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Arnold JM, Tyerman DJ, Crump D, Williams KL, Oswald SA.2015. Contemporary premature feather loss (PFL) among common tern chicks in Lake Ontario: the return of an enigmatic developmental anomaly. PeerJ PrePrints3:e1196v2https://doi.org/10.7287/peerj.preprints.1196v2
In July 2014, we observed premature feather loss (PFL) among non-sibling, common tern Sterna hirundo chicks between 2 and 4 weeks of age at Gull Island in northern Lake Ontario, Canada. Rarely observed in wild birds, to our knowledge PFL has not been recorded in terns since 1974, despite the banding of tens of thousands of tern chicks across North America since then. The prevalence (5% of chicks) and extent of feather loss was more extreme than in previous reports but was not accompanied by other aberrant developmental or physical deformities. Complete feather loss from all body areas (wing, tail, head and body) occurred over a period of a few days but all affected chicks appeared vigorous and quickly began to grow replacement feathers. All but one (recovered dead and submitted for post-mortem) most likely fledged 10-20 days after normal fledging age. Secondary covert feather samples were collected from PFL chicks (n=6; including shed feathers and re-growing live feathers) and normal individuals (n=8; plucked live feathers) and were analyzed for corticosterone concentrations. There was striking temporal association between the onset of PFL and persistent strong southwesterly winds that caused extensive mixing of near-shore surface water with cool, deep lake waters. We found no evidence of feather dystrophy, concurrent developmental abnormalities or nutritional shortfall among affected chicks. Thus, the PFL we observed among common terns in 2014 was largely of unknown origin but may have been caused by unidentified pathogens or toxins welling up from these deep waters along the shoreline. PFL was not observed among common terns at Gull Island in 2015, although we did observe similar feather loss in a herring gull Larus argentatus chick in that year. Comparison with sporadic records of PFL in other seabirds suggests that PFL may be a rare, but non-specific response to a range of potential stressors. Its reemergence in penguins, and now gulls and terns, may indicate widespread environmental changes that could lead to health risks for birds and other wildlife.
This version is immediately prior to submission for peer review. Thanks to much welcome feedback, we have incorporated a review table of other instances of PFL in seabirds. We have also added corticosterone analyses from samples collected and the post-mortem results of the PFL chick that died.
Raw data underlying results in the manuscript
Contains the following:Summaries of weather data downloaded from Environment Canada (see paper and detailed links for more details about each metric);Data for measurements of mass and wing for PFL chicks and mass for normally developing chicks at Gull Island in 2014 ;Daily wing (maximum wing chord) growth rates for PFL chicks and matched controls ;Daily tail (maximum length of longest outer tail feather) growth rates for PFL chicks and matched controls ;Measurements of mass (g) of chicks different ages (days) through development used in construction of composite growth curves from 8 PFL chicks and 159 control chicks at Gull Island in 2014 ;Notes taken on the condition of chicks and the progression of PFL for the eight PFL chicks.