Seeking Out the Hoary Marmot: Habitat Characteristics of an Alpine Obligate

Alpine ecosystems likely will be impacted by climate change, which will shift distributions of alpine species. To predict these shifts reliably, an increased understanding about the habitat characteristics that are important to alpine species will be necessary to manage for their continued presence on the landscape. We have very limited information about habitat for hoary marmots (Marmota caligata) in Montana. To address this knowledge gap, we investigated the relative importance of habitat characteristics for marmot occupancy. During the summers of 2014 and 2015, we surveyed 184 sites in 5 mountain ranges throughout western Montana. We surveyed each site 2-5 times (average = 4.25 surveys/site) and detected marmots in 61 sites using two survey methods. Wind speed, survey method, cloud cover, and percent of the site that was visible all influenced detection probability. We estimated that marmots occurred in 36% of all sites (95% CI = 29-46%).  Occupancy of marmots increased with snow and shrub cover and decreased with slope and distance to water. Given that snowpack, precipitation, and water sources are predicted to be impacted by climate change, our results begin to illustrate where this species of concern may become susceptible. If snowpack and the number of water sources decrease or shift geographically, this may reduce or alter the available habitat for marmots. We hope to augment the paucity of information about hoary marmots at the southern end of their distribution and aid management of this species under an uncertain climate future

Influence of Boulder Size on Occupancy and Detection of Hoary Marmots (Poster)

Hoary marmots (Marmota caligata) can be found in boulder fields throughout alpine areas of western Montana, but we know little about their specific habitat requirements. We sought to determine the influence of boulder size on occupancy and detection probability of the hoary marmot during occupancy surveys. We conducted 532 visual occupancy surveys of 147 sites between June and September 2015. We estimated variation in occupancy and detection probability based on four size categories of boulders. We did not detect differences in occupancy of marmots as the size composition of boulders changed. Detection probability was most influenced by medium and large boulders. Probability of detecting a marmot was 38% (95% CI=0.24–0.53) when medium boulders were absent, but decreased to 3% as the proportion of medium boulders increased to 60% (95% CI=0–0.15). Probability of detecting a marmot was 16% when large boulders were absent (95% CI=0.1–0.24) but increased to 92% when just 5% of the site consisted of large boulders (95% CI=0.61–0.99). Accounting for this variation in detection probability with changes in boulder size will be important for designing a long-term monitoring protocol that can produce accurate estimates of occupancy for hoary marmots. A monitoring protocol incorporating key habitat requirements would be valuable for the future management and conservation of a species living in harsh alpine environments where climate change is predicted to occur rapidly

Habitat Selection by Chiricahua Leopard Frogs During Summer Monsoons

One-third of the described species of amphibians worldwide are threatened with extinction, including the Chiricahua leopard frog (Lithobates chiricahuensis).  This frog is highly aquatic, found in portions of Arizona and New Mexico, and listed as threatened under the Endangered Species Act.  Currently, the Chiricahua leopard frog is restricted to anthropogenic sources of water, including tanks maintained for livestock, throughout most of its range.  Movement habits of this frog and patterns of dispersal between disjunct water sources are not well understood.  We attached radio transmitters to 44 total frogs on the Ladder Ranch in southern New Mexico during summer 2014 and located each frog daily for up to 8 weeks (mean = 29 days).  We quantified habitat characteristics at each frog location and a random location 5 meters away.  We assessed fine-scale habitat selection using conditional logistic regression and also explored the degree of variation in selection among individual frogs.  Frogs chose areas with more low-lying cover (especially aquatic vegetation and woody debris), less overstory cover, and a mud substrate.  Whether the location was far from or close to water and the amount of overstory cover did not appear to be important for selection, suggesting that frogs are able to find areas that provide habitat away from water One-third of the described species of amphibians worldwide are threatened with extinction, including the Chiricahua leopard frog (Lithobates chiricahuensis).  This frog is highly aquatic, found in portions of Arizona and New Mexico, and listed as threatened under the Endangered Species Act.  Currently, the Chiricahua leopard frog is restricted to anthropogenic sources of water, including tanks maintained for livestock, throughout most of its range.  Movement habits of this frog and patterns of dispersal between disjunct water sources are not well understood.  We attached radio transmitters to 44 total frogs on the Ladder Ranch in southern New Mexico during summer 2014 and located each frog daily for up to 8 weeks (mean = 29 days).  We quantified habitat characteristics at each frog location and a random location 5 meters away.  We assessed fine-scale habitat selection using conditional logistic regression and also explored the degree of variation in selection among individual frogs.  Frogs chose areas with more low-lying cover (especially aquatic vegetation and woody debris), less overstory cover, and a mud substrate. Whether the location was far from or close to water and the amount of overstory cover did not appear to be important for selection, suggesting that frogs are able to find areas that provide habitat away from water bodies.  The variation among individuals was low, suggesting that tracked were selecting similar habitat characteristics. The findings of this study will inform active management of amphibians in anthropogenic settings, where managers can enhance amphibian habitat characteristics between occupied sites to improve population connectivity

