Drowned Starlings Raise Conservation Concerns; New Study Investigates Deaths

Increased drowning mortalities among groups of young common starlings (Sturnus vulgaris) have raised some concerns. That's why a team of scientists led by the Zoological Society of London (ZSL) investigated 12 separate and mysterious incidents of starling drowning events recorded between 1993 and 2013.

While a single drowning event would not be seen as suspicious, drowning as a cause of death among groups of wild birds is generally rare. In the recent starling cases, however, groups of 10 or more juvenile birds that were just a few months old drowned during spring and early summer months. When exploring other causes of death, researchers found no evidence of underlying diseases, according to news release.

"Drowning appears to be a more common cause of death amongst younger birds, as they may be inexperienced in identifying water hazards. This combined with the fact that starlings are a highly social species could potentially explain why multiple birds drown together," Dr. Becki Lawson, lead author of the recent study and a wildlife veterinarian at ZSL, explained in the release. "Members of the public from around Great Britain have been instrumental in bringing this unexpected cause of starling mortality to our attention by reporting these incidents. With starling numbers declining in general across the U.K., we need to learn more about how and where these phenomena happen, in order to better understand why."

Starlings are stocky, loud and boisterous songbirds known throughout much of Europe. The birds generally travel in large groups and are characterized by their short tails, triangular wings, and long, pointed bills. In the summer they sport purplish-green iridescent feathers, but in the winter they develop a brown plumage covered in white spots.

"Starlings are a Red-listed species in the U.K., under threat from issues including loss of nesting sites and a lack of insect food sources -- so much so that their population has declined 79 percent in the past 25 years. While drowning is an unexpected cause of death, it's not thought to be a conservation threat as -- fortunately -- these incidents are currently relatively rare," Rob Robinson, co-author and Associate Director of Research at the British Trust for Ornithology (BTO), explained. "However, we still need to better understand factors such as disease that might be contributing to this decline. We would therefore ask people to keep up the good work by reporting incidents of starling death, whatever the apparent cause, via the Garden Wildlife Health website."

Young starlings may also be drowning during the early summer months because water acts a vital resource for the wild birds, particularly at this time of year when ponds have only recently thawed and birds dip in for a quick bath or to quench their thirst. However, in order to minimize the number of fatalities, researchers suggest installing a sloping exit or ramp to local bodies of water. Ultimately they hope this will help starlings, among other animals, easily access and exit water sources.

Their study was recently published in the journal Scientific Reports. Additionally, if you spot sick or dead wildlife throughout parts of Britain, you can report the sighting on the project's website.

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