Gulf Coast Network Texas Tortoise Monitoring in Palo Alto Battlefield National Historical Park: Protocol Narrative—Version 3.0

Carlson, Jane; Woodman, Robert; Granger, Whitney; Bracewell, Jeff; Buhlmann, Kurt; Garrett, James; Segura, Martha

The mission of the National Park Service (NPS) is to conserve unimpaired the natural and cultural resources of the national park system for the enjoyment of this and future generations (NPS 1999). To uphold this goal, the NPS has implemented a science-based program to document and monitor important natural resources in more than 270 parks, which are organized into 32 Inventory and Monitoring (I&M) networks. During program development each I&M network worked with its parks to identify a set of high-priority “Vital Signs” that are monitored as indicators of park ecosystem health. At Palo Alto Battlefield National Historical Park, the Gulf Coast Network (GULN) selected the Texas tortoise (Gopherus berlandieri) as one of their vital sign for long-term monitoring. This species is designated as threatened by the state of Texas due to population declines and range loss caused by habitat conversion. At the park, it is a valued faunal component of the park’s shrublands, which mainly occur on low-rising ridges called lomas. The Texas tortoise population at Palo Alto Battlefield NHP is subject to several specific threats. First, park tortoises may be geographically isolated from outside populations by ditches, roads and developed lands. Second, park tortoises may be lost to illegal collection, road mortality, or predation. Third, park tortoises may be impacted by the conversion of some of the park’s shrublands into grasslands, in an effort to return park landscapes to the conditions present during the Mexican-American War in 1846. Long-term monitoring data will inform the park on how to best manage for and protect Texas tortoises and their habitats. These data will also contribute to the broader regional assessment of Texas tortoise populations across their limited geographic range. To monitor the park’s Texas tortoises, the Gulf Coast Network conducts a long-term mark-recapture study using time-and-area defined survey events that occur in the fall of each year. On seven permanent sampling units representing each of the park’s major lomas, tortoises are encountered, marked and measured, and their GPS locations are recorded. Monitoring objectives addressed by this protocol include: 1. To provide a detailed depiction of the status of Texas tortoises across the park’s major lomas, including catch per unit effort, within-park tortoise movements, tortoise body condition, and the distribution of sizes and sexes captured. Catch per unit effort and tortoise body condition are also analyzed for change over time. 2. To assess tortoise population parameters across the park’s major lomas and track how these parameters change over time, including estimated abundance and survivorship from mark-recapture data. The protocol consists of a narrative and nine standard operating procedures (SOPs). Together, these documents detail how the Gulf Coast Network collects, manages, disseminates, and reports on monitoring data for Texas tortoises over the long term, using statistically-defensible and repeatable methods. To the extent possible, trends detected in these data will be considered in light of park management actions, habitat alterations, and other stressors.

Gulf Coast Network Texas Tortoise Monitoring in Palo Alto Battlefield National Historical Park: Protocol Narrative—Version 3.0

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