Mountain Plover responses to deltamethrin treatments on prairie dog colonies in Montana.

Pyrethroid insecticides containing deltamethrin provide broad spectrum insect control that can adversely affect food supplies of insectivorous birds. I hypothesized that this could result in lowered nest survival for a ground-nesting insectivorous bird, the Mountain Plover (Charadrius montanus), which preferentially nests on prairie dog colonies. I studied Mountain Plover nest survival in 2003-2010 at a small cluster of black-tailed prairie dog (Cynomys ludovicianus) colonies in north-central Montana. Three colonies were treated with deltamethrin to control fleas and limit the spread of plague; four untreated colonies served as controls. I monitored 412 plover nests during the 8 year study (264 on treatment colonies and 148 on control colonies) and found a strong negative effect of deltamethrin treatments on nest survival (ß(Dust) = -1.24, 95 % CI was -2.00 to -0.48) in the years following the actual treatment (2004-2006). I conclude that the observed treatment effect most likely occurred because of changes in insect (food) availability for the plover, and this in turn lowered nest survival because adults spent more time off nests or switched to less desirable insect prey. These results lend support to the need to consider the indirect effects of insecticide treatments on non-target species and suggest a potential conflict in current plague management strategies for prairie dogs.

Using variance components to estimate power in a hierarchically nested sampling design.

We used variance components to assess allocation of sampling effort in a hierarchically nested sampling design for ongoing monitoring of early life history stages of the federally endangered Devils Hole pupfish (DHP) (Cyprinodon diabolis). Sampling design for larval DHP included surveys (5 days each spring 2007-2009), events, and plots. Each survey was comprised of three counting events, where DHP larvae on nine plots were counted plot by plot. Statistical analysis of larval abundance included three components: (1) evaluation of power from various sample size combinations, (2) comparison of power in fixed and random plot designs, and (3) assessment of yearly differences in the power of the survey. Results indicated that increasing the sample size at the lowest level of sampling represented the most realistic option to increase the survey's power, fixed plot designs had greater power than random plot designs, and the power of the larval survey varied by year. This study provides an example of how monitoring efforts may benefit from coupling variance components estimation with power analysis to assess sampling design.

Song type variations of Louisiana Waterthrush (Parkesia motacilla) and their geographic distributions.

Louisiana Waterthrush (Parkesia motacilla) is a familiar singer in the Western Hemisphere family Parulidae, yet apparent geographic variations in its song and potentially related causal mechanisms have not received detailed examination in previously published studies. Here, we analyzed song pattern variations of 651 Louisiana Waterthrush singers in audio spectrogram recordings obtained from our field work and publicly accessible bioacoustics archives. Visual and auditory assessment of the introductory note sequence of each song identified three distinct song types (A, B, and C) and most of the songs were assigned to one of these types. Linear Discriminant Analysis and Random Forest methods were used to verify the assignments and showed strong agreement for Type A with slightly less agreement on Types B and C. User error rates (proportion of the Linear Discriminant Analysis classifications that were incorrect) were low for Types A and B, and somewhat higher for Type C, while producer error rates (proportion of the song type for which the Linear Discriminant Analysis was incorrect) were somewhat higher for Types A and C than the minimal levels achieved for Type B. Our findings confirmed that most between-individual variation was in the number of notes and note sequence duration while most within-individual variation resulted from the percent of downstrokes. The location of each singer was plotted on a map of the breeding range and results suggested the song types have large-scale discrete geographic distributions that co-occur in some regions but not range-wide. Evaluation of the distributions provided tentative support for a hypothesis that two of the song types may independently exhibit congruence with the geographic extent of Pleistocene glacial boundaries and the third song type may be distinguished by a lack of congruence, but further investigation is needed to elucidate whether the song variations represent subpopulations with three separate evolutionary histories.

Detection and density of breeding marsh birds in Iowa wetlands.

