Tag Archives: Durrell

Around the world with invasive species

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By Glyn Young for Jersey Invasive Species Week 2022

I cannot remember not being interested in (ok, obsessed with) the world’s birds. I’ve long wanted to see as many as I can, wherever I can. I’ve been very lucky in that I’ve been able to get close to birds as a profession too. In fact, my profession has changed my involvement with birds from simply watching them to wanting to save them from dying out, to help the rarest of the rare from becoming extinct. Working at Durrell has involved me with some serious problems and three times I’ve worked with birds considered the rarest on earth. That they aren’t the rarest now is not because they died out but because Durrell and its partners succeeded in getting them through the crisis. They are still rare but there is hope.

At Durrell, we typically become involved with a species when it is already very rare and it is considered that our involvement can help it turn the corner. Planning a recovery project requires us to look at three key things: pressure, state and response. That is, why is our bird so rare and what are the drivers of its decline? How many are there and exactly where do they live? And then, what can we do to change the future for the species? However, while we need to map our species’ current distribution, count how many there are and then determine what we can do for them and who we will work with, we generally have a pretty good idea what is making them so rare.

We think of habitat loss and conversion, of hunting and persecution as drivers of bird decline. But inevitably, invasive alien species (IAS) are going to be in there somewhere. So many of the world’s animals and plants are now being pushed towards extinction by alien species, the ones we call invasives or often, quite correctly, exotic species. All species that are not native and have come from somewhere else, introduced either deliberately or accidentally, are exotic, whereas only those that have a negative impact on native species by outcompeting with them or directly killing them or their eggs and young are called invasive species. The trouble is, it’s often very hard to tell whether an exotic species is harmless or whether you just haven’t looked closely enough (ruddy ducks in the UK were once considered a benign introduction and we know what happened with them).

At Durrell, my work has been to look at the pressures on and the state of a bird population and then use the findings towards establishing the responses. The first bits we might lead on, but the responses are more likely to involve a wider group, partners with their own particular skills like Island Conservation. Increasingly, where the role of one or more invasive species is key to our bird’s situation, we will work with partners who may be directly involved with reduction, or hopefully total eradication, of the invasive threat. If our bird lives on a small island, threatened by rats, or cats or a whole host of other invasives, its best chance of survival will be the complete removal of all the invasives. And here, Durrell may work to ensure the survival of the native species while its habitat is made safe by our partners. This is where we’ve been involved in recent years in the Galápagos.

I first cut my teeth in Mauritius in the 1980s where I joined our small team on the island working with birds on the very edge of extinction. My tasks were in observing and recording nesting echo parakeets (less than 20 birds in the world) and taking young into captivity. This was the first known nest in many years. I also made notes on pink pigeons and Mauritius kestrels, two further species with wild populations of under 20. Although a dire history of habitat loss, hunting and pesticide use had pushed these birds into ever smaller areas of forest it was the non-native rats, cats, mongooses, monkeys, mynahs and dense thickets of privet and guava in the forest remnants that would finish the job. Today, these birds can be found in much healthier numbers through some serious hard work and the establishment of captive populations. I also made trips out to Round Island shortly after the removal of goats and rabbits, animals put out there as food for ships and responsible for the near extinction of several reptiles and plant species extinct on the main island, and the last populations in the country of several seabirds. The mammals went in the nick of time and the saved reptiles and plants have gone on to repopulate other recovered islets.

From Mauritius, in 1989, I searched a lake system in Madagascar for Madagascar pochard. This lake, Alaotra, was the only known site of the duck which, although formerly widespread, had been considered common here only a few years before. But that was before a whole series of exotic fish were released into the lake. Fish that went on to see the loss of many native species as they out-competed many and disastrously altered the habitat needed for many others. We couldn’t find the previously common pochard or find any hope of its survival and declared it ‘probably extinct’ in 2004 despite constant effort. To say that I was excited on its rediscovery in 2006 would be an understatement!

