Investigations into the ecology and management of ocellated turkeys in Campeche, Mexico
Mcroberts, Jon T.
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The ocellated turkey (Meleagris ocellata) is a neotropical galliform native to the Yucatán Peninsula of Mexico and northern portions of Belize and Guatemala. Little information exists on the ecology or management of the species and previous research has been anecdotal, based on limited visual observations, or is centered on turkeys in protected areas that are semi-habituated to humans. Ocellated turkey populations are currently threatened by unauthorized subsistence hunting and habitat alteration throughout much of their range and sound ecological data are necessary to guide conservation and management decisions. To address this need, I studied ocellated turkeys in Campeche, Mexico during 2010–2013 with field seasons typically spanning January–June. Broad objectives of my study included, 1) the development and assessment of field techniques used to research ocellated turkeys, 2) a study of food habits of ocellated turkeys in an agricultural environment, 3) an evaluation of the trap and transfer method to reestablish or augment areas with translocated ocellated turkeys, and 4) an assessment of ocellated turkey life history traits including survival, cause-specific mortality, movement patterns, and home range estimates. I accomplished these objectives by capturing and monitoring turkeys at two study areas: the community owned Las Flores and Carlos Cano Cruz Management Units for Conservation and Sustainable Use of Wildlife (UMA) as well as the privately owned La Montaña UMA. The Las Flores and Carlos Cano Cruz UMAs were a forest-agriculture matrix marked by production agricultural development and the La Montaña UMA was intact forest with few clearings, no agricultural production, and greater topographic relief than Las Flores. La Montaña was located approximately 65.85 km to the south-southwest of Las Flores. I relied on walk-in traps and a cannon net to capture ocellated turkeys. After capture, I recorded sex and age class and equipped turkeys with either a 95-g Very High Frequency (VHF) or 80-g Global Positioning System (GPS) backpack style transmitter. Radio tracking was challenged by thick vegetation, turkey mobility, and poor access to remote areas. At La Montaña I used walk-in traps with a capture rate of 158.36 trap-days/turkey and a capture mortality rate of 18.18%. Field tests indicated that VHF signal range was 3.89 ± 0.62 (95% CI) km and 1.77 ± 0.23 km in jungle-agriculture matrix and jungle habitats, respectively. When using a GPS transmitter I documented a 90.7% fix-rate from an ocellated turkey hen inhabiting the jungle-agriculture matrix. My combined VHF and GPS transmitter recovery rate was 63.0%. Aerial telemetry was helpful when VHF transmitters were used. To assess food habits I collected the upper digestive tracts (n=64) of ocellated turkeys at Las Flores and Carlos Cano Cruz during February–May, 2013. I quantified food items consumed by ocellated turkeys using dry weight and frequency of occurrence and found that seeds contributed most to diets with grain sorghum (Sorghum spp.), corn (Zea spp.), and soybeans (Glycine spp.) the most consumed plant species during the study period. Results showed that ocellated turkeys fed heavily on anthropogenic food sources and these habitats should be considered when developing conservation plans. During my assessment of the trap and transfer methods for ocellated turkey conservation I monitored turkeys (n=18) that were transferred between Las Flores and La Montaña and found that the survival rate of translocated birds was 0.186 (SE = 0.168) and that mortalities occurred near the release site (769.10 m; SE=325.04 m). I also concluded that mortalities were due to small carnivores and subsistence hunters. To increase the likelihood of successful trap and transfers efforts, wildlife managers should release birds in habitats that share characteristics with the capture location, minimize time transporting turkeys, and monitor the fate of released birds. I used wild-caught ocellated turkeys (n=24) for survival analysis and found an annual survival rate of 0.505 (SE=0.119). Cause-specific mortality results were inconclusive because of a low radio recover rate and challenges identifying a cause of death; however, I did identify small felids and sport- and subsistence hunters as mortality factors. I was able to collect an adequate number of samples to calculate a home range estimates for 5 ocellated turkeys and found that average 95% fixed kernel and 100% minimum convex polygon home range estimates were 9.69 km2 (SE=2.76) and 8.34 km2 (SE=1.83), respectively. Displacement movements occurred in February–April and the average one-way displacement distance was 19.81 km (SE=4.89) and the maximum movement I documented from an ocellated turkey was 36.50 km. Despite being limited by sample sizes, these results are the most comprehensive assessment of ocellated turkey ecology and management and can be used to guide conservation activities. Additional study is critical in order to better understand the species. Researchers should focus on determining population recruitment metrics, the current occupied range of the species, developing a reliable monitoring method, and identifying strategies to manage subsistence hunting pressure and habitat alteration while simultaneously considering the needs of local people.