Forage Selection and Grouping Patterns of Male and Female Scimitar-horned Oryx (Oryx dammah) on Mason Mountain Wildlife Management Area, Mason, Texas
Abstract
Little is known about resource selection patterns of scimitarhorned oryx (Oryx dammaty in Texas, information that is vital for
informed management decisions. Scimitar-horned oiyx are less
dimorphic in body size (males approximately 12% larger than females)
than most ruminants (males 20 - 50% larger than females). Ruminants
dimorphic in body size display intersexual differences in diet and spatial
patterns, presumably because of body size differences. Consequently,
scimitar-horned oryx is an ideal species to test for intersexual differences
in spatial patterns, diet and food selection. I hypothesized that male and
female scimitar-homed oiyx associate in mixed-sex groups and do not
exhibit intersexual differences in forage selection. My study was initiated in June 2006 at Mason Mountain Wildlife Management Area in central
Texas and data collection was completed in April 2007. I measured
grouping patterns from systematic vehicle surveys conducted at dawn
and evening in six different months. I observed males and
femalesthrough binoculars and collected fecal samples from known sex
individuals in six different months. I determined food habits by
identifying plant fragments in fecal samples. Forage availability was
measured seasonally by establishing 100 m transects in areas where
fecal samples were collected. Mixed-sex groups were encountered more
commonly than other group types and most males and females
encountered (> 0.69) were in mixed-sex groups. There were no
differences between the diet of males and females. Scimitar-horned oryx
displayed differences among months in forage selection. In summer and
fall, there was an inverse correlation between availability and use of food
items. In winter there was a positive correlation and no correlation
between availability and use of food items in spring. The majority of the
diet was grasses, such as Sporobolus sp., Eragrostis sp., and forbs. The
findings of this study support expectations based on body size, males
and females occur in the same groups and consume similar forages.
Unlike many ruminants, managers do not have to consider separate
habitat requirements of each sex when managing scimitar-horned oryx.
Citation
Robinson, S. E. (2008). Forage selection and grouping patterns of male and female scimitar-horned oryx (Oryx dammah) on Mason Mountain Wildlife Management Area, Mason, Texas (Unpublished thesis). Texas State University-San Marcos, San Marcos, Texas.Download
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