From Rare Bird Alert

A new report published this month has highlighted the threat marine plastic pollution poses to seabirds in the north-eastern Atlantic region. Researchers found that, of 34 seabird species investigated, 74% had ingested plastic.

The authors of the new study, from the North Highland College UHI’s Environmental Research Institute, part of the University of the Highland and Islands, and the RSPB Centre for Conservation Science collated data from all known studies reporting instances of plastic ingestion and nest incorporation in seabirds around northern Europe, Scandinavia, Russia, Greenland, Svalbard, the Faroes and Iceland.

Dr Nina O’Hanlon, of Environmental Research Institute, explains: “Marine plastic pollution is an increasing and global environmental issue which poses a major threat to marine biodiversity. The production of plastic continues to rise with millions of tons entering the oceans each year. Seabirds can ingest plastic, become entangled in it or incorporate it into their nests, causing impacts which may have negative consequences on reproduction and survival.”

Dr Alex Bond, RSPB senior conservation scientist, said: “The north-eastern Atlantic Ocean is home to internationally important breeding populations of seabirds and an amazing array of other marine life. Solutions to plastic pollution in the oceans require concerted action at its source on land – 80% of marine litter is thought to come from land – especially by producers and users.

“The properties which make plastics desirable are the very things which make it problematic,” Dr Bond continues. “Due to its low cost, approximately half of all plastic items are produced for single-use. Plastic never breaks down, it only breaks up, into smaller fragments which remain in the environment and, as its density varies, it can be found throughout the water column, increasing the number of species which come into contact with it.”

While the team’s research highlights some concerning statistics, its report concludes that more coordinated, comprehensive and detailed investigations are required on plastic ingestion and nest incorporation to assess the full impact marine plastic is having on seabird populations.

Dr O’Hanlon explains: “In the north-eastern Atlantic Ocean, an area of international importance for seabirds, there has been little effort to better understand how marine plastic affects different seabird species over time and regionally. We actually know very little about the current prevalence of plastic ingestion and nest incorporation for many species, several, like the long-tailed duck and Atlantic puffin, which are globally threatened. Only 49% of the 69 species which are commonly found in the region have been investigated for plastic ingestion. We believe it’s vital to have a multi-jurisdictional, coordinated and collaborative effort to gain a more comprehensive and current understanding of this important issue.”

The group’s research was undertaken as part of Circular Ocean, a project funded by the EU’s Northern Periphery and Arctic Programme, which aims to incentivise the reuse and recycling of marine plastic litter in remote and rural regions.

The full paper Seabirds and marine plastic debris in the northeastern Atlantic: A synthesis and recommendations for monitoring and research can be read here

From Rare Bird Alert

Calling European storm petrels have been recorded for the very first time on the Shiant Isles, Scotland this summer, an important milestone for the Shiant Isles Recovery Project, which is working to attract these small seabirds to nest on the islands. The characteristic “churring” call of storm petrels was heard from burrows, their breeding habitat, an encouraging sign that the project’s conservation work is paying off.

The EU LIFE+ funded partnership project between RSPB Scotland, Scottish Natural Heritage, and the Nicolson family, the custodians of the islands, began in 2014 to provide safe breeding grounds for Scotland’s globally threatened seabirds on this cluster of islands in the Minch, five miles off the coast of Harris. A population of invasive non-native black rats on the islands were thought to be limiting the breeding success of the colonies of puffins, razorbills and guillemots, whilst storm petrels and Manx shearwaters were not found there at all.

Following a rat eradication programme in the winter of 2015/16 the project has been focused on monitoring how the wildlife has responded, ensuring the biosecurity of the islands, and attempting to attract storm petrels and Manx shearwaters to breed, as there is ideal nesting habitat for them. It will be March 2018 before the islands can be officially declared free of rats, provided none are found between then and now.

Storm petrels are little bigger than sparrows and only come to shore in summer to breed. Scotland’s internationally important population currently only nests at a limited number of potentially available sites on offshore islands because of their vulnerability to predation. They are known to abandon and avoid nesting sites where rats or other ground based predators are found.

While these small seabirds have been recorded flying past the Shiants for many years by the Shiants Auk Ringing Group prior to the recovery project beginning there was no evidence that they were landing on the islands or attempting to nest there. Last summer night vision cameras captured footage of several of these small seabirds, but this is the first year their churring has been heard in burrows.

This summer a speaker broadcasting a recording of a storm petrel churring (hear storm petrels here) was placed by some boulder scree near the shore and played throughout the night. The project hoped that this would not only attract storm petrels to the area so they could discover the nesting sites, but also to settle and start a breeding colony there. Calls from birds were recorded from three separate sites close to the speaker.

A night vision camera also captured footage of a storm petrel displaying nesting behaviour; looking relaxed and heading into a burrow. While it’s possible that birds may have successfully bred on the islands this summer confirming this is difficult due to them only entering and leaving their nest burrows in darkness and would have risked disturbing them due to the locations of the calls.

