We may not have all our chicks blood sampled and sexed yet but there are plenty of signs of relationships developing between the juveniles and a few of our young females. We’re still seeing Sallow, a (potential) male chough from Kevin & Wally’s brood, getting very friendly with Portelet, a female which was wild hatched in 2020. Birch, another potential male chough from Dusty & Chickay’s brood, is becoming acquainted with Chewbacca. As the juveniles settle into their places within the flock, more may be taking their pick of the single ladies of the group. Rocco who was wild hatched in 2020 has been seen arriving at the aviary and allopreening with Alder another potential male from Dusty & Chickay’s clutch. Without the blood sample results we cannot be one hundred percent certain yet that these are true pairs emerging, but looking at the size of these birds, and we have some weights, we have a good idea that they are. Looking at behaviours we’ve been seeing between these new acquaintances too, it could be that within the next few years, or even next year, we’ll hopefully have a few new wild hatched pairs to produce truly wild chicks!
Grazers bring the goods
The National Trust for Jersey’s shepherd is currently managing the coastal landscapes by moving sheep (the grazers) around the Island. Some of those sheep are currently in several fields around Sorel, where the choughs spend most of their time foraging alongside them. The sheep act as a natural land management tool to help restore vegetation and plant and bird communities. The sheep graze in neighbouring fields around the aviary and on the coastline giving our choughs and other bird species a good place to forage. Choughs, favour shorter length grasslands and this is typically where insect diversity is higher. But the choughs do not only forage alongside the sheep, the sheep also provide the choughs with tasty insect larvae that are found in their faeces. During the year we’ve had sightings of the choughs regularly returning to a field containing cattle in St Mary; cattle provide similar benefits to the sheep. But once the cattle were moved, it was not a shock to find that the choughs had moved on to a new foraging spot. It won’t be too long until the choughs start using the grazers for another purpose too – their wool!
Everyone deserves a present
It’s coming to the end of the year, 2022, and we all know what that means, Christmas! But it’s not only us humans who get to enjoy celebrating over the Christmas holidays; the choughs deserve a piece of the joy at Sorel as well. The keepers got creative this year by making some ‘Christmas present’ enrichment. Compared to the scary bright orange pumpkin that loomed in the field at Halloween, the choughs were much less cautious of their new ‘Christmas present’ in one of their usual foraging fields. With some insect persuasion it wasn’t long until the choughs approached their Christmas gift. Interestingly, it was not the juvenile choughs that approached the present first, it was the adults.
End of year review
The wild chough flock on the island has a population of 43 currently. To our knowledge we’ve had no adults go missing over the course of this year. We have also had our highest record of chick survival since the project began; lucky number thirteen. There may be more breeding pairs in the coming year too, not just from the juveniles, as we located our highest number of nest sites around the Island – 15 nests! Who knows, we may even have a breeding pair nest in Guernsey as we know at least two of our females enjoyed a weekend trip away. The chough team are looking forward to what the new year brings for this growing population.
The fishing of sandeels in British waters might be banned this year under UK government plans to protect Atlantic puffin and (black-legged) kittiwake numbers
The tiny fish are important parts of seabird diets and many are harvested, mainly by non-UK fishing boats, to be made into feed for farmed salmon and livestock. While the largest threat to their population numbers is heating seas under climate breakdown, industrial fishing pressures them further.
A call for evidence by the Department for Environment, Food and Rural Affairs (Defra) last year found that the industrial fishing of sandeels could be negatively affecting the populations of some of the UK’s endangered seabird species.
Now, as revealed by the Guardian, sources at the department have confirmed that a ban on the practice will be put in motion early this year, starting with a consultation of stakeholders in January. While the move is likely to dismay some in the fishing industry, wildlife campaigners have welcomed a potential ban.
The RSPB’s head of marine policy, Helen McLachlan, said: “A UK-wide ban on industrial trawling for sandeels would be gamechanging in our efforts to help save our threatened seabirds. The UK’s globally important seabird colonies are in trouble with iconic birds like puffins and kittiwakes at risk of being pushed to the brink of extinction.