Accounting for imperfect detection is an important process when obtaining estimates of density or abundance for breeding birds, and this is particularly true when researchers are monitoring birds to assess the success of restored wetlands. Due to the dramatic decline in areal cover and habitat quality, wetland restoration in the Prairie Pothole Region (PPR) is critically important to breeding birds. The Shallow Lakes Restoration Project (SLRP), a partnership between the Iowa Department of Natural Resources and Ducks Unlimited, Inc., aims to restore degraded shallow lakes throughout the Iowa PPR. We conducted unlimited-radius point counts with call-broadcast surveys for breeding marsh birds at 30 shallow lakes in various stages of restoration in 2016 and 2017. Our goals were to assess the impact of covariates on detection probability and estimate density of these species at non-restored, younger (1-5 years since restoration), and older (6-11 years since restoration) restorations. Detection probability ranged between 0.07 ± 0.009 (SE) for Red-winged Blackbird and 0.40 ± 0.09 (SE) for Common Yellowthroat. Percent cattail had a positive quadratic effect on detection probability for four species, with detection decreasing sharply as percent cattail increased and increasing slightly with 100% cattail cover. Wind speed negatively influenced the detection probability of Pied-billed Grebes but had a negative quadratic effect on the detection probability of Marsh Wrens. Both restored shallow lakes had greater densities of breeding Pied-billed Grebes, Marsh Wrens, and Yellow-headed Blackbirds than non-restored shallow lakes, but there was no significant difference between younger and older restorations. Including both habitat and environmental covariates on models for detection probability can improve the precision of estimates for density and should be considered when assessing bird populations pre- and post-restoration of shallow lakes.

Survival of white-tailed deer fawns in central Iowa.

Understanding demographic parameters such as survival is important for scientifically sound wildlife management. Survival can vary by region, sex, age-class, habitat, and other factors. White-tailed deer fawn survival is highly variable across the species' range. While recent studies have investigated fawn survival in several Midwestern states, there have been no published estimates from Iowa for 30 years. We radio-collared 48 fawns in central Iowa from 2015-2017 to estimate survival, home range size, and habitat composition and identity causes of mortality. Estimated fawn survival (± SE) was similar to other Midwest studies at 30 (0.78 ± 0.07)) and 60 days (0.69 ± 0.08), but considerably lower at 7 months (0.31 ± 0.02). Survival was positively associated with woodland habitat through 30 and 60 days, but not related to habitat at 7 months. Female fawns avoided agricultural habitat in their home ranges. Fawn 95% kernel density home ranges were smaller than in other studies in the Midwest (21.22 ± 2.74 ha at 30 days, 25.47 ± 2.87 ha at 60 days, and 30.59 ± 2.37 ha at 7 months). The large amount of woodland and grassland (>90%) in our study area meant that fawns did not have to travel far to find suitable cover, which may explain their small home ranges. We recorded 21 mortalities, the leading cause of which was disease (n = 9; 56% epizootic hemorrhagic disease [EHD]) followed by suspected predation (4) and harvest (3). The mortality associated with an outbreak of EHD in 2016, all of which occurred after 60 days post-capture, is the most likely explanation for our low survival estimate at 7 months. While predation, usually early in life, is the leading cause of mortality in most studies, sporadic diseases like EHD can be a major source of mortality in older fawns in some years.

Exploring the amphibian exposome in an agricultural landscape using telemetry and passive sampling.

This is the first field study of its kind to combine radio telemetry, passive samplers, and pesticide accumulation in tissues to characterize the amphibian exposome as it relates to pesticides. Understanding how habitat drives exposure in individuals (i.e., their exposome), and how that relates to individual health is critical to managing species in an agricultural landscape where pesticide exposure is likely. We followed 72 northern leopard frogs (Lithobates pipiens) in two agricultural wetlands for insight into where and when individuals are at high risk of pesticide exposure. Novel passive sampling devices (PSDs) were deployed at sites where telemetered frogs were located, then moved to subsequent locations as frogs were radio-tracked. Pesticide concentration in PSDs varied by habitat and was greatest in agricultural fields where frogs were rarely found. Pesticide concentrations in frogs were greatest in spring when frogs were occupying wetlands compared to late summer when frogs occupied terrestrial habitats. Our results indicate that habitat and time of year influence exposure and accumulation of pesticides in amphibians. Our study illustrates the feasibility of quantifying the amphibian exposome to interpret the role of habitat use in pesticide accumulation in frogs to better manage amphibians in agricultural landscapes.

