USGS USGS Patuxent Wildlife Research Center

Procedures for collection, analysis, and display of data collected at several geographic scales: Migratory Bird Research at the Patuxent Wildlife Research Center

The Maryland-Delaware Miniroute Project

United States Department of the Interior
Laurel, MD, USA

The Sample Protocol

Miniroutes are a (generally) roadside-based sampling procedure for birds. The Maryland-Delaware Miniroute Project was developed in conjunction with Breeding Bird Atlases in each state, and were designed to provide a more-quantitative measure of bird abundance than atlas data, within the same scale of sampling. Consequently, miniroutes are conducted within atlas blocks, but differ from atlas data in providing a relative index to abundance. The Atlas sample units are 3.75' longitude and 2.5' latitude blocks, representing 1/6 of a U. S. Geological Survey topographic quadrangle map.

Each miniroute consists of 15 stops spaced at 0.5 mi intervals, at which 3-minute point counts were conducted. Habitats were sampled in proportion to their occurrence within the block, and some routes were partially sampled by canoe, foot, or bicycle to ensure that all habitats were sampled. Routes were sampled between sunrise and 2.5 hrs after sunrise.

Most of the routes were surveyed during the years 1982-1987, but a few routes were surveyed in 1988. Most routes were surveyed in June. The index to abundance on miniroutes was the number of stops (0-15) at which the species was observed.

Statistical Analysis

Observations were then entered into our Geographic Information System (GIS), and mapped to allow analysis of bird distributions. Inverse distancing was used to estimate abundances in unsampled locations. In this procedure, the abundance at a location is estimated as a weighted average of counts in adjacent routes, with weights proportional to the distance of the actual datum from the location of interest.

Abundance categories on the maps are presented in 5 groups. The abundance categories present regions with (1) 1 bird/route; (2) 2-3 birds/routes; (3) 4-6 birds/route; (4) 7-10 birds/route; and (5) 11-15 birds/route.