Olive-sided Flycatcher Surveys Yield Sobering Results

Posted on November 5, 2014

OSFL-(D-Forsyth-Aug-'14)-webThe Olive-sided Flycatcher (Contopus cooperi, OSFL) is a large flycatcher found in coniferous forests across the boreal and montane areas of North America. Across this broad range, the species has been in consistent decline since at least the mid-1960s, with an average loss of 3.5% per year according to the Breeding Bird Survey. These declines are also seen in Breeding Bird Atlases, where projects repeated in the early 2000s have consistently shown range retractions when compared with original Atlases from the 1970s and 1980s. Atlases in New York, Vermont, and Massachusetts found OSFLs in roughly a third fewer blocks than 20-30 years previously. Causes for the decline are unknown, but may include habitat loss or alteration on the breeding and/or wintering grounds.

Based largely on these declines, the OSFL is considered a “Special Concern” species in New Hampshire. Although available data suggest a decline, there was need for a more accurate assessment of the species’ current range. To this end, I initiated an OSFL survey in the summer of 2014. To start, I collected all available records of the species since 2000 and plotted them on a map of the state. This map was compared to the map generated by the New Hampshire Breeding Bird Atlas in the early 1980s to identify areas in need of further searching. Sites where there were flycatchers during the Atlas but which had not been checked recently were the highest priority, followed by other areas with no recent records.

Volunteers were recruited to survey priority areas in June and July, with surveys involving repeated visits to locations with suitable habitat. A total of 13 observers adopted one or more areas to survey, and additional supplemental data were obtained from eBird and other observers. In the end, we obtained data from 35 priority areas, but OSFL were found in only 11. Of 16 areas in the southwestern part of the state, only one had an OSFL, and this was at the northern edge of the region. In contrast, the species was detected in six of 13 areas in central NH and five of six areas in Coos County. Looking only at areas that had OSFL during the Atlas, none were found in nine areas in the southwest, three of eight in central NH, and three of four in the north.
This pattern of decreasing occupancy to the south mirrors the range retractions seen in neighboring states and supports the hypothesis that the decline is a regional problem. Surveys will continue in 2015, when effort will shift into central and northern New Hampshire. After two years of data are collected and analyzed, we will have a much better picture of the species’ status in the state, which may in turn lead to ideas for conservation action. People interested in helping with these surveys should contact me at phunt@nhaudubon.org.

Funding for the Olive-sided Flycatcher surveys has come from the Nuttall Ornithological Club’s Blake-Nuttall Fund and the Davis Conservation Foundation.

-Pamela Hunt

Published in Afield: Winter 2014 – 2015