Monthly Archives: July 2022

Chough report: June 2022

Posted on by

By Charlotte Dean

1st June

The choughs greeted the keeper closer than ever! It’s quite clear at this time of year that the choughs recognise the keepers. They spot you on the walk up the coastal path towards the aviary, circling and vocalising loudly, following you along the foot path before finding a place to land. As you can see, the closest and safest spot was the entrance gate to the National Trust’s land. The choughs wing-begged and shouted, they really do know how to welcome their food providers!

Aviary maintenance

Now is an even more important time than ever to be keeping up to date on our aviary maintenance. At this time of year, we are eagerly anticipating the arrival of ‘choughlets’ (chough fledglings) at the aviary. About four weeks after fledging, the chicks’ parents will stop feeding them so it’s essential for the chicks to watch their parents and learn how to forage for themselves. Choughs forage over coastal grasslands; they are often spotted in shorter grass fields, and this is because the insect abundance is generally higher where grass is short. Therefore, mowing the grass, strimming the hedgerows and neatening edges within and outside the aviary is important as it acts as a natural food source for the choughs and chicks that come to the aviary. Along with keeping the grass length short, we also provide ‘enrichment squares’; this is an added foraging obstacle which includes pinecones, slates and branches. These squares engage the choughs to lift and move objects to find the scattered insects – enabling them to work for their ‘free food’.

Is that a ‘choughlet’ I can see?!

Exciting news! We had our first ‘choughlet’ appearance at the Sorel aviary on 10th June! But there wasn’t just one chick, there were three! Our first sighting of the fledglings was in a field opposite the aviary – they were causing quite a stir in the flock. It wasn’t long until they flew in and landed on the aviary roof with Kevin & Wally. We assumed that these three must be theirs as they arrived together, and we had predicted this pair’s fledging dates back in May when we visited their nests to ring and age them! While monitoring the choughs at the aviary, it became clear that these three chicks were definitely from Kevin & Wally’s nest as we’ve witnessed many parent to chick feedings on top of the aviary. It wasn’t long, however, that more fledglings started arriving at the aviary. The next breeding pair’s chicks to arrive at the aviary belonged to Dusty & Chickay – four chicks on the 13th! Dusty & Chickay have always been pretty consistent with four chicks in the past; but it’s exciting to see the chicks that we saw in the nest arrive at the aviary happy and healthy!

Since those first arrivals, we’ve had Trevor & Noirmont’s chick, Manitou arrive at the aviary being very vocal, much like the majority of the chicks. It’s good to see the one chick we managed to ring at the nest arrive safely. By mid-month we started to see other breeding pairs bringing their chicks too, including Green & Pyrrho and Percy & Icho with their two chicks and Lee & Cauvette seen with one chick so far. It’s safe to say that the supplementary feeds at the aviary have been very loud and eventful this month! We may not have seen all of the chicks that were viewed at the quarry nests yet; we are still hopeful for more arrivals!

Time flies

The past few weeks have been pretty hectic, but our former colleague Paul has been very useful in helping us monitor our chough activity in Ronez Quarry. We had our estimated fledging dates but hadn’t seen all chicks arrive at the aviary. But sure, enough there were plenty of chicks flying around the Sorel Lighthouse and quarry as acknowledged by Paul. The chicks will practice their flying before they are strong enough and brave enough to join their parents at the aviary for the supplementary feeds. We greatly appreciate the many chough enthusiasts that help us with our chough project; but don’t forget that anyone can help.

Follow this link and you can do your bit by sending in public sightings of any choughs you see around Jersey Island!

Catch up time!

As the chough chicks keep arriving; it was time to take action and loosen up the hatch wires for the first chick ‘catch ups’ at the aviary. Why are we catching them up you ask? It’s to be able to identify each individual for monitoring with the use of colour-rings (which in turn allows us to know which breeding pair the chick belongs to through observations – see below), to indicate that they are owned and thrive in Jersey, to measure their bills, tarsus and weight. This is essential information we collect and keep records of for all the individuals in the wild free-flying flock. We haven’t needed to ‘catch up’ any choughs in quite some time so it took a few tries to loosen the hatch wires! But between the team, we’ve currently caught eight of the current fifteen chicks floating around with their parents.

Not something we want to see

One of Kevin & Wally’s fledglings had been limping since the first time it was seen arriving at the aviary. It was clear it had quite a large laceration to its left tarsus; but to be able to examine it properly we had to wait until the fledglings were more confident in going in and out of the aviary to carry out a ‘catch up’. We closely monitored the chick until we could catch it up within the aviary. On close examination it was clear how large the injury was but thankfully it had already scabbed over nicely and had no sign of infection, therefore, no additional action was needed. Fledglings are not always the most agile in flight and/or landing at first, something that is learnt over time. One can only assume that it crash-landed somewhere causing itself an injury. But one thing is for sure, it’s now a much better flier!

During these catch-ups we also quickly put the temporary, coloured plastic, rings on the chicks. We only have a short window of opportunity to see exactly which chick belongs to which pair of adults. After only a fairly short time, the chicks start to feed themselves, beg from their parents less and join groups of other juveniles. Groups who take great delight in begging from any passing adults (adults who aren’t fooled) and confusing the patient observer. As opportunities to catch newly arriving chicks inside the aviary are hard to predict, we do these catch-ups fairly randomly – often with long frustrating periods of watching a chick stare imploringly at their parents through the netting, through an open hatch, field etc and our sitting in the bracken or lying in a spot on a field that the sheep have only recently vacated. With everyone identified and, in a few weeks’ time, more likely to go into the aviary when we want them to, we will ask the licenced ringers from the Channel Islands Ringing Scheme to put permanent, numbered metal rings on.

Hottest day on record since 1894!

