Project

Northern Goshawk Population Ecology in the Northern Great Basin, USA

Goal: Investigating multiple factors influencing the population stability of Northern Goshawks within the naturally fragmented forest landscapes of the northern Great Basin. Factors under investigation include forest structural influences, prey abundance, diet, anthropogenic disturbance, disease and parasites, genetic diversity and connectivity, source/sink dynamics, adult survival, juvenile mortality and dispersal, and habitat transition as a result of management actions and climate change.

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Project log

Robert A. Miller
added a research item
Weather is thought to influence raptor reproduction through effects on prey availability, condition of adults, and survival of nests and young; however, there are few long-term studies of the effects of weather on raptor reproduction. We investigated the effects of weather on Northern Goshawk (Accipiter gentilis; henceforth goshawk) breeding rate, productivity, and fledging date in south-central Idaho and northern Utah, USA. Using data from 42 territories where we found evidence of breeding attempts in !1 yr from 2011-2019, we analyzed breeding rates using 315 territory-season combinations, analyzed productivity for 134 breeding attempts, and analyzed fledging date for 118 breeding attempts. We examined 35 predictor variables from four categories: precipitation, temperature, wind, and snowpack. Of the variables we evaluated, April precipitation, previous year's April-July precipitation, April-May mean temperature, and March-May mean temperature were related to measures of goshawk reproduction. Greater April-July precipitation in the previous year and lower April precipitation in the current year were associated with higher breeding rates. Years with warmer average April-May temperatures were associated with increased goshawk productivity. Years with greater April-July precipitation during the previous year and lower mean March-May temperatures were associated with later fledging dates. Based on these relationships, we considered projected changes in weather in the northern Great Basin over the next 50 yr as a result of climate change (without directly accounting for habitat changes caused by climate change), and predicted that climate change will: (a) have no significant effect on goshawk breeding rate, (b) have a positive effect on goshawk productivity, and (c) cause a shift toward earlier goshawk breeding. Our results indicate that weather is significantly related to goshawk reproduction in the northern Great Basin, and we suggest that the relationship between raptor breeding and weather be further investigated to enable higher resolution predictions of how changes in the climate may influence their populations, particularly changes that may not have been captured by our study.
Robert A. Miller
added a research item
Telomere length dynamics are an established biomarker of health and aging in animals. The study of telomeres in numerous species has been facilitated by methods to measure telomere length by real‐time quantitative PCR (qPCR). In this method, telomere length is determined by quantifying the amount of telomeric DNA repeats in a sample and normalizing this to the total amount of genomic DNA. This normalization requires the development of genomic reference primers suitable for qPCR, which remains challenging in non‐model organism with genomes that have not been sequenced. Here we report reference primers that can be used in qPCR to measure telomere lengths in any vertebrate species. We designed primer pairs to amplify genetic elements that are highly conserved between evolutionarily distant taxa and tested them in species that span the vertebrate tree of life. We report five primer pairs that meet the specificity and reproducibility standards of qPCR. In addition, we demonstrate an approach to choose the best primers for a given species by testing the primers on multiple individuals within a species and then applying an established computational tool. These reference primers can facilitate qPCR‐based telomere length measurements in any vertebrate species of ecological or economic interest.
Robert A. Miller
added a research item
The role of telomere dynamics in health and aging has been facilitated by the development of qPCR-based telomere length measurements. However, the widespread application of this approach has been limited because of the challenge of developing appropriate reference primers in non-model organisms with genomes that have not been sequenced. Here we develop reference primers to highly conserved DNA elements and validate their use in qPCR-based telomere length measurements across the vertebrate tree of life.
Robert A. Miller
added a research item
Population regulation within an area is driven by many intrinsic and extrinsic factors. Understanding the effects and relative importance of these factors is essential to either prioritize management actions or to use population metrics of a given species as an indicator of ecosystem health. As populations become smaller or rarer on the landscape, the resolution of traditional population metrics become less precise and difficult to measure. Individual-based modeling consists of simulating the behavior and life-history traits of individual agents within a system (e.g., Northern Goshawks [Accipiter gentilis]). Individuals are then aggregated into populations where population-level dynamics can be calibrated and responses to perturbations can be explored. We demonstrate how this method has helped inform our research into the population dynamics of the Northern Goshawk within the Minidoka Ranger District of the Sawtooth National Forest.
Robert A. Miller
added a project goal
Investigating multiple factors influencing the population stability of Northern Goshawks within the naturally fragmented forest landscapes of the northern Great Basin. Factors under investigation include forest structural influences, prey abundance, diet, anthropogenic disturbance, disease and parasites, genetic diversity and connectivity, source/sink dynamics, adult survival, juvenile mortality and dispersal, and habitat transition as a result of management actions and climate change.