Roost Site Characteristics of Great-Tailed Grackles (Quiscalus Mexicanus) in Texas




Dean, Elanor

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Great-tailed Grackles (Quiscalus mexicanus) are black birds (Family Icteridae) that form large roosts in urban areas during winter. Roosts are generally not maintained during the remainder of the year. Little information is available regarding Great-tailed Grackle roost site selection during the winter. I investigated habitat components characteristic of 15 Great-tailed Grackle roosts compared with 15 non-roost sites. I conducted a Principal Components Analysis (PCA) on habitat characteristics to assess potential differences between roost and non-roost sites. Principal Components Analysis revealed that Great-tailed Grackles select sites with taller trees and wider canopies. I used a student’s t-test to compare the PCA values of the x-axis for Great-tailed Grackle roost sites versus non-roost sites, confirming that tree heights and canopy widths are greater at Great-tailed Grackle roost sites. Other factors (available light, number of food sources, and number of trees per 100 m2) did not directly influence selection of roost sites.



Roost, Great-tailed grackle, Urban


Dean, E. S. (2012). <i>Roost site characteristics of great-tailed grackles (Quiscalus Mexicanus) in Texas</i> (Unpublished thesis). Texas State University-San Marcos, San Marcos, Texas.


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