Rocky Mountain Population Research Articles

Time of year and weather influence departure decisions of sandhill cranes at a primary stopover

The Rocky Mountain Population (RMP) of greater sandhill cranes uses a key stopover area, the San Luis Valley (SLV) in Colorado. Parameters of migration phenology can differ between autumn and spring and are affected by weather and environmental factors. We hypothesized that sandhill cranes in the SLV would have a longer stopover duration in autumn than in spring, and that wind assistance, crosswinds, temperature change, barometric air pressure, and surface water area would influence persistence probability. We used data from sandhill cranes fitted with transmitters that spanned autumn and spring, 2015-2022. We used an open robust design mark-recapture model to estimate stopover duration, arrival probability, and persistence probability. We examined the effects of weather and surface water on the persistence probability for 106 sandhill cranes in the SLV. Stopover duration was longer in autumn than in spring and had higher variability across years. Arrival probability to the SLV peaked on 13 October in autumn and 21 February in spring. Persistence probability declined around mid-December in autumn and mid-March in spring. We found that several weather covariates influenced persistence in both seasons. In autumn, sandhill cranes departed the SLV with higher tailwinds, lower crosswinds, and higher surface water availability. In spring, sandhill cranes departed the SLV with lower crosswinds and higher barometric air pressure at the surface and higher wind speeds at altitudes of about 3,000 m. The effect of wind speed was stronger later in the spring. Given the lower variability of arrival and persistence probability and shorter stopover duration in spring compared to autumn, we suspect that RMP sandhill cranes are using a time-minimization strategy during spring. However, given the use of supportive winds and weather conditions ideal for soaring, RMP sandhill cranes appear to be using strategies that save energy in both seasons. Our study identifies the optimal timing of water management and surveys for RMP sandhill cranes and confirms that weather influences their persistence. Understanding differences in migration patterns between seasons and the factors that influence persistence at stopover sites will also be important for anticipating phenological impacts from climate change and land use alterations.

Movement dynamics influence population monitoring and adaptive harvest management strategies in migratory birds

Informed population monitoring efforts are essential for sound management of harvested species, and adaptive strategies that provide detailed information to monitoring efforts often require data inputs from complimentary sources. Movement ecology information is seldom directly incorporated into population monitoring or adaptive harvest management strategies, yet can provide valuable information on species distributions, emigration and immigration rates, and aid in determining optimal population monitoring timing. The Rocky Mountain Population (RMP) of Sandhill Cranes is a harvested population subject to a stringent adaptive harvest management framework and an annual aerial survey to estimate population abundance, but movements of Sandhill Cranes during survey windows, and subsequent changes to harvest quotas based on their movement and distribution have not been investigated. We used seven years of GPS tracking data to estimate state-specific emigration and immigration rates, using a Bayesian multi-state capture-recapture model, among states within the RMP distribution to understand how seasonal crane movements may influence optimal aerial survey timing. We then leveraged these transition probabilities in conjunction with aerial survey count data to model how changes in aerial survey timing and movement-informed crane distribution would influence the current RMP Sandhill Crane adaptive harvest management model resulting in estimated changes to harvest allocation among states based on Sandhill Crane movement. We found that Sandhill Crane emigration from northern states began to increase the week of the aerial survey in late September, and continued to increase as autumn migration progressed into October. As expected, immigration to southern states began as emigration from northern states increased. Importantly, little movement among states occurred prior to the current aerial survey design timing. Overall, we found that current survey timing and shortly thereafter (∼1 week) did not greatly influence estimates of Sandhill Crane distribution, and did not greatly influence the harvest reallocation to each state until mid to late October (range of −42–+52 tag allocation change), much later than the current survey design would allow. Using GPS locations, we found that optimal population monitoring efforts could be improved to account for both detection and seasonal movements, while minimally influencing current adaptive harvest management strategies to stakeholders. Linking movement ecology with population monitoring efforts and subsequently adaptive harvest management strategies yields insightful information that can be beneficial for conservation planning, decision-making, and optimal species management of a migratory bird.

Genomic divergence and introgression between cryptic species of a widespread North American songbird.

