Vermont’s second generation Breeding Bird Atlas began in 2001 with a gathering of Vermont’s leading bird conservationists to determine whether and how a second generation bird Atlas would be carried out. In 2002, a committee was formed and a director hired to carry out the Atlas under the auspices of the Vermont Institute of Natural Sciences (VINS).
Volunteers or “citizen scientists” were responsible for the majority of the data collected during the Atlas. Volunteer county coordinators (generally accomplished birders), were responsible for coordinating block assignments, providing logistical and skills support, coordinating logistics, overseeing data submission and entry, data quality control, following up on reports of rare species, and in some cases, organizing or leading workshops or field trips.
After the five-year collection period, the Atlas project migrated to the Vermont Center for Ecostudies, where final data entry, error checking and maps and data summaries were produced.
Data quality and the niche for Atlas data
Breeding bird atlases provide a relatively large number of samples at a large spatial scale. Compared to data produced by more intensive survey methods carried out over a smaller spatial scale, the data are generally of lower quality. Atlas data are a compromise between intensive, small-scale studies and coarser, less precise surveys and are able to provide broad-scale data for species that are not usually not well surveyed such as waterbirds, nocturnal species, and irruptive species.
Each participant in the project, referred to as an observer or ‘atlaser’, is assigned one or more blocks (grid cells) in which to conduct extensive area searches. They record any breeding evidence observed for each bird species; this evidence is categorized as “confirmed”, “probable” or “possible”. The results can be mapped and will then provide comprehensive information about the distribution of breeding birds in the region covered. For more information on BBAs see the North American Ornithological Atlas Committee (NORAC) website.
Sampling and Block Coverage
Vermont was divided into “priority blocks” – sections of land throughout the state that were surveyed in the first Atlas or were selected for this Atlas. Each block consisted of 1/6 of a USGS 7.5 minute topographic quad. One priority block from each quad and some secondary priority blocks from many quads were randomly chosen and surveyed. A total of 179 blocks were selected to be surveyed in the first Atlas-these were referred to as “Priority 1 blocks”. The secondary blocks chosen-referred to as “Priority 2 blocks”-were surveyed in the second Atlas along with Priority 1 blocks, in order to double the land area covered.
In order to choose Priority 2 blocks, we randomly selected a block from the five non-priority blocks in each of the 179 quadrangles used in the first Atlas. If the the randomly selected block had less than 69 species recorded in the first Atlas and a different non-priority block had at least 69 species recorded, we used the latter block. If there was more than one non-priority block with at least 69 species in the first Atlas, we used the block with the greatest number of species. In the first Atlas, some quadrangles did not fall entirely within Vermont and were not included in the block selection process. In the second Atlas, blocks were added in these borderline areas as Priority 2 blocks. A total of 186 Priority 2 blocks were added in the second Atlas. The total number of Priority 1 and 2 blocks was 365. The remaining 872 non-priority block were not selected to be surveyed, but were surveyed opportunistically.
Inexperienced birders were usually paired with more experienced birders. Many counties held workshops to discuss objectives, protocols, tips and to answer questions. Support materials were provided to atlasers and reminders and updates via a Vermont Breeding Bird Atlas listserv provided valuable information as well as a way to maintain momentum, share interim results, and create a sense of community around the Atlas.
Participants were assigned one or more blocks to survey, the number assigned depending on how much time they could commit during the five-year survey period and their birding skill level. Blocks were surveyed for anywhere from 1 to 5 years, depending on the amount of effort expended on a block in a given year. In order to avoid falsely recording a migrant as a potential breeder, we established “safe dates” for each species. Safe dates were established using data from the first Vermont Atlas, Records of Vermont Birds, and research and monitoring projects within the state. When Vermont data or expertise was not available for a species, data from neighboring states were used to estimate appropriate dates for Vermont. Most blocks were surveyed between 15 May – 1 August.
The protocol for surveying a block followed that of other atlases, and in accordance with the general principles outlined in the North American Atlas Committee (NORAC) guidelines.The goal was to survey the block until at least 75% of the species likely to occur in the block were found, and evidence of nesting of at least 50% of these species was confirmed. Atlasers recorded all bird species detected within safe dates and any breeding evidence observed for each bird species. The amount of time needed to survey a block depended on topography, habitat complexity and diversity, accessibility of habitats, and, to some extent, skill level of the volunteer. On average, complete coverage of a block required ~ 50 hours of field work.
Incidental observations made when people were not actively atlassing were also recorded, but without associated effort hours.
Breeding Evidence Codes and Categories