Arginine-rich peptides destabilize the plasma membrane, consistent with a pore formation translocation mechanism of cell penetrating peptides

Recent molecular dynamics simulations (Herce and Garcia, PNAS, 104: 20805 (2007)) have suggested that the arginine-rich HIV Tat peptides might be able to translocate by destabilizing and inducing transient pores in phospholipid bilayers. In this pathway for peptide translocation, arginine residues play a fundamental role not only in the binding of the peptide to the surface of the membrane but also in the destabilization and nucleation of transient pores across the bilayer, despite being charged and highly hydrophilic. Here we present a molecular dynamics simulation of a peptide composed of nine arginines (Arg-9) that shows that this peptide follows the same translocation pathway previously found for the Tat peptide. We test this hypothesis experimentally by measuring ionic currents across phospholipid bilayers and cell membranes through the pores induced by Arg-9 peptides. We find that Arg-9 peptides, in the presence of an electrostatic potential gradient, induce ionic currents across planar phospholipid bilayers, as well as in cultured osteosarcoma cells and human smooth muscle cells freshly isolated from the umbilical artery. Our results suggest that the mechanism of action of Arg-9 peptide involves the creation of transient pores in lipid bilayers and cell membranes.Comment: This is an extended version of the published manuscript, which had to be shortened before publication to fit within the number of pages required by the journa

How Do Nonnative Plants Affect Small Mammals? Effects of Vegetation Structure on Escape Ability of Small Mammals

Nonnative plants can alter habitat of native animals through changes in vegetation structure and availability of food resources. Invasion of nonnative cheatgrass (Bromus tectorum L.) is an acute threat to persistence of native wildlife in the sagebrush steppe ecosystem of southwestern Montana. Cheatgrass invasion increases vegetation density and litter depth between shrubs, potentially increasing risk of predation by impeding an animal’s ability to escape. We examined how vegetation density and litter depth affects maximum sprint speed, as one component of a project investigating how changes in the structural complexity of vegetation due to cheatgrass invasion affects small mammals. Using artificial materials to mimic cheatgrass structure and litter, we timed deer mice (Peromyscus maniculatus) sprinting through a range of litter depths and structure densities along a 2 m-long track, to assess each animal’s ability to flee from a predator. We found that median sprint time increased 15 percent (95% CI = 13-18%) for every additional 1000 stems/m2; increases in litter depth ? 9 cm had little effect on sprint speed. If predation is a limiting factor for small mammal populations within sagebrush steppe, management tools that can reduce vegetation density of nonnative plants may be beneficial. Litter removal may only benefit small mammals if accumulations are reduced to less than 9 cm in depth. Increasing our understanding of how small mammals respond to changes in vegetation architecture caused by nonnative plants may help inform management and restoration efforts, especially when complete eradication is unlikely

Mechanisms Driving Nonnative Plant-Mediated Changes in Small Mammal Populations and Communities

Nonnative plants can dramatically alter habitat of native animals through changes in vegetation structure and availability of food resources. Range expansion by nonnative cheatgrass (Bromus tectorum L.) is an acute threat to persistence of native species in the sagebrush-steppe ecosystem of southwestern Montana. As climate changes over the next century, rangelands in Montana are likely to become more hospitable to this invasive grass. Although declines in small mammal diversity and abundance previously have been documented with cheatgrass invasion, we know little about the underlying mechanisms driving these changes. We will explore potential mechanisms for nonnative plant-mediated changes on three species of native mammals: deer mouse (Peromyscus maniculatus), montane vole (Microtus montanus), and sagebrush vole (Lemmiscus curtatus) in sagesteppe communities at the Gravelly-Blacktail Wildlife Management Area (WMA). We will quantify changes in vegetation characteristics in areas invaded by cheatgrass; based on this information, we will develop experimental treatments that mimic individual modified characteristics. We will apply these treatments to randomly selected plots on the WMA and establish appropriate controls. Using standard capture-mark-recapture methods, we will estimate abundance and species diversity of small mammals and make comparisons between treated and control plots to quantify effects. We will also quantify and compare body condition, predator avoidance, and diet to explore additional mechanisms driving changes in mammalian abundance and diversity. Identifying the mechanisms for how cheatgrass invasion alters populations and communities of native species will provide critical information to inform conservation and management of some of Montana’s native small mammals

Survival and Reproduction of Wild Turkeys in the Northern Black Hills of South Dakota