Analysis of genomic variation among related populations can sometimes reveal distinct species that were previously undescribed due to similar morphological appearances, and close examination of such cases can provide much insight regarding speciation. Genomic data can also reveal the role of reticulate evolution in differentiation and speciation. White-breasted nuthatches (Sitta carolinensis) are widely distributed North American songbirds that are currently classified as a single species but have been suspected to represent a case of cryptic speciation. Previous genetic analyses suggested four divergent groups, but it was unclear whether these represented multiple reproductively isolated species. Using extensive genomic sampling of over 350 white-breasted nuthatches from across North America and a new chromosome-level reference genome, we asked if white-breasted nuthatches are comprised of multiple species and whether introgression has occurred between divergent populations. Genomic variation of over 300,000 loci revealed four highly differentiated populations (Pacific, n = 45; Eastern, n = 23; Rocky Mountains North, n = 138; and Rocky Mountains South, n = 150) with geographic ranges that are adjacent. We observed a moderate degree of admixture between Rocky Mountain populations but only a small number of hybrids between the Rockies and the Eastern population. The rarity of hybrids together with high levels of differentiation between populations is supportive of populations having some level of reproductive isolation. Between populations, we show evidence for introgression from a divergent ghost lineage of white-breasted nuthatches into the Rocky Mountains South population, which is otherwise closely related to Rocky Mountains North. We conclude that white-breasted nuthatches are best considered at least three species and that ghost lineage introgression has contributed to differentiation between the two Rocky Mountain populations. White-breasted nuthatches provide a dramatic case of morphological similarity despite high genomic differentiation, and the varying levels of reproductive isolation among the four groups provide an example of the speciation continuum.

Availability of Supplemental Corn for Sandhill Cranes, Light Geese, and Dabbling Ducks Wintering in New Mexico

Abstract The Middle Rio Grande Valley of central New Mexico overwinters the majority of the Rocky Mountain Population of greater sandhill cranes Antigone canadensis tabida and numerous Midcontinent Population lesser sandhill cranes A. c. canadensis, light geese (i.e., snow Anser caerulescens and Ross's geese Anser rossii), and dabbling ducks (i.e, Anas spp.). Stemming from changes in agricultural practices and loss of habitat, these species have become largely dependent on public lands where corn supplements natural foraging resources, providing a key dietary component while also discouraging crop depredation on private lands. To evaluate if supplemental corn provides a sufficient resource base, we estimated energy available in corn resources and seasonal energy requirements of the sandhill cranes, which consisted of the Rocky Mountain Population and Midcontinent Population. Additionally, we considered energetic requirements for two other wintering guilds, light geese and dabbling ducks. Depletion rates of postmowed corn increased throughout winter from 3,673 ± 843 kg/ha/d (mean ± SE) in December to 7,014 ± 1,884 kg/ha/d in February. The estimated seasonal energetic requirement of the Rocky Mountain Population and Midcontinent Population was 1.14 × 109 kcal (95% CI = 1.07 × 109 to 1.21 × 109 kcal). The combined seasonal energetic demand of the Rocky Mountain Population, Midcontinent Population, light geese, and dabbling ducks was 4.23 × 109 kcal (95% CI = 3.81 × 109 to 4.53 × 109 kcal) or 911,813 kg of corn (95% CI = 820,821–1,006,894 kg). From 2014 to 2017, corn production on public lands in the Middle Rio Grande Valley was 1,052,006 ± 58,965 kg grown on an average of 76 ha, sufficient for winter energetic requirements of all guilds. Interagency collaboration, effective planning during the growing season, and strategic schedules for mowing supplemental corn crops that integrate population abundances and their respective energy demands should further promote success of the supplemental corn program in the Middle Rio Grande Valley.

