Biology subjects

Andersen, D. E.

Publications and source records attributed to Andersen, D. E..

3 recordsLinked to original sources

bioRxiv2025

Landscape suitability and range expansion estimates for the North American Interior Population of trumpeter swans

The Interior Population of trumpeter swans (Cygnus buccinator) has grown and expanded substantially since reintroduction efforts began in the 1950s. To support management of this population, we developed a landscape suitability model and range expansion estimates (2023 2033). We assessed landscape suitability for breeding trumpeter swans with a use-available modeling design based on GPS collar data (20191iJ2023) and derived home range information from swans in the western Great Lakes Region of the U.S. and Canada. We related occurrence and pseudo-absences to landscape-scale summaries of upland and wetland conditions in a logistic mixed-effects model. We spatially applied the model and incorporated these estimates into a range-expansion model that identified the likelihood of a 50-km grid cell being occupied by 2033. We summarized time-series citizen-science data within cells and related newly occupied range cells and unoccupied cells (2004 2023) to year, survey effort, the amount of suitable breeding landscapes, and distance to previously occupied cells in a logistic regression model. Landscape suitability was positively related to greater amounts of wetland perimeter and foraging areas. New range cells were positively associated with suitable breeding landscapes and survey intensity and negatively associated with year and distance to previously occupied cells. We estimated a 4.4% (95% CI: 2.0-6.9%) annual range expansion rate from 2023 to 2033, with expansion occurring in the Prairie Pothole Region of the Dakotas and the Boreal Shield and James Bay Lowlands of Canada. North Dakota and South Dakota allow tundra swan (Cygnus columbianus) hunting but not for trumpeter swans. Our models can be useful for targeting hunter education at a local scale to mitigate unintended take of the similar looking species, allowing for pioneering trumpeter swans to establish persistent populations. Furthermore, our range expansion model can help jurisdictions with no or low breeding trumpeter swan populations anticipate future swan distribution and abundance.

ecology↗

bioRxiv2024

High variability of migration strategies in a re-established Trumpeter Swan population

BackgroundThe Interior Population (IP) of trumpeter swans (Cygnus buccinator), formerly extirpated by market hunting, was re-established in eastern North America by releasing individuals from both migratory and non-migratory populations. Their current annual movement patterns are largely unknown. Our goal was to describe their seasonal movements and quantify the proportion of the IP that is migratory, the extent and phenology of seasonal movements, and associations between movement patterns and breeding status and breeding location. MethodsWe deployed 113 GPS-GSM transmitters on IP trumpeter swans in six U.S. states and one Canadian province across the current IP breeding range. Using data from 252 swan-years, we estimated dates of migration events by segmenting the annual cycle using piecewise regression models fit to each yearly time-series of displacement from the breeding site. We fit a latent-state model to characterize population-level associations between breeding latitude and maximum extent of migration, and linear mixed models to quantify associations between individual characteristics (e.g., breeding status, sex) and migration phenology. ResultsAt the individual level, 59% of swans moved to distant non-breeding-period areas (long-distance migration, defined as moving >100 km from the breeding site), 16% exhibited regional migration (25-100 km from breeding site), 19% exhibited non-migratory but local movements (<25 km from breeding site), and 6% exhibited multiple migration strategies. Swans breeding at more-northern latitudes departed their territories earlier in autumn and returned later in the spring than those breeding at more southern latitudes. Breeding swans departed later in the autumn than non-breeders, but breeding status did not have a strong association with arrival in the spring. ConclusionIP trumpeter swans are partial migrants, with a continuum of strategies each year, from local movements to long-distance migration. Much of the variability in movement patterns was related to factors tied to natural history demands (e.g., breeding status) and response to environmental conditions (e.g., through associations with breeding latitude).

ecology↗

bioRxiv2021

Using Piecewise Regression to Identify Biological Phenomena in Biotelemetry Datasets

Technological advances in the field of animal tracking have greatly expanded the potential to remotely monitor animals, opening the door to exploring how animals shift their behavior over time or respond to external stimuli. A wide variety of animal-borne sensors can provide information on an animals location, movement characteristics, external environmental conditions, and internal physiological status. Here, we demonstrate how piecewise regression can be used to identify the presence and timing of potential shifts in a variety of biological responses using GPS telemetry and other biologging data streams. Different biological latent states can be inferred by partitioning a time-series into multiple segments based on changes in modeled responses (e.g., their mean, variance, trend, degree of autocorrelation) and specifying a unique model structure for each interval. We provide five example applications highlighting a variety of taxonomic species, data streams, timescales, and biological phenomena. These examples include a short-term behavioral response (flee and return) by a trumpeter swan (Cygnus buccinator) immediately following a GPS collar deployment; remote identification of parturition based on movements by a pregnant moose (Alces alces); a physiological response (spike in heart-rate) in a black bear (Ursus americanus) to a stressful stimulus (presence of a drone); a mortality event of a trumpeter swan signaled by changes in collar temperature and Overall Dynamic Body Acceleration; and an unsupervised method for identifying the onset, return, duration, and staging use of sandhill crane (Antigone canadensis) migration. We implement analyses using the mcp package in R, which provides functionality for specifying and fitting a wide variety of user-defined model structures in a Bayesian framework and methods for assessing and comparing models using information criterion and cross-validation measures. This approach uses simple modeling approaches that are accessible to a wide audience and is a straightforward means of assessing a variety of biologically relevant changes in animal behavior.

ecology↗