Geology topics

Jay Alan VonBank

Publications and source records attributed to Jay Alan VonBank.

5 recordsLinked to original sources

USGS2025

Developing research tools for demographic study of Rhynchophanes mccownii (thick-billed longspurs)

Like numerous other North American grassland bird species, Rhynchophanes mccownii (thick-billed longspur) has experienced severe population declines in the last 50 years. Little is known about population-limiting factors, and knowledge gaps limit conservation efforts on the species; however, before research studies aimed at improving conservation and management actions can be developed, other research must resolve notable knowledge gaps that exist in field techniques for efficient and effective large-scale demographic studies. We examined several techniques for the capture, marking (metal, color bands, and transmitters), and reencountering (resights and telemetry) of thick-billed longspurs in croplands and prairies in Valley County, Montana, during the 2022 and 2023 breeding seasons. Our goal was to evaluate the feasibility of obtaining within- and between-season resights of individual thick-billed longspurs using optical equipment and cameras, transmitter receivers, and the Motus automatic receiving station network. This report includes observations and insights that may aid researchers embarking on future demographic studies of thick-billed longspurs, as well as other grassland birds that provide similar research challenges.

Open-File Report↗

USGS2024

Evidence of longitudinal differences in spring migration strategies of an Arctic-nesting goose

During spring, migratory birds are required to optimally balance energetic costs of migration across heterogeneous landscapes and weather conditions to survive and reproduce successfully. Therefore, an individual's migratory performance may influence reproductive outcomes. Given large-scale changes in land use, climate, and potential carry-over effects, understanding how individuals migrate in relation to breeding outcomes is critical to predicting how future scenarios may affect populations. We used GPS tracking devices on 56 Greater White-fronted Geese ( Anser albifrons ) during four spring migrations to examine whether migration characteristics influenced breeding propensity and breeding outcome. We found a strong longitudinal difference in arrival to the breeding areas (18 days earlier), pre-nesting duration (90.9% longer), and incubation initiation dates (9 days earlier) between western- and eastern-Arctic breeding regions, with contrasting effects on breeding outcomes, but no migration characteristic strongly influenced breeding outcome. We found that breeding region influenced whether an individual likely pursued a capital or income breeding strategy. Where individuals fell along the capital-income breeding continuum was influenced by longitude, revealing geographic effects of life-history strategy among conspecifics. Factors that govern breeding outcomes likely occur primarily upon arrival to breeding areas or are related to individual quality and previous breeding outcome, and may not be directly tied to migratory decision-making across broad scales.

Louisiana, Texas↗

USGS2024

Human-induced range expansions result in a recent hybrid zone between sister species of ducks

Landscapes are consistently under pressure from human-induced ecological change, often resulting in shifting species distributions. For some species, changing the geographical breadth of their niche space results in matching range shifts to regions other than those in which they are formally found. In this study, we employ a population genomics approach to assess potential conservation issues arising from purported range expansions into the south Texas Brush Country of two sister species of ducks: mottled ( Anas fulvigula ) and Mexican ( Anas diazi ) ducks. Specifically, despite being non-migratory, both species are increasingly being recorded outside their formal ranges, with the northeastward and westward expansions of Mexican and mottled ducks, respectively, perhaps resulting in secondary contact today. We assessed genetic ancestry using thousands of autosomal loci across the ranges of both species, as well as sampled Mexican- and mottled-like ducks from across overlapping regions of south Texas. First, we confirm that both species are indeed expanding their ranges, with genetically pure Western Gulf Coast mottled ducks confirmed as far west as La Salle county, Texas, while Mexican ducks recorded across Texas counties near the USA–Mexico border. Importantly, the first confirmed Mexican × mottled duck hybrids were found in between these regions, which likely represents a recently established contact zone that is, on average, ~100 km wide. We posit that climate- and land use-associated changes, including coastal habitat degradation coupled with increases in artificial habitats in the interior regions of Texas, are facilitating these range expansions. Consequently, continued monitoring of this recent contact event can serve to understand species’ responses in the Anthropocene, but it can also be used to revise operational survey areas for mottled ducks.

Genes↗

USGS2024

Developing a photography-based harvest survey to estimate age and subspecies composition of midcontinent sandhill cranes

Midcontinent sandhill cranes ( Antigone canadensis ) are managed as a single population, but hunting regulations are structured so harvest is targeted towards the more numerous lesser sandhill cranes ( A. c. canadensis ). However, research indicates that greater sandhill cranes ( A. c. tabida ) have been disproportionally exposed to harvest at a rate exceeding their proportion within the midcontinent population. In addition, harvest has increased 22% per year in the U.S. Central Flyway states. The midcontinent population appears to be growing in recent years, but variability in annual abundance estimates has increased substantially. With limited resources and harvest management uncertainty increasing, we developed methods for a citizen science, photography-based harvest survey to estimate age and subspecies composition of harvested midcontinent sandhill cranes. To develop survey methods, we collected physical parts from 284 sandhill cranes in North Dakota in 2019 and 2020. We manually measured the culmen and tarsus using calipers, and digitally measured these parts using photographs and computer software. All digitally derived measurements were 2.5% to 5.9% larger than manual measurements; therefore, we developed linear models that adjusted digital measurements, facilitating subspecies prediction using an existing morphometric-based technique. In 2021, we requested an equal number of hunters to participate using 2 data collection methods to test if hunters could reliably take photographs suitable for digital measurement. Collection method 1 involved photographing the head and leg simultaneously, and Collection method 2 involved photographing the head only. Hunters submitted a total of 239 photographs. Only 80 of these photographs were submitted using Collection method 1, and 72% were suitable for digital measurement. Conversely, hunters submitted twice as many photographs using Collection method 2, and 88% of these photographs were deemed suitable. Although obtaining the tarsus measurement slightly improved subspecies predictability, Collection method 2 increased participation and usable data. We believe our results could be used to develop an operational survey of age and subspecies composition of midcontinent sandhill cranes, wherein a sample of crane hunters throughout the midcontinent population range would be asked to electronically submit a photograph of the head of each bird they harvest. A time series of age and subspecies composition of this population would provide managers with valuable information and improve harvest management at minimal additional cost and burden, compared to a traditional parts collection survey administered by mail.

Wildlife Society Bulletin↗

USGS2023

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.

Colorado, Idaho, Montaha, Utah, Wyoming↗