Lisa J. Faust

Rapid population growth in an elephant Loxodonta africana population recovering from poaching in Tarangire National Park, Tanzania

We studied the demography of a subpopulation of African elephants Loxodonta africana in Tarangire National Park, Tanzania, from 1993 to 2005. The Tarangire elephants had been affected by heavy poaching prior to 1993. We monitored 668 individually known elephants in 27 family groups. The population increased from 226 to 498 individuals, with mean group size increasing from 8.4 to 18.3. The average annual growth rate was 7.1% (range 2.0–16.9%). This approaches the maximal growth rate for African elephants, with corresponding minimal values for demographic parameters. The mean interbirth interval was 3.3 years, mean age of first reproduction 11.1 years, average annual mortality of elephants younger than 8 years 3%, and average annual mortality of adult females 1%. Probability of conceiving was positively correlated with annual rainfall. No significant density-dependent effects were recorded. Rapid growth was aided by high rainfall, low population density and release from the stresses of poaching. These results demonstrate that elephant populations are capable of rapid population increases for extended periods of time given the right ecological and social conditions. This has consequences for elephant conservation and management.

Birth sex ratio in captive mammals: Patterns, biases, and the implications for management and conservation

Sex allocation theory predicts that a female should produce the offspring of the sex that most increases her own fitness. For polygynous species, this means that females in superior condition should bias offspring production toward the sex with greater variation in lifetime reproductive success, which is typically males. Captive mammal populations are generally kept in good nutritional condition with low levels of stress, and thus populations of polygynous species might be expected to have birth sex ratios biased toward males. Sex allocation theory also predicts that when competition reduces reproductive success of the mother, she should bias offspring toward whichever sex disperses. These predicted biases would have a large impact on captive breeding programs because unbalanced sex ratios may compromise use of limited space in zoos. We examined 66 species of mammals from three taxonomic orders (primates, ungulates, and carnivores) maintained in North American zoos for evidence of birth sex ratio bias. Contrary to our expectations, we found no evidence of bias toward male births in polygynous populations. We did find evidence that birth sex ratios of primates are male biased and that, within primates, offspring sex was biased toward the naturally dispersing sex. We also found that most species experienced long contiguous periods of at least 7 years with either male- or female-biased sex ratios, owing in part to patterns of dispersal (for primates) and/or to stochastic causes. Population managers must be ready to compensate for significant biases in birth sex ratio based on dispersal and stochasticity. Zoo Biol 19:11–25, 2000.

Climatic and geographic predictors of life history variation in Eastern Massasauga (Sistrurus catenatus): A range-wide synthesis

Elucidating how life history traits vary geographically is important to understanding variation in population dynamics. Because many aspects of ectotherm life history are climate-dependent, geographic variation in climate is expected to have a large impact on population dynamics through effects on annual survival, body size, growth rate, age at first reproduction, size–fecundity relationship, and reproductive frequency. The Eastern Massasauga (Sistrurus catenatus) is a small, imperiled North American rattlesnake with a distribution centered on the Great Lakes region, where lake effects strongly influence local conditions. To address Eastern Massasauga life history data gaps, we compiled data from 47 study sites representing 38 counties across the range. We used multimodel inference and general linear models with geographic coordinates and annual climate normals as explanatory variables to clarify patterns of variation in life history traits. We found strong evidence for geographic variation in six of nine life history variables. Adult female snout-vent length and neonate mass increased with increasing mean annual precipitation. Litter size decreased with increasing mean temperature, and the size–fecundity relationship and growth prior to first hibernation both increased with increasing latitude. The proportion of gravid females also increased with increasing latitude, but this relationship may be the result of geographically varying detection bias. Our results provide insights into ectotherm life history variation and fill critical data gaps, which will inform Eastern Massasauga conservation efforts by improving biological realism for models of population viability and climate change.

