeding sites when competition in the quarry forces new pairs to look elsewhere.

There are plenty of caves and crevices along the north coast, but many are cut off at high tide. Devil’s Hole has always looked appealing and resembles may of the Cornish breeding sites. On this particular day the choughs were flying high above Sorel Point, but they frequently visit Devils Hole. The boat trip does not go as far round as Les Landes and Plémont. Even if it did, we would have run out of time that day. A pod of dolphins complete with baby, kept crew and passengers engaged a lot longer than anyone anticipated both there and back.

Sorel Point as viewed from the sea. Photo by Liz Corry.

The entrance to the blow hole at Devil’s Hole can only be accessed by kayak at low tide (and calm seas). Photo by Liz Corry.

Dolphins are a fairly common sight along the north coast of Jersey. Photo by Liz Corry.

It is well worth hopping on board a Jersey Seafaris excursion and seeing the Island from a completely different perspective. It becomes clear, very quickly, why it is important to protect Jersey’s natural heritage on both land and sea.

Below is a video of the trip filmed by Mark Errington. You won’t be able to ‘play spot the choughs’, but there is a split second cameo by yours truly.

Visitors to Sorel

Durrell and the National Trust were proud to host Maggie Walker from the Audubon Society and her sister Jane Kramer on 5th and 6th October. Maggie and Jane visited Durrell’s Wildlife Park and the choughs before getting a guided tour of the National Trust conservation fields and other areas of their work.

by Liz Corry

The six imported birds from Paradise Park, together with Durrell’s four foster chicks, begrudgingly completed their quarantine period this month. The foster chicks took an instant dislike to the latex gloves and quarantine footwear staff had to adorn which resulted in abject horror any time staff came near.

After a week of meet and greet between the half-inch mesh divide we mixed the Durrell four with the ‘newbies’. It was all very amicable and a lot of relief expressed amongst the newbies who took the opportunity to stretch their wings in the poly-tunnel. Having spent a week under cover they could also bathe in sunlight/shower in the rain/blow-dry in the crosswinds. Their frustration at being locked in the aviary was still apparent each time the free-living group returned to the aviary.

The quarantine group in the aviary paid a lot of attention to the free-living choughs. Often because they had no choice in the matter. Photo by Bea Detnon.

Weekly faecal screening showed that both groups had various levels of nematodes present in their faeces. Quarantine conditions were not going to eliminate Syngamus (gapeworm) from the group. They arrived with it and the outside group already had it prevalent in the population. However, to ensure that the group have the best chance of survival post-release we will worm the birds prior to release. In the meantime all staff could do was monitor the birds’ physical condition, try and minimise stress, and maintain hygiene standards.

A couple of this year’s wild-hatched chicks continued to have respiratory issues this month due to Syngamus. It is a lot harder now to trap the free-living group inside the aviary. The older birds (i.e. with more experience) have learnt to become more vigilant around staff if they see them near the release hatches. We did manage to lure in one of the wild chicks and treat with ivomec. He was quite thin and a lower weight than expected for a healthy bird his age. He was released straight away and has shown great improvement since. The other chick, from a different clutch, is still at large. She is sneezing and struggles with breathing if stressed. Easy to identify at the aviary at least. We will continue to monitor her and attempt to treat her when possible.

Wild chick (PP003) with parent back in July before she started showing signs of a Syngamus infection. Photo by Liz Corry.

A potential opportunity to worm the individuals with clinical signs of Syngamus arose when we caught the 2016 captive-bred chicks to attach radio-transmitters for post-release monitoring. The group we released in July were not fitted with transmitters because the manufacturers were still processing the order. This meant we now had all 10 locked inside to fit and the two parent-reared Durrell chicks to lure in from outside.

Sadly, the day the radio transmitters arrived in the post was the same day one of the parent-reared chicks went missing. Chick S  has not been seen since 18th September. He is the only chough to go missing in that time which adds to the suspicion that he has met an untimely end rather than flown away from Sorel. His disappearance is a significant loss to the group as a male and as Durrell’s first parent-reared chick.

One of Durrell’s parent-reared chicks is missing presumed dead after two months of being released into the wild. Photo by Bea Detnon.

We still had another eleven birds to catch up and attach transmitters to so work began with the inside group.

A radio-transmitter being fitted to the central tail feathers. The cardboard is used to keep the other feathers away from the glue. Photo by Liz Corry.

We teamed up with Durrell’s Vet Department to try and get as many birds as possible processed in one morning. With two people fitting the transmitters the entire group was done before lunchtime. Well we did start at 9am and had already given Chick X her gear a few days earlier.

With the bird in the hand it also gave the Vet an opportunity to check it over pre-release and for leg rings to be adjusted accordingly. The newbies had arrived with striped rings to distinguish between individuals. Some of the colours had proven difficult to read in the aviary. Once flying free it could only get worse so these were changed in-line with our ringing scheme.

Of course the one really obvious ring (green and white striped) turned out to be the only one that had broken and needed replacing. She now has the privilege of being the only Jersey chough with two red and white striped rings.

One of the Paradise Park choughs developed a swelling on one of their digits since moving into the release aviary. Photo by Liz Corry.

