The First Breeding Bird Atlas of Vermont (1976-1981)

Study Extent

State of Vermont, United States

Sampling

In the first atlas (1976-1981), one block in each quadrangle in Vermont was randomly selected to be surveyed—these were called “priority blocks.” A total of 179 blocks were selected to be surveyed in the first atlas. Field work for the first atlas was carried out during 1976 - 1981. Each block was surveyed for 1 to 5 years, depending on the amount of effort expended on a block in a given year. Blocks without a dedicated volunteer were block-busted; that is, surveyed intensively during a short period, usually by at least two people per block. Blockbusting was carried out by both volunteers and paid field technicians. In addition to observations collected during formal atlasing efforts, incidental observations were recorded and were especially encouraged for rare species in non-priority and priority blocks. The protocol for surveying a block followed that of other atlases and was in accordance with the general principles outlined in the North American Atlas Committee (NORAC) guidelines. Atlasers conducted extensive area searches of each block in all of the habitats represented. They recorded all bird species detected within safe dates and any breeding evidence observed for each bird species. Evidence of breeding was categorized as “Confirmed”, “Probable”, or “Possible”. A minimum number of species and confirmations were required to declare a block “completed.” This approach ensures a standard, minimum amount of coverage and survey effort on blocks. Observers were required to survey in as many different habitat types as possible on the block. Using a minimum number of species, while imprecise, is preferable to using the amount of time spent on a block as a measure of effort. The latter is problematic because the amount of time needed to survey a block adequately can vary depending on factors such as topography, habitat complexity and diversity, accessibility of habitats, times periods when surveying occurs, and especially skill level and motivation of the observer. In the first atlas, surveying on a block was considered complete when at least 75 percent of the species expected to occur in the block were found, and evidence of nesting was confirmed for at least half of those species. Based on an assumption that the average block in Vermont harbors 100 breeding bird species, a block was considered complete when at least 75 species had been documented, and at least 35 of those species were confirmed breeding. The 75/35 rule could not be strictly applied to blocks with relatively homogenous habitat. Forested blocks with few openings or wetlands, for example, do not have a diversity of habitats adequate to support 100 breeding bird species. Most of these blocks were located in the Northeastern Highlands biophysical region and in blocks in the Green Mountains, where blocks were extensively forested and supported few other habitat types.

Method steps

1. See Sampling description.
2. Because no database existed for the atlas, custom software was created by Ted Murin, atlas volunteer, to read scans of the species maps on pages 31-407 of the Atlas of Breeding Birds of Vermont (Laughlin, Sarah B. and Douglas P. Kibbe, eds. 1985. The Atlas of the Breeding Birds of Vermont. Hanover, NH: University Press of New England. 456pp. https://doi.org/10.6084/m9.figshare.11449779.v1). Original paper forms from the atlas are stored at the Vermont Center for Ecostudies. This file was used to created a DwC file for the project.

1. Aves
   common name: birds rank: class

State of Vermont, United States