Resource selection, movement patterns, and survival of post-fledging grassland birds in Missouri

The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file.Title from title screen of research.pdf file viewed on (May 25, 2006)Includes bibliographical references.Vita.Thesis (Ph. D.) University of Missouri-Columbia 2005.Dissertations, Academic -- University of Missouri--Columbia -- Fisheries and wildlife.Current grassland management paradigms focus on addressing nesting requirements for grassland birds, but ignore post-fledging requirements. I described resource selection, movement patterns, and survival of dickcissels (Spiza americana) and eastern meadowlarks (Sturnella magna) in southwestern Missouri, from 2002 to 2004 using radio telemetry. Across species at the micro-scale, there was support for the predation hypothesis (both species) and the thermal refuge hypothesis (dickcissels only). Woody cover (both species) and vegetation height (meadowlarks) had the highest relative importance across years. At the landscape scale, uniformly shrubby prairies, longer distances to forests, roads, and grazing were negatively associated with juvenile dickcissels. Crops, pastures, increasing distances to ponds and streams were positively associated with juvenile meadowlarks. Core home range sizes (50%) were similar across species, but 95% home ranges were 25% larger for meadowlarks (80.9 ± 13.9 ha) than dickcissels (51.2 ± 8.8 ha). Home range patterns were mostly non-linear and categorized as central or exploratory. Across years, biological factors (number of siblings, order of fledging) were the best predictors of home range size. Survival was higher and the instantaneous probability of death declined faster for meadowlarks compared to dickcissels. My results indicate that our working concepts of suitable breeding habitat need to be modified to accommodate post-fledging requirements and maximize the effectiveness of conservation strategies

Comparison of Microclimate at Grassland Bird Nests with Different Substrates

We compared the effects of two different nest placement strategies (shrubs vs. bunchgrasses) on microclimate conditions for grasshopper sparrow (Ammodramus savannarum) and lark sparrow (Chondestes grammacus) in Oklahoma. We predicted that the intensity and duration of extreme temperatures (greater than 39° C) and their variability would be reduced at shrub nests compared to bunchgrass nests. A verage maximum temperatures were similar at nests of grasshopper sparrow and lark sparrow, but confidence intervals were more variable and included biologically detrimental temperatures at grasshopper sparrow nests compared to lark sparrow nests. The proportion of time greater than 39° C also was similar at nests of both species, but on average grasshopper sparrow nests exceeded 39° C for 1.2 hr compared to 2.6 hr per 29-hr sampling period for lark sparrow nests. Our results indicate shrub nesters (lark sparrow) might be able to moderate the intensity and duration of biologically detrimental temperatures at their nests more successfully than bunch grass nesters (grasshopper sparrow)

Comparison of Microclimate at Grassland Bird Nests with Different Substrates

We compared the effects of two different nest placement strategies (shrubs vs. bunchgrasses) on microclimate conditions for grasshopper sparrow (Ammodramus savannarum) and lark sparrow (Chondestes grammacus) in Oklahoma. We predicted that the intensity and duration of extreme temperatures (greater than 39° C) and their variability would be reduced at shrub nests compared to bunchgrass nests. A verage maximum temperatures were similar at nests of grasshopper sparrow and lark sparrow, but confidence intervals were more variable and included biologically detrimental temperatures at grasshopper sparrow nests compared to lark sparrow nests. The proportion of time greater than 39° C also was similar at nests of both species, but on average grasshopper sparrow nests exceeded 39° C for 1.2 hr compared to 2.6 hr per 29-hr sampling period for lark sparrow nests. Our results indicate shrub nesters (lark sparrow) might be able to moderate the intensity and duration of biologically detrimental temperatures at their nests more successfully than bunch grass nesters (grasshopper sparrow)

EFFECTS OF RADIO-TRANSMITTERS ON FECAL GLUCOCORTICOID LEVELS IN CAPTIVE DICKCISSELS

We determined the effects of a leg-harness transmitter on fecal glucocorticoid levels of wild male Dickcissels (Spiza americana) in captivity. During the post-breeding season of 2001, we captured 10 male Dickcissels in central Missouri and housed them in individual pens of an outdoor aviary. We radio-tagged five birds; the other five were captured and handled, but were not radio-tagged. We collected fecal samples every other day prior to attachment (31 July– 21 August) and after attachment (24 August–20 September). Body condition and morphology were similar between control and transmitter-equipped birds. We observed a significant interaction between transmitter attachment and time since attachment. Compared to baseline levels, fecal glucocorticoid metabolites were significantly lower in control (6.1 ± 13.7 ng g-1) than transmitter-equipped (102.3 ± 13.7 ng g-1) birds during the first 24 hr after attachment. Although transmitter- equipped birds showed elevated fecal glucocorticoid levels, the response was acute and returned to baseline levels within 48 hr