In South Dakota, wild turkeys are a high-interest species for both consumptive and non-consumptive uses.  Harvest records indicate that the population segment residing in the northern Black Hills may be declining.  Although data on hen survival, nesting survival, and early poult survival were collected for the southern Black Hills in the early 2000s, there is currently a paucity of demographic data for the northern Black Hills.  We seek to inform wild turkey management by characterizing demography specifically for the northern Black Hills.  We radio-tracked 80 turkey hens (40 adults/40 juveniles) in 2016 to estimate rates of hen survival, nesting, nesting success, and early poult survival; this two-year study will continue in 2017.  Based on preliminary data, rates of nesting by adult hens are lower in the northern Black Hills than the southern Black Hills (77.5% vs. 98%), as are rates of renesting by adult hens (33% vs. 75%).  We are in the process of estimating hen survival, but preliminary results indicate that annual survival is approximately 50%.  Poult survival to 4 weeks is comparable in the northern and southern Black Hills, but lower than in other portions of the range of Merriam’s wild turkey.  Although the northern and southern Black Hills are in close proximity, the substantial climatic differences likely explain the reduced productivity of the turkey population in the northern Black Hills.  Limiting fall harvest of wild turkey hens in the northern Black Hills may be required to sustainably manage this important game species

Where are Long-Toed Salamanders Found in a Game of Hide-And-Seek With Trout?

In many alpine lakes, trout have been introduced for recreational fishing and have replaced native amphibians as top predators. In these systems, trout are associated with reducing the abundance of amphibians and have extirpated populations of long-toed salamanders ( Ambystoma macrodactylum) from many lakes. Although rare, salamander coexistence with trout may occur in some lakes where habitat characteristics such as emergent vegetation and physical barriers are present, as these environments can provide refugia from predation. We sought to identify what key habitat features might allow this co-occurrence. We sampled seven lakes with salamanders and fish and seven with only salamanders in northwestern Montana between July and August 2012. We used minnow traps to capture salamander larvae and we quantified habitat characteristics (e.g., vegetation density, structural complexity) where salamanders were captured. We compared capture rates and habitat characteristics to determine whether lakes with and without fish differed. Preliminary results suggest that salamander capture rates were higher in lakes with fish (33%, 95% CI = 13-84%), but salamanders were smaller, as larvae had 68 percent shorter tails (51-91%) in lakes with fish. Despite these differences, we did not detect any differences in habitat characteristics. Unless minnow traps were used as refugia, our findings suggest that salamanders utilize similar habitat in these lakes regardless of the presence of fish. Future work will examine factors influencing salamander growth and tail length and determine whether adding habitat complexity is an effective strategy to facilitate coexistence of salamanders and fish

Bats in Buildings: Assessing Human Structures as Roost Sites in Glacier National Park (Poster)

Many bat populations are declining due to factors such as spread of white-nose syndrome (WNS) and changes in land use, increasing the need for information to prevent further declines. The little brown bat (Myotis lucifugus) is a species of concern in Montana, is susceptible to WNS, is the most common bat in Glacier National Park (GNP) and is frequently found roosting in buildings. We sought to document the locations and types of bat roosts in human structures throughout GNP. We conducted daytime inspections of 579 of the >900 buildings in GNP during summer 2015. When we detected a roost, we determined whether it was a day or night roost and recorded characteristics of the building and roost. In total we found 451 roost sites; most were night roosts. Buildings with tin siding were less likely to be used as night roosts, whereas buildings with masonry were more likely to be used as night roosts. Buildings with a bat house were more likely to be used as day roosts. We also found some evidence that bats preferred to day roost in buildings with tin roofs or logs. These baseline data on locations and numbers of bat roosts will allow biologists to better assess potential impacts of WNS should it arrive in Montana. These data also will provide GNP staff with the necessary information to develop mitigation measures to protect bats

Investigating Coexistence Between Trout and Long-Toed Salamanders and the Indirect Effects of Fish Predators

In many, formerly fishless lakes in western North America, trout have been introduced for recreational fishing, replacing native amphibians as top predators. Trout are associated with reducing the abundance of amphibians and have extirpated populations of long-toed salamanders (Ambystoma macrodactylum). Salamanders and trout may coexist in some lakes, as larvae often are able to alter foraging behavior, use of open water, and time in refugia in response to predatory cues. However, salamanders are still subject to attacks and may have different body morphology in environments with fish. We sought to estimate minimum population sizes of long-toed salamanders, as well as investigate indirect effects of fish on salamander morphology. We sampled lakes with and without fish in northwestern Montana during the summers of 2012 and 2013. We caught salamander larvae using minnow traps, took several body measurements, and compared capture rates and morphological measurements between lakes with and without fish. Preliminary results suggest that more salamanders were captured per trap in lakes with fish (1.8 salamanders/trap, 95% CI = 1.3-2.4), compared to lakes without fish (0.58 salamanders/trap, 0.36-0.81), which could reflect higher population sizes or increased use of traps as refugia. However, salamanders in lakes with fish were smaller: they weighed less, had shorter snout-vent lengths, and had shorter and narrower tails. Even if salamanders are more abundant in lakes with fish, growth may be reduced. Further research into the coexistence of long-toed salamanders and trout may aid in developing conservation strategies for these and other amphibians affected by novel predators