by Liz Corry

Despite a turbulent start to the breeding season the choughs at Durrell had their most productive year to date. We took a slightly different approach to our management of the pairs this year and it seems to have paid off.

We left Issy and Tristan to parent-rear in the display aviary. Out of the three pairs we have, they were the most likely candidates to succeed here despite the aviary being on-show and susceptible to disturbance. We would, of course, step in if the need arose, but in the end all they needed from staff was a constant supply of food.

Issy’s clutch of eggs visible on the nest camera monitor. Photo by Liz Corry.

Issy laid four eggs in total. On 6th May the first two eggs hatched. The chicks looked healthy and the parents were very attentive. The following morning a third chick was visible on the nest camera although it was not very active.

Sadly this last chick did not live very long and by the end of the day the parents had removed the dead chick from the nest.

The fourth egg stayed in the nest for a few days. When it was apparent it was not going to hatch the parents discarded it and focused their efforts on raising their two chicks.

We have been successful in the past with chicks hatching under their parents. However, the few chicks we have had only survived for a few days to a week at the most. Understandably staff were nervous. Visitors to Durrell may have questioned why the aviary was so overgrown when our signage clearly states that choughs require short-cropped grassland. The simple response is “Would you want a large animal with a noisy strimmer spewing grass, thistles, and weeds in front of your baby’s cot?”. We didn’t want to do anything that would distress the parents and could lead to the nest being abandoned.

The on-show display aviary became the breeding aviary for Tristan and Issy this month. Photo by Liz Corry.

However, we do need the birds to be able to forage naturally so the chicks can learn skills for surviving in the wild. The solution was to wait for the chicks to be a couple of weeks old, i.e. past the critical stage, and go in at feeds times with hand shears. Spending five minutes here and there trying to keep on top of things until the family are accepting of a ‘large animal with a  strimmer’.

Tristan and Issy dutifully cared for their two chicks. Photo by Liz Corry

By the 24th, the chicks were almost adult-sized with feathers head-to-tail. They had reached a milestone never achieved at Durrell before. To mark the momentous occasion we gave them leg rings. More out of need than celebration. The best time to add rings and obtain DNA for sexing is when the chicks are three-weeks old. We assigned names to the chicks following the alphabetical system of previous years. These chicks will be S and T. Full names will be given once genders are known and they have been moved up to Sorel which should be in July.

Keeper Kathryn Smith with a three-week-old chough chick ready to collect DNA. Photo by Liz Corry

The story proved to not be as straightforward for the other pairs. We anticipated problems based on previous experience and the fact that we had a new pairing. The plan for these pairs was to allow partial parental incubation then remove eggs to artificially and/or foster incubate the remainder of the time. Once hatched, the chicks would be hand-reared for the first five days before recruiting Gianna to help foster rear until they fledge. Using Gianna as a foster mum helps reduce the chance of the chicks imprinting on the keepers. It also means we get out of having to do the early morning and evening feeds as Gianna can take care of them.

Both pairs laid a clutch of four eggs. This is where it gets complicated. We rescued one egg from Gwinny before her partner had time to do any damage. Once he was relocated she laid another three which we left with her. We only managed to recover two eggs from Mrs Denzel. All three rescued eggs were given to Gianna to carry on incubating.

Keeper Jess Maxwell with the chough eggs in the incubation room. Photo by Liz Corry

Gianna was already incubating three infertile eggs of her own so we simply swapped them over. Since Gianna is very tame she was very accommodating to staff when they needed to weigh and candle the eggs to check on progress. We were not so sure how Gianna would cope with hatching eggs having never experienced it before. To optimise everyone’s chances we relocated the eggs to the incubator at the Bird Department on 18th May a few days prior to hatch date. We gave Gianna dummy eggs to ensure she continued sitting until the time was right to start fostering.

Gwinny incubating her egg. Photo by Liz Corry

Following so far? All this time Gwinny had been incubating three of her own eggs. On the 18th we went to her nest to candle the eggs and found that all three were fertile and on-course for hatching.

Gwinny has looked after hatchlings before, but never succeeded in getting them much beyond that stage. Without a male to help feed her and the chicks we were concerned the odds would be against her.