Dr Charlie Main, Senior Project Manager for the Shiant Isles Recovery Project said: “The churring of a storm petrel is very distinctive and we’re delighted that it’s been recorded on the Shiants this summer. While we are still some way off the islands being officially declared rat free these calls indicate that all the biosecurity work we’re doing to keep these islands predator free and make them ideal breeding sites for seabirds is paying off.

“It’s even more exciting to think that the birds may have bred on the islands this year, although the risk of disturbing nesting birds meant we were unable to confirm this. These calls are very positive signs for the future and we hope that next year we’ll be able to record even more calls and footage of the birds. The long term aim is to allow a breeding colony of storm petrels to establish at the Shiants.”

Dr Andrew Douse, Policy & Advice Manager, Ornithology at Scottish Natural Heritage said: “The return of storm petrels as a breeding species on the Shiants is one of the key aims of the project for SNH, so the news of birds recorded calling is very welcome. Storm petrels only occur on islands without rats, which means that they are very vulnerable to the effects that arise from invasive species such as these. The Shiants are an ideal breeding location for storm petrels and hopefully they will go on to become an important stronghold for this species.”

In the Channel Islands we have a healthy population of storm petrels on (rat-free) Burhou (Alderney) but the presence of rats elsewhere, even in otherwise suitable areas of the coast like Plémont, mean that we have nowhere near as many as we could have in the islands with adequate management.

From Carbon Brief

Flying back too early or too late for spring is costly for migratory birds. Their arrival must coincide with the emergence of food sources, such as caterpillars, in order to enable them to feed and successfully rear their young.

Birds that overwinter in warmer climes, including willow warbler, tree pipit and barn swallow, will be unable to cut their migrations short as climate change causes spring to arrive earlier in many parts of Europe, as new evidence suggests that some birds are much less adaptable to climate change than previously hoped.

Time to fly

Each winter, around half of the UK’s birds take off to find food in a more temperate climate, returning to their ancestral breeding grounds the following spring. However, scientists fear that this annual migration could be disrupted by climate change, which is causing spring to arrive six-to-eight days earlier in Europe than it did 30 years ago.

Evidence suggests that some birds will be able to adapt by leaving for their winter grounds later in the year or wintering closer to home (see BOTE report here). However, not all birds are able to perceive subtle shifts in temperature and instead rely on the number of daylight hours – which is unaffected by warming – to tell them when it’s time to fly.

For these birds, keeping pace with an earlier spring means getting back from their wintering grounds more quickly. But the solution isn’t as simple as flying at a faster speed because birds simply do not have the energy to beat their wings any harder during their lengthy migrations. A new study, published in Nature Climate Change, looks at a third option: reducing the length of “stopovers”. These are the avian version of a pit stop, where birds feed and rest before continuing their journey. While shorter stopovers can significantly speed up a migration, it’s unlikely to be enough, the study finds.

For example, cutting time spent resting by 50% would lead to birds arriving in their spring grounds just two days earlier, on average. In comparison, the peak availability of caterpillars – a key source of food for birds – in UK forests advanced by 20 days between 1980 and 2008. This mismatch between the arrival time of birds and their foods could spell trouble for many bird species that are unable to adjust the start of their spring migration, says lead author Dr Heiko Schmaljohann from the Institute of Avian Research in Germany:

“The inability to sufficiently adjust or adapt the breeding area arrival timing leads to an increasing mismatch between food availability and its demand. If this mismatch increases for a species population, it is possible that this may lead to a population decline.”

Schmaljohann adds that although there are some birds which seem to be adjusting their spring arrival date in response to climate change, such as the pied flycatcher, it is still not known which species are most at risk of decline:

“The pied flycatcher has advanced its breeding area arrival timing the most. Whether they have a better ability of detecting how conditions will be at the breeding area in one to two months is totally unknown. It is extremely unlikely that birds, being still at their African wintering grounds, can anticipate the environmental conditions they will experience at the breeding areas in advance.”

Calculating migration speed

To understand what drives the speed of a migration, the researchers reviewed data from 49 tracking studies of 46 different bird species.

They found that the overall migration speed is largely dependent on the number of stopovers, which they defined as spending more than one day in the same location. Researchers then used mathematical modelling to predict how reducing the amount of time resting while flying home could help birds to speed up.

Their modelling considered the average flying speed, the total migration distance and how birds can vary their speed in response to changing environmental conditions. In the future, birds may actually be forced to take longer breaks as their stopover grounds will likely be affected by climate change, says Dr Schmaljohann:

“When birds experience unfavourable conditions, such as drought, heavy rain and cold temperatures, the feeding conditions deteriorate. The feeding conditions directly affect total speed of migration via stopover duration.”

Adapting on the fly

This new research may help to explain why birds appear increasingly unable to keep pace with climate change, says Dr Stephen Mayor, an ecologist from the University of Florida, who wasn’t involved in the study:

“You would think that birds which migrate thousands of kilometres with the changing seasons would be experts at adapting to climate change, but this evidence suggests birds are much less adaptable than we might hope – probably because the climatic changes are so rapid and variable.”

The full paper The limits of modifying migration speed to adjust to climate change, Nature Climate Change can be seen here