“A ban on sandeel fishing in UK waters would protect the very fish that our amazing seabirds, their chicks and many other marine species need to survive. Over the last few decades our seabirds have declined in the face of increasing threats from climate change and other human activity.
“We’re running out of time to save some of the UK’s most loved wildlife and a ban on industrial sandeel fishing could be the single greatest thing decision-makers can do next year to throw our seabirds a lifeline.”
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!
This month, the aviary has been surprisingly quiet. Now that the fledgling season and drought is over on the Island; the choughs seem to be less frantic when it comes to gaining sustenance within the aviary. Choughs arrive to the feed in small trickles on the majority of days. The young choughs are arriving earlier than the adults to wing-beg at the keepers and presumably to get their fill before the adults take over feeding stands. The lack of food desperation is allowing adult pairs in the flock to express their affections towards their partners more often as of late. As choughs are generally monogamous, it’s brilliant to see that the parent pairs of this breeding season still have a great bond. This can be observed as pairs allopreen and/or feed one another. Hopefully they will bring more success in their next breeding season.
Queen Elizabeth II
The choughs have seen some big events in Jersey since 2013 and on 8th September they were witness to the passing of HRH Queen Elizabeth after 70 years on the throne. The Queen has been known locally as ‘Duke of Normandy’ and toasted as ‘La Reine, notre duc‘ (‘The Queen, Our Duke’), although this tradition can be very confusing. Jersey had a public holiday for the funeral on 19th September and the Zoo was shut that day; but for the team, and the choughs, life went on.
Eyes, head, legs & feet.
What are we referring to? Ticks of course! They don’t only affect mammals; they affect all species, so that includes birds. It’s come to that time of the year where the ticks become more active. A bite from a tick can spark many detrimental cascading affects in both birds and mammals. This means the keepers need to be extra vigilant when it comes to monitoring their birds. Thankfully, as choughs have a communal based social life it poses less of a threat due to their mutual preening.
Strimming in session
It may still be a hot September so far; but the drop in temperature from the past few months has allowed the keepers to change their priorities to some well needed vegetation clearing. The hedgerow to the right of aviary was becoming so over-grown that the team couldn’t see over the bank to the field behind. The view isn’t a necessity but is useful to see what and/or where the choughs are if they haven’t braved (or bothered?) going inside the aviary for the supplementary feed. But it’s not just the view that this over-grown bank causes as a problem; it also greatly reduces the functionality of the hatch wires. The wires can easily get tangled between the fern and other vegetation on the bank. Now that it’s been cleared, we should be able to carry out more catch-ups in the future if necessary, with ease – if the choughs don’t out smart us!
Rodent activity
Although in Jersey we’re now starting to get some wet weather, it seems that a few furry friends are still making their way into the Sorel aviary to make use of our water tray and likely, some free food. As we have no intention in trapping protected species, the team came up with a great idea to try and identify the culprits, on camera with the use of camera traps. However, we’ve not managed to get any footage of our four-legged friends. So far, the main footage captured has been magpies enjoying a good bathe. The rodent population may have foiled us so far, but the camera traps did make light by capturing some rather elegant footage of two choughs drinking from the water tray in synchronous drinking.
A very special guest
On 28th September we were very pleased to show Max Benatar, visiting the Island from Germany for a course at Durrell, the choughs at Sorel. Max is no stranger to the birds; he was our student in 2014 and formed a great affection for the chough flock. While Max was proud to have been part of the project and to learn of its ongoing success, he was possibly most pleased to catch up with an old favourite, Dingle. The photographs show that Max has changed his appearance over the years, while, and take it from us, Dingle looks just the same!