However, we wanted her to have a chance and gain the experience. We took two of the eggs back to the incubation room and left her with one in the hope that she would cope with having just the one chick to feed. With five eggs in the incubator (three belonging to Gwinny and two belonging to Mrs Denzel) it might give the impression that the next bit was just a breeze. Sit back and wait for the eggs to hatch. Alas no.

To summarise, it feels like an injustice to the work the keepers put in, but to save on digital ink lets just say we had to assist all but one of the eggs. A few had ‘holes’ drilled into the shell to increase air-flow. Two were assisted at hatch because the chick was struggling to do so alone. One egg sadly didn’t make it to hatch because the chick was badly malpositioned and unable to even attempt to break free.

A small hole was ‘drilled’ into a chough egg to aid successful hatching. Photo by Liz Corry.

The first egg to hatch in the incubation room did so on the 21st. Two days later there was a second and the following day, with some help, the final two hatched. In order of hatching the chicks were named U, V, W, and X in hope that all four will succeed and make it to Sorel.

Chough egg hatching at Durrell. Photo by Liz Corry

Assisted hatch at Durrell. Photo by Liz Corry.

A chough chick seconds after hatching at Durrell. Photo by Liz Corry.

The egg left with Gwinny failed to hatch. She remained incubating it for a long time after the due date, but eventually gave up. The egg was taken to the Vet Department for a post-mortem.

Chicks U, V, W and X were hand-fed using tweezers every hour quickly progressing to every two hours as they grew. Feeds began at 6am and finished at 11pm. The chicks were healthy and developing well. When the first chick was five-days-old we relocated it to Gianna‘s nest where she had been patiently waiting. Within three days all four chicks were in the foster nest with Gianna.

Foster mum Gianna helped with feeding the chicks once they reached five days of age. Photo by Liz Corry.

Myself and Bea, the chough placement student, took turns feeding the chicks and Gianna. Five feeds a day from 7.30am until 5.30pm. Gianna carried out the remainder of the feeds. Occasionally trying to feed us too! Luckily Gianna took responsibility for cleaning the nest and disposing of the faecal sacs. In turn we had to clean Gianna before a new species of white-billed chough evolved.

There was a slight worry on the second day of chick V being in the foster nest as it was looking lethargic and had not put on any weight. Chick U had put on weight and was obviously being fed by Gianna. As a precaution V was moved into a heated brooder and regularly hand-fed for the rest of that day. It was then returned to the foster nest before the last feed to spend the night with Gianna and its sibling. The next day V had improved so it stayed in the nest and we target fed that chick whilst Gianna looked after the others.

Regular monitoring of the chicks meant that we could quickly see and react to anything untoward. Fortunately for the rest of the month there were no concerns. With a fledging period of 42 days there is still a long way to go.

The ‘fab four’ chough chicks in their foster nest. Photo by Liz Corry.

By Liz Corry

The choughs in Jersey have had an extremely busy month. There is so much to tell that we have had to break up the report into two parts to save it becoming a Tolstoy-esque report of epic proportions. This first instalment will highlight what has been happening out at Sorel with the free-living group. This will be followed with an update from the choughs in the Wildlife Park whose offspring will hopefully join the flock out on the north coast this summer.

We are very proud to announce that the three nesting pairs in the quarry gained a status promotion this month to ‘breeding’ pairs. We suspected the females had started incubating towards the end of April because they were only leaving their respective nest sites maybe two or three times a day to feed. The rest of the time their partners were providing the food. With a suspected (hatching) due date of Friday 13th we were naturally anxious to see what would happen.

Breeding pair Green and Black. Photo by Liz Corry

Green and his partner Black are a new pairing this year. Green is a proven breeder having reared the wild chick last year with his previous partner Blue. After her mystery disappearance at the start of the year he quickly paired with Black.

Black has managed to keep a secret from the chough team this year. How many chicks will fledge the nest?

The pair  re-used Blue’s old nest. Considering that this was where the wild chick hatched in 2015 we felt fairly confident it would be successful. The exact location of the nest makes it difficult to see inside so we do not know how many eggs she laid.

A week after the due date we went to check on their progress. We attempted to look in the nest using cutting edge modern technology….a video camera gaffer taped to a fishing rod. Disappointingly size does matter. We were an inch short of reaching the centre of the nest.

