scholarly journals Home range, population structure and density estimates at removal catches with edge effect

1969 ◽  
Vol 14 ◽  
pp. 153-160 ◽  
Author(s):  
Lennart Hansson
Keyword(s):  
Population Structure ◽  
Home Range ◽  
Edge Effect ◽  
Density Estimates

scholarly journals Does the punishment fit the crime? Consequences and diagnosis of misspecified detection functions in Bayesian spatial capture-recapture modelling

2021 ◽  
Author(s):  
Soumen Dey ◽  
Richard Bischof ◽  
Pierre P. A. Dupont ◽  
Cyril Milleret
Keyword(s):  
Home Range ◽  
Space Use ◽  
Relative Bias ◽  
Diagnostic Tools ◽  
List Type ◽  
Detection Function ◽  
Density Estimates ◽  
Use Patterns ◽  
Wide Range ◽  
Capture Recapture

AbstractSpatial capture-recapture (SCR) is now used widely to estimate wildlife densities. At the core of SCR models lies the detection function, linking individual detection probability to the distance from its latent activity center. The most common function (half-normal) assumes a bivariate normal space use and consequently detection pattern. This is likely an oversimplification and misrepresentation of real-life animal space use patterns, but studies have reported that density estimates are relatively robust to misspecified detection functions. However, information about consequences of such misspecification on space use parameters (e.g. home range area), as well as diagnostic tools to reveal it are lacking.We simulated SCR data under six different detection functions, including the half-normal, to represent a wide range of space use patterns. We then fit three different SCR models, with the three simplest detection functions (half-normal, exponential and half-normal plateau) to each simulated data set. We evaluated the consequences of misspecification in terms of bias, precision and coverage probability of density and home range area estimates. We also calculated Bayesian p-values with respect to different discrepancy metrics to assess whether these can help identify misspecifications of the detection function.We corroborate previous findings that density estimates are robust to misspecifications of the detection function. However, estimates of home range area are prone to bias when the detection function is misspecified. When fitted with the half-normal model, average relative bias of 95% kernel home range area estimates ranged between −25% and 26% depending on the misspecification. In contrast, the half-normal plateau model (an extension of the half-normal) returned average relative bias that ranged between −26% and −4%. Additionally, we found useful heuristic patterns in Bayesian p-values to diagnose the misspecification in detection function.Our analytical framework and diagnostic tools may help users select a detection function when analyzing empirical data, especially when space use parameters (such as home range area) are of interest. We urge development of additional custom goodness of fit diagnostics for Bayesian SCR models to help practitioners identify a wider range of model misspecifications.

Edge Effect on Density Estimates of a Radiotracked Population of Yellow-Necked Mice

2009 ◽  
Vol 73 (2) ◽  
pp. 184-190 ◽  
Author(s):  
Silvia Tioli ◽  
Francesca Cagnacci ◽  
Anna Stradiotto ◽  
Annapaola Rizzoli
Keyword(s):  
Edge Effect ◽  
Density Estimates

scholarly journals Great Gray Owl home range and habitat selection during the breeding-season

2019 ◽  
Vol 42 ◽  
pp. 90-96
Author(s):  
Katherine Gura ◽  
Bryan Bedrosian ◽  
Anna D. Chalfoun ◽  
Susan Patla
Keyword(s):  
Habitat Selection ◽  
Home Range ◽  
Breeding Season ◽  
Resource Selection ◽  
Home Range Size ◽  
Breeding Habitat ◽  
Home Ranges ◽  
Effective Management ◽  
Density Estimates ◽  
Resource Requirements

Identifying resource requirements of under-studied species during key stages such as breeding is critical for effective management. We quantified breeding-season home-range attributes and habitat selection of adult Great Gray Owls across multiple spatial (home-range and within-home-range level) and temporal (nesting and post-fledging; day versus night) scales in western Wyoming, USA. In 2018 and 2019 we outfitted adult male owls (n = 18) with GPS remote-download transmitters and collected hourly location data throughout the breeding season (1 May – 15 September). Using 50% and 95% kernel density estimates (KDE), mean core area was 1.2 km2 and mean home-range size was 6.2 km2 (n = 16). Resource selection analyses incorporated both remotely-sensed and microsite data. We conducted microsite surveys at used and available points within 95% KDE home ranges using a stratified random sample design (n = 661). Determining home-range and breeding habitat requirements will improve density estimates and facilitate the effective management of Great Gray Owls and their habitat. We found differing patterns between habitat selection at the home-range and within-home-range scales.   Featured photo by YNP on Flickr. https://flic.kr/p/SA17KT