WEST NILE VIRUS IMPACTS ON BLACK-BILLED MAGPIE POPULATIONS

West Nile Virus (WNV) is an epizootic virus known to effectively kill Black-billed Magpies (Pica hudsonia). After WNV infection of humans appeared in the western United States, Black-billed Magpies birds per party-hours on Christmas Bird Counts (CBC) declined significantly. Trends for both CBC and Breeding Bird Surveys (BBS) shifted from positive before WNV infections of humans to negative during WNV infections, then rebounded to positive after WNV infection declined. Black-billed Magpies in Canada had no significant differences on CBC before or after WNV infections of humans. Canadian magpies had positive trends both before and after WNV infections on both CBC and BBS, but with negative trends during WNV infections. WNV invasion varied temporally across the continent, and Black-billed Magpies consistently showed significant and often dramatic declines soon after WNV invasion of a region. The southern Prairie region was severely hit, with Prairie states such as Kansas and Nebraska showing significant declines on CBC after WNV invasion, shifting from positive trends on CBC and BBS before invasion to negative trends during and after WNV invasion. WNV has potentially triggered or accelerated a retraction of Black-billed Magpie range in this region. The northern part of the Prairie region was less affected. Most southern and central Rocky Mountain, Intermountain, and Pacific region Black-billed Magpie populations showed significant negative effects from WNV infections. States in these regions with higher densities of Black-billed Magpies such as Colorado, Nevada, and Idaho showed significant dramatic declines during WNV invasion, but positive trends after WNV infections declined, a sign of recovering populations. California populations significantly declined with WNV invasion and have not recovered. Populations in northern and higher-elevation regions had little or no impact from WNV and populations were often stable or increasing.

Low Genetic Diversity in a Potential (Glacial) Relict: The Rocky Mountain Capshell, Acroloxus coloradensis (Henderson, 1930) (Gastropoda: Acroloxidae)

Acroloxus coloradensis is a rare and potentially glacial relict freshwater limpet species endemic to North America. However, despite its remarkable patchy distribution across the continent, only very few genetic data is available for the different populations. Here, we sequenced two standard barcoding markers for individuals from five populations to shed some light on the genetic population structure of this species. Overall, our genetic analyses revealed low genetic variation and identified three and two haplotypes for COI and 16S rRNA, respectively. The three Rocky Mountain populations differed only slightly for COI and shared the same haplotype for 16S rRNA. For both markers, no genetic variation was detected within the two populations sampled in Quebec. The present genetic data suggest that A. coloradensis is indeed a relict species and that the distribution of this species was strongly affected by the last glacial retreat in North America.

Population genomic diversity and structure at the discontinuous southern range of the Great Gray Owl in North America

Species' distributions are often discontinuous near the edge of the range where the environment may be more variable than the core of the range. Range discontinuity can reduce or cut off gene flow to small peripheral populations and lead to genetic drift and subsequent loss of genetic diversity. The southern extent of the Great Gray Owl (Strix nebulosa) range in North America is discontinuous, unlike their northern core range across the boreal forests. We sampled owls from five different locations on the periphery of the range across the western US (Wyoming, Idaho, California, northern Oregon, and southern Oregon) to investigate genetic population structure and genetic diversity. Using a reduced-representation genomic sequencing approach to genotype 123 individuals at 4817 single nucleotide polymorphic loci, we identified four genetically differentiated populations: California, southern Oregon, northern Oregon, and Wyoming and Idaho grouped together as a single Rocky Mountain population. The four genetically differentiated populations of Great Gray Owls identified in this study display high differentiation and low genetic variation, which is suggestive of long-term isolation and lack of connectivity, potentially caused by range discontinuity. The populations that lack habitat connectivity to the rest of the breeding range (i.e. those in California and Oregon) had lower genetic diversity than the Rocky Mountain population that is connected to the core of the range. These factors and other risks (such as disease and human-caused mortality) heighten susceptibility of these range-edge populations to future habitat and climate changes, genetic diversity erosion, and potential extinction vortex. For these reasons, protecting and monitoring this species on the southern edge of their range is vital.

Land Use, anthropogenic disturbance, and riverine features drive patterns of habitat selection by a wintering waterbird in a semi-arid environment.

River ecosystems in semi-arid environments provide an array of resources that concentrate biodiversity, but also attract human settlement and support economic development. In the southwestern United States, land-use change, drought, and anthropogenic disturbance are compounding factors which have led to departures from historical conditions of river ecosystems, consequently affecting wildlife habitat, including important wintering areas for migratory birds. The Rio Grande (River) in central New Mexico is the lifeblood of the Middle Rio Grande Valley (MRGV), maintaining large urban and agricultural centers and riparian and wetland resources, which disproportionately support a diversity of wildlife. The MRGV has been identified as the most important wintering area for the Rocky Mountain Population of greater sandhill cranes (Antigone canadensis tabida). Presently, however, changes in the hydrogeomorphology of the Rio Grande and landscape modification by humans have reshaped the MRGV and winter habitat for sandhill cranes. To evaluate these impacts, we investigated how land-use practices, anthropogenic disturbance, and river morphology influenced patterns of diurnal and roosting habitat selection by sandhill cranes. During the diurnal period, sandhill cranes relied heavily on managed public lands selecting agriculture crops, such as corn fields, and wetlands for foraging and loafing while avoiding areas with increasing densities of human structures. Sandhill cranes selected areas for roosting in the Rio Grande characterized by shallower water interspersed with sandbars, wide channel width, low bank vegetation, and farther away from disturbances associated with bridges. Our results establish and identify the central processes driving patterns of diel habitat selection by wintering sandhill cranes. Land use and riverine trends have likely gradually reduced winter habitat to managed public lands and limited reaches of the Rio Grande, underscoring the importance of natural resources agencies in supporting migratory birds and challenges involved when managing for wildlife in highly pressured semi-arid environments.

