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Neighborhood Nestwatch Data Summary

Nests

Since the inception of Neighborhood Nestwatch in 2000, 606 nests from 8 different kinds of birds, commonly found in Washington D.C. backyards, have been monitored.

  • Robin

  • Chickadee

  • Carolina Wren

  • Catbird

  • House Wren

  • Cardinal

  • Mockingbird

  • Song Sparrow

Table 1, below, summarizes the nest data. You can click on a column header to sort the table by that column.

Table1: Nest Data Summary
Bird Nests1 Clutch Size2 Success3

Key:

  1. Total number of nests by that species of bird
  2. Average number of eggs laid in a nest
  3. Percent of nests that fledge at least one young bird
American Robin 86 2.37 50%
Carolina Chickadee 32 4.13 72%
Carolina Wren 26 3.12 46%
Gray Catbird 194 2.73 52%
House Wren 177 4.51 68%
Northern Cardinal 51 2.16 31%
Northern Mockingbird 27 2.56 56%
Song Sparrow 13 3.08 62%

Preliminary analyses suggest that cavity-nesting birds, such as chickadees and house wrens, tend to have higher nesting success and lay larger clutches than open-cup nesting birds. This may be because their nests are predated less often or that they make fewer nesting attempts per season. In addition, it may be that adults don't live very long.

Birds that have a long nesting season, for example robins and cardinals, lay fairly small clutches and have fairly low nesting success. They may not "put all their eggs in one basket", so to speak.

Table 2, below, shows how backyard bird nests in rural areas differ from those in urban areas. A GIS was used to calculate the percent of impervious surface, roads, houses, and the like, within 500 meters of each nest. For all species except the robin, clutch sizes are smaller in urban areas. Perhaps this is because of predation, urban birds may spread out their nesting attempts, or perhaps there is less food in urban areas, country birds can raise more young because there is more food.

Table2: Clutch Size by Habitat
Bird Rural
Clutch Size1,2		 Urban
Clutch Size3

Key:

  1. Percent of impervious surface (e.g. roads) within 500 meters of the nest is less than 10
  2. By putting your cursor over the clutch size, you can see the number of nests that were averaged.
  3. Percent of impervious surface is greater than 10
American Robin 2.27 2.45
Carolina Chickadee 4.59 4.10
Carolina Wren 3.78 1.14
Gray Catbird 2.85 2.74
House Wren 4.31 3.99
Northern Cardinal 2.25 2.23
Northern Mockingbird 2.67 2.36
Song Sparrow 3.00 2.50

Banding

To get an idea of how long backyard birds live, and to see how well individual birds raise young (and who pairs with whom), birds are marked with a unique color combination on their legs. To date, 5991 birds have been banded of which 497 have been resighted in subsequent years.

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