Conservation and Ecology of Mammals II

Contributed Paper
ROOM: Room 140 – Aztec

10:30AM Resource Utilization of American Marten in the Hiawatha National Forest in the Upper Peninsula of Michigan
Brad Silet; Gary Roloff; Eric Clark; Joe Lautenbach; Russell Aikens; Aimee Baier; John Powell; Steve Sjogren
We examined resource utilization of American marten (Martes americana) in the Hiawatha National Forest (HNF) in the Upper Peninsula of Michigan. The Hiawatha National Forest 2006 Forest Plan identified the marten as an indicator species of ecosystem health and an early warning system of environmental change within late successional forest types. Marten are an important component of the Hiawatha’s native fauna, and the Forest strives to provide viable marten populations through monitoring and management of their habitat. We collared seven marten (6 males, one female) with GPS collars and attempted to collect a location every 15 minutes. We used Brownian bridge movement to determine utilization distributions for each individual. A total of 3,056 locations were downloaded from the collars (436.6 locations/marten). For each GPS fix, we modeled resource utilization (dependent variable) as a function of independent variables using generalized linear mixed models. Fixed effects included forest structural characteristics collected at the patch level, and a site productivity gradient. We used patch as a random effect. Preliminary results indicated that marten use is positively correlated with basal area and site productivity, and that use increases as patch age decreases. If a patch was forested, site productivity appeared to have the largest impact on marten use. Our findings provide quantitative relationships on habitat characteristics for marten that the HNF can use to manage for this species.
10:50AM Influence of Manatees’ Diving on Their Risk of Collision with Watercraft
Holly H. Edwards; Julien Martin; Charles J. Deutsch; Robert G. Muller; Stacie M. Koslovsky; Alexander J. Smith; Margaret E. Barlas
Watercraft pose a threat to endangered Florida manatees (Trichechus manatus latirostris). Mortality from watercraft collisions has adversely impacted the manatee population’s growth rate, therefore reducing this threat is an important management goal. To assess factors that contribute to the risk of watercraft strikes to manatees, we studied the diving behavior of nine manatees carrying GPS tags and time-depth recorders in Tampa Bay, Florida, during winters 2002-2006. We applied a Bayesian formulation of generalized linear mixed models to depth data to model the probability (Pt) that manatees would be no deeper than 1.25 m from the water’s surface as a function of behavioral and habitat covariates. Manatees above this threshold were considered to be within striking depth of a watercraft. Seventy-eight percent of depth records (individual range 62-86%) were within striking depth (mean = 1.09 m, max = 16.20 m), illustrating how vulnerable manatees are to strikes. In some circumstances manatees made consecutive dives to the bottom while traveling, even in areas >14 m, possibly to conserve energy. This is the first documentation of potential cost-efficient diving behavior in manatees. Manatees were at higher risk of being within striking depth in shallow water (<0.91 m), over seagrass, at night, and while stationary or moving slowly; they were less likely to be within striking depth when ≤50 m from a charted waterway. In shallow water the probability of a manatee being within striking depth was 0.96 (CI = 0.93-0.98) and decreased as water depth increased. The probability was greater over seagrass (Pt = 0.96, CI = 0.93-0.98) than over other substrates (Pt = 0.73, CI = 0.58-0.84). Quantitative approaches to assessing risk can improve the effectiveness of manatee conservation measures by helping identify areas for protection.
11:10AM Indirect Effects of Human Disturbance: How Risk-Averse Behavior Affects Use of the Foodscape
Samantha Dwinnell; Hall Sawyer; Jill Randall; Jeffrey L. Beck; Gary L. Fralick; Kevin L. Monteith
Heterogeneity in availability and quality of forage on the landscape constitute the foodscape within which animals make behavioral decisions in acquisition of foraging resources. Novel changes to the foodscape, such as human disturbance, can alter behavioral decisions animals make by prompting behaviors that favor risk-aversion over acquisition of food. Although behavioral alterations and population declines often coincide with the introduction of human disturbance, the mechanistic link between behavior and population trajectory are largely undocumented. Risk-averse behavior that reduces the use of available forage can indirectly affect populations; however, indirect effects of behavioral responses to human disturbance are not well understood. Furthermore, whilst direct losses of foraging resources resulting from development of infrastructure are apparent, the additional losses in foraging resources resulting from