Avian habitat affinity in the Lost Pines region of Texas

Date

2003-12

Authors

White, Clayton J.

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Abstract

Avian diversity has been used by many in the past as an indicator of habitat quality due to the relative ease of detecting birds. Even within habitats and seasons, primary components of the habitat that are most associated with avian diversity have been identified. Combining the habitat health and primary components of the habitat approaches will allow an investigator to identify not only the higher quality habitats, but also the factors that are most influential on the diversity in those habitats. The Lost Pines region of Texas is a well known area in central Texas. However, little scientific knowledge is known about the area. I investigated four identified habitat types located on Griffith League Ranch within the Lost Pines, Grassland habitats, Oak/Cedar habitats, Pine habitats and Pond habitats. Within each habitat, point counts were preformed in all seasons to identify the avian community present in the 100 m fixed radius sample area. 3,487 detections of 75 avian species were recorded from 300 point counts, indicating a relatively low abundance and low species richness for the area. Primary components of the vegetation were measured to identify associations of avian diversity with habitats. These measures included: percent canopy cover and density of each woody species, horizontal obscurity at 0.5 m height increments, herbaceous vegetation cover, and duff depth. Results from the ANOVA and orthogonal contrasts identified Oak/Cedar, Pine and Pond habitats as similar and most diverse, but different from Grassland habitats in three of four seasons. Fall had no difference in diversity values among the four habitat types. All possible subsets regression preformed on each season was used to identify components most associated with avian diversity. Diversity in winter had a positive correlation with yaupon and post oak canopy cover and an inverse correlation with duff depth. Diversity in spring had a positive correlation with yaupon and pine canopy cover and an inverse correlation with horizontal obscurity 0.0 to 0.5 m above ground level. Diversity in summer had a positive correlation with post oak canopy cover. Diversity in fall had a positive correlation with yaupon and eastern red cedar canopy cover and an inverse correlation with horizontal obscurity 0.0 to 0.5 m above ground and post oak canopy cover. The diversity of habitat components associated with avian diversity among seasons corresponds with original thoughts of diverse habitats supporting more diverse avian communities.

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Keywords

birds, biodiversity, habitats, lost pines

Citation

White, C. J. (2003). Avian habitat affinity in the Lost Pines region of Texas (Unpublished thesis). Texas State University-San Marcos, San Marcos, Texas.

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