Origins of Wilson’s Warblers migrating through southwest Canada: Adding value to banding data by using stable isotopes and genetic markers

Abstract Stopovers used by birds during migration concentrate individuals from broad geographic areas potentially providing important information on catchment areas of birds moving through these sites. We combined stable isotope (δ2H), genetic fingerprinting and band recovery data to delineate the molt origins of Wilson’s Warblers (Cardellina pusilla) migrating through a stopover site in southwestern Canada in the fall. We assessed changes in δ2Hf indicating latitudinal origins with ordinal date to show this species likely underwent leapfrog migration through this site. Using the combined approach to determine origins, Wilson’s Warblers migrating through southwestern Alberta in 2015 were mostly from the western boreal population (n = 155, 96%) with some individuals from the Pacific Northwest (n = 1, 0.6%), Rocky Mountain (n = 2, 1.2%) and eastern boreal (n = 3, 1.8%) populations. Our results suggest that individuals migrating through our study site come from a broad catchment area potentially from a large part of northwestern North America. Future studies should link population changes at banding stations with other information to determine associations with large-scale landscape-level drivers (e.g. climate, land use).

Circadian Rhythms and Reproductive Phenology Covary in a Natural Plant Population.

The circadian clock is a molecular timekeeper that matches endogenous rhythms in diverse traits with 24-h cycles in the external environment. Although a lack of clock resonance to the environment is detrimental to performance, clock phenotypes in wild populations nevertheless deviate substantially from the predicted optimal cycle length of 24 h, and significant genetic variation exists for circadian parameters. Here, we describe covariation between 2 traits considered to reflect adaptation to different aspects of temporal environmental heterogeneity, circadian rhythms (adaptation to daily environmental cycles) and flowering time (adaptation to seasonal cycles), in a Rocky Mountain population of the mustard Boechera stricta, a North American relative of Arabidopsis thaliana. We found that 18 families that differ in circadian period in leaf movement by 3.5 h expressed genetic diversity in first-year growth, reproductive phenology, vegetative size at reproduction, and starch concentration following vernalization. The families exhibited a large (~90-day) range in mean flowering time, even though the spatial scale of population sampling covered only a few hundred meters. Circadian period covaried with other traits such that longer-period families flowered earlier and at a larger size, a trait combination predicted to yield a fitness benefit in the wild. Circadian clock research in model systems has previously shown that mutations in clock genes influence phenology. Our results widen the scope of this research by illustrating a link between naturally segregating clock variation and reproductive phenology among wild genotypes, suggesting that the causes of genetic diversity in the clock lie partly in adaptation to seasonal environmental heterogeneity.

SURVEY OF GROSS AND HISTOPATHOLOGIC FINDINGS IN TWO WINTERING SUBPOPULATIONS OF SANDHILL CRANES ( ANTIGONE CANADENSIS).

