Source and seasonality of epizootic mycoplasmosis in free-ranging pronghorn (Antilocapra americana)

Mycoplasma bovis is an economically important bacterial pathogen of cattle and bison that most commonly causes pneumonia, polyarthritis and mastitis. M. bovis is prevalent in cattle and commercial bison; however, infections in other host species are rare. In early 2019, we identified the first known cases of M. bovis in free-ranging pronghorn (Antilocapra americana). Here we report on additional pronghorn mortalities caused by M. bovis occurring in the same geographic region of northeastern Wyoming one year later. Genetic analysis by multilocus sequence typing (MLST) revealed that the mortalities were caused by the same M. bovis sequence type, which is unique among all sequence types documented in North America. To determine if pronghorn maintain chronic infections and to assess M. bovis status in other sympatric species, we performed surveillance in free-ranging ungulates. We found no evidence of subclinical infections in pronghorn (n=231) or mule deer (Odocoileus hemionus) (n=231) based on PCR testing of nasal swabs. To assess the likelihood of environmental transmission from livestock to pronghorn, we examined persistence of M. bovis in various substrates and conditions, revealing that M. bovis remains viable for 6 hours following inoculation of shaded water, and up to 3 hours in direct sunlight substrates. Our results indicate that environmental transmission of M. bovis from livestock to pronghorn is possible, and seasonality of infection could be due to shared resources during the late winter. This study also highlights the importance of further investigations to better understand transmission dynamics, to assess population level impacts to pronghorn, and to determine disease risks among other ungulate taxa.

Skull ontogeny of the pronghorn (Antilocapra americana) in the comparative context of native North American ungulates

The pronghorn (Antilocapra americana (Ord, 1815)) is the single survivor of a largely extinct, isolated pecoran lineage (Antilocapridae) native to North America. We describe postnatal ontogeny of its skull in a comparative framework inclusive of representatives of other typical North American ungulate linages, all of which partially overlap in geographic distribution and share habitat with A. americana. To describe allometric growth, we took 23 linear cranial measurements in 30 specimens of A. americana and applied bi- and multi-variate statistics. The skull of A. americana generally grew with negative rates in width and height dimensions, and with positive rates in length, including an elongation of rostrum, particularly the nasals, and a relative narrowing of the braincase. We compared skull development in A. americana with development in two cervids (white-tailed deer (Odocoileus virginianus (Zimmermann, 1780)) and wapiti (Cervus canadensis Erxleben, 1777)) and two bovids (bighorn sheep (Ovis canadensis Shaw, 1804) and American bison (Bison bison (Linnaeus, 1758))). The multivariate ontogenetic trajectory of A. americana overlapped greatly with that of Odocoileus virginianus, and differed from the other species in varying degrees. These results indicated an essentially convergent pattern of skull growth with species showing important functional similarities, such as cervids of comparable size and feeding habits.

Systematic review of equids and telemetry collars: implications for deployment and reporting

Data from animals equipped with global positioning system collars have advanced our understanding of vertebrates, but this technology has rarely been employed to study feral equids. Hesitation to equip feral equids with telemetry collars in the USA can often be attributed to safety concerns stemming from one study from the 1980s, where injuries were sustained by feral horses (Equus ferus caballus) equipped with radio-collars. Improvements in collar design over the ensuing quarter-century may have decreased risk of collar-related complications; however, telemetry-based studies on feral equids continue to be limited. In the present review, studies from wild and feral equids worldwide were systematically reviewed to better understand the mortality and injury risk in application of telemetry collars to equids. Our goals were to: (1) report the number of individual equids fitted with telemetry collars (1979–2017); and (2) document the number of individual equids that reportedly died or suffered injuries from collars or other sources. A comparative review of elk (Cervus canadensis), mule deer (Odocoileus hemionus) and pronghorn (Antilocapra americana) was also conducted to evaluate the relative risk of collar-related complications among equids and routinely collared North American ungulates. In total, 1089 wild and feral telemetered equids were identified across 48 studies. Of these, 87 (8.0%) were reported to have died, with only one (0.09%) mortality attributable to a collar. Comparatively, 23.0% (1095) of 4761 elk, mule deer and pronghorn fitted with telemetry collars were found to have died in the same number of studies, though no mortalities were reported to be related to the collar. Although wild and feral equids did not experience increased natural mortality compared with the other ungulates, studies have not provided sufficient information to assess relative risk of collar-related complications. Explicit reporting and discussion of telemetry collar impacts in future publications of all animal species are recommended, especially equids, to improve understanding of how telemetry collars can affect study individuals.

