Tag Archives: Ringing

Annual Chough report 2023

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Background

Red-billed choughs are considered a rare species in the UK, Ireland, Isle of Man and north west France and, until recently, were classified as locally extinct in the Channel Islands. Changes in agricultural practices decimated their habitat and primary food source, resulting in their rarity. Several other bird species have suffered a similar fate.

Birds On The Edge is a conservation initiative to restore coastal farmland habitat in order to benefit these species. The chough (caûvette in Jerriais) is the flagship for this work and in 2010 Durrell began a captive-breeding programme with the intention of releasing offspring into the wild.

Intensively managed releases between 2013 and 2018, coupled with post-release monitoring and care have resulted in a highly successful reintroduction. The Channel Islands is home once again to a breeding population of choughs.

Notable Events and Successes in 2023

The majority of our breeding success in 2023 centred around our pairs nesting in Ronez Quarry. Interesting observations were noted when checking the nests at the site. There were many more nest spots than usual; which suggested to us that others, perhaps younger choughs, were practicing for when they are mature enough to pair-up and breed. It will be exciting to see if our predictions come true in 2024!

Kevin feeding a chick on the aviary. Photograph by Charlotte Dean.

We recorded 18 chicks in nests within Ronez quarry during the year and one from another location which will be ‘assessed’ in the next breeding season. Fifteen of the total 18 chicks fledged to the aviary. Ten of the 18 chicks are still alive to this day and only two chicks out of the 15 that were blood sexed were male. This being said, due to an issue with the laboratory we use to sex birds, we have nine birds that are currently unsexed and who will remain so until they show breeding behaviour in the future. Given the historic sex ratio skew favouring females, we’re hoping that in 2024 a few more males will be produced.

Table 1, indicating the current population size along with the flocks known sex ratio.

Our only ‘wild-hatched’ pair attempted to nest in a stable during 2023 but were unsuccessful in their endeavours. They subsequently returned to Plemont where they have nested before. While it is believed chicks were hatched, sadly they were never seen at the aviary, suggesting they perished.

The pair of chough that have successfully nested at Simon Sands Ltd. were seen nest prospecting in out-buildings at the airport. This behaviour was dissuaded on health and safety grounds. It is hoped they return to the safer location of the old sand extraction site in 2024.

Impatient choughs awaiting supplementary food. Photograph by Charlotte Dean.

Breeding pair Vicq & Pinel surprised the team this season. They brought one chick to the aviary at the very end of July. This is the first time (to our knowledge) this pair has had a successful breeding season. While there were initial reports of them nesting in a stable building in Trinity, they subsequently chose to nest somewhere else, the location of which is currently unknown. We hope that this will be the start of a successful breeding pair for the future.

The flock has lost a total of nine individuals over the course of the year, but has gained ten new members. Of those choughs that have disappeared, their partners have re-paired up and we hope to see some new successful breeding pairs next season. Overall, it has been a successful year.

Activities in 2023

Primary activities continued as detailed below:

Supplemental feeding

Provision of supplemental food continues daily at Sorel. Attendance by the flock varies seasonally and between individuals. It remains a reliable way to ascertain population size. There are currently forty-seven individuals of which over two thirds are now wild-hatched (Released: 13: wild hatched: 34).

Supplemental feeding allows staff to closely monitor health issues and inter-flock behaviour. Concerns can be flagged up quickly and often dealt with on the spot.

Notable leavers and losses

After forty years of service at Durrell Wildlife Conservation Trust, Dr Glyn Young hung up his boots for the last time in August. He will be enjoying the retired life after much dedication to the Trust. His wisdom and knowledge will continue through the next generation of conservationists who all benefited from his experience.

A picture of Liz and Glyn when the project began!

Sadly, we lost the oldest chough of the flock and one of the two remaining choughs from the project’s first releases back in 2013. Green, although gone has contributed to the population by siring forty-two chicks over the past twelve years; fifteen of which are still alive today.

Green & Pyrrho enjoying the summer heat. Photograph by Charlotte Dean

Research and monitoring

There have been no exciting island-hops for the usual, same-sex pair of choughs to Guernsey this year. Usual visitors to the island, this pair appeared to have broken up, with only one female being observed foraging at Pleinmont. The other female has now found a male worth sticking around for! This could lead to an exciting new breeding pair in the next coming year.

There a few visits to Ronez quarry this year to undertake nest checks. Only two clutches of chicks were ringed in the nest however, as inclement weather prevented other nests being accessed. Subsequent ringing was carried out when youngsters were caught at the aviaries, but three remain unringed at present.

Three chicks in Kevin & Wally’s nest. Photograph by Tobias Cabaret.

