Returning the Red-Billed Chough to Jersey
We started releasing our captive-bred red-billed choughs onto Jersey’s north coast in August 2013. This was undoubtedly later than we originally planned but is a trial! By October, bad weather had forced the birds back into their aviary on the cliff tops at Sorel in St John, about five miles from Durrell’s Wildlife Park and our own office. You can read all about the project and the need to restore Jersey’s coastline on the Birds On The Edge website at www.birdsontheedge.org.
The choughs at Sorel spent the winter months riding out the gales in the aviary. All hatches firmly battened down. Four birds from last year were joined in the release aviary by four new, young, choughs from Paradise Park in Cornwall. With conditions favourable and all health checks passed it was time to restart the releases and on 9th April this year the hatches were opened and the birds allowed to fly free once again. The intention was to give them thirty minutes of playtime before calling them back in for food. What happened in those thirty minutes was exhilarating, poetic, and simply nerve-wracking for both chough and keeper.
The group of eight choughs took the air, rising higher and higher, swooping left, swooping right. Sometimes in a 3, 3, 2 formation, at others in a 2, 2, 4, and 5, 1, 2. It was like watching a red arrows display only without the trailing smoke (we are discussing this for next year’s releases).
As the stop-clock ticked down and we were about to call them back for dinner, the inevitable happened. They headed for nearby Ronez Quarry – a spot much favoured by the birds last year.
Chough release aviary at Sorel. Photo by Liz Corry
Chough at Sorel. April 2014. Photo by Mick Dryden
Interestingly, one bird, Red, headed back to the aviary. She did the same thing last year. She has the desire to explore, but maybe it is overcome by her knowledge of easy food and protection at the aviary.
It is hard to tell who is who when they are flying high above your heads, but we know that Yellow parted ways after the thirty minute mark on the first day of release. When the others flew to the quarry, Yellow headed inland. Rather naively we thought he was heading the long way round to the quarry, but after a relatively short time of radio-tracking to account for the other six birds we had lost his signal completely. Not only had he ditched Red but the entire group. We expected from previous behaviour that the two older males would not want to hang out together given the choice, but we didn’t expect a new arrival to leave the entire group.
By the end of the first day there was one chough in the aviary, five roosting in the quarry, and two missing. It is worth noting that the birds in the quarry visited the exact same sites as they did last year and did not deviate. They returned to the aviary over the course of the next two days and were locked back inside as they arrived. Releases were put on hold until we had a better idea of where the missing birds were.
Two new project students Pierre and Adam were put to the test straight away. The team covered many miles on foot and even more by car in an attempt to radio search the island in as short a time as possible. After two days of hearing nothing but white noise it was a tremendous feeling to be able to hear the beep beep of a transmitter signal once again.
It was Yellow’s signal, detected at Noirmont Point (in Jersey’s south-west) but coming from the St Aubin side. This is an area 9.5km south of the release site. In fact it is quite close to the last reported breeding site for choughs back at the start of the 20th Century. The cliffs to the west of the point seem favourable for a roosting chough and Noirmont has a large area of suitable feeding ground.
Six choughs against the clouds. Photo by Liz Corry
Radio tracking from the air. April 2014. Photo by Liz Corry
However, these days it is a popular tourism and recreational area so disturbance is frequent. What didn’t quite fit was the exact location of the transmitter; low sandy cliffs and a forested area above them. Visual searches were hampered by the tides and when access was finally gained the signal had disappeared. No sight or sound of Yellow has been detected since. Nothing at all has been heard from Cerise.
Within the first few days of their disappearance two other search methods were adopted based on previous studies. Lee Durrell kindly allowed the use of her plane piloted by Colin Stevenson. Whilst the choughs in the aviary could be detected from the air no other signals were picked up. This method has its flaws. It is very dependent on the bird being out in the open. It is also easy to miss something as you can’t tell the pilot to “stop, back up, I think I heard something”.
A search from the water was also attempted. Peter Haworth of New Era Vets loaned his boat and services to search the north coast. Signals from the Sorel choughs could be detected, but no others. Time constraints meant that further boat searches have not been attempted.
The releases of the six remaining choughs continued on 15th April. At first the birds were behaving as individuals. The pair Green and Mauve would fly off to the quarry in search of the buildings. The lone females, Black, Blue, and Red would follow but head to the grassy areas in the quarry. They would return to the aviary but often Black and Blue would look to Green and Mauve for guidance as to when to do this. White, the 2013 male brought over in December, did the opposite.
Choughs at Sorel. Photo by Liz Corry
His behaviour was typical of a scared bird that wanted to be with other choughs but didn’t want to leave the security if the aviary. His first day of release on the 9th saw him return in the evening to the cliffs by the aviary. He spotted the team but was too anxious to take food and went back to the quarry to roost with the others. He returned the next morning and went straight into the aviary. For the next week or so any time the hatches were opened he would fly to them with the others but never actually leave. He would fly straight back to the other end and call loudly. Almost as if he was shouting “Where are you going? Why can’t we just stay here where the food is? I don’t like wide open spaces. Come back”.
Finally he caved-in to the pressure of being left alone each day and joined the group. By this point the other five had started flying and feeding together. April was a hectic time for all involved. Yet all signs were positive that the release process was heading in the right direction and choughs were once again flying free in Jersey.
By May the six had started to fly as a group, feed as a group, and play in the quarry buildings as a group. But, when it came to returning to the aviary they still had their own ideas. Sometimes they would fly back in twos or threes. We could, with relative ease, shut them in to the back sections and reopen hatches waiting for the remainder to return.
Chough waiting on the roof of the aviary. Photo by Liz Corry
When they returned as a group of six it often made it impossible to shut the hatches. There might be at least one bird on the roof on lookout whilst the others fed inside. Any movement like a passing cyclist or friendly team member approaching the hatches and an alarm call would send the group fleeing.
