Friday, June 13, 2014

Guest Blog: I don’t think we’re in Texas anymore

The following is a guest blog by MS student Rachel Granberg.  Rachel is currently working in central Texas on a horned lizard habitat suitability project.  



As I was wrapping up my second week in the field today, I stumbled upon two Grevy’s zebra (Equus grevyi) just across the tall game fence.  The mating pair seemed curious at my presence, often stepping closer to get a better look at my ATV.   As I quietly snapped pictures, a common eland (Taurotragus oryx) approached, obviously looking for handouts.  Within an hour, a herd of 6 impala (Aepyceros melampus) wandered onto the same patch of grass.

The native range of the Grevy’s zebra once covered much of the Horn of Africa.  They are now restricted to small areas within Kenya and Ethiopia.

For readers not familiar with African ungulates, this particular species of zebra is listed as endangered with the IUCN.  With approximately 750 mature individuals left in the wild, the range of this species is restricted to the Horn of Africa (Moehlman et al. 2013).  Although current population trends suggest growth in Kenya and Ethiopia (Mwasi and Mwengi 2007), human-related impacts (largely the effects of agriculture and grazing on water sources) remain a huge issue in the conservation of this species (Moehlman et al. 2013).
The presence of endangered, exotic game species is not unique to this particular ranch in Texas.  Texas is globally renowned for its high fence game ranches hosting collections of outlandish species that would never coexist in the wild.  In fact, the Grevyi’s zebra I found were not nearly as lucrative as the addax, dama gazelle, and the scimitar horned oryx which all are now legally hunted on Texas game ranches without permitting under the Endangered Species Act. 

 A mating pair of endangered Grevy’s zebra (Equus grevyi) in habitat quite unlike their native savanna.

There are many arguments for (ex: conservation of the species is successful on these ranches) and against (ex: this isn’t true conservation if we are raising them like cattle) exotic game ranches.  Neither camps have considered the effects of high fence ranches (not just exotic ranches) on habitat connectivity or genetic structure of native species.  While conservation of endangered species matters, so does providing optimal habitat for our native endangered species here in Texas.  Too often, these high fence ranches provide no brush management and exclude fire (a natural form of disturbance in this ecosystem) from their management regime.  Without much public land to rely on, species such as the Texas horned lizard (don’t forget bobwhite quail, black-capped vireo, and golden-cheeked warbler) need sound land management on private parcels in order to persist.
Something that these big game ranchers fail to realize is that the little guys, such as birds and reptiles, often indicate overall health of the ecosystem.  The ranch I observed earlier today was nearly devoid of forbs and grasses because Ashe juniper had grown into a dense, monotypic stand (thanks to lack of fire).  The animals were probably so curious about my ATV because they need to be supplementally fed, thrown bales of alfalfa off the bed of a pickup.  In a healthy ecosystem, there would be ample forage for these animals to survive (along with our vulnerable native species) without supplemental feeding.
            With the manual thinning of juniper, followed by a few prescribed burns, this ranch would provide ideal habitat for the bobwhite quail and Texas horned lizards that occur on neighboring parcels.  Just because this ranch specializes in exotic game, doesn’t mean it can’t support native species.

The difference in rangeland health is dramatic between these two parcels.  On the right, light grazing and prescribed fire have created suitable habitat for the Texas horned lizard and bobwhite quail.  To the left, over grazing along the fire perimeter is a stark contrast.  Lack of fire on this ranch has allowed Ashe juniper to form dense thickets, disallowing the establishment of grasses and forbs required by these African grazers

LITERATURE CITED
Miller, C. L. 2006. The price-size relationship: Analyzing fragmentation of rural land in Texas.  Thesis,  Texas A&M University, College Station, USA.
Moehlman, P.D., Rubenstein, D.I. & Kebede, F. 2013. Equus grevyi. In: IUCN 2013. IUCN Red List of Threatened Species. Version 2013.2. <www.iucnredlist.org>. Downloaded on 31 May 2014.

Mwasi, S. and Mwangi, E. 2007. Proceedings of the National Grevy’s Zebra Conservation Strategy Workshop 11-14 April 2007. KWS Training Institute, Naivasha, Kenya.

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