EDGE-EFFECT BIAS IN THE SAMPLING OF SUB-CORTICAL INSECTS

1971 ◽  
Vol 103 (2) ◽  
pp. 240-255 ◽  
Author(s):  
L. Safranyik ◽  
K. Graham
Keyword(s):  
Experimental Data ◽  
Edge Effect ◽  
Mountain Pine Beetle ◽  
Unit Area ◽  
Sampling Unit ◽  
Density Estimates ◽  
Pine Beetle ◽  
Average Individual ◽  
Shape And Size ◽  
Unit Edge

AbstractTwo general models are presented to describe the relations between the average number of insects bisected by sampling unit boundaries, the per cent edge-effect bias of mean-brood-density estimates, the shape and size of the average individual, and the shape and size of the sampling unit. The two general models, when expanded specifically for sampling late-stage mountain pine beetle broods, gave excellent fit to experimental data. The expanded equations are approximations since individual insects were considered as being rectangular in shape and the angles of the long axes of their orientation relative to the sampling unit boundary were considered to have a uniform frequency distribution. Edge-effect bias was a function of the size and shape of the organism and those of the sampling unit. Edge-effect bias resulting from faulty sampling-unit-area delineation is also considered, and suggestions are made for its reduction in sample surveys of sub-cortical insects.

scholarly journals Home range and density of three sympatric felids in the Southern Atlantic Forest, Brazil

2016 ◽  
Vol 76 (1) ◽  
pp. 228-232 ◽  
Author(s):  
C. B. Kasper ◽  
A. Schneider ◽  
T. G. Oliveira
Keyword(s):  
Home Range ◽  
Radio Telemetry ◽  
Home Range Size ◽  
Fragmented Landscape ◽  
Range Data ◽  
Telemetry Data ◽  
Mesopredator Release ◽  
Density Estimates ◽  
Leopardus Pardalis ◽  
Kernel Density Estimates

Abstract Home range and minimal population densities of Southern tiger cat (Leopardus guttulus), margay (Lepardus wiedii) and jaguarundi (Puma yagouaroundi) were estimated between 2005 and 2006 in Taquari Valley, near the southern edge of the Atlantic Rainforest in Brazil. Home range data were collected by conventional radio telemetry (VHF) locations in a highly fragmented landscape. The average home range size, calculated using 95% kernel density estimates, was 16.01 km2 for Southern tiger cat, 21.85 km2 for margay and 51.45 km2 for jaguarundi. Telemetry data were used to obtain minimal density estimates of 0.08 Southern tiger cats / km2, and 0.04 jaguarundi / km2. The density estimates arise from areas where ocelot (Leopardus pardalis) and other larger-bodied carnivores were locally extinct, and they suggest a specific type of mesopredator release known as the ocelot effect, which is likely enabling the increase in smaller felid populations in this area.

scholarly journals Dingo Density Estimates and Movements in Equatorial Australia: Spatially Explicit Mark–Resight Models

Animals ◽  
2020 ◽  
Vol 10 (5) ◽  
pp. 865
Author(s):  
Vanessa Gabriele-Rivet ◽  
Julie Arsenault ◽  
Victoria J. Brookes ◽  
Peter J. S. Fleming ◽  
Charlotte Nury ◽  
...  
Keyword(s):  
Home Range ◽  
Spatial Correlation ◽  
Disease Transmission ◽  
Indigenous Communities ◽  
Camera Trap ◽  
Disease Spread ◽  
Spatially Explicit ◽  
Ecological Knowledge ◽  
Northern Australia ◽  
Density Estimates

Australia is currently free of canine rabies. Spatio-ecological knowledge about dingoes in northern Australia is currently a gap that impedes the application of disease spread models and our understanding of the potential transmission of rabies, in the event of an incursion. We therefore conducted a one-year camera trap survey to monitor a dingo population in equatorial northern Australia. The population is contiguous with remote Indigenous communities containing free-roaming dogs, which potentially interact with dingoes. Based on the camera trap data, we derived dingo density and home range size estimates using maximum-likelihood, spatially explicit, mark–resight models, described dingo movements and evaluated spatial correlation and temporal overlap in activities between dingoes and community dogs. Dingo density estimates varied from 0.135 animals/km2 (95% CI = 0.127–0.144) during the dry season to 0.147 animals/km2 (95% CI = 0.135–0.159) during the wet season. The 95% bivariate Normal home range sizes were highly variable throughout the year (7.95–29.40 km2). Spatial use and daily activity patterns of dingoes and free-roaming community dogs, grouped over ~3 month periods, showed substantial temporal activity overlap and spatial correlation, highlighting the potential risk of disease transmission at the wild–domestic interface in an area of biosecurity risk in equatorial northern Australia. Our results have utility for improving preparedness against a potential rabies incursion.