At around this time every year we update the list of all those bird species recorded in the Channel Islands. Records will have been verified by each island’s ornithological committees. Where once birds may have been shot to confirm ID, records of new species and rarities became submitted through detailed notes and, today, they are often shown to us in high quality photos that leave little doubt about identification. We still like the notes.
Interestingly, while our overall bird list and those of the islands continue to increase, there have also been some species lost. We are always revising our opinions and, sometimes, we learn more about a species and question older records’ validity. Jersey’s first black-eared (in 1980) was scrubbed when we started to consider that it had almost certainly been a desert wheatear but that the observer was no longer confident. We also lose species to taxonomic splits.
As bird taxonomy becomes more and more detailed through use of some very fine, molecular level, ways of determining differences between species, we are often seeing traditional sub-species ‘elevated’ to species level. Then, that warbler for instance that we recorded but didn’t get a photo of may become several different warblers. But, which one was ours? Did we get sufficient detail noted to know which it was? You’ll see the problem in the full list. Especially in the warblers!
We also, well those of us of a certain age, grew up with a very set, long-established, view of the order that species occur in. We start with divers and grebes and end with crows. Well, actually that went out years ago as we learn more about relationships between birds and can even age when particular groups evolved. As a duck enthusiast, I’m pleased that they now rightly start off the CI List. They followed the pheasant, partridges and quail last year. So, species you are looking for may not always be where you expect them. They may also not be with old friends in the list and may have new company – have you got used to hawks and falcons not being related? Or that falcons and shrikes are next to each other in the list? And that grebes and divers aren’t closely related, and that crows are nowhere near the end?
So, back to the updated list. After being restricted to home over most of 2020, we began to travel again in 2021. However, the birds at home were still a draw it seems and records came in in good numbers.
We had two additions to the list which strangely went up by five! Guernsey’s Bonaparte’s gull in February and March and an October eastern olivaceous warbler in Jersey were the proper additions. The other increases came from re-organising warblers. However, as some of the older records of Bonelli’s and subalpine warbler are not identified to newer species, the list total could go down again in future.
Other notable birds were first ruddy shelduck and green-winged teal in Jersey (the former most likely from the establishing population in northern Europe) and a first rustic bunting in Alderney. Alderney saw their first corn crake in 43 years and first stone curlew in 134 years! Remarkably Alderney also saw their fourth great bustard in seven years, all from the UK reintroduction project, and the only bustards (of two European species) likely to have enjoyed their visit to the Channel Islands!
Breeding species continue to have mixed fortunes but it is very pleasing to note that short-eared owl bred in Guernsey and nightjars bred for a second year in Jersey.
And the individual islands’ totals? Jersey now has 340 recorded species, Guernsey 331, Alderney 308 and Sark 226.
State of the World’s Birds 2022 paints most concerning picture for nature yet
BirdLife’s newly launched flagship State of the World’s Birds report paints the most concerning picture for the natural world yet, with nearly half of the world’s bird species now in decline. While further underlining that we are in the midst of a biodiversity crisis, it also highlights the critical solutions we desperately need to save nature – we now urgently need the political will and financial commitment to implement these at scale and at pace.
From albatrosses soaring gracefully over the high seas, chicken-like maleos digging nests deep in remote rainforests to emperor penguins fishing to depths over half a kilometre underwater and peregrine falcons nesting high on skyscrapers towering over great metropolises, birds can be found almost anywhere on earth and are a key indicator of the health of the planet.
As a world leader in conservation science, BirdLife publishes its landmark State of the World’s Birds report every four years. The report is an extraordinary summary of data tirelessly collected by researchers, conservationists and citizen scientists alike, highlighting the plight of the avian world, the key threats it faces and the urgent measures needed to protect it. Given bird calls echo across nearly every corner of the world, it tells us more than just the health of this extraordinarily diverse group, but also that of nature as a whole.
However, the latest edition of State of the World’s Birds paints the most concerning picture for nature yet. Nearly half of the world’s bird species are now in decline, with only six per cent having increasing populations. One in eight species (or 1,409 species in total) are now threatened with extinction. Nearly three billion birds are estimated to have been lost since 1970 in North America alone, and a further 600 million have been lost in the European Union since 1980, an area five times smaller.
