Vacant lots as a habitat resource: nesting success and body condition of songbirds

Vacant lots are a common feature throughout many cities and may provide necessary habitat resources for urban bird populations. We evaluated the quality of vacant lots throughout Baltimore, Maryland, by determining how differences in vacant lot properties related to songbirds' nesting success and body condition. We observed 130 nests from American robins (Turdus migratorius), gray catbirds (Dumetella carolinensis), and northern cardinals (Cardinalis cardinalis) across the city and assessed body condition of 19 adult robins. Nesting success for all three species was greatest within areas of vacant lots with high shrub densities. The robins' body condition index did not vary extensively and was not related to any vacant lot site-or landscape-level variables. Even so, we found vacant lots to be actively used by 60 bird species for a variety of resources, with those containing more shrubs to be the most beneficial for bird species' nesting attempts. Vacant lots should no longer be discarded and underestimated; instead, they should be valued for the opportunities they provide for generalist bird species through small-effort habitat management practices.