: Sandhill Cranes ( Antigone canadensis) of the midcontinent population (MCP) and Rocky Mountain population (RMP) are migratory game birds with stable populations that travel between Canada and the southern US and Mexico. In the winters of 2012-14, we performed gross and histologic examinations of 43 hunter-harvested Sandhill Cranes in Texas (MCP) and New Mexico (RMP) to assess the impact of disease on populations. Lesions were significantly more common in the MCP relative to the RMP, likely reflecting differential environmental exposure to pathogens and parasites. Grossly, liver nodules and esophageal granulomas were present in 8-39% of birds. In feces from over half of birds, we found coccidian oocysts with mitochondrial gene sequences identical to those of Eimeria gruis and Eimeria reichenowi previously obtained from sympatric Whooping Cranes ( Grus americana). Over one-quarter of birds had liver and cardiac lesions suggestive of disseminated visceral coccidiosis. We documented proliferative colitis due to Cryptosporidium in a wild Sandhill Crane. Additionally, several endoparasites were found in histologic sections from several cranes, including a bird with respiratory trematodiasis and two birds with Tetrameres sp. in the proventriculus associated with ductal ectasia. In addition to describing lesions and parasites that impact Sandhill Crane health, these pathology data may also be relevant for the conservation of endangered Whooping Cranes using a surrogate species approach.

Autumn Snowfall Controls the Annual Radial Growth of Centenarian Whitebark Pine (Pinus albicaulis) in the Southern Coast Mountains, British Columbia, Canada

ABSTRACTWhitebark pine (Pinus albicaulis), an endangered keystone alpine tree species, faces multiple threats across its western North American range. Little is known of whitebark pine in the southern Coast Mountains of British Columbia relative to well-studied Rocky Mountain populations, especially with regard to the effects of climate on annual radial growth. Our results indicate centenarian whitebark pine annual radial growth is negatively influenced by the onset of snowfall in the prior autumn. This unusual growth limitation likely stems from the truncation of the prior year growing season and reduced physiological preparedness for growth in the following year. Autumn snowfall is moderated by temperature and the Pacific Decadal Oscillation (PDO), which controls largescale weather patterns in the study region. Our results are distinct from studies of mature whitebark pine trees in continental populations where growth is typically limited by summer temperature, or occasionally by winter snowfall due to a reliance on snow meltwater during spring/summer. We suggest that predicted warmer and wetter climate and reduced snowpacks in the southern Coast Mountains may benefit the growth of the young population of maritime whitebark pine over the next few decades.

Evaluating and improving count-based population inference: A case study from 31 years of monitoring Sandhill Cranes

ABSTRACT Monitoring animal populations can be difficult. Limited resources often force monitoring programs to rely on unadjusted or smoothed counts as an index of abundance. Smoothing counts is commonly done using a moving-average estimator to dampen sampling variation. These indices are commonly used to inform management decisions, although their reliability is often unknown. We outline a process to evaluate the biological plausibility of annual changes in population counts and indices from a typical monitoring scenario and compare results with a hierarchical Bayesian time series (HBTS) model. We evaluated spring and fall counts, fall indices, and model-based predictions for the Rocky Mountain population (RMP) of Sandhill Cranes (Antigone canadensis) by integrating juvenile recruitment, harvest, and survival into a stochastic stage-based population model. We used simulation to evaluate population indices from the HBTS model and the commonly used 3-yr moving average estimator. We found counts of the RMP t...

New Summer Areas and Mixing of Two Greater Sandhill Crane Populations in the Intermountain West

Abstract Population delineation throughout the annual life cycle for migratory birds is needed to formulate regional and national management and conservation strategies. Despite being well studied continentally, connectivity of sandhill crane Grus canadensis populations throughout the western portion of their North American range remains poorly described. Our objectives were to 1) use global positioning system satellite transmitter terminals to identify summer distributions for the Lower Colorado River Valley Population of greater sandhill cranes Grus canadensis tabida and 2) determine whether intermingling occurs among any of the western greater sandhill crane populations: Rocky Mountain Population, Lower Colorado River Valley Population, and Central Valley Population. Capture and marking occurred during winter and summer on private lands in California and Idaho as well as on two National Wildlife Refuges: Cibola and Sonny Bono Salton Sea National Wildlife Refuges. A majority of marked greater sandhill cranes summered in what is established Lower Colorado River Valley Population breeding areas in northeastern Nevada and southwestern Idaho. A handful of greater sandhill cranes summered outside of traditional breeding areas in west-central Idaho around Cascade Reservoir near Donnelly and Cascade, Idaho. For example, a greater sandhill crane colt captured near Donnelly in July 2014 survived to winter migration and moved south to areas associated with the Rocky Mountain Population. The integration of the greater sandhill crane colt captured near Donnelly provides the first evidence of potential intermingling between the Lower Colorado River Population and Rocky Mountain Population. We suggest continued marking and banding efforts of all three western populations of greater sandhill cranes will accurately delineate population boundaries and connectivity and inform management decisions for the three populations.