Changing emphasis to Madagascar’s west coast in 1992 I began to focus on the Madagascar teal. Even this mangrove specialist faced threats from rats and cats – we found cat tracks in mangrove islands cut off at high tide. Through this work I was sponsored by New Zealand’s Department of Conservation (DOC) to visit many of their bird restoration projects in 1996. New Zealand has a long and awful history of invasive species and so each programme included work with invasives – some expected like brown teal (rats, cats, stoats etc), some more specialised like blue duck (rainbow trout) and some much less obvious like black stilt (lupins). Who would have guessed that lupins could be such a threat! 

I was quickly on the scene when around 20 wild Madagascar pochards were found in a distant, fish-free, mountain lake in 2006. With little hope of long term survival, with partners including Wildfowl & Wetlands Trust we collected eggs in 2009 to start a captive population in Madagascar. The Durrell run breeding centres have bred many ducks and we began to return birds to another lake in 2018, a lake that they’ve been breeding at ever since.

In 2006 I also spent time surveying the remnant population of Saint Lucia’s white-breasted thrasher. A species that had also been considered extinct in the past until found in areas of eastern dry forest earmarked for development. While the final straw for this species might have been the development, it was the introduction of mongooses that had pushed it towards oblivion. The mongooses had done a good job on a lot of other native animals too.

The year before, in 2005, I began working in Isabela in the Galápagos. Durrell had been invited to look at the mangrove finch, the rarest bird in the islands and one that had not been recorded breeding in several years. The entire population of this finch, well under 100 birds, was living in a couple of tiny mangrove patches. Mangroves full of rats which we quickly proved were eating the eggs. The rats were removed, and the finches bred again. Our excitement was, however, short-lived as another invasive species, the parasitic vampire fly took over and killed chicks that the rats had previously prevented from ever hatching. No one has yet stopped the flies but they are working on control methods. In the meantime, other agencies in the Galápagos have taken on our work and the mangrove finch is still there. Isabela is a very big island and despite an incredible effort to remove a large and destructive population of goats, rats can only be kept out of the mangroves and survive elsewhere on the island.

In 2007 I was asked by the Galápagos authorities to look at the Floreana mockingbird. This incredible bird was the inspiration behind Charles Darwin’s theory of evolution by natural selection. However, since Darwin met the mockingbirds on Floreana, the population had died out through loss of natural vegetation, eaten by cattle, goats and donkeys and predation of nests by rats and of adults by cats. The loss was not complete though as a few mockingbirds remained on two tiny islets. The challenge, to get them back safely on to the main island. We took on the challenge but, despite some great plans and plenty of research, only the complete removal of Floreana’s unwelcome mammals would allow the return. And that’s where we are right now, the removal is scheduled although it was delayed by the pandemic. Durrell has taken on safeguarding Floreana’s many native finch populations to make sure that they aren’t caught up in the rodent and cat programmes. We have two aviary complexes ready on the island and have trialled catching large numbers of finches, holding them in the aviaries, releasing them and tracking them later. All bodes well for Floreana, the mockingbird and other native animals and plants. Later in 2022 we will start drawing up plans for the return of 13 missing animal species.

So, that’s work. What about free time? Well, it’s surprising how the two can meet and it’s lucky that I have a family happy to go along. And that they like seeing wild bird populations (often puffins it seems) and learning what it takes to ensure that these will survive. We don’t dislike rats, cats, mongooses, cichlid fishes and lupins etc but we know we need to keep them away from the birds.

 

Chough report: November 2021

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November afternoons at Sorel. Photo by Liz Corry.

By Liz Corry

At the start of November, I was still wearing shorts to work. By the end, several layers, gloves, a woolly hat, and the obligatory waterproofs. The choughs also noticed the change in weather. The entire flock are now waiting for supplemental food each afternoon. Some birds even wing-begging for food. Clearly, wild supplies of invertebrates were not meeting energy demands for birds battling winds and trying to stay warm.

