Songbirds and Soils: Relating Forest Ecosystem Quality to Nutrient Availability

Open Access
- Author:
- Pabian, Sarah Elizabeth
- Graduate Program:
- Wildlife and Fisheries Science
- Degree:
- Doctor of Philosophy
- Document Type:
- Dissertation
- Date of Defense:
- June 22, 2010
- Committee Members:
- Margaret Brittingham, Dissertation Advisor/Co-Advisor
Margaret Brittingham Brant, Committee Chair/Co-Chair
Elizabeth Weeks Boyer, Committee Member
Erica A H Smithwick, Committee Member
Walter Matthew Tzilkowski, Committee Member - Keywords:
- ovenbird
acidic deposition
snails
calcium
dolomitic lime
habitat quality - Abstract:
- Many forest songbird populations may be at threat from soil acidification and associated changes in habitat quality. Forest soils in much of the Northeast are becoming increasingly acidic and nutrient depleted as a result of land use and acid deposition. Forest songbirds may be particularly sensitive to soil acidification because they require large amounts of calcium to reproduce, and acidification can deplete soil calcium and calcium-rich food sources required for reproduction. The purpose of this research was to use an ecosystem-level approach to examine how forest songbird abundances and demographics are related to soil conditions, to understand how current conditions are affecting birds. I investigated the relationships between forest songbirds and soils and potential mechanisms using a lime application experiment, and two observational studies at different scales. Based on the results of these three studies, abundances of most bird species were associated with soil conditions in three main ways: (1) Several bird species were most abundant in areas with less acidic soils, a well-developed understory, and higher snail abundances. These bird populations are likely at greatest risk from soil acidification. (2) Several bird species, like the Ovenbird (Seiurus aurocapillus), were abundant in most forests, regardless of soil conditions. However, the Ovenbird may be calcium-limited in acidified forests because reproduction and territory size were related to soil calcium, and responded positively to the increased calcium availability resulting from liming. (3) Several bird species were most abundant in areas with very acidic soils and high densities of mountain laurel (Kalmia latifolia). Habitat for these bird species may be increasing in PA as soils become increasingly acidic, but they may be calcium-limited because the abundances of many responded positively to liming. These complex relationships between birds and soils will likely result in different responses to further soil acidification. Based on these results, I concluded that the reproduction, abundance and distribution of many forest songbird species have a strong relationship to soil conditions, mediated via vegetation structure and invertebrate prey availability. I recommend that soil conditions be integrated into future forest songbird conservation and management activities.