Optimal population prediction of sandhill crane recruitment based on climate-mediated habitat limitations.

1. Prediction is fundamental to scientific enquiry and application; however, ecologists tend to favour explanatory modelling. We discuss a predictive modelling framework to evaluate ecological hypotheses and to explore novel/unobserved environmental scenarios to assist conservation and management decision-makers. We apply this framework to develop an optimal predictive model for juvenile (<1 year old) sandhill crane Grus canadensis recruitment of the Rocky Mountain Population (RMP). We consider spatial climate predictors motivated by hypotheses of how drought across multiple time-scales and spring/summer weather affects recruitment. 2. Our predictive modelling framework focuses on developing a single model that includes all relevant predictor variables, regardless of collinearity. This model is then optimized for prediction by controlling model complexity using a data-driven approach that marginalizes or removes irrelevant predictors from the model. Specifically, we highlight two approaches of statistical regularization, Bayesian least absolute shrinkage and selection operator (LASSO) and ridge regression. 3. Our optimal predictive Bayesian LASSO and ridge regression models were similar and on average 37% superior in predictive accuracy to an explanatory modelling approach. Our predictive models confirmed a priori hypotheses that drought and cold summers negatively affect juvenile recruitment in the RMP. The effects of long-term drought can be alleviated by short-term wet spring-summer months; however, the alleviation of long-term drought has a much greater positive effect on juvenile recruitment. The number of freezing days and snowpack during the summer months can also negatively affect recruitment, while spring snowpack has a positive effect. 4. Breeding habitat, mediated through climate, is a limiting factor on population growth of sandhill cranes in the RMP, which could become more limiting with a changing climate (i.e. increased drought). These effects are likely not unique to cranes. The alteration of hydrological patterns and water levels by drought may impact many migratory, wetland nesting birds in the Rocky Mountains and beyond. 5. Generalizable predictive models (trained by out-of-sample fit and based on ecological hypotheses) are needed by conservation and management decision-makers. Statistical regularization improves predictions and provides a general framework for fitting models with a large number of predictors, even those with collinearity, to simultaneously identify an optimal predictive model while conducting rigorous Bayesian model selection. Our framework is important for understanding population dynamics under a changing climate and has direct applications for making harvest and habitat management decisions.

A hormone priming regimen and hibernation affect oviposition in the boreal toad (Anaxyrus boreas boreas)

Declines of the southern Rocky Mountain population of boreal toad (Anaxyrus boreas boreas) have led to the establishment of a captive assurance population and reintroduction program, in an attempt to preserve and propagate this geographically isolated population. One of the unique adaptations of this species is its ability to survive in cold environments by undergoing long periods of hibernation. In captivity, hibernation can be avoided altogether, decreasing morbidity caused by compromised immune systems. However, it is not entirely clear how essential hibernation is to reproductive success. In this study, the effects of hibernation versus nonhibernation, and exogenous hormones on oviposition, were examined in boreal toad females in the absence of males. In the summers of 2011 and 2012, 20 females housed at Mississippi State University were treated with a double priming dose of hCG and various ovulatory doses of hCG and LH-releasing hormone analog but denied hibernation. Exogenous hormones, in the absence of hibernation, could not induce oviposition over two breeding seasons (2011–2012). In contrast, during the summer of 2012 and 2013, 17 of 22 females (77%) housed at the Native Aquatic Species Restoration Facility (Alamosa, CO, USA) oviposited after they were treated with two priming doses of hCG (3.7 IU/g each) and a single ovulation dose of hCG (13.5 IU/g) and LH-releasing hormone analog (0.4 μg/g) after hibernation. There was a significant difference in oviposition between females that were hibernated and received hormones (2012, P < 0.05 and 2013, P < 0.01) compared to hibernated control females. In 2013, 12 of 16 remaining Mississippi State University females from the same group used in 2011 and 2012 were hibernated for 1, 3, and 6 months, respectively and then treated with the same hormone regimen administered to females at the Native Aquatic Species Restoration Facility. Together, hibernation and hormone treatments significantly increased oviposition (P < 0.05), with 33% of females ovipositing. These results suggest that (1) hibernation is a key factor influencing oviposition that cannot be exclusively circumvented by exogenous hormones; (2) females do not require the presence of a male to oviposit after hormone treatments; and (3) longer hibernation periods are not beneficial for oviposition. The hormonal induction of oviposition in the absence of males and shorter hibernation periods could have important captive management implications for the boreal toad. Furthermore, the production of viable offspring by IVF where natural mating is limited could become an important tool for genetic management of this boreal toad captive population.

