Animal site fidelity structures space use, population demography and ultimately gene flow. Understanding the adaptive selection for site fidelity patterns provides a mechanistic understanding to both spatial and population processes. This can be achieved by linking space use with environmental variability (spatial and temporal) and demographic parameters. However, rarely is the environmental context that drives the selection for site fidelity behaviour fully considered. We use ecological theory to understand whether the spatial and temporal variability in breeding site quality can explain the site fidelity behaviour and demographic patterns of Gunnison sage‐grouse (Centrocercus minimus). We examined female site fidelity patterns across multiple spatial scales: proximity of consecutive year nest locations, space‐use overlap within and across the breeding and brooding seasons, and fidelity to a breeding patch. We also examined the spatial and temporal variability in nest, chick, juvenile and adult survival. We found Gunnison sage‐grouse to be site faithful to their breeding patch, area of use within the patch and generally where they nest, suggesting an “Always Stay” site fidelity strategy. This is an optimal evolutionary strategy when site quality is unpredictable. Further, we found limited spatial variability in survival within age groups, suggesting little demographic benefit to moving among patches. We suggest Gunnison sage‐grouse site fidelity is driven by the unpredictability of predation in a relatively homogeneous environment, the lack of benefits and likely costs to moving across landscape patches and leaving known lek and breeding/brooding areas. Space use and demography are commonly studied separately. More so, site fidelity patterns are rarely framed in the context of ecological theory, beyond questions related to the win‐stay:lose‐switch rule. To move beyond describing patterns and understand the adaptive selection driving species movements and their demographic consequences require integrating movement, demography and environmental variability in a synthetic framework. Site fidelity theory provides a coherent framework to simultaneously investigate the spatial and population ecology of animal populations. Using it to frame ecological questions will lead to a more mechanistic understanding of animal movement, spatial population structuring and meta‐population dynamics. A free Plain Language Summary can be found within the Supporting Information of this article.
Unlike other North American prairie-nesting dabbling ducks, northern pintail (Anas acuta) populations have not increased since the early 1990s and remain well below the long-term average for traditional survey areas. Previously reported estimates of annual survival and recovery rates for pintails did not investigate any spatial or temporal factors to explain annual variation of these rates. We used bandrecovery data from 1970 to 2003 to test the influence of temporal periods defined by differing harvest regulations and habitat conditions of breeding grounds with spatially delineated regions on survival and recovery rates of northern pintails in North America. We separated regions based on a multiresponse permutation procedure to identify banding blocks with dissimilar recovery distributions based on a cluster analysis. We categorized time by grouping years into temporal periods based on bag limits, season lengths, or overflight versus nonoverflight years. We used the Brownie approach in Program MARK to evaluate 46 a priori models estimating survival and recovery rates. The best approximating model indicated that survival varied with age, sex, and region with additive time and interactive time-by-age and time-by-region effects. Recovery rate was best represented by a fully interactive term comprised of age, sex, region, and year. There were no statistical differences among average annual survival point estimates between age and sex classes within each region, and our estimates were similar to previous unpublished studies. We found the eastern region had decreased survival and increased recovery rates compared to other regions. Trends in pintail survival suggest that variation in annual survival was not the cause of the initial decrease in the northern pintail population and is unlikely the dominant factor preventing the population from increasing. The influence of other population parameters, such as recruitment rate, should be investigated to further evaluate other causes for the population status of northern pintails. Use of the top-ranked model to estimate annual survival and recovery rates for northern pintails in North America, which indicated that annually varying estimates of survival rates were better supported by the data than grouping years into temporal classes (i.e., based on bag limits, season lengths, and overflight yr) can be used by managers and policy makers when considering annual harvest regulations and effects of conservation efforts. Managers should incorporate these estimates into future demographic studies of pintails as well as consider using the top-ranked model for future analyses of band-recovery data.