Although long-term population data is far more comprehensive for species in these regions, signs point to similar catastrophic declines elsewhere across the globe. For instance, since 1850, forest and wetland specialist species in Japan are estimated to have declined by a staggering 94 and 88 per cent respectively, while populations of Kenya’s raptor species have declined on average by nearly three quarters since 1970.
“We have already lost over 160 bird species in the last 500 years, and the rate of extinction is accelerating,” says Lucy Haskell, Science Officer for BirdLife and lead author of State of the World’s Birds. “Historically, most extinctions were on islands, but worryingly there is a growing wave of continental extinctions, driven by landscape-scale habitat loss.”
The drivers of declines
Beyond highlighting the dramatic declines of birds, the report also outlines the key factors driving them. Across the world, birds are impacted by an array of different threats, nearly all of which are caused by human actions. Agriculture – both through its expansion into important habitats and the increasing use of machinery and chemicals as it intensifies – is the leading threat to bird species, impacting at least 73 per cent of threatened species.
In Europe, this has resulted in an over 50 per cent decline in abundance of the continent’s farmland birds since 1980 and, further south, the conversion of grasslands to croplands has resulted in an 80 per cent decline in the population of the Liben lark (Critically Endangered) in just 15 years. Endemic to Ethiopia, there are now fewer than 50 breeding pairs of the species restricted to just two sites, and it is feared it may become continental Africa’s first bird extinction in modern times unless there is rapid conservation action.
The unsustainable logging and management of forests is another significant threat. Over seven million hectares of forest are lost every year – an area larger than the Republic of Ireland– and this impacts nearly half of the world’s threatened bird species. Species that depend on large, old-growth trees are particularly affected, such as the harpy eagle, the world’s most powerful bird of prey. Resident of the rainforests of South America, where it hunts on prey such as monkeys and sloths, 90 per cent of the trees it prefers for nesting are targeted by logging, and it has recently been uplisted by BirdLife to Vulnerable on the IUCN Red List.
Worryingly, climate change is already having a substantial impact, affecting 34 per cent of threatened species. Already driving unprecedented levels of storms, wildfires and drought, its impact will undoubtedly increase rapidly over the coming years. Alongside this, threats such as bycatch from fisheries, overexploitation and invasive species, which throughout history have been the leading cause of avian extinctions, continue to drive population declines.
A critical moment for a brighter future
While these findings are no doubt extremely concerning, State of the World’s Birds also highlights the most important solutions for saving nature. This comes at a crucial time as governments prepare for the upcoming Convention on Biological Diversity meeting (CBD COP 15) in December, where the Global Biodiversity Framework – a 10- year strategy for nature – will be finalised and adopted.
“Birds tell us about the health of our natural environment – we ignore their messages at our peril,” says Patricia Zurita, BirdLife’s CEO. “Many parts of the world are already experiencing extreme wildfires, droughts, heatwaves and floods, as human-transformed ecosystems struggle to adapt to climate change. While the COVID pandemic and global cost of living crisis have undoubtedly diverted attention from the environmental agenda, global society must remain focused on the biodiversity crisis.”
The most important solution for the largest proportion of threatened species is to effectively conserve and restore the critical sites that birds depend upon. BirdLife has identified more than 13,600 Important Bird and Biodiversity Areas (IBAs), which form the core of a wider network of Key Biodiversity Areas. Given there is increasing momentum for a commitment to conserve 30 per cent of the world’s land and sea area, it is vital these sites are used as a blueprint for the designation of protected areas. Alongside this, addressing other key threats, such as eradicating invasive species from remote islands, and implementing species-specific conservation actions is also vital to many threatened species.
