You are here: Home
/ Publication Information
Title: Demography of Bell's Vireos in Missouri grassland-shrub habitats
Author: Budnik, Joel M.; Ryan, Mark R.; Thompson III, Frank R.;
Source: The Auk. Volume 117. Issue 4. 2000. 925-935
Publication Series: Scientific Journal (JRNL)
Description: Numbers of Bell's Vireos (Vireo beltii) have declined throughout much of the breeding range in recent years, yet little information exists to determine factors that are causing these declines. We studied Bell's Vireos nesting in grassland-shrub habitats at two study areas in central Missouri to determine reproductive performance, survival, and population growth potential. Birds were color banded and observed during the breeding seasons of 1996, 1997, and 1998 to determine seasonal fecundity. We monitored 124 breeding pairs (127 pair years) and 213 nests. Density declined from 1.00 to 0.80 territories per 10 ha at the first site and increased from 1.11 to 1.33 at the second site during the study. Mean nesting success was 31 +/- SE of 0.03% overall and ranged from 13 to 42% among years and study areas; 57% of the pairs fledged at least one young. Low annual production was a function of high rates of nest predation (41% of all nests observed, accounting for 44 to 78% of daily nest mortality annually) and nest parasitism by Brown-headed Cowbirds (Molothrus ater; 29% of nests observed, 17 to 37% of daily nest mortality annually). Mean seasonal fecundity was 1.60 young fledged per pair per year (range 1.00 to 1.79). Annual survival of adults was 61 + 0.04% and was higher than previously reported. We used our estimates of seasonal fecundity and annual survival of adults to determine the finite rate of increase (k) for our study population. Our study areas seemingly comprised sink habitats (k = 0.85). Thus, the vireos on our study areas likely were limited by low reproductive success. Population declines also may be caused by habitat loss, which highlights the need for investigation of historical and current rates of loss of grassland-shrub habitat.
Keywords: demography, Missouri, grassland-shrub, habitats, brown-headed Cowbirds, parasitism
- We recommend that you also print this page and attach it to the printout of the article, to retain the full citation information.
- This article was written and prepared by U.S. Government employees on official time, and is therefore in the public domain.
- This publication may be available in hard copy. Check the Northern Research Station web site to request a printed copy of this publication.
- Our on-line publications are scanned and captured using Adobe Acrobat. During the capture process some typographical errors may occur. Please contact Sharon Hobrla, email@example.com if you notice any errors which make this publication unusable.
XML: View XML
Budnik, Joel M.; Ryan, Mark R.; Thompson III, Frank R. 2000. Demography of Bell''s Vireos in Missouri grassland-shrub habitats. The Auk. Volume 117. Issue 4. 2000. 925-935
Get the latest version of the Adobe Acrobat reader or Acrobat Reader for Windows with Search and Accessibility