We look forward to 2024 when we welcome a PhD student from Anglia Ruskin University to research the choughs for effects of sound disturbance during the breeding season.

Veterinary cases

One of Kevin and Wally’s chicks from last year’s season (Sallow), was found grounded by a local birder in St John. Initially taken to the JSPCA, Durrell ultimately took responsibility for the bird. It was suspected to have a broken coracoid due to the visual bruising in the area; however, this was thankfully not the case. The chough was also seen to have a low platelet count and was underweight. The veterinary team supplied the chough with pain relief and fluids. The Bird Department provided the diet previously used for the captive choughs. Additional food supplements and tasty treats were given to help fatten him up. In our care, the chough gained 20 grams before he was taken back to the aviary. Before being fully released, we had a licensed ringer, ring the chough and then shut him into one of the sheltered sections of the aviary. He was kept here for a few days to habituate once again to his surroundings and for staff to evaluate his flying ability. Once the team were happy with his progress, he was re-released and is still looking happy and healthy to this day.

The remains of a youngster from 2022, Birch, were found at Ronez. Scant remains were collected, so no post-mortem was performed, but rings allowed us to identity it.

Release aviary maintenance

The Sorel aviary is considered a temporary structure for official planning purposes. Permission to keep the structure standing for the next five years was approved in 2023, which means it will be standing until at least 2027.

Storm Ciaran left devastation throughout the island in 2023 and the aviary at Sorel sustained significant but not catastrophic damage. Large holes were ripped in the netting, and aluminium panelling at the side of the aviary was ripped off. Some of the wooden support structures of the enclosure itself were also left weakened and broken.

The aviaries fallen wooden framework. Photograph by Charlotte Dean.

The aviary netting holes require National Trust assistance to help bring our large henchman ladder to the aviary to have the holes reachable to fix. We are working on these repairs between the National Trust and our own staff availability. The wooden framework is a much bigger job which will be fixed at a later date by our maintenance team at Durrell.

Choughs flying over the aviary. Photograph by Abbie Thomson.

In autumn, we secured a grant from the Government of Jersey’s Countryside Enhancement Scheme to fund new netting for the aviary. Thanks to the States of Jersey for this funding, which will enable us to replace the damaged netting in 2024.

Chough report – June 2023

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By Charlotte Dean

Our sincere apologies for the delays in circulating monthly reports. We hope to start catching up.

Wild weather
It’s that season again when the chough team make arrangements with Ronez Quarry to access the chough nests for the first nest checks and chick ringing. Unfortunately, the weather this year was not in our favour. As the quarry is an unsheltered area along the north coast, there is no easy or safe way to access high nests in winds above F4. Most of June had this level of wind so the team and quarry staff agreed it wasn’t worth the risk. However, we could at least access some of the nests on foot. The pairs we managed to access this way were those of Kevin & Wally, which had three very noisy chicks inside, and Bo & Flieur whose nest surprised us with four chicks! The chicks were ringed with our year colour for 2023 which was Pink and will be accompanied with another coloured ring for easy identification in the field. The chicks were also blood sexed, weighed and measured before being placed back into their respective nests. Without access to the other nests the team can at least acknowledge that there are currently seven chicks in two nests so far; but as there is plenty of activity in other well-known nests, we’re sure we’ll have more chicks.

Quarry updates
The quarry also witnessed a few unsuccessful fledging events this year due to the adverse weather; practically a whole month of high winds. One chick was found dead beneath a nest site for pair Green & Pyrrho. We believe that it could have died from the impact after falling from the nest, it was not, however, of fledging age and, therefore, we assume it’s death may have been caused by some sibling rivalry for space in the nest. Later, fledglings emerging from Kevin & Wally’s nest were also found on the ground near their nest site. Both were initially going to be collected by quarry staff to be assessed for cause of death by the Durrell veterinary team. However, one chick had already been predated by then. We were thankful to know that at least one chick from Kevin & Wally had also been seen by quarry staff wing-begging at its parents from the staircase just outside their nest site, looking active and healthy. Since Kevin & Wally’s chick emerged from their nest, the quarry staff have contacted us about other chicks that have been seen around the quarry as well; we can safely say that the quarry is starting to get more noisy than usual!

Plémont pair
The Plémont pair, Minty & Rey had been seen feeding chicks in their cave nest at a few days old at the end of May, which was very exciting news for our truly wild pair. Both Minty & Rey had both been seen at the Sorel Aviary every day since then. To the team, this seemed like a big issue. This could indicate that Minty & Rey were not finding enough food from foraging around their nesting area and, therefore, were coming to the aviary for food. When spending long periods of time at the aviary as a pair, they were leaving their newly hatched chicks in a nest unprotected. The chough team visited their nest the week after and were faced with silence. It was assumed that while they were still coming to the aviary for food, their chicks were predated in their absence. It has been a great shame to witness the silence from within their nest again this year. We are hopeful that they will find a new and successful place next breeding season. 

