Rural structures pose greater relative threat to birds than urban ones

Common yellowthroat (2). Photo by Mick DrydenFrom Rare Bird Alert

Further news on the numbers of birds that die each year colliding with buildings.

About one billion birds are killed every year when they unwittingly fly into human-made objects such as buildings with reflective windows. Such collisions are the largest unintended human cause of bird deaths worldwide—and they are a serious concern for conservationists.

A study published in June finds that, as one might suspect, smaller buildings cause fewer bird deaths than do bigger buildings. But the research team of about 60 also found that larger buildings in rural areas pose a greater threat to birds than if those same-sized buildings were located in an urban area.

The research team monitored 300 buildings of varying size and environmental surroundings for bird mortality at 40 college and university campuses in North America in the autumn of 2014. This included six buildings on the University of Washington’s Seattle campus. They designed a standardised monitoring protocol so that the field crews documented bird mortality uniformly. In all, they documented 324 bird carcasses of 41 species. At each site, somewhere between zero and 34 birds met their feathery demise.

Ovenbird. Photo by Mick Dryden

“Consistent with previous studies, we found that building size had a strong positive effect on bird-window collision mortality,” Hager and team wrote in a statement about the continent-wide research. “But the strength of the effect on mortality depended on regional urbanisation.”

Why is that? The researchers think it might be related to how birds select habitats during migration, and differences in bird behaviour between urban and rural populations. For example, they write, forest-adapted birds often select rural habitats with lots of open space and fairly few impervious surfaces over more urban areas.

Lighting patterns may also play a part, they reason. Lights from large, low-rise buildings in rural areas may act to attract migrating birds in what the team dubbed a “large-scale beacon effect,” where this effect may be “more diluted among large buildings in urban areas.”

Another theory is that urban birds may actually learn from “non-fatal” collisions and gain “new anti-collision behaviours” that help them avoid colliding with windows in urban areas. Previous research, they note, “suggests that the relatively large brain size in birds makes them primed for learning.”

The results suggest, the authors write, that measures taken to prevent bird collisions “should be prioritised at large buildings in regions of low urbanisation.”

The paper Continent-wide analysis of how urbanization affects bird-window collision mortality in North America, Biological Conservation can be seen here

Rufous hummingbird. Photo by Mick Dryden


Plea to dog owners after lambs are chased off cliff

p1730186From the Jersey Evening Post

Shepherd Aaron Le Couteur has urged dog owners to ensure their animals are kept on leads while walking in areas with lambs after two of his livestock were killed by being chased off a cliff.

The Jersey States police are now investigating following the incident, involving two Manx loaghtan lambs that grazed on land owned by the National Trust for Jersey near Devil’s Hole and are an integral and much-loved part of the Birds On The Edge project. Red-billed choughs need sheep!


Aaron, who put his “heart and soul” into looking after the large flock, said that the incident was “incredibly frustrating”. “It happened at about 3 pm on Sunday [16 July]”. Two lambs were chased off the edge of a cliff by a dog and unfortunately died as a result. “Because there is an eye-witness the police are investigating, using the leads that they have available, and there is visual evidence” he said.

Aaron said that about 90 per cent of dog owners were responsible and had “exactly the right attitude”, but he added: “There is also the ten per cent who are a lot more difficult to get through to”. He added: “it is pretty obvious. There are signs on the gates as you walk in warning you that there are lambs on the site and to tell people to put their dogs on leads. We are trying to keep this open as a public space rather than restrict people from using it. What we have got to try to get across is that these are living, breathing animals and rearing them is no mean feat”.

Charles Alluto CEO of the National Trust for Jersey added “unfortunately some people do not appreciate that the land in question is agricultural land and in private ownership. Public access is totally at the discretion of the land owner and is a great pity that this is abused by a small number of people not fully controlling their dogs as requested at the entry points. All dogs, however well trained, are a potential threat to livestock as their inherent instincts can over-ride any controls. If this was more fully and widely appreciated then undoubtedly we could avoid such tragic incidents occurring in future”.

Under the Dogs (Jersey) Law 1961, it is an offence for dogs to chase or worry livestock or to not be under proper control. Anyone in breach of the law is liable to a fine of up to £1,000.

Read news about the sheep here