21Characterizing animal space use is critical to understand ecological relationships. Despite 22 many decades of using radio-telemetry to track animals and make spatial inference, there are 23 few statistical options to handle these unique data and no synthetic framework for modeling 24 animal location uncertainty and accounting for it in ecological models. We describe a novel 25 azimuthal telemetry model (ATM) to account for azimuthal uncertainty with covariates and 26 propagate location uncertainty into ecological models. We evaluate the ATM with commonly 27 used estimators in several study design scenarios using simulation. We also provide illustra- 28 tive empirical examples, demonstrating the impact of ignoring location uncertainty within 29 home range and resource selection analyses. We found the ATM to have good performance 30 and the only model that has appropriate measures of coverage. Ignoring animal location un-31 certainty when estimating resource selection or home ranges can have pernicious effects on 32 ecological inference. We demonstrate that home range estimates can be overly confident and 33 conservative when ignoring location uncertainty and resource selection coefficients can lead 34 to incorrect inference and over confidence in the magnitude of selection. Our findings and 35 model development have important implications for interpreting historical analyses using 36 this type of data and the future design of radio-telemetry studies. 37 Introduction 38 Understanding animal space-use and its implications for population and community dynam-39 ics is a central component of ecology and conservation biology. The need to understand 40 animal spatial relationships has led to the increasing refinement and utility of telemetry de-41 vices (Millspaugh et al. 2001). Traditional telemetry data were solely collected using VHF 42 ("very high frequency") radio signals to track individual animals with radio tags; VHF radio-43 telemetry started around the mid-1960s and is still often employed. These data are collected 44 by observers recording azimuths in the direction of the radio signal from known locations. 45Modern telemetry data are often collected using Argos satellites, aerial location finding (i.e., 46 2 via fixed-winged aircraft), or the global positioning system (GPS). While newer forms of 47 telemetry data are often collected, radio-telemetry devices are still relatively inexpensive. 48They also typically have low energy requirements, which allows for miniaturized and long-49 lasting devices to be fixed to small and volant animals for obtaining high spatial resolution 50 data with minimal risk to incurring costs on survival and movement (Ponchon et al. 2013). 51More so, digital VHF is quickly becoming an important way to monitor the movements of 52 small-bodied species at regional scales (Loring et al. 2017). 53It is well recognized that spatial locations from telemetry devices are not without 54 error and estimation uncertainty (Frair et al. 2004; Patterson et al. 2008). Observed locations ...
Agriculture and development have caused landscape change throughout the southwestern Great Plains in the range of the lesser prairie-chicken (Tympanuchus pallidicinctus). Landscape alteration within the lesser prairie-chicken range may contribute to range contraction and population losses through decreases in survival rates. Our objectives were to determine if: (1) landscape configuration (i.e., the spatial arrangement of habitat) or composition (i.e., the amount of habitat), at the study-site scale, affected annual survival of females, (2) relationships exist between landscape context (i.e., landscape configuration and composition) and weekly survival to assess effects of landscape composition and configuration on lesser prairie-chicken populations, and (3) anthropogenic features influenced daily mortality risk. We captured 170 female lesser prairie-chickens and used very-high-frequency and GPS (Global Positioning System) transmitters to track their movement and survival for 2 y. We used known-fate survival models to test if landscape configuration or composition within three sites in Kansas were related to differences in female survival among sites. In addition we tested for relationships between weekly survival and landscape configuration or composition within home ranges. Finally, we used Andersen-Gill models to test the influence of distance to anthropogenic features on daily mortality risk. Differences in survival were evident between sites with differing landscape compositions as annual survival in Northwestern Kansas (Ŝ ¼ 0.27) was half that of Clark County, Kansas (Ŝ ¼ 0.56), which corresponded with 41.9% more
Article (refereed) -postprintSearle, Kate R.; Rice, Mindy B.; Anderson, Charles R.; Bishop, Chad; Hobbs, N.T. 2015. Asynchronous vegetation phenology enhances winter body condition of a large mobile herbivore. Oecologia, 179 (2). 377-391. 10.1007/s00442-015-3348-9 Contact CEH NORA team at noraceh@ceh.ac.ukThe NERC and CEH trademarks and logos ('the Trademarks') are registered trademarks of NERC in the UK and other countries, and may not be used without the prior written consent of the Trademark owner. AbstractUnderstanding how spatial and temporal heterogeneity influence ecological processes forms a central challenge in ecology. Individual responses to heterogeneity shape population dynamics, therefore understanding these responses is central to sustainable population management. Emerging evidence has shown that herbivores track heterogeneity in nutritional quality of vegetation by responding to phenological differences in plants. We quantified the benefits mule deer (Odocoileus hemionus) accrue from accessing habitats with asynchronous plant phenology in northwest Colorado over three years. Our analysis examined both the direct physiological and indirect environmental effects of weather and vegetation phenology on mule deer winter body condition. We identified several important effects of annual weather patterns and topographical variables on vegetation phenology in the home ranges of mule deer. Crucially, temporal patterns of vegetation phenology were linked with differences in body condition, with deer tending to show poorer body condition in areas with less asynchronous vegetation green-up and later vegetation onset. The direct physiological effect of previous winter precipitation on mule deer body condition was much less important than the indirect effect mediated by vegetation phenology. Additionally, the influence of vegetation phenology on body fat was much stronger than that of overall vegetation productivity. In summary, changing annual weather patterns, particularly in relation to seasonal precipitation, have the potential to alter body condition of this important ungulate species during the critical winter period. This finding highlights the importance of maintaining large contiguous areas of spatially and temporally variable resources to allow animals to compensate behaviourally for changing climate-driven resource patterns.
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