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	Whipoorwill Monitoring in 2003

Whip-poor-will Surveys in the Piscataquog River Watershed

by Pam Hunt, Ph.D.  Biodiversity Project Coordinator

The Whip-poor-will (Caprimulgus vociferous) was once widespread over much of New Hampshire but in recent years has shown a gradual but persistent decline. Many people report that they don't hear the species as often as they used to, and this pattern has been broadly observed over much of the Northeast. Because Whip-poor-wills are nocturnal, there are very few data on actual abundance and population trends that could be used to demonstrate a clear decline, and without such data it is hard to tell how healthy a local or regional population actually is. With this in mind, a Whip-poor-will survey project was initiated in the spring of 2003 in the Piscataquog River watershed. The project was jointly sponsored by the Piscataquog Watershed Association, New Hampshire Audubon, UNH Cooperative Extension, and the Living Legacy Project with funding provided by the U.S. Forest Service. The Living Legacy Project is a public-private partnership among state agencies and conservation groups to conserve the state's biological diversity. The intent of the surveys was to obtain baseline data on Whip-poor-will abundance throughout the watershed and determine whether this distribution was at all related to habitat features. In May of 2003, 16 Whip-poor-will survey routes were established in the Piscataquog River Watershed. Each route was 4.5 miles long and consisted of 10 stops spaced 0.5 mile apart. Volunteer observers were to survey each route three times between May 20 and early July, starting a half-hour after sunset. At each stop, the observer recorded all Whip-poor-wills detected in a five-minute period, noted noise levels, and recorded any other nocturnal birds heard. Volunteers were trained and assigned routes in mid-May. Of the sixteen routes, fourteen were surveyed three or more times. Five routes never recorded any Whip-poor-wills, and of the remaining nine, two recorded a single bird over the course of the summer. Numbers of birds on the remaining routes ranged from two to eight, and the average number of Whip-poor-wills at occupied routes was 3.8. Habitats along each route were evaluated both by the observers and through remote sensing (photo interpretation). Some of the routes were initially established in areas where aerial photographs showed potential Whip-poor-will habitat (oak and/or pine forests on dry soils, open or disturbed areas, and gravel pits). Two analyses looked at the relationship between habitat and Whip-poor-will abundance. The first compared routes as a whole, where each route was assigned to one of three habitat categories based on the amount of potential Whip-poor-will habitat: "none," "some," and "mostly." The average maximum number of Whip-poor-wills at sites of each type was as follows: none = 2.2, some = 1.8, and mostly = 3.5. There is something of a trend here, and the mean for "none" is inflated because of a single route that had six birds on one night and none on the other two surveys. An alternate analysis looked at data on a point-by-point basis. Each point was placed into one of two categories, "yes" or "no," based on whether or not it was near potential Whip-poor-will habitat. Within each category, points were further subdivided based on the number of surveys there on which Whip-poor-wills were detected. The resulting table looks like this: # visits Habitat Yes No 0 51 70 1 4 5 2-4 8 2 total 63 77 The differences between "yes" and "no" points is very slight, but note the relatively large number of "yes" points with two or three visits with Whip-poor-wills. It turns out that this small difference is large enough for the pattern to be almost statistically significant. In other words, both analyses suggest that within the Piscataquog River Watershed, Whip-poor-wills are more likely to occur in areas where we think the habitat is better for them. This may seem obvious, but remember that the habitat definition was based entirely on aerial photographs; the sites in question were not visited. Mind you, there are still more sites, even in good habitat, without Whip-poor-wills than with them, so the next step may involve some fine-tuning of habitat classification. Some of the data collected by the observers may help with this, but those have not been analyzed at this time. For instance, areas with high noise or extensive development that otherwise appear to be suitable habitat may not support Whip-poor-wills, or at least make them harder to detect. Beyond the question of habitat, the geographic distribution of records from the survey is particularly interesting. The vast majority of records, and all the points with more than one detection, are in the northeastern portion of the watershed. Not all of these locations are necessarily in good habitat either, suggesting that the concentration in the northeast may be due to other factors. One possibility is that there is a core area of good habitat around Clough State Park and the associated flood-control area, and that birds elsewhere in the northeast are thus overflow from this source population. Again, more detailed data, potentially including new routes, would help tease apart this pattern. In future years, it may be a better use of observers' time to focus efforts in the better habitats and conduct fewer surveys in areas where Whip-poor-wills appear to be absent, particularly the higher elevations in the western portion of the watershed. Finally, it should be noted that three Whip-poor-will survey routes were established in the Concord-Hopkinton-Webster area in 2003. Two of these found the species, although only a route in Webster had them consistently. Other surveys were coordinated by the New Hampshire Fish and Game Department in the Piscassic River watershed near Great Bay, but the results were not available at this time. It is hoped that these two projects can grow to incorporate a larger portion of the state and continue for several years so that we can obtain a better picture of Whip-poor-will distribution and abundance across New Hampshire, thus potentially help us understand the reasons for their decline. Many thanks to all the volunteers who made this project such a success, and we hope to be surveying Whip-poor-wills for many years to come!