The sheep left. Not necessarily related to the weather, I think they have been moved to St Ouen. This might add to the choughs’ hunger if there are less dung invertebrates around Sorel in the sheeps’ absence.

Hungry choughs waiting for the supplemental food. Photo by Liz Corry.

Storm Arwen caused more minor damaged at the aviary. Of note, the keeper door had been blown wide open when the force of the wind bent the bolt out of place!

I was quite surprised we didn’t suffer more, especially considering last month’s gale damage. Luckily, I managed to fix the damaged panelling before Storm Arwen hit.

Lily leaves the flock

Lily, a three-year old female, appears to have either perished or left the Island. She was last seen on 5th November at Sorel. She has not been reported elsewhere.

Lily is an example of how post-release management has played an important role in the project’s success. Lily hatched in the wild in 2018. We had to catch her up in December that year when we spotted her digit caught in her ring. Durrell vets had to intervene as the toe needed amputating (click here to learn more). She was released back into the wild the same day and formed a partnership with another female looking out for each other over the years.

Lily and Vicq hanging out together this summer. Photo by Liz Corry.

New partnerships

Since Lily disappeared, her ‘partner’ Vicq has been seen preening Pinel. He is a wild hatched bird from 2020. If this new partnership continues over winter, it could mean a new breeding pair. 

Likewise, Danny and Portelet are also showing promising signs of being a new pair for 2022. Both pairings will need to find a nest site and establish a new breeding territory. No doubt keeping the project team on their toes next season.

Roost monitoring

We have been without a student placement all November which has restricted certain tasks, one being the biannual roost checks. I’ve not been able to check all the known roost sites due to sunset times clashing with the supplemental feed.

I have been able to monitor the aviary and, as suspected, several of the quarry birds are roosting at the aviary again. I suspect they will switch back to the quarry once sunset times start occurring after Ronez have clocked off for the day.

Leg rings

We finally managed to trap Monvie in the aviary to fit her metal ring. This is engraved with details of Jersey Museum in case the bird is recovered by a member of the public. Also, it comes in really useful when a plastic colour ring drops off and we can’t be sure on identity. Case in point, Archirondel, who we also managed to catch the same day and replace her white ring.

Monvie having a metal leg ring fitted by a licensed ringer. Photo by Liz Corry.

Bo and Minty evaded several catch-up attempts this month. We will keep trying although, at least for now, we can still distinguish them in the flock. Then on the 29th, Lee arrived missing one of his rings so he gets added to the ‘to do’ list for December. 

French news

Our friend Yann commented on last months’ report to say he has not seen Cappy since spring. Disappointing if she has perished although not a surprise. It would be nice to think she has moved south, along the coast towards Brittany under the radar of French birders. 

And finally

Camera trap footage at Sorel often throws up a few surprises. This month it was the camera itself with the surprise. I found an orb weaver (spider) and ladybird ‘hiding’ behind the camera. The spider’s full name is Nuctenea umbratica, commonly known as a walnut orb-weaver. Apparently also known as the toad spider although I’m not sure why – a tendency to hide behind things?

I logged the find with the Jersey Biodiversity Centre using the iRecord app. Both are common species but it is still important to record when you can.

Camera traps throw up all sorts of surprises at the aviary. Photo by Liz Corry.

 

 

Chough report – June 2021

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A chough sunbathing in June’s mini heatwave. Photo by Liz Corry.

By Liz Corry

June. The month chough chicks leave the nest and, after a long wait, the month I leave Jersey to see family and friends. That being said I still have a lot to write about despite having half of June off.

Plémont celebrations

I was on staycation for the first week in June. Naturally that meant a visit to Plémont to check on the nest. Coffee, cake, and chough chicks. Perfect holiday setup. By this stage the chicks were large enough to be seen and loud enough to hear from Sorel! OK, maybe not, but they certainly were not inconspicuous whenever the parents returned with food.