Cause for optimism
Promisingly, despite the desperate state of the natural world, birds also provide a cause for optimism, showing that with effective conservation efforts, species can be saved and nature can recover. Since 2013, 726 globally threatened bird species have directly benefited from work by the BirdLife Partnership. Advocacy by BirdLife Partners has also helped 450 IBAs be designated as protected areas, including 2022’s establishment of Ansenuza National Park to protect Argentina’s Mar Chiquita Lagoon, following extensive work by Aves Argentinas (BirdLife Partner), in turn protecting half a million migratory waterbirds, including the Andean flamingo (Vulnerable).
“There is no denying that the situation is dire, but we know how to reverse these declines. Our research shows that between 21 and 32 bird species would have gone extinct since 1993 without the conservation efforts undertaken to save them,” says Dr Stuart Butchart, Chief Scientist at BirdLife International. “Species like the echo parakeet, California condor, northern bald ibis and black stilt would no longer exist outside museums were it not for the dedicated efforts of the many organisations in the BirdLife Partnership and beyond. If we give nature a chance, it can recover.”
Protecting birds also reaps fantastic rewards for humans too. Birds pollinate plants, control agricultural pests and large seeds over vast distances – critical to the long-term carbon storage of rainforests. Protecting and restoring natural habitat is also one of the most cost-effective way of tackling climate change. Alongside this, there is growing evidence linking healthy bird communities to our own wellbeing.
While 2022’s State of the World’s Birds undoubtedly highlights that we are in the midst of an unprecedented biodiversity crisis, the report’s examples prove that conservation works. It is now imperative that nature is put at the forefront of political and economic agendas, and that these solutions are implemented rapidly and at scale.
Download the report State of the World’s Birds 2022here
This summer is proving to be a particularly hot one; one which we probably shouldn’t complain about! With rising temperatures and further limited rainfall though, the struggle for water supplies up at the Sorel aviary are beginning to show. At Sorel, it is clear how little rain we’ve received over the past month or so as the water butt, which is usually filled by Jersey’s plentiful rainwater, has been getting topped up by keepers. It may be physically challenging lugging water containers to the aviary in the recent heat but at least the choughs have clean water, and the keepers are becoming that little bit fitter! But, with rainwater being in short supply, lack of water wasn’t the only worry as the ground became hard and compact, potentially making foraging spots for choughs a little sparse; not an ideal start for the choughlets. Our Plémont pair Minty & Rey are normally rarely seen at the aviary but have been very frequent as of late; making us worry more about the state of foraging across the Island.
Bird flu, captive and wild bird devastation
The other worry on the Island is bird flu. So, what is bird flu? Bird flu is a type of influenza virus which is mainly spread amongst birds. The virus itself can be spread in two ways; directly (through contact) or indirectly (through faecal matter). It can affect mammals, but the risk is very low compared to the transmission between bird species. Bird flu was found on the Island in February this year and has caused quite a stir. This month, the number of cases seen across the Island has increased and the coasts are becoming scattered with many suspected avian flu fatalities, mostly seabirds. It is very important for us to state that the public must help prevent further spread by following the Government of Jersey Natural Environment guidelines and not picking up, touching or going near wild sick or dead birds. However, it is useful for the public to notify Natural Environment about any dead birds; especially if several dead birds are found in close proximity of each other. The most susceptible wild birds seem to be birds of prey, owls, wildfowl and seabirds. Notifying of dead birds will allow Natural Environment to test and confirm any new cases on the Island and set quarantine protocols. Although the photos below show herring gull fatalities across the cliffs at Devil’s Hole (which is very close to Sorel); we’re thankful to announce that the wild chough population is currently stable/unchanged.
Praising mother nature
The keepers couldn’t have been happier to see some much-needed rainfall and accompanying thunderstorms when they came, to clear away some of those high temperatures. We finally had a significant amount of rainfall. The ground around the aviary is still feeling pretty tough but at least it’s gained some form of hydration this month. Once we’d had a few days of rainfall, the grass in the aviary was looking a healthy green again after many months of looking very dried out and brown. But with rainfall comes plant growth, and it is truly amazing how much grass grows after a bit of rain! The keepers are now back into their routine of regularly mowing and strimming the grass inside and outside the aviary – hopefully giving the choughs another great foraging spot for tasty insects.