The Vet was happy with the condition of the birds taking into account the family of nematodes the choughs are harbouring at Sorel.

One individual presented with a swollen toe-pad evoking scary thoughts of bumblefoot.

The bird has not appeared to be in discomfort whilst being in the aviary or when we had her in the hand. We will continue to monitor this, but it terms of release she was given the all clear.

The last bird to be fitted with a transmitter was Chick T, the parent-reared Durrell chough living outside. With a bit of patience this was achieved a couple of days after the vet visit.

We had managed to trap two other birds in at the same time and had hoped to change a faded plastic ring on one of them. However, the weather was not in our favour so use of hand-nets in the wind and misty rain restricted us to our primary objective. Chick T was very compliant and was fitted with a transmitter in record time. He has now been officially named Trevor. A nod to Trevor Smith who works on Durrell’s Site Services team. He helped build the aviary and continues to help when major repair work is needed.

Chick T was the last of the 2016 captive-bred chicks to be fitted with a radio transmitter. Photo by Liz Corry.

The only concern we had with Trevor (the chough that is) was the presence of stress lines in his central tail feathers. These occur as the feather is growing at times when, for various reasons, the nutrients required for growth were not assimilated correctly. It is often associated with caged birds living in poor conditions, but can also be when healthy birds have a change in diet. For Trevor it might be related to the move from the aviary at Durrell to the aviary at Sorel where the diet is slightly different and the bird has access to a wider variety of insects.

Stress bars in the central tail feathers of a captive-bred chough. Photo by Liz Corry.

Trevor was released straight away to re-join the outside group who had been waiting around the aviary for the morning supplemental food. The free-living group have been getting on with life at Sorel relatively incident free. They appear to be finding more food in the wild, possibly related to the change in weather no longer desiccating insect larvae. There have been a few fights around the supplemental food bowls. With 25 birds and more to add soon, competition at feed times is to be expected. To address this we are looking to switch the ceramic dishes for specially designed chough troughs.

The checkout assistant may have questioned why I needed six end caps for one  length of guttering, but I left the DIY store content with my purchase and proceeded to make three new feeders. The choughs seem happy enough as now several birds can feed at the same time (or several feed whilst one walks down the middle).

Newly installed ‘chough trough’ at Sorel to help reduce competition. Photo by Liz Corry.

The group has been observed using the area around the dirt-bike track a lot more for feeding as well as trips over to Devil’s Hole. They may well be going beyond that as we are not surveying them continuously. We had a report of a bird with an unusual call around the grounds of a house at the top of Waterwork’s Valley. The owner suspected it was a chough, but had no visual sighting. I also received a report of a single chough flying over a house at Victoria Village in the early morning.

Lee, Cauvette and Pyrrho have switched back to roosting at the aviary using the external roost boxes. Photo by Liz Corry.

Whilst each report had an element of doubt to it we can’t deny that the choughs will do things to surprise you and throw your own knowledge into doubt. Roost checks towards the end of the month revealed that three of the older birds have ditched their roost site in the quarry in favour of the external boxes at the aviary. Lee and Caûvette followed closely by Pyrrho return to the aviary at sunset.

There was a confused wild chick one evening who had become separated from the quarry group. After ‘discussions’ with the group locked inside he flew off towards the quarry calling all the way.

A wild chick separated from his roost group shortly before sunset looked for alternative accommodation at the aviary, but was turned away. Photo by Liz Corry.

The roost checks also revealed another interesting sight at Sorel….

If you look hard enough at the photo of the three older choughs returning to the aviary (Lee, Caûvette and Pyrrho above) and, to be fair, use a certain amount of imagination, you will see a kestrel perched in the hawthorn tree. There are several kestrels around Sorel and an ongoing love/hate relationship with the choughs. The aviary provides a useful vantage point for hunting and attracts a lot of rodents (i.e. food). Of late the bond between chough and kestrel seems to have strengthened. This month they have been seen preening next to each other, sharing the same perch at the front of the aviary, and, more amusingly, flying together on the cliff face.

Lee and a few other choughs were observed hanging out with a kestrel on the cliffs flying in unison from rock to rock. Photo by Liz Corry.

We don’t know if it is the same kestrel each time, but there does appear to be one chough in particular who crops up in all the photos of these events; Lee. There is evidence of choughs associating with kestrels in other countries. Normally related to breeding territories and the benefit kestrels provide by deterring other bird of prey species which predate choughs. A lot more clinical and less anthropomorphic than our observations imply.

And finally….

The International Air show at the start of the month meant that once again the red-billed choughs ‘joined in’ with the Red Arrows display. Although this could only be appreciated from Sorel and photographic evidence is poor. A few of the planes used the north coast to turn around and re-group. Unlike last year the Red Arrows did not fly over the aviary much to the delight of the choughs locked inside. Those outside were making the most of the air currents along the cliff tops and put on an impressive display.

The Red Arrows in Jersey viewed from the release aviary at Sorel. Photo by Liz Corry.

The Red-billed choughs flying in Jersey (Red Arrows just out of frame to the right). Photo by Liz Corry.