Two weeks later one brave chick started bouldering outside of the nest clinging to the cliff face making mum and dad work even harder. This coincided with my trip back to England. Typical!

Paul Pestana, ex-Durrell and onetime student on the chough project, kept me updated with their activities. The current student, Riccardo, did his best to keep track of them too. Every time he went it was either raining (and therefore the birds were sheltering out of sight) or the family were off gadding about. It’s almost as if the choughs were playing a game with us. 

Paul spotted two of the three chicks out by the 20th and up at the headland near the main car park. These are the first chicks whose parents are both wild-hatched. Genuine Jersey choughs! 

Fingers crossed all three chicks continue to avoid peregrine and black-backed gulls and find enough food to survive into July. At least they have their parents to follow around for several weeks before becoming independent.

Ronez nests fledge

Plémont was one of the last nests to fledge. The first of the eight surviving nests in Ronez Quarry began fledging at the start of June. The youngsters could be seen outside of their respective nest buildings practicing flying and building confidence. The chicks had to compete to be heard over the noise from several black-backed gull and dozens of herring gull nests.

Prize for spotting the four choughs in this photo! Photo by Liz Corry.

Kevin and Wally’s chicks made their first appearance at the supplemental feed on the 7th shortly followed by Dusty’s three chicks on the 10th.

A recently fledged chough with her mum Chickay arrived at the supplemental feed. Photo by Liz Corry.

As reported last month, we knew Dusty and Chickay had three chicks in the nest and it was really pleasing to see all three fledge. The other nests remained a mystery until fledging because our plans to ring chicks in the nest had to be cancelled twice. On one occasion we postponed due to the force 9 gales blowing around the bottom quarry. Not the best time to be up a ladder!

On the 16th, Bo and Flieur arrived with three chicks in tow. The following day Trevor and Noirmont arrived with two chicks and Lee and Caûvette  were next with one chick. So far, the other three pairs have failed to show with chicks.

Kevin and Wally were the first to bring their fledged chicks to Sorel. Photo by Liz Corry.

One pair have good reason. We believe the male is missing presumed dead and his partner, Pyrrho, has re-paired with Green whose brood died last month. The other two pairs, nesting in boxes, should have fledged chicks by now so it appears the chick(s) perished before making it over to Sorel.

Icho seems to have been unlucky this year unless her chicks are late bloomers. Photo by Liz Corry.

As the month came to a close, we had accessioned twenty chicks. Eleven of which had joined the flock at the supplemental feed.

Expectant offspring at Sorel. Photo by Liz Corry.

Ringing chicks at the aviary

Once fledged, the young will remain with their parents for several weeks following them around begging for food. They gradually learn to become independent, growing in confidence every day. You can see this happening in real time when you visit the supplemental feed site: at first, they sit on the roof of the aviary expecting their parents to go get the extra food. It takes about a week before they start getting confident enough to venture inside. A few weeks later and they race their parents to get to the food.

To be inside or not to be inside, that is the chough chick dilemma when they first arrive at the feeding site. Photo by Liz Corry.

For us, this means we have to bide our time before we can start trapping young inside the aviary to fit identity rings and get DNA samples to determine sex. Our first attempt this year was on 30th June.

We managed to trap three of the new chicks inside the aviary along with several adults. This year’s colour ring is yellow; the yellow rings also have a number stamped on to help ID in the field.

Yellow (stamped with a number) is the colour ring indicating a chough hatched in 2021. Photo by Liz Corry.

The ‘Jersey’ red and white striped rings are no longer available. Until we can find a new supplier the birds will just have the metal Jersey Museum ring on one leg and two plastic rings on the other. We might stick with this combo as it means less ‘baggage’ for the birds.

One of the chicks was noticeably smaller and still had some grey colouration to its bill. This suggests it was younger and, therefore, from a different brood.

You can approximate the age a chough by the colour of their bill. Photo by Liz Corry.

