2010 Breeding Bird Population Trend Analysis

2010 Breeding Bird Population Trend Analysis 

This study could not have been possible without the enthusiasm, dedication and support of the Forest Preserve District’s experienced volunteers.

Background
In 1997 the Forest Preserve District initiated a volunteer program to monitor populations of breeding birds. The goal was to analyze trends and to prioritize habitat-management efforts that could help declining species.

In 2010 the District concluded 14 monitoring seasons with the following combined accomplishments:

  • 66 volunteers
  • 49 preserves
  • 1,390 points surveyed
  • 6,120 surveys
  • 65,534 observations
  • 152 species

Data Collection 

  • Volunteers completed point counts between June and mid-July from 1997 through 2010.
  • Volunteers monitored sites once per week for six weeks between sunrise and 9 a.m. on mornings without rain or high winds.
  • Each monitor stood at a predetermined point for 10 minutes and recorded all birds seen or heard within a 50-meter radius in woodlands and wetlands and a 100-meter radius in grasslands.

Red-Bellied Woodpecker Gallery1 

Regional Comparison  

  • District ecologists compared the directional trend for each species with analyses from the Bird Conservation Network and Breeding Bird Survey to identify regional trends.
  • The Bird Conservation Network  compiled over 180,000 point counts in over 10 Chicagoland counties between 1999 and 2007 from volunteers from the BCN, forest preserve districts and other local land managers.
  • The Breeding Bird Survey, a nationwide program coordinated through the U.S. Geological Survey, collected data in Illinois from 1999 to 2009.

Results 

  • Thirteen species showed significant positive trends in DuPage County: the downy woodpecker, willow flycatcher, American robin, indigo bunting, bobolink, sedge wren, field sparrow, gray catbird, red-bellied woodpecker, white-breasted nuthatch, eastern towhee, Henslow’s sparrow and blue-gray gnatcatcher.
  • Five species showed significant decline: the ovenbird, American crow, great-horned owl, swamp sparrow and grasshopper sparrow.
  • Directional trends agreed for 28 species from the three regional analyses (Table 1) — 20 positive and eight negative.

For a complete list of the analysis, click here.

Management Recommendations 

  • Habitat loss, degradation and fragmentation seem to be the most significant factors that lead to the decline of some species. They can reduce suitable breeding habitat, foraging areas, nesting habitat and perching locations.
  • Habitat management should focus on increasing connectivity between suitable habitats, increasing the size of suitable habitats, reducing invasive species, promoting native vegetation, and maintaining disturbance to diversify the height of vegetation within the suitable habitat.
  • Land managers should conduct prescription burns and mow outside of the breeding season, which is generally April 15 through Aug. 15.
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