Choughlet update
As we came closer to the end of August, the aviary became less ‘noisy’ as the youngest chicks belonging to breeding pair Bo & Flieur were becoming independent feeders. Less ‘choughlet’ begging behaviour at their parents and more wing-begging behaviours directed at the keepers! The young choughs are now arriving in their own little flock for the supplementary feed; it’s quite fantastic to see how they’ve learnt, grown and thrive, especially with all this hot weather. Although the feeds may have become quieter in regard to chick begging behaviour, there were still plenty of social hierarchy challenges amongst the young choughs and the adults. Plenty of scrabbles between siblings, young choughs of different parents as well as between some young choughs and adult pairs – the young choughs will soon find their place within the flock’s social structure.
Chough adults
Now that the young choughs are more independent; the parents are becoming less attentive. When the chicks started to feed for themselves the parent pairs would land on a food stand, allow their chicks to join and then move themselves to another stand; almost as if to give the young birds a fighting chance of a free meal before another more dominant pair took over the stand. However, now, the parent pairs will bat away any chicks, including their own! Since the aviary has become quieter, more pairs and other adults that have rarely been seen over the breeding and fledgling season became more frequent visitors such as Corbière pair Danny & Jaune. These two, along with other adults, have been known to avoid the aviary in fledgling season; and I don’t blame them, the choughlets are very noisy and demanding from anyone who will feed them!
In October, the European Parliament will vote on a report calling for an “EU cormorant management plan”. In plain text this means, controlling their population through lethal measures. Here are five reasons why this plan is not a good solution.
Seabirds are going to… eat fish. The aquaculture industry is mad at seabirds for foraging fish. Meanwhile, almost all our waters are overfished by humans, who are also wiping out fish habitats while they are at it. The cormorant diet consists of fish. It’s as simple as that. Just like bees feed on pollen and nectar. So, it’s obvious that, when they are out foraging, cormorants will be attracted to bodies of water where fish are abundant and easy to catch. Does that mean that some of them will be attracted to aquaculture facilities? Yes. Should they be killed because of this? Absolutely not. Science suggests that reducing the overall population of cormorants will not reduce conflicts at a local scale (i.e. aquaculture facility) – unless you put an enormous destructive effort on it. If a site is popular, whatever cormorants that are left, will continue to come back – no matter how well the population is “managed”.
Cormorants (great cormorant) almost went extinct in the 1970s due to human persecution and habitat loss primarily caused by humans. Thanks to the EU Birds Directive, as of 1979 it became illegal to disturb, capture, or kill them, as well as destroying their nests or robbing their nests. That, coupled with the reduction of water pollution and a ban on some dangerous pesticides has helped the great cormorant population bounce back across Europe in the past 30 years. Surely it would be a pity to undo all this great work just because cormorants like eating fish?
We’re ignoring the real problems. It is easy for industries to blame cormorants for the decline of fish population, but the reality is much more complex. The INTERCAFE research project showed that when cormorants are identified as a problem for fisheries there’s actually a whole range of reasons why fish production is in decline, including: invasive species, climate change, impoverished water quality, pollution, or the increase of algae in waters (aka eutrophication). In short, to produce fish, the restoration of natural habitats is key. Killing off cormorants won’t change anything – restoring the natural habitats of cormorants and fish, and sustainably managing wetlands, however, can provide part of the solution to these problems.