Of the adults, we had caught Minty and Rey which meant we could replace Rey’s missing white and faded cerise rings. We released them and the other adults immediately so they could return to their chicks.

Dusty and Chickay were the only choughs to stick around outside the aviary whilst all this was going on. Upon release, two of the chicks flew directly to them heavily hinting at possible parentage. We now get to play match-the-ringed-chick-to-the-adult as they continue to feed their young. If we can catch them in time!

Zoo surprise

Far easier to manage are the chough chicks in the Zoo. Penny and Tristan have reared another brood. Well mostly Penny has since Tristan was temporarily moved out when he started showing signs of aggression. We knew we had at least two chicks from the begging noises coming from the box. Electrical issues with the camera set-up meant we had to wait until we ringed them in the nest to discover we actually had four chicks!

All four were ringed and DNA sexed and are now flying around on public display.

Four Zoo chough chicks were ringed in the nest this month. Photo by Bea Detnon.

 

Chough report: May 2021

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Broken and faded leg rings used on choughs. Photo by Liz Corry.

By Liz Corry

Housekeeping

Another ‘catch up’ with the choughs this month. This time Bo, Percy, Trevor, and Chickay all needed replacement leg rings. It provided an opportunity too to check their general health through body weights and visual inspection of feather and body condition.  

Happy to report they all looked well and it’s always nice to reconnect with Chickay again who we hand-reared back in 2014.

In contrast, we declared six adults and four juveniles (< 12 months of age) as missing, presumed dead. A few had been missing for a while; in particular, the juveniles who in this species tend to struggle to get through their first winter. Others like Beanie Baby had suddenly gone from their territory making it more obvious to detect the loss. An updated ID list for the Jersey flock is available here. 

Mystery chough in England

Of course one or more of the missing list may have taken flight off-island. No COVID-restrictions for them! A chough of unknown origin was spotted in Dorset early on in May. The video below was taken at Portland Bill near Weymouth. There was a later possible sighting on the Isle of Wight.  

 

The bird in Dorset was unringed and likely to be a Cornish bird dispersing along the coast. Devon have carried out a lot of habitat management to try and encourage choughs to disperse east from Cornwall, which might have helped this one to reach Dorset.

Whilst doubtful it was a Jersey traveller; I contacted the Portland Bird Observatory just in case. All our captive-bred released birds are fitted with transponders. A quick scan with a pet microchip reader would detect if a transponder had been fitted. This requires the bird to be in the hand, a long shot for Portland, but at least they now know about our project and can bear it in mind next time they have a surprise visitor. 

Choughs travel with Blue Islands airline

England did receive one influx of Jersey choughs this month though. The three males we bred in the Zoo last year finally secured passage to Paradise Park, Cornwall. Ever changing COVID travel restrictions in both the UK and Jersey had placed the export on hold for several months.

Pre-export checks include checking the chough’s transponder number matches the paperwork. Photo by Liz Corry.

Export routes are limited now because only certified ports are permitted live animal transfers. Portsmouth (ferry), Heathrow and Gatwick (plane) are the usual routes we use to transfer zoo animals between the UK and Jersey. Neither were an option this time around and after a lot of ‘blue sky thinking’, red-tape cutting, paperwork signing, and (I imagine) a magic 8-ball, our Animal Registrar managed to open up a route via Exeter. This relied heavily on the generosity of Blue Islands airline who have previously supported Durrell’s work. Port staff handling the transfer at Exeter were equally helpful and handed over the birds to David Woolcock who then drove them down to Hayle.

Once they clear quarantine, these males will join the non-breeding flock housed at Paradise Park and eventually be paired up for 2021. They may even find themselves travelling back past Exeter on to one of the planned reintroductions in Kent or the Isle of Wight.