It was quickly becoming apparent that not all of the choughs liked being shut in. We did not want them to start viewing the aviary as a negative experience. The soft-release method had to be adapted. Instead of locking them in as they returned we waited until roost. At this point if the birds were in the aviary they were already fed, settled, and hopefully asleep and oblivious to the keepers. Hatches were reopened the next day and the timing brought forward by 30-60 minutes each day. So eventually the birds were being released at 8am then locked in again at 9pm.
Pierre tracking choughs at Sorel. Photo by Liz Corry
It meant that the team faced a long day spending the last hour before roost accounting for all six birds, then lurking in gorse bushes or hedgerows while waiting until sunset. On a couple of occasions the radio signals indicated that all six were at the aviary, but due to fading light and roost boxes it wasn’t obvious to see exactly where they were. We would not know until sunrise. Twice we found a bird had spent the night in the external roost box on the side of the aviary.
On one or two occasions Mauve would roost in the quarry whilst her partner chose to roost in the aviary with the others. She would reappear at the aviary in the morning for breakfast.
By the end of May the birds had clearly settled into a routine and were adapting well to life outside the aviary. The hatches were finally left open so the birds could come and go as they pleased.
Radio-tracking sessions started to blur into feeding sessions as the birds quickly learnt what time of day to expect staff to be at the aviary. At the first visit at 7:30am you might find them probing the ground by the edge of the cliff path, but as soon as they catch site of you or hear the gate opening they take to the air calling and fly to the aviary. It would also happen during the day, providing they were hungry enough. This time of year there are plenty of insects around to keep them occupied. As well as other distractions/attractions (depending on your view) at Sorel this time of year.
Chough at Sorel. May 2014. Photo by Miranda Collett
With the exception of the missing birds, the released choughs have not ranged far from their release site. We know choughs can fly far if they feel the need to. Yet during the breeding season they tend to stick within a few hundred metres of their nest site. Our choughs are not exactly in a normal situation though. What is more they are entering into an environment with no other choughs for guidance (or competition) and a habitat that still needs improving.
Last year they quickly turned the quarry into their second home and would venture no further. In fact they didn’t really spend much time elsewhere except the aviary. The only ground they touched in between was Sorel Point.
In April it looked like it was going to be much the same. As the group cohesion outside the aviary strengthened and the birds became more confident it quickly changed. By May they were foraging the grazed land next to the aviary. Probing for insects in amongst the flock of sheep.
After a week or so of exploring this area they decided to take it up a gear. During the phase of releases when hatches were opened around 10:30 and closed at sunset the group spent a few days visiting Crabbé.
Like clockwork they would fly west when the hatches opened. At first just circling the valley before heading to 2km west then soon straight to their destination. By the time the radio-trackers had jumped in the car and driven round the group would be back at Sorel.
We pre-empted them one day by splitting up and stationing one person at Crabbé before the hatches opened. Sure enough they flew over and continued over the shooting range out of site. Very quickly they returned, flew around Île Agois, then back to the aviary. They did this three times within 60 minutes and never landed at Crabbé.
Choughs near Sorel Point. May 2014.
Photo by Pierre Rauscher
These were exploratory flights which obviously told them they were better off staying at Sorel as they soon stopped going. This could be for very several reasons. Firstly the raven chicks had just fledged. They don’t pose a threat to the choughs but the parents definitely didn’t want the extra company in ‘their’ air space. A more likely threat would come from the nearby peregrine parents with their newly hatched, hungry chicks. Gunshot from inside Crabbé’s shooting range didn’t scare the choughs but guaranteed they weren’t going to land on the sand bank and grassy areas. The big drawback would be current habitat. A lot of agricultural fields, bracken and other overgrown vegetation are not what the choughs are looking for. There is a small area of short grass around the cliff path approach, but at the time of the chough visits there were hikers and farm vehicles that would deter a first time chough visitor from landing.
What is interesting is their lack of desire to explore the Devil’s Hole side of the valley where the sheep roam. They can see the land from the aviary, but as far as the team know the birds have never touched down over there. Maybe in time when they deplete their insect supply at Sorel.
Choughs at Sorel. Photo by Liz Corry
The choughs also seem to avoid exploring the rocky cliffs on foot and the lower grazed areas that slope down into the sea. Again this might be something that comes with time. For now they seem happy around the aviary. Free board and lodgings. Why look anywhere else?
When people hear about how the releases have ‘skewed’ off plan they are quick to assume that the behavioural training that we’ve been doing since early in 2013 has not worked. A bird is a bird; it will do its own thing. In some respects this is true. They haven’t always returned to the aviary when the whistle was blown for dinner but it may not be because they don’t know what the whistle means. There are many reasons why they don’t return and each bird has its own reason.
Evidence that the training has worked came to light once the birds gained confidence and started settling into a routine of returning to the aviary at night.
The choughs are now frequently flying up from the surrounding cliff top when they hear the whistle and heading straight to the aviary. They then land on the target boards where the keeper has left the food. If the food is left inside the aviary they can be cautious and wait patiently on the netting above until the keeper has left. They feel less restricted when the food is left outside and can fly within inches of the keeper’s head following them from target to target.
This has also meant we can continue to record body weights when they land on the scales in just the same ways as when they were locked in the aviary.
An interesting indirect pay-off of the training this year has been evident when they have encountered peregrines. The peregrine nesting season has probably meant there have been fewer interactions with the choughs compared to August and September last year. When a peregrine has flown along the cliff path the choughs take to the air and return to the aviary. They have obviously learnt to associate the aviary not just with food but with safe shelter.
Choughs at Sorel. May 2014. Photo by Pierre Rauscher
Posted 18 July 2014