Mercury Exposure in Bald Eagles (Haliaeetus leucocephalus) Admitted for Rehabilitation in Iowa, USA.

To gain insight into mercury exposure in Bald Eagles ( Haliaeetus leucocephalus ) in Iowa, US we collected blood from 22 rehabilitation eagles in 2012-13. The geometric mean blood mercury level was 0.144 µg/g (95% confidence interval: 0.066-0.314) and was at the lower end of the range of levels reported elsewhere.

Using landscape habitat associations to prioritize areas of conservation action for terrestrial birds.

Predicting species distributions has long been a valuable tool to plan and focus efforts for biodiversity conservation, particularly because such an approach allows researchers and managers to evaluate species distribution changes in response to various threats. Utilizing data from a long-term monitoring program and land cover data sets, we modeled the probability of occupancy and colonization for 38 bird Species of Greatest Conservation Need (SGCN) in the robust design occupancy modeling framework, and used results from the best models to predict occupancy and colonization on the Iowa landscape. Bird surveys were conducted at 292 properties from April to October, 2006-2014. We calculated landscape habitat characteristics at multiple spatial scales surrounding each of our surveyed properties to be used in our models and then used kriging in ArcGIS to create predictive maps of species distributions. We validated models with data from 2013 using the area under the receiver operating characteristic curve (AUC). Probability of occupancy ranged from 0.001 (SE < 0.001) to 0.995 (SE = 0.004) for all species and probability of colonization ranged from 0.001 (SE < 0.001) to 0.999 (SE < 0.001) for all species. AUC values for predictive models ranged from 0.525-0.924 for all species, with 17 species having predictive models considered useful (AUC > 0.70). The most important predictor for occupancy of grassland birds was percentage of the landscape in grassland habitat, and the most important predictor for woodland birds was percentage of the landscape in woodland habitat. This emphasizes the need for managers to restore specific habitats on the landscape. In an era during which funding continues to decrease for conservation agencies, our approach aids in determining where to focus limited resources to best conserve bird species of conservation concern.

Mountain plover responses to plague in Montana.

Plague is a bacterial (Yersinia pestis) disease that causes epizootic die-offs in black-tailed prairie dog (Cynomys ludovicianus) populations in the North American Great Plains. Through their grazing and burrowing, prairie dogs modify vegetation and landscape structure on their colonies in ways that affect other grassland species. Plague epizootics on prairie dog colonies can have indirect effects on species associated with colonies. The mountain plover (Charadrius montanus) preferentially nests on black-tailed prairie dog colonies and is thus negatively impacted by the loss of prairie dogs. We studied the effects of plague and colony spatial characteristics on the occupancy of 81 prairie dog colonies by nesting plovers in Phillips County, Montana, during a 13-year period (1995-2007). We used a robust design patch occupancy model to investigate how colony occupancy and extinction and colonization rates were affected by plague history, colony size, and colony shape. Here extinction and colonization rates refer to the probability that a colony loses/gains plovers in a subsequent nesting season, given that it had/lacked plovers in that breeding season. Colony occupancy was best explained by a model with no annual variation or plague effects. Colony extinction rates were driven by a combination of a quadratic of colony area, a 3-year plague response, and a measure of colony shape. Conversely, colonization rates were best explained by a model with a 4-year plague response. The estimated annual proportion of colonies occupied by plovers was 0.75 (95% confidence interval = 0.57-0.87). Estimated extinction probability ranged from a low of 0.07 (standard error [SE] = 0.02) in 2002 to a high of 0.25 (SE = 0.03) in 1995; colonization probability ranged from 0.24 (SE = 0.05) in 2006 to 0.35 (SE = 0.05) in 2000. Our results highlight how a bird that depends on prairie dogs for nesting habitat responds to plague history and other spatial characteristics of the colony. Ultimately, this information will broaden our understanding of the impact of plague on species other than the host.