First choughlet at the aviary
The wait is finally over, the team finally heard the calls of a hungry chick at the aviary. The first pair whose fledged chicks came to the aviary this year were, perhaps unsurprisingly, Kevin & Wally on 15th June. And it wasn’t long before the other pairs started to bring their chicks too. Green & Pyrrho and Percy & Icho both brought two chicks a few days later. Dusty & Chickay, Bo & Flieur and Lee & Caûvette brought chicks at the very end of the month. Dusty & Chickay and Bo & Flieur both brought two chicks and Lee & Caûvette brought the one. Trevor & Noirmont’s nest was looked at in our Ronez Quarry visit but their chicks were a lot younger than the other breeding pairs’ – we expect them to arrive early next month.

 

Chough report: November 2022

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By Charlotte Dean

Wind, rain & DIY!

The wind and rain have been battering the aviary a lot this month, so the keepers have been kept hard at work carrying out regular aviary structure checks, keeping the hatch wires tight and tying down and fixing any loose panelling. With all these strong winds, the aviary definitely has a low groan, while still standing strong. Thanks to the strong winds and heavy downpours it’s been a month of aviary surprises. As you will see in the photograph, one of our release hatches broke at the hinges – just goes to show how windy it has been! Thankfully, it wasn’t a hatch that is regularly used so it didn’t cause any harm to the keepers or the birds. The hatch was fixed but will eventually be replaced with a new one in the New Year. Considering the aviary was built almost 10 years ago, it is surprising that it doesn’t have more wear and tear and, despite the terrible weather, it is quite clear that it doesn’t stop the choughs from having fun!

Colour-rings

It has come to that time of year when colour rings start dropping off our choughs; this is most likely caused by the drastic change in temperature making the already long worn colour rings brittle enough to fall off. This in turn can bring identification concerns, but nothing a catch-up and re-ring can’t fix! If we can catch them that is. We have recently had a few of our adults fly into the aviary with colour-rings missing but thankfully these are some of our pairs and, therefore, it’s easy to know who’s who by identifying the other bird in the pair. We can just be thankful though that they’ve been lost and haven’t caused any ring-related issues. As choughs are relatively large birds, we use ‘wrap-around’ plastic rings which can, luckily very rarely, trap toes and/or claws; but in most cases, other ring options can have similar problems.

When a chough has its toe and/or claw stuck in a colour-ring, it doesn’t worry the keepers too much as this is a common occurrence for some birds. Furthermore, trapped digits are often more common in female choughs during the breeding season as their rings get stuck while they’re incubating. However, the birds generally manage to correct themselves without the keepers intervening. At the moment, however, we have a two adults in the flock that have their digits stuck in their colour rings, which we are closely monitoring. So far, they’ve not shown any signs of injury, but it may be that they will be caught up in the near future if the problem doesn’t naturally correct itself.

Juveniles catch-up

An attempt was made at the end of November to catch some adults with plastic ring issues; however, as ever, the adults outsmarted the keepers and flew away before they had a chance to set up! As we had arranged a ‘back up’ of other happy helpers to the aviary, we took the opportunity to catch some unsuspecting juveniles that let their hunger get the better of them by entering the aviary. So, five of the thirteen 2022 chicks were caught in the aviary. Although the newest additions to this wild populations have already been given names, we took blood samples from the briefly held juveniles to find out their sexes! The first five choughs caught, and blood sampled were: Willow, Liberty, Pine, Sallow & Birch. The blood samples themselves will take a few weeks to be processed and for us to receive the results. However, on visual observations, some choughs are more obvious through sexual size dimorphism than others. Male choughs are generally much heavier and larger than female choughs. On close inspection it became very clear that Sallow is a very large bird and most likely a male, it was the largest of all five caught. Portelet, a female which hatched in 2020, has been warming to Sallow of late and was spotted waiting outside the aviary for Sallow’s release. This brings great hope for a new pairing of Sallow & Portelet in the near future. Birch was quite average in size, however, but like Sallow & Portelet; Chewbacca was also seen waiting outside the aviary for its release so there could be another pair on the horizon. In the meantime, watch this space!

 

Chough report: July 2021

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By Liz Corry

Plémont success

Last month we reported our first successful rearing of young from a wild-hatched pair. Three chicks in the Plémont nest followed by the subsequent fledging of two.