Assessing prehistoric genetic structure and diversity of North American elk (Cervus elaphus) populations in Alberta, Canada

North American elk (Cervus elaphus L., 1758) are an important component of Canada’s natural ecosystems. Overhunting and habitat decline in the 19th century led to the near eradication of Rocky Mountain elk (Cervus elaphus nelsoni Bailey, 1935) and Manitoban elk (Cervus elaphus manitobensis Millais, 1915) within Alberta. Though elk populations have been restored within provincial and national parks, it is unknown to what degree historic population declines affected overall genetic diversity and population structuring of the two subspecies. This study targeted 551 bp of mitochondrial D-loop DNA from 50 elk remains recovered from 16 archaeological sites (2260 BCE (before common era) to 1920 CE (common era)) to examine the former genetic diversity and population structure of Alberta’s historic elk populations. Comparisons of ancient and modern haplotype and nucleotide diversity suggest that historic population declines reduced the mitochondrial diversity of Manitoban elk, while translocation of animals from Yellowstone National Park in the early 20th century served to maintain the diversity of Rocky Mountain populations. Gene flow between the two subspecies was significantly higher in the past than today, suggesting that the two subspecies previously formed a continuous population. These data on precontact genetic diversity and gene flow in Alberta elk provide essential baseline data integral for elk management and conservation in the province.

Neidiopsis hamiltonii sp. nov., N. weilandii sp. nov., N. levanderi and N. wulffii from western North America

Neidiopsis hamiltonii sp. nov. and Neidiopsis weilandii sp. nov. are described from a stream, lakes and ponds in western North America. The new species are readily distinguished from the three other published species of Neidiopsis by valve size, valve shape and the nature of the proximal raphe ends. In both new species, loculi along the valve margins are continuous and form hollow longitudinal canals, as in Neidium. Diagnostic features common to all five Neidiopsis species include: (1) a mix of uniseriate and biseriate striae; (2) striae arranged in two offset ranks; (3) distal raphe fissures simple (not bifurcate); (4) habitat restricted to cold oligotrophic streams, lakes and ponds with low conductivity; and (5) distribution limited to the Arctic, sub-Arctic and alpine zones of temperate regions in the northern hemisphere. Considerable variation in valve shape, including apical shape, is demonstrated in Rocky Mountain populations of N. hamiltonii, N. levanderi (Hustedt) Lange-Bertalot & Metzeltin and N. wulffii (Petersen) Lange-Bertalot. A comparison of morphometric data for various populations of N. levanderi and N. wulffii indicates that valves from the Rocky Mountains tend to be larger than valves from European and more northerly North American populations.

