North American grasslands and grassland birds have declined drastically due to
habitat degradation by fire suppression (i.e., woody encroachment), fragmentation, and
conversion to croplands. A better understanding is needed of the relationships among
disturbance regimes (e.g., fire), resultant vegetation changes, and grassland bird
communities to effectively manage remaining grasslands and grassland birds. I assessed
the relationship between post-fire succession, and mean relative abundance and nesting
ecology of breeding grassland birds (i.e., nest-site selection and nest success) in
mesquite-dominated rangeland of the Texas Rolling Plains, where prescribed fire is used
as a tool to manage shrub encroachment. Brush cover, grass cover, and visual
obstruction generally increased with post-fire succession, and bare ground decreased
with post-fire succession. Species richness, grasshopper sparrows (Ammodramus
savannarum), CassinâÂÂs sparrows (Aimophila cassinii), and dickcissels (Spiza americana)
responded positively to post-fire succession, and lark sparrows (Chondestes grammacus)
responded negatively to post-fire succession.; abundance of these avian groups was low
on the control sites. During 2004âÂÂ2005, 90 grassland bird nests were monitored. I
found conflicting results for vegetation parameters important to nest site selection and probability of nest success. For all species except lark sparrows, nest-site location was
positively associated with visual obstruction and with grass or forb cover. However, the
probability of nest success increased with lower visual obstruction, bare ground cover, or
grass cover. Grassland bird abundance, nest-site location, and nest success had differing
associations with vegetation variables. These results suggest that to effectively manage
remaining grasslands for sustainable breeding grassland bird populations, managers
should engage in practices that keep habitat in multiple vegetative successional stages.
| Identifer | oai:union.ndltd.org:tamu.edu/oai:repository.tamu.edu:1969.1/4672 |
| Date | 25 April 2007 |
| Creators | Lee, Stephanie L. |
| Contributors | Ransom, R. Dean, Jr., Slack, R. Douglas |
| Publisher | Texas A&M University |
| Source Sets | Texas A and M University |
| Language | en_US |
| Detected Language | English |
| Type | Book, Thesis, Electronic Thesis, text |
| Format | 489507 bytes, electronic, application/pdf, born digital |
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