However, we did hear a chick, possibly two chicks, begging from the nest and the metaphorical bottle of champagne was cracked open.

Our second pairing White and Mauve failed to rear any chicks last year. White is slightly more mature this year and more focused. Regular and prompt visits to the nest ensured that Mauve was well looked after. When we checked their nest we found two healthy looking chicks and two eggs. Sadly those two eggs should have hatched by that stage. That didn’t stop us uncorking metaphorical bottle number 2 in celebration of the two chicks. This now meant we had two confirmed breeding pairs.

White and Mauve’s nest containing two chicks and two unhatched eggs. Photo by Liz Corry

The third pair, Dingle, our hand-reared chick from 2014, and Red were an unknown quantity. Red has never had much luck with the boys and tried desperately to breed last year during her brief five-day fling with Green. As a hand-reared bird no one knew how Dingle would take to parenting. Luckily we had our mole on the inside, Kevin Le Herissier, keeping a cautious watch on the pair. He had no choice really. They nested in his building down in the quarry. Yet again the choughs had chosen a warm, dry, fully operational building to nest in. Rather considerate of them to also choose a site easily accessible.

Chough footprints give the team a clue as to which buildings the birds are using. Photo by Liz Corry

Under guidance, Kevin checked the nest on several occasions so we were able to know that the pair laid a clutch of four eggs. Red started incubating a few days after Black which meant she had a less ominous due date of Sunday 15th May. We left them undisturbed until 20th May when a check confirmed she had two chicks. No sign of the other two eggs. This was amazing news for the team and a proud moment for everyone involved (and cue metaphorical bottle number 3).

Red keeping guard as we checked her nest. Photo by Liz Corry

Two chicks in Red and Dingle’s nest only a few days after hatching. Photo by Liz Corry

Three metaphorical bottles of champagne in one day seemed a little excessive. Especially considering these chicks were only 5-7 days old and had another 35-37 days to get through before fledging. At three-weeks old the nest sites will be revisited to fit leg rings to the chicks and take DNA samples for sexing. By this stage any surviving chicks should make it to fledge. Fingers crossed there will be four to six wild fledglings by the end of June.

In other news…

In the very first week we were concerned over the health of White. He had been sneezing on and off for a couple of weeks. It was difficult to know at first whether this was just due to all the nesting activity in the rock dust at the quarry buildings or an illness. A faecal sample tested positive for Syngamus (gapeworm) so White was caught up in the aviary, medicated, and let straight back out. The sneezing stopped almost immediately and he has not shown any other signs of illness for the rest of the month.

White was treated for Syngamus at the start of May. Photo by Liz Corry

The non-breeding birds

The other non-breeding choughs had a relatively quiet month making the most of having no responsibilities and just playing, bonding, and foraging around Sorel and the quarry. As can be seen in this video:

Or so they would have us believe. The birds started moulting in May which meant the tracking devices starting dropping off one by one. As far as myself and the student were aware, the choughs were always around for the twice-daily feeds and, therefore, always at Sorel. Thanks to a few reports from the public we know that was not the case. There were confirmed sightings of small groups over at Devil’s Hole, Grève de Lecq and Grosnez. We have also had intriguing reports of one or two flying around St Saviour’s parish. Both reports on the same day.

Jersey National Park

There was a strange sighting of a chough at the north end of St Ouen’s Bay hanging out with a puffin at the start of May. There is photographic evidence. Unfortunately for the people involved there is also video evidence.

Caûvette the chough (aka Bea the student) and The National Trust’s puffin made cameos at the launch of the Jersey National Park hosted by Jersey Pearl on 3rd May. The park extends over an area of approximately 30 miles (48km) of Jersey’s coastline including Les Ecréhous, Les Minquiers and Pierres De Lecq or Paternosters.

The real Caûvette and the other choughs at Sorel feature in the launch video using a 360 degree camera.

Dung is fun!

We had another visit in May from the Dung beetle UK Mapping Project team (DUMP) based at Oxford University’s Natural History Museum. Darren Mann, Ceri Watkins, and Sally-Ann Spence returned to Jersey to study the island’s beetle fauna more closely after last year’s surprise find of the rare Aphodius affinis beetle. This time round they enlisted the help of Simon Robson, one of Jersey’s top entomologists, and quite literally delved into the island’s dung.