Regional and seasonal patterns of nutritional condition and reproduction in elk

ABSTRACTDemographic data show many populations of Rocky Mountain (Cervus elaphus nelsoni) and Roosevelt (Cervus elaphus roosevelti) elk have been declining over the last few decades. Recent work suggests that forage quality and associated animal nutritional condition, particularly in late summer and early autumn, influence reproduction and survival in elk. Therefore, we estimated seasonal nutritional condition of 861 female elk in 2,114 capture events from 21 herds in Washington, Oregon, Wyoming, Colorado, and South Dakota from 1998 to 2007. We estimated ingesta‐free body fat and body mass, and determined age, pregnancy status, and lactation status. We obtained estimates for most herds in both late winter–early spring (late Feb–early Apr) and in autumn (Nov–early Dec) to identify changes in nutritional condition of individuals across seasons.Body fat levels of lactating females in autumn were consistently lower than their non‐lactating counterparts, and herd averages of lactating elk ranged from 5.5% to 12.4%. These levels were 30–75% of those documented for captive lactating elk fed high‐quality diets during summer and autumn. Body fat levels were generally lowest in the coastal and inland northwest regions and highest along the west‐slope of the northern Cascades. Adult females in most herds lost an average of 30.7 kg (range: 5–62 kg), or about 13% (range: 2.6–25%) of their autumn mass during winter, indicating nutritional deficiencies. However, we found no significant relationships between spring body fat or change in body fat over winter with winter weather, region, or herd, despite markedly different winter weather among herds and regions. Instead, body fat levels in spring were primarily a function of fat levels the previous autumn. Thinner females in autumn lost less body fat and body mass over winter than did fatter females, a compensatory response, but still ended the season with less body fat than the fatter elk.Body fat levels of lactating females in autumn varied among herds but were unrelated to their body fat levels the previous spring. Within herds, thinner females exhibited a compensatory response during summer and accrued more fat than their fatter counterparts over summer, resulting in similar body fat levels among lactating elk in autumn despite considerable differences in their fat levels the previous spring. Level of body fat achieved by lactating females in autumn varied 2‐fold among herds, undoubtedly because of differences in summer nutrition. Thus, summer nutrition set limits to rates of body fat accrual of lactating females that in turn limited body condition across the annual cycle.Pregnancy rates of 2‐ to 14‐year‐old females ranged from 68% to 100% in coastal populations of Washington, 69% to 98% in Cascade populations of Washington and Oregon, 84% to 94% in inland northwestern populations of Washington and Oregon, and 78% to 93% in Rocky Mountain populations. We found evidence of late breeding, even in herds with comparatively high pregnancy rates. Mean body mass of calves (n = 242) in 3 populations was 75 kg, 81 kg, and 97 kg, representing 55–70% of potential mass for 6‐ to 8‐month‐old calves on high‐quality diets. Mean mass of 11 yearling females caught in autumn was 162 kg, approximately 70% of potential for autumn, and pregnancy rate was 27%. Mean mass of 28 yearlings caught in spring was 163 kg and pregnancy rate was 34%.Our data suggest widespread occurrence of inadequate summer nutrition. Summer ranges of just 3 herds supported relatively high levels of autumn body fat (11–13% body fat) and pregnancy rates (&gt;90%) even among females that successfully raised a calf year after year. Most other summer ranges supported relatively low autumn levels of body fat (5–9% body fat), and reproductive pauses were common (&lt;80% pregnancy rates). Overall, our data failed to support 2 common assumptions: 1) summer and early autumn foraging conditions are typically satisfactory to prevent nutritional limitations to adult fat accretion, pregnancy rates, and calf and yearling growth; and 2) winter nutrition and winter weather are the principal limiting effects on elk productivity. Instead, a strong interaction existed among level of summer nutrition, lactation status, and probability of breeding that was little affected by winter conditions—adequacy of summer nutrition dictated reproductive performance of female elk and growth as well as growth and development of their offspring in the Northwest and Rocky Mountains. Our work signals the need for greater emphasis on summer habitats in land management planning on behalf of elk. © 2013 The Wildlife Society.

Stress hormone concentration in Rocky Mountain populations of the American pika (Ochotona princeps).

The American pika (Ochotona princeps) is considered a sentinel species for detecting ecological effects of climate change. Pikas are declining within a large portion of their range, but previous studies have focused only on local pika extinction as a metric of change. We designed a procedure which can provide an earlier warning signal, based on non-invasive sampling and analysis of physiological stress in living pikas. Pikas were sampled at several locations in the Rocky Mountains for the measurement of glucocorticoid metabolites (GCMs) in faeces. Using a time series of faecal pellets from 12 individuals, we detected a significant increase in faecal GCM level in response to capture, thus biologically validating the use of a corticosterone enzyme immunoassay. We also established baseline, peak, and post-peak GCM concentrations for pikas in the Rocky Mountains, which varied according to gender and individual. This is the first study to measure stress hormone metabolites in any species of pika. The methods developed and validated in this study can be used to add non-invasive measurements of physiological stress to pika monitoring programmes and other research designed to assess pika vulnerability to predicted changes in climate. Pika monitoring programmes currently in place use a protocol that relates current site use by pikas with data on local habitat characteristics, such as elevation, to infer potential effects of climate change. Data generated by these monitoring studies can be used to identify the trends in site use by pikas in relationship to habitat covariates. However, this approach does not take into account the role of behavioural thermoregulation and the pika's use of microhabitats to ameliorate variations in climate. Incorporating a stress metric, such as GCM concentration, will provide relatively direct evidence for or against the hypothesis that pikas can be stressed by climate regardless of behavioural adaptations.