Publications

One of the noteworthy, but troubling, finds of the 2021-2 NCBP biodiversity survey of the New Hope Bottomlands was a strong decline in the number of breeding bird species compared to what had been recorded in a survey conducted in the 1980s. To confirm that this was not just a particularly bad year, with numbers recovering to a more normal level thereafter, a more intensive breeding bird survey was conducted in 2024 by Steve Hall (NCBP), David Bradley (Durham Open Space Program), and the following members of the New Hope Bird Alliance: Jin Bai, Gail Boyarsky, Vicki Nebes, and David Anderson. Unlike the 2021-2 survey, which was qualitative – recording species as present or absent over a series of survey trips – the method used in this survey was quantitative, based on the type of territory mapping approach that has long been the gold standard for assessing the density of breeding bird populations. However, instead of using a large grid typical of those studies, we mapped the territories intersecting a 40-meter-wide corridor following the loop trail that runs through the bottomlands. By using the same protocols for handling edge territories as used in the traditional approach, we were able to compare our results to those of the breeding bird surveys conducted by Haven Wiley, Helmut Mueller, and their students at Mason Farm from the 1970s to 2010s. Among the neotropical migrant species, twelve species had either smaller territorial densities than were recorded in the Mason Farm surveys or were missing altogether. On the other hand, four migratory species had slight increases in density, as did eight of the eleven species of permanent residents. Overall, there was a net loss of 1.64 territories per hectare, but with a net loss of 4.43 among just the neotropical migrants. These results are consistent with trends measured over eastern North America.