Oregon Breeding Bird Atlas
Introduction
The purpose of the Oregon Breeding Bird Atlas Project was to conduct a
volunteer-based statewide survey of all birds that potentially or
actually nest in Oregon.
The intent was to determine the species that are present in every part
of the state during avian breeding seasons and, if possible, obtain
evidence of breeding.
The Atlas is the largest and most
comprehensive statewide inventory of birds ever conducted in Oregon.
The collected information is crucial to improving
the accuracy and precision of previously published maps and lists of
species distributions. Such maps and lists are widely used by land
managers in assessing resource management priorities and impacts, and
by scientists and amateur birders for understanding bird distributions.
Field surveys were conducted over a five year period from 1995 through 1999.
Over 800 volunteers participated in the surveys.
Observers used whatever search techniques they felt were
most effective in locating the widest variety of species in an area
and confirming breeding by those species. No attempt was made to estimate
relative or absolute abundance of any
species.
Some 844 standard-sized
areas (grid units) of 435 km2 and 25 km2 were surveyed statewide.
Survey efforts were not confined to "priority" units.
The data provide a permanent record of where different birds lived in
the late 20th century, and can be used by future scientists to document
changes in species' geographic ranges and effects of humans.
What�s special about Oregon�s Breeding Bird Atlas Project?
- Of atlas projects conducted and published in over 20 states, this is the first to be published as an interactive CD-ROM.
- Breeding birds were not surveyed in a random or systematic sample of geographic units, but rather in contiguous units that spanned the state comprehensively.
- Project volunteers found 275 possibly-breeding species and confirmed nesting of 253 (92%) of these.
- Volunteers discovered and confirmed the breeding of one species that had never been proven to breed in Oregon � Blue Grosbeak � and provided the best documentation yet for nesting of Red-shouldered Hawk and Northern Mockingbird.
- Volunteers provided less definitive evidence of breeding of several species that have not been proven to nest in Oregon in recent times. These include Common Goldeneye, Merlin, Boreal Owl, Yellow-billed Cuckoo, Plumbeous Vireo, Virginia�s Warbler, Pine Grosbeak, White-winged Crossbill, and Black-chinned Sparrow.
- The project was completed in 5 years by over 800 volunteers
(111 square mile per volunteer, average), who spent a total of 39,854 hours surveying birds in the state.
- More than 68% of the 430 contiguous atlas units (hexagons) achieved their individual targets for number of species found. The targets were based on number of species expected, given the location and habitat.
- The project (including this CD) was completed on a total budget of just $68,000, and employed no salaried staff or field personnel.
- This is the first state atlas project to test ("ground-truth") habitat-based predictions of species occurrence ("Gap analyses") on a statewide basis.
- This is the second state atlas (Washington�s was the first) to map the distribution of habitats integrally with distribution data for bird species that use those habitats.