Then, like a high street in lockdown, it went eerily quiet.

There was no sign of the third chick out and about. The Plémont cliffs are not very forgiving at high tide for a young bouldering chough. Easy to imagine it not surviving. Yet also hard to determine since we weren’t seeing any members of the Plémont family.

When Minty and Rey, the parents, eventually appeared at the feed they showed no interest in any of the juveniles. Observations were further hampered by the lack of choughs at the feed. We had to put in the extra mileage, literally, to travel in search of choughs or wait until the evening when they start heading home to roost.

A roost check at Plémont provided no answers just a stunning sunset.

The only info we had was from a member of the public who had photographed Minty and Rey with one unringed juvenile at the Pinnacle on the northwest coast. This was taken in June before we had managed to ring any of this year’s young.

The first Jersey juvenile from wild-hatched choughs. Photo by Anthony Morin.

Four weeks of not knowing then suddenly we had our answer. Reviews of camera trap photos set at the aviary showed Minty passing food to a chick. A chick we had ringed on 14th July and had seen at the feed every day since! Until that last week in July we had never witnessed Minty or Rey show any interest in the youngster.

Maybe that is their parenting style? The young chough is fairly robust, gets on with things, is confident around the aviary and within the flock. They raised her well.

We have named her Rémi which means ‘the first ones’ in Gaulish. Rather apt for the first true Jersey chough resulting from the reintroduction.

Family hierarchy: Rey. Minty, and Rémi. Photo by Liz Corry.

Five ‘gold’ rings

With much effort, we continued to try and trap unringed juveniles in the aviary. As already mentioned, the birds were not hanging around Sorel as much as in previous years. Leftover supplemental food and their preference of sites such as Grosnez, Les Landes, and L’Étacq implied they had resources elsewhere.

When choughs were present at the aviary they were, and still are, not as confident about going inside. No doubt for multiple reasons although strong influences will be the peregrines hunting above the aviary field and the overgrown vegetation potentially harbouring threats.

We switched tactics to try catching later in the day, around 7pm, by which point choughs roosting at Sorel or Ronez would be foraging closer to home. This worked on two occasions allowing us to ring, measure, and sample two juveniles.

By the close of July there were no more unringed choughs to be found. In total we had ringed five chicks all with a yellow ring to represent 2021 and a second unique colour. Sadly, that meant some youngsters had perished.

The yellow ring represents 2021, the bird’s year of hatch. Photo by Liz Corry.

2021 Breeding Season summary

Of the ten nests we knew about, only 50% survived to fledge a chick or more. We accounted for twelve fledged chicks yet only four still alive.

There is a slim chance a fifth chick, ringed pale blue over yellow, is simply playing an unintentional game of hide and seek with us. Seven adults are consistently absent at the afternoon feed. A few of those have been spotted along the coastline from Grosnez to Le Pulec. Is the missing chick with them? A task for August will be monitoring this northwest corner and determine the whereabouts of the pairs.

Wally Jnr. keeping close to her parents at Sorel. Photo by Liz Corry.

There was an eleventh pairing in spring who were busy collecting nesting material in Trinity. As first timers we did not hold out much hope. It appears they did not even make it to the egg laying stage. No nest was found. Lots of false hope through seeing them steal twigs from pigeon nests. No actual Trinity chough nest.

This may or may not be related to the disappearance of the female. Then this month, the male was seen with a different female over in… guess where…Grosnez.

Tracking down choughs at Grosnez. Photo by Liz Corry.

Pinel was starting to worry us until we found him at Grosnez. Photo by Liz Corry.

Green fingers

We are carrying out several ‘gardening’ tasks around the aviary to create a less imposing surrounding for choughs, open up some foraging opportunities for them, and allow us to see when operating the hatches from the adjacent field. It should also mean less cover for feral ferrets to hide in and less attractive areas for rats.

Where are the sheep when you need them?! Photo by Liz Corry.

This meant a lot of grass strimming and removal of bracken. Hedgehogs, slow worms, and green lizards inhabit the embankment, so care is required. I also discovered a bumblebee nest and several ant nests; the latter a favourite of wild choughs.

Slow worm and an ant nest uncovered at Sorel. Photo by Liz Corry.

In amongst the bracken there are shrubs the National Trust planted about ten years ago. Each year we try and help these out by removing the vegetation suppressing them like the delightfully named sticky willy. I’ve left the aromatic wormwood…how do we feel about a Birds On The Edge branded absinthe? We could raise a glass to toast the wild Jersey choughs!

Wormwood Artemisia absinthium, is one of many herbaceous plants found at Sorel. Photo by Liz Corry.