Hatching underway in Jersey

The wild Jersey breeding pairs became very active at Sorel as hungry bills started to hatch out. We think that the first nests to hatch belonged to  Betty and Pyrrho and Percy and Icho. The males would be waiting at the aviary for the supplemental feed, snatch what they could and zoom back to their quarry nests. They would then return with the females to repeat procedure and spend the next hour or so flying back and forth roughly every five minutes.  

Females tend to stay on the nest for the first week post-hatch when the chicks are most vulnerable. Once they get their body feathers, mum will help in collecting food such as ant eggs/pupae, beetle larvae and, in Jersey, the supplemental diet of mealworms. 

Ronez Quarry reported a new nest in a building the choughs have not used before. We suspect this is Betty and Pyrrho since her last known nest site no longer exists. Ronez also sent through photos on 11th May confirming Dusty and Chickay had succeeded in hatching three chicks. These were the first to be accessioned in 2021 and given temporary names of PP066, PP067, and PP068. Whilst not the most attractive of names it signifies that they are the 66th, 67th, and 68th chicks to hatch in the wild since the reintroduction began. 

Chough chicks around 17 days old) in the quarry. Photo taken under license by Toby Cabaret.

I should add that some chicks hatch out, die, and get discarded from the nest without us knowing, therefore, the total number hatched is likely to be higher. The same day we were given the good news about Dusty’s family, Ronez called again to say they had found three other chicks prematurely out of their nest.  

The nest these chicks were from is in a box in the secondary crusher building used by Green and his new partner Vicq. Standard procedure would be to return the chicks to the box and hope the parents continue to feed. This option was off the cards as access to the box requires a scissor lift and at 5pm, with hire companies closed, we had to think outside the box. Sorry, even I just sighed at that pun.  

Luckily Ronez had a spare nest box which they placed on the elevated walkway inside the building. One chick was wobbly to say the least when he was picked up. The other two seemed ok despite the fall. Whilst not ideal it meant the chicks were off the ground out of the way of gulls, predators, and morning site traffic. 

Unfortunately, the three chicks did not survive the night. I collected the bodies on the way to work for the Durrell vet to carry out post mortems. He believes at least one was still being fed by the parents judging by the quantity of undigested mealworms he found.

We don’t know how or why the chicks found themselves on the floor. I suspect the nest box is too small to provide adequate air flow in that quarry building which can lead to over-heating, aspergillus, and/or compromised breathing. We had planned to replace the box with a bigger one for the 2020 breeding season. Lockdown stopped that then and again in 2021.  

Even more of a mystery was what happened next with Green and Vicq. The day after the nest failed, Green was seen flying around with his old partner Pyrrho. Then Vicq reunited with her ‘best friend’ Lily who she spent most of 2020 preening and hanging out with.  

Plémont hatch-trick

Plémont Bay. Photo by Liz Corry.

We all needed some good news after that which is where the Plémont pair come in. Minty and Rey started behaving like new parents desperately looking for food around 14th May. There is sparse foraging habitat within the immediate vicinity of the nest. 

Bracken smothers most of the land in the immediate vicinity of the Plémont chough nest. Photo by Liz Corry.

However, 800 metres away at Les Landes there are fields grazed by horses and the racecourse next door. The male could be seen making regular visits to this site whilst the female remained with the nest. 

The Plémont pair source food for their chicks from paddocks like these around Les Landes. Photo by Liz Corry.

On a visit to the nest on the 19th, I heard the unmistakable sound of a begging chough chick. Too young to be visible. The parents on the other hand were visible. Especially if the raven family flew past. Minty has done a sterling job of keeping the nest predators away shouting at any who dared to go near.

Choughs are expert rock-climbers. Photo by Liz Corry.

By the end of the month, we had visual confirmation of chicks in the nest. Minty and Rey were still busy feeding and nest visits every five minutes gradually changed to every twenty minutes or so as the chicks grew and gained strength. The site of a parent carrying away a faecal sac from the nest is a joyous one. To a select few I guess. We are extremely excited to see what June has in store.

Rey, the female chough brooding chicks at Plémont. Photo by Liz Corry.