PLASMA ELECTROPHORETIC PROFILES IN THE EASTERN MASSASAUGA (SISTRURUS CATENATUS) AND INFLUENCES OF AGE, SEX, YEAR, LOCATION, AND SNAKE FUNGAL DISEASE

Abstract:  The purpose of this study was to establish reference intervals of the protein electrophoretic fractions and the acute-phase proteins hemoglobin binding protein (as determined by the haptoglobin assay) and C-reactive protein (CRP) and assess any possible correlations between varying age class, sex, location (Illinois or Michigan), year, or presence of snake fungal disease (SFD). Banked plasma samples were assayed from 130 eastern massasaugas from 2009 to 2014 in Illinois and Michigan. Snakes from Michigan had higher total protein (mean: 5.50 g/dl), albumin/globulin ratio (0.42), albumin (1.59 g/dl), and gamma globulins (0.55 g/dl) than from snakes in Illinois (4.72 g/dl, 0.29, 1.03 g/dl, 0.38 g/dl, respectively). Snakes in Illinois (22.19 g/ml) had higher CRP than snakes in Michigan (10.89 mg/ml). Adults had higher gamma globulins (0.47 g/dl) than juveniles (0.28 g/dl). Males had higher alpha-2 globulins (0.98 g/dl) and CRP (21.4 mg/ml) than females (0.85, 11.6, respectively). There were no significant differences in absolute plasma proteins in SFD-positive snakes, but the percentage of gamma globulins was significantly higher in positive snakes. Future research in this area can now build on this data to determine changes in population health over time or due to specific environmental or disease threats.

Extinction risk assessment for the species survival plan (SSP®) population of the Bali mynah (Leucopsar rothschildi)

The Bali mynah Species Survival Plan (SSP), an Association of Zoos and Aquariums program, strives to maintain the genetic and demographic health of its population, avoid unplanned changes in size, and minimize the risk of population extinction. The SSP population meets current demographic and genetic objectives with a population size of 209 birds at 61 institutions and 96% genetic diversity (GD) retained from the source population. However, participating institutions have expressed concerns regarding space allocation, target population size (TPS), breeding restrictions, inbreeding depression, and harvest in relation to future population availability and viability. Based on these factors, we assess five questions with a quantitative risk assessment, specifically a population viability analysis (PVA) using ZooRisk software. Using an individual-based stochastic model, we project potential population changes under different conditions (e.g. changes in TPS and genetic management) to identify the most effective management actions. Our projections indicate that under current management conditions, population decline and extinction are unlikely and that although GD will decline over 100 years the projected loss does not exceed levels acceptable to population managers (less than 90% GD retained). Model simulations indicate that the combination of two genetic management strategies (i.e. priority breeding based on mean kinship and inbreeding avoidance) benefits the retention of GD and reduces the accumulation of inbreeding. The current TPS (250) is greater than necessary to minimize the risk of extinction for the SSP population but any reduction in TPS must be accompanied by continued application of genetic management. If carefully planned, birds can be harvested for transfer to Bali for a reintroduction program without jeopardizing the SSP population.

Plasma Vitamin, Mineral, and Biochemistry Concentrations in Free-Ranging, Adult Eastern Massasauga (Sistrurus catenatus) during Spring Egress

Abstract The purpose of this study was to determine vitamin (A, D, E), mineral (cobalt, copper, molybdenum, manganese, iron, selenium, zinc), and plasma biochemistry concentrations in free-ranging, eastern massasauga rattlesnakes (EMR) (Sistrurus catenatus) in relation to age, sex, reproductive status, and season. Plasma samples were collected from 24 snakes post-brumation (April–May) in Michigan. Significant increases in weight and plasma vitamin E, iron, molybdenum, calcium, phosphorus, triglycerides, and cholesterol were detected in gravid compared to non-gravid females. Vitamin D synthesis from ultraviolet B radiation may be possible in EMR and requires further research. Gravid snakes appear to bioaccumulate molybdenum in tissues. Although the sample size and methodology did not meet ASVCP guidelines for establishing reference ranges, the data provide an important first step in elucidating the role of vitamin and trace minerals in relation to EMR health and reproduction. These data can be used to compare trends across free-ranging and zoo-managed EMR populations and may help to guide changes in husbandry and nutrition programs for the zoo-managed EMR.