Effect of predation on adult pronghorn Antilocapra americana (Antilocapridae) in New Mexico, Southwestern USA

The effect of predation on ungulate populations remains contentious, despite a lack of evidence showing impacts in arid Southwestern USA populations where low precipitation and frequent drought limit ungulate nutritional condition. These conditions can increase predisposition of prey to mortality, which is prerequisite for predation to be compensatory. Consequently, we tested the effect of predation on adult pronghorn Antilocapra americana (Ord 1815) in two populations in arid New Mexico by modeling transformed annual survival rates as a function of predation rates. For this conservative test, a slope=0 indicates complete compensation, whereas a slope=−1 indicates complete additivity. The corrected slope of mortality potentially attributable to predation was >−0.14, and this result was consistent among individual populations. Thus, predation was primarily compensatory. Primarily compensatory predation was related to the relatively low condition of pronghorn individuals, as predated individuals were all below the mean condition of the population, similar to results seen in previous tests of the compensatory versus additive predation hypothesis in the arid Southwest USA. Conditions that predispose individual ungulates to mortality are present more often than not in arid environments, and thus managers should not assume that predation is limiting, regardless of predation rates.

Assessment of Hazardous Metal Concentrations in Organs of Selected Game Animals in the Natural Environment

The study was conducted to determine the levels of hazardous metals in game animals. A total of eighteen (18) animals which comprised six species of three (3) each from the same location were trapped or hunted and sacrificed. Organs analyzed for hazardous metal levels were skin, liver, kidney and heart using Atomic Absorption Spectrometry and content expressed in mgkg-1. The statistical analysis was done with Genstat (2007). Results obtained showed that all the hazardous metals under study were present in the organs at variable concentrations. Lead: skin (0.18 – 0.46) mgkg-1, liver (0.03 – 0.4) mgkg-1, heart (0.25 – 0.58) mgkg-1 and kidney (0.38 1.12) mgkg-1; Cadmium: skin (0.08 – 0.58) mgkg-1 and kidney (0.09 – 0.7) mgkg-1; Zinc : skin ( 0.46 – 0.66) mgkg-1, liver (90.04 – 0.82) mgkg-1, heart (0.42 – 1.21) mgkg-1 and kidney (0.43 – 1.58) mgkg-1; Copper: skin (6.13 – 12.57) mgkg-1, liver (5.1 – 9.56) mgkg-1, heart (6.89 - 15.15) mgkg-1 and kidney (7.63 – 24.87) mgkg-1; Iron : skin (9.53 – 26.35) mgkg-1, liver (8.07 -28.08) mgkg-1, heart (13.83 - 46.40) mgkg-1 and kidney (12.43 – 47.61) mgkg-1. Iron was highly (p <0.05) deposited in all species of animals in the heart 19.88 mgkg-1, 46.40 mgkg-1, 40.83 mgkg-1, 13.83 mgkg-1 and 41.38 mgkg-1 respectively for civet (Civettictis civeta), antelope (Antilocapra americana), grasscutter (Thryonomys swiderianus), hedgehog (Atelerix albiventris) and bush dog (Speothos venaticus) except the bush rat (Rattus fuscipes) that had its highest deposition (46.71 mgkg-1) in the kidney. Copper was also highly deposited in animals after iron with higher concentrations in heart and kidney. The highest concentration was recorded for bush rat (Rattus fuscipes) (15.15 mgkg-1) in heart and 24.87 mgkg-1 in kidney. Due to bioaccumulation of hazardous metals, care should be taken in patronizing bushmeat obtained from the studied ecosystem since failure could be perilous to the health of consumers as their concentrations are beyond the safe limits for the respective metals. It is further recommended that environmental safety principles for safe disposal of hazardous metals are appropriately carried out.

Comparing performance of multiple non-invasive genetic capture–recapture methods for abundance estimation: a case study with the Sonoran pronghorn Antilocapra americana sonoriensis

Demographic monitoring is required in threatened species management, yet effective and efficient monitoring is challenging for species that are difficult to capture or susceptible to capture stress. One possible monitoring approach for such species is non-invasive genetic sampling with capture–recapture methods (genetic capture–recapture). We evaluated the performance of genetic capture–recapture in a challenging model system, monitoring the threatened Sonoran pronghorn Antilocapra americana sonoriensis. In an effort to determine the best (i.e. efficient, accurate, precise, cost-effective) method for abundance estimation, we used simulations to examine the optimal genetic capture–recapture faecal sampling design for this population. We simulated encounter histories for 100–300 individuals, with 0.33–3.33 samples/individual/session, in 1–3 sampling sessions. We explored trade-offs between sample size, number of sessions and multi-session (MARK) versus single-session (capwire) closed capture–recapture abundance estimators, and an accurate and precise estimate. We also compared the cost between the genetic capture–recapture approaches and current aerial monitoring methods. Abundance was biased positively in capwire and negatively in MARK. Bias increased and precision decreased with fewer samples/individual/session. Annual genetic capture–recapture monitoring cost was nearly twice the cost of aerial surveys, although genetic capture–recapture methods provided much higher precision. However at the current estimated abundance (c. 200), the same level of precision achieved with aerial methods can be obtained by collecting 0.75 samples/individual in a single session, for an annual cost saving of > USD 4,000. This approach of comparing estimator performance and cost can easily be applied to other systems and is a useful evaluation for managers to implement prior to designing capture–recapture studies.