They were amazed at the wide diversity of dung beetle species present on the tiny island, but alarmed at the lack of abundance. It most likely reflects the quality of habitat and the agricultural practices of modern day Jersey. The addition of sheep at Sorel is the only reason why certain species of beetle are present there. They only feed and, therefore, breakdown and dispose of sheep faeces. Birds On The Edge will feature a report of their visit in the next couple of weeks. Sign up for regular updates to discover why #DungIsFun.

By Liz Corry

Easter may have been early this year, but our chough eggs waited until April was in full swing to make an appearance. The first sign of egg-laying at the Wildlife Park was on 12th April when the nest cameras revealed an egg in Iseult’s nest. Within a week she had finished laying and started incubating.

Iseult’s eggs – view from the nest camera monitor. Photo by Hester Whitehead.

Choughs normally lay around five eggs in captivity with the female starting incubation when the third egg is laid. Issy appeared to be quite restless at first, leaving the nest whenever she was disturbed. As the aviary is on show to the public the decision was made to cordon off the footpath which runs alongside the nest site. This seemed to work well and Issy continued incubating.

The public footpath was blocked to prevent disturbance to the nest whilst Isuelt was incubating. Photo by Liz Corry.

Egg-laying for the other two breeding pairs in the Park was not as straightforward. Both pairs took a long time to progress from a few twigs in their nest-box to a fully lined chough nest. Then it was a matter of waiting for the first egg. It turned out to be a very long wait to the point we had almost given up expecting anything. Seventeen days after Issy laid her first egg Gwinny and Mrs D started laying their own.

Denzel and Mrs D have very little experience in breeding and this is their first time together. Everything appeared ok when Mrs D laid her first egg. Then keepers had a moment of doubt when they checked the nest cameras. “I’m sure there was an egg there before?”, “Is that an egg or a bit of wool?”, “It’s ok its still there”, “Wait, has the egg gone again?” Checking back over the camera footage we realised that what was hoped to be lighting issues and camera trickery was actually Denzel carefully removing the egg from the nest and Mrs D laying her second egg. He did the same thing to the second egg in the evening when staff had gone home.  The remaining eggs were rescued before he had chance to act and given to Gianna to foster incubate.

A slightly different scenario played out next door in Gwinny and Lucifer‘s nest-box. This time it was not just the eggs in danger. Gwinny and Lucifer have had clutches for the past two seasons. There have been issues with each clutch and eggs being tampered with. Staff usually have to rescue to artificially incubate. CeCe being the result of last year’s rescue efforts. We were quite prepared for the same to happen this year. What we were not prepared for was Lucifer‘s reaction to the first egg. As can been seen in the video below he became extremely aggressive to the point where Gwinny was in danger.

Staff reacted quickly and re-housed Lucifer away from the breeding aviaries. There was the slight risk that Gwinny may abandon egg-laying due to the disturbance and not her ‘partner’ not being around. The risk to Gwinny by leaving him in the aviary far outweighed this and our actions were justified as she continued to lay over the next few days and has incubated consistently since then.

Staff rescued the first egg as planned and gave it to Gianna to foster-incubate along with Mrs D‘s two rescued eggs. Gwinny went on to lay three more eggs which were left with her to incubate as she was sitting so well.

Gianna has shown that she has learnt from her experience as a first time mother last year and is even more attentive to her nest this year. As with last year she was given a dummy egg to stimulate egg-laying. This seemed to work and a few days later she produced her own, followed by two more. This is quite interesting as last year her first egg was her only egg. Gianna will be used for foster-incubating and foster-rearing. We are not 100% confident in her ability to look after hatching eggs so any fertile eggs she has will be transferred to an incubator in the Bird Department and subsequent chicks hand-reared for the crucial first few days before returning to Gianna.

Gianna will hopefully help out again by foster rearing this year. Photo by Liz Corry.

Over in Cornwall our partners at Paradise Park appear to be having an easier time with their five breeding pairs. You can watch live footage from their nest cameras by clicking here. Potentially one or more of the chicks you will see on camera will be joining the flock out at Sorel later on this year.Update from Sorel

It was a little harder to determine when the choughs at Sorel started egg-laying. There was a period towards the end of the nest-building stage when the males started displaying to their partners and several mating attempts were observed. Green in particular liked to show off by spreading his wings to full extent and parading around Black. Or any other female that happened to be in sight.