There are other solutions! The INTERCAFE project developed a toolbox with a wide range of management actions to reduce the vulnerability of fish to predation and deter cormorants from specific sites. This includes solutions to make sites less attractive to cormorants for nesting or feeding and measures to protect the fish (e.g. artificial refuges for fish, audible and visual deterrents for cormorants, nets and overhead wires, etc.) While there is no perfect measure that will work in every situation, all these techniques have been proven useful to reduce “conflicts” and deserve additional resources, such as from the new European Maritime Fisheries and Aquaculture Funds (EMFAF), to explore, develop and test them.
It’s really not so difficult. Just listen to the science. The ongoing discussion in the European Parliament on the “necessary management” of great cormorants is not based on the latest scientific consensus. The CormoDist project (endorsed by the Commission) clearly concluded that population management does not have an effect on specific site interactions. And it is not possible to know where the reduction of the population will have an impact.
In Jersey, cormorant is considered to be threatened and is RED on the local bird redlist. Despite seeming to be common, cormorants only nest in a very small number of sites and are vulnerable to disturbance and persecution. The rapid decline of the closely related shag, once a very common bird in Jersey, should serve as a salutary reminder of how fast a bird species’ fortune can change.
Chaffinch numbers dropped by 29% in the UK between 2008 and 2018, with a loss of 67% of the country’s greenfinches over the same period. As a result, greenfinch was moved on to the UK Red List in the most recent Birds of Conservation Concern assessment, published last year.
This new study used large-scale citizen science data and reveals that both species have declined in ways consistent with the impact of trichomonosis, a disease that was first detected in UK finches in 2005. Earlier work by the same organisations demonstrated that the disease had driven the decline in greenfinch populations – but the cause of the chaffinch’s decline, which began several years later, was unknown before now.
Scientists looked at patterns of change in greenfinch and chaffinch populations since the emergence of trichomonosis. They found that the declines were driven by a reduction in the survival of adult birds, a pattern that corresponds with the high levels of disease observed. A shift in recent years has seen trichomonosis diagnosed most often in chaffinches – previously it was diagnosed most often in greenfinches. This led the researchers to conclude that it was probably behind that species’ decline, too.
The joint BTO/IoZ study showed that survival rates of greenfinches and chaffinches were lowest in human-associated habitats. Disease transmission may be higher in these environments, where birds congregate at garden feeders. Trichomonosis makes swallowing difficult and can cause birds to regurgitate food, contaminating shared sources of food and water with their saliva.
Following best practice advice for feeding garden birds is recommended as a way to reduce the spread of disease. This includes regularly cleaning feeders and bird baths and, if possible, rotating the position of feeders around the garden to avoid build-up of food waste in one area. If sick birds are seen, temporarily suspending feeding will allow birds to disperse and may reduce the risk of transmission.
Other UK Red- and Amber-listed species, including house sparrow and bullfinch, are also susceptible to trichomonosis. Understanding the potential for the disease to spread to other species at bird feeding stations and working out how we can feed birds more safely are also priorities. Anyone can help us learn more about the diseases that affect garden birds by reporting sightings of sick or dead birds to the Garden Wildlife Health project, where you can also find best practice advice on feeding garden birds to help safeguard their health and welfare.
Dr Hugh Hanmer, BTO Research Ecologist and lead author on the paper, said: ‘Information derived from organised citizen science surveys has been vital to understanding what is happening to the populations of these two common bird species.
The results from our study put a spotlight on the use of supplementary bird feeding, both in gardens and as a conservation management tool, highlighting the importance of balancing the trade-offs between the positive conservation and engagement benefits of feeding with potential negatives of disease transmission that need to be better addressed.’
Dr Becki Lawson, ZSL IoZ co-author on the paper, said: ‘The emergence of trichomonosis in 2005 and dramatic declines of finches that have since occurred highlight the importance of understanding threats that affect the health of our garden birds and how disease can negatively affect biodiversity. We appeal to the public to continue to help us learn more about the conditions that affect garden birds, by reporting signs of ill health in garden wildlife to www.gardenwildlifehealth.org.’
Paper Habitat-use influences severe disease-mediated population declines in two of the most common garden bird species in Great Britain here