Between our catch ups, on Friday 17th June 2022, we had the highest June temperature in Jersey since records began in 1894. The temperatures hit a scorching 33.1 degrees Celsius. It’s not surprising that on this day most of the choughs were seen with their beaks wide open. This is because unlike most mammals; birds lack sweat glands and, therefore, they cool themselves down by keeping their beaks open. This is called ‘gular fluttering’ it is the avian equivalent of panting. Gular fluttering is just one of the few behaviours bird species express to stay cool in those hot weather days. Birds also submerge themselves in water either to swim and/or bathe. Sometimes you’ll catch a chough all wet and puffed up sitting on top of the aviary; this is their way of letting the breeze through their wet feathers to help them stay cool. As much as the choughs distinct jet-black plumage and striking red beak are beautiful; I do not envy them their plumage in that heat!



Rising temperatures implicated in decline of the willow warbler

Posted on by

From Rare Bird Alert

New research from BTO implicates rising temperatures in the steep decline of the willow warbler, one of the UK’s most tuneful harbingers of spring.

The study shows that willow warblers are doing better in Scotland, where temperatures are cooler. Evidence is building to suggest the population in southern Britain is a casualty of recent anthropogenic climate change.

BTO researchers used volunteer bird counts and habitat data from the BTO/JNCC/RSPB Breeding Bird Survey to separate the impacts of climate change and habitat change on willow warbler and chiffchaff populations. The analysis revealed that willow warbler numbers across the UK fell by 41% between 1994 and 2018, while those of the closely related chiffchaff grew by 133%. The picture was very different in Scotland, where temperatures are cooler than the UK average. North of the border, willow warblers increased by 77% and chiffchaffs by 244%.

During the period studied, the mean breeding season temperature was 12.7°C in England and 10.2°C in Scotland, close to the optimum breeding temperatures for chiffchaff (13.5°C) and willow warbler (11°C), respectively. However, UK Met Office data show that UK temperatures in the last 30 years have been about 1°C warmer than those during the three preceding decades. Changes like these can have impacts including producing a mismatch between young birds’ food requirements and insect abundance, an overall reduction in food abundance and shifts in habitat suitability.

The BBS habitat data showed that woodland and scrub, the preferred habitat for willow warblers and chiffchaffs, increased across the UK, with more habitat improvements in Scotland. However, this study showed that the increases in Scotland were more likely to be linked to climate change than habitat change.

Its UK decline means willow warbler has been on the Birds of Conservation Concern Amber List since 2002. With global temperatures forecast to keep rising, studies like this demonstrate the importance of long-term monitoring to ensure conservation measures are targeted effectively. More woodland and scrub, for example, would be more likely to be taken up by breeding willow warblers if it were concentrated in cooler areas of the UK.

Blaise Martay, BTO lead author on the paper, said: ‘We’ve discovered that these two superficially similar warblers have quite different temperature requirements during the breeding season. Climate change means willow warblers are now faring worse in warmer parts of the country, something that has implications for future conservation measures, such as habitat creation. The connection we’ve uncovered between temperature and breeding success suggests that conservation interventions for this species should be targeted in cooler parts of the UK.

She added, “I’d like to thank all the volunteers who take part in the BTO/JNCC/RSPB Breeding Bird Survey. Their records allow scientists like me to undertake analyses like this one and help us understand the pressures birds face as a result of climate change.’

In Jersey we have lost willow warbler as a breeding species although we still see birds in spring and autumn on migration. The annual north coast bird survey carried out in May or June each year when willow warblers and chiffchaffs would be nesting highlights the status of both these species. In Jersey, willow warbler is on the Red List. 

See the abstract of Breeding ground temperature rises, more than habitat change, are associated with spatially variable population trends in two species of migratory bird here

Infrastructure, hunting and climate change linked to huge migratory bird declines

Posted on by

From Rare Bird Alert

Migratory birds are declining globally because of the way that humans have modified the landscape over recent decades – according to new research.

The new study reveals that population declines have been greatest among species that migrate to areas with more human infrastructure – roads, buildings, power lines, wind turbines – as well as higher population densities and hunting levels.

Habitat degradation and climate change have also played a part in driving long-term declines.

The research team hope their work will help inform how best to target conservation efforts. James Gilroy, from UEA’s School of Environmental Sciences, said: “We know that migratory birds are in greater decline than non-migratory species, but it’s not clear why.

“We wanted to find out where in their life cycles these migratory species are most exposed to human impacts.”

The team identified 16 human-induced threats to migratory birds, including infrastructure associated with bird disturbance and collisions, conversion of land from natural habitat to human land use, and climate change. Advances in satellite imagery allowed the team to map each of the 16 threats across Europe, Africa and Western Asia. The team also created the first ever large-scale map of hunting pressure across the region.

A total of 103 species of migrating birds were studied, including many rapidly declining species like turtle dove and the common cuckoo, using large-scale datasets.

The team calculated “threat scores” for factors such as habitat loss and climate change, across breeding locations, as well as non-breeding ranges. They then explored the relationships between these threat scores and bird population trends calculated from 1985 to 2018 by the Pan-European Common Bird Monitoring Scheme (PECBMS).

Claire Buchan from UEA, said: “One of the biggest impacts seems to be caused by things that would kill a bird outright – for example flying into a wind turbine, a building, being electrocuted on a powerline, hit by a vehicle or hunted. We found that exposure to these human-induced ‘direct mortality’ threats in the bird’s wintering ranges are reflected in population decreases in breeding birds.”

Aldina Franco, also from UEA, said: “Our findings are important because we need to understand where declining species are being most impacted by humans across their seasonal migrations. Pinpointing where birds are most exposed to these threats could help us target conservation actions.”

Download the paper Spatially explicit risk mapping reveals direct anthropogenic impacts on migratory birds here