Green showing off the size of his wings to his partner (on the right) on the roof of the aviary. Photo by Liz Corry.

Dingle joined in with collecting wool for his nest with Red. This is really promising behaviour and progress from last season when he partnered up for the first time. He has also been observed taking nesting material from the quarry in the form of lagging around pipes. Very resourceful. A recent roost check showed that the pair have switched from roosting at the aviary to roosting in the quarry. A sure sign they now feel invested in their nest and want to keep a close eye on it.

Dingle collecting nesting material from outside the aviary. Photo by Liz Corry.

We determined that the females had started incubating eggs by observing behaviour before and after the supplementary feeds at the aviary. Black was the first no-show of the three incubating females. As it is only the females who incubate the eggs they try not to leave the nest too often. When they need to leave, they need to know ‘abandoning’ their eggs is worthwhile. The choughs know when to expect food at the aviary because staff stick to set times. Sometimes, however, staff are delayed so instead of taking the risk of flying to the aviary to find there are no food dishes out Black waits for Green to return with the supplementary diet, thereby letting her know staff have put the food dishes in the aviary. After a minute or two discussing the tardiness of the keepers and what’s on today’s menu, the pair will then head over to the aviary, quickly feed, and return on a full stomach to continue incubating the eggs. Mauve and Red followed suit so now all that remains is to continue observing behaviour and count down the days to the expected hatch dates.

We still have the young pairs feeding and preening each other but not yet ready to nest. A new pairing we noticed this month was that of Lee and Caûvette. It will be interesting to see if this relationship continues throughout the year. Caûvette was hand-reared. Any nesting attempt by her will be followed with great enthusiasm not just by the chough team, but by other reintroduction projects around the world.

Lee and Cauvette, a hand-reared female, have paired up. Too young for this year’s breeding season but promising for next year. Photo by Bea Denton.

The other new pairings appear to be going well. Q and his female Noir can be seen below taking part in a spot of mutual preening after lunch.

Q and Noir have bonded over the past couple of months. Photo by Bea Denton.

Q invites Noir to return the favour and preen him. Photo by Bea Denton.

We had one piece of information this month which helped add solid facts to our breeding records, but also brought with it upsetting news. Early morning on the 4^th April and email came in from quarryman Kevin Le Herissier that said “have a bit of good news and a bit of bad news”. I might have then stolen his thunder by suggesting the good news was the discovery of a chough nest.

Dingle and Red’s nest before Red starting laying. Chough nests are protected in the UK and cannot be photographed or approached without a licence. Photo by Liz Corry

What could not have been predicted was the bit that came next. The bad news.

Kevin had been working in the asphalt plant that morning and suddenly heard a group of choughs alarm-calling outside. He noticed several birds looking very distressed, hopping around on the ground, shouting at something. When he got closer he realised that in amongst the cacophony of choughs there was a chough head! No body, no feathers, just a head. We arrived on site shortly after the phone call and after a little detective work we found, at various sites, a piece of wing, intestines, and tail feathers with a radio transmitter attached. From this and her absence at the aviary feeds we knew the deceased was Ormer one of the 2015 chicks from Paradise Park.

Ormer was found dead in the quarry this month potentially predated by great black-backed gulls. Photo by Liz Corry.

Whilst not wanting to sound uncaring, quarry and bird staff breathed a sigh of relief. It was not one of the breeding females and it was not Dusty the wild chick. A loss nonetheless though. I presented the remains to a somewhat perplexed vet team to try to gather as much information as possible from a post mortem examination. Blunt trauma fracture on the skull and descriptions from quarry staff suggest that Ormer and the others had had a run-in with the gulls who also nest in the quarry. Great black-backed gulls are notorious for their aggressiveness and predatory behaviour and were seen nearby (a number of pairs nest in the quarry alongside the more numerous herring gulls) and were considered responsible.

We have observed choughs chase off gulls (normally, or always, herring gulls) simply so they could play on the rocks the gulls were sitting on. Some may use the term ‘bullying’, but we like to think of it as being over-confident. Unfortunately this time around Ormer met with an even more confident species.

Another impressive sunset as staff carry out a roost check. Photo by Bea Denton.