indirect habitat loss caused by risk-averse behavior are more difficult to quantify. We sought to elucidate the mechanisms underlying indirect effects of human disturbance on populations by testing whether behavioral responses of mule deer to human disturbance resulted in a reduction in the use of available foraging resources. Mule deer exhibited behaviors of risk-aversion in response to human disturbance across multiple behavioral scales (e.g., animals avoided habitat near, selected movements away from, and increased vigilance near human disturbance), and these strong behavioral responses resulted in a reduction in the use of available foraging resources within the foodscape. Consequently, behavioral avoidance resulted in a loss of otherwise available forage that was 4.6 times greater than forage lost because of development of infrastructure (i.e., direct habitat loss); thus, further reducing the capacity of the foodscape to support mule deer populations. Our findings unveil the mechanisms by which human disturbance can affect populations of large herbivores and provide a missing link to understanding why population declines often coincide with the introduction of human disturbance.
11:30AM Seasonal Shifts in Marine Mammal Core Use Areas and Vessel Traffic in the Alaskan Arctic Ocean
Benjamin K. Sullender; Melanie Smith
As oil and gas development expands in the Chukchi and Beaufort Seas, overlap between industrial activities and marine mammals may lead to behavioral changes, degradation of acoustic habitat, or avoidance of core use areas. Spatially quantifying these interactions is important to assess threats to migratory wildlife and to anticipate shifts in critical marine mammal habitat, particularly as vessel routing plans are developed in the Arctic. First, we calculated marine mammal observation rates adjusted for survey effort and created a series of core use areas using the 50% isopleth from an anisotropic kernel density analysis for walrus (Odobenus rosmarus), beluga whales (Delphinapterus leucas), bowhead whales (Balaena mysticetus), and gray whales (Eschrichtius robustus). Next, we analyzed shipping data for all vessels in the Alaskan Arctic Ocean in 2014, 2015, and 2016, creating unique vessel tracks and generating monthly track density. Core areas were compared across years and analyzed in tandem with vessel traffic patterns to assess avoidance behavior during times of high use by both vessels and mammals. Marine mammal core areas and vessel traffic hotspots were identified at several locations within the project area. During the 2015 open-water season (July to October), vessel traffic greatly increased as part of exploratory drilling operations in the Chukchi Sea: average vessel track density within the Burger Prospect was 22 km/km2, nearly 10 times greater than traffic in non-drilling seasons. Core use areas for marine mammals appeared to shift farther away from this site than in other years. We identified marine mammal core areas to delineate both critical destinations and bottlenecks between seasonally important habitats. By applying these insights to the future extent of permitted oil development in the Beaufort Sea, as well as increasing international vessel traffic through the Northwest Passage, we identify current and emerging shipping threats to Arctic marine mammal populations.
11:50AM Can Community Driven Conservation Improve Small Mammal Diversity and Health in Eastern Madagascar?
Jordan Broadhead; Sarah Zohdy
Deforestation on the island of Madagascar contributes to the endangerment of some of the world’s most threatened species. Therefore, community driven conservation efforts in Madagascar have the potential to improve the health and diversity of endemic wildlife populations. Here, we examine if community driven conservation efforts improve wildlife health and diversity in the eastern rainforests of Madagascar by comparing small mammal health diversity and health indicators in a community protected forest with those in a disturbed forest. Small mammals such as mouse lemurs, rats, and tenrecs were captured using Sherman live trap transects in both sites over the summer and winter seasons. Species diversity, body mass, and ectoparasites for small mammals captured was compared across sites. Endemic species diversity was greater in the protected forest than in the disturbed forest. Small mammals in the protected forest were not heavier or more parasitized than those in the disturbed forest. More individual invasive rodents (Rattus rattus) were captured in the disturbed forest. In this study we compared species small mammal diversity and indicators of health such as body mass and ectoparasites across a gradient of habitat disturbance. Our results indicate that community driven conservation efforts can potentially improve endemic wildlife diversity and health in biodiversity hotspots.


Contributed Paper
Location: Albuquerque Convention Center Date: September 26, 2017 Time: 10:30 am - 12:10 pm