scholarly journals Food Variety of Lesser Whistling Duck in Malaysian Lakes

2020 ◽  
Vol 28 (4) ◽  
Author(s):  
Martins Chukwuemeka Onwuka ◽  
Muhammad Nawaz Rajpar ◽  
Mohamed Zakaria
Keyword(s):  
Population Structure ◽  
Home Range ◽  
Aquatic Invertebrates ◽  
Avian Species ◽  
Sampling Point ◽  
Terrestrial Vertebrates ◽  
Food Items ◽  
Potamogeton Perfoliatus ◽  
Aquatic Vertebrates ◽  
Food Variety

Food distribution and diversity is a significant factor that determines the habitat and site selection of avian species. Its effects on the health, reproduction, survival rate, diversity indices, population structure and home range of avian species. In wetland ecosystem, bird home range and population structure is influenced by richness and diversity of food resources and availability of suitable foraging sites. The aim of the study was to ascertain the food variety of Lesser Whistling Duck - Dendrocygna javanica in Paya Indah Wetland Reserve (PIWR). A scan method was employed from strategic places or blinds using a spotting scope and binocular to determine the food selection and density by Distance sampling point count method. Food items were categorised into the aquatic plants (AP), aquatic invertebrates (AIV), aquatic vertebrates (AV), terrestrial plants (TP), terrestrial vertebrates (TV) and terrestrial invertebrates (TIV). Distance analysis indicated that PIWR harboured 3.88 &#177; 0.00 birds per ha (n = 188 individuals). In addition, the results revealed that higher bird relative abundance of Lesser Whistling Duck concentrated in the shallow of Belibis lake that was rich in submerged and emergent vegetation (Eleocharis dulcis, Philydrum lanuginosum, Utricularia vulgaris, and Potamogeton perfoliatus). Kruskal-Wallis H test showed that food items were significantly different. Lesser Whistling Duck showed strong correlationship with AIV (r2 = 1.00, P<0.05) and negative relationship with water TP (r2 = -0.061, P<0.05). The regression model highlighted that Lesser Whistling Duck significantly preferred aquatic invertebrates, r2 = -0.686&#177;0.68; P<0.001 and aquatic vertebrates, -0.459&#177;0.26) than other food items. The results revealed that shallow marshy-based lakes rich in aquatic vertebrates and invertebrates harboured higher population of Lesser Whistling Ducks to utilize it and performed multiple activities than other habitats.

scholarly journals No leading-edge effect in North Atlantic harbor porpoises: Evolutionary and conservation implications

2020 ◽  
Author(s):  
Yacine Ben Chehida ◽  
Roisin Loughnane ◽  
Julie Thumloup ◽  
Kristin Kaschner ◽  
Cristina Garilao ◽  
...  
Keyword(s):  
Population Structure ◽  
Edge Effect ◽  
North Atlantic ◽  
Environmental Changes ◽  
Isolation By Distance ◽  
Leading Edge ◽  
Species Response ◽  
The North ◽  
The North Atlantic ◽  
Harbor Porpoises

AbstractUnderstanding a species response to past environmental changes can help forecast how they will cope with ongoing climate changes. Harbor porpoises are widely distributed in the North Atlantic and were deeply impacted by the Pleistocene changes with the split of three sub-species. Despite major impacts of fisheries on natural populations, little is known about population connectivity and dispersal, how they reacted to the Pleistocene changes and how they will evolve in the future. Here, we used phylogenetics, population genetics, and predictive habitat modelling to investigate population structure and phylogeographic history of the North Atlantic porpoises. A total of 925 porpoises were characterized at 10 microsatellite loci and one-quarter of the mitogenome (mtDNA). A highly divergent mtDNA lineage was uncovered in one porpoise off Western Greenland, suggesting that a cryptic group may occur and could belong to a recently discovered mesopelagic ecotype off Greenland. Aside from it and the southern sub-species, spatial genetic variation showed that porpoises from both sides of the North Atlantic form a continuous system belonging to the same subspecies (Phocoena phocoena phoceona). Yet, we identified important departures from random mating and restricted intergenerational dispersal forming a highly significant isolation-by-distance (IBD) at both mtDNA and nuclear markers. A ten times stronger IBD at mtDNA compared to nuclear loci supported previous evidence of female philopatry. Together with the lack of spatial trends in genetic diversity, this IBD suggests that migration-drift equilibrium has been reached, erasing any genetic signal of a leading-edge effect that accompanied the predicted recolonization of the northern habitats freed from Pleistocene ice. These results illuminate the processes shaping porpoise population structure and provide a framework for designing conservation strategies and forecasting future population evolution.

scholarly journals Densities of the Eurasian Threetoed Woodpecker Picoides tridactylus calculated from sap row surveys are on par with estimates from fixed route bird censusing

Ornis Svecica ◽  
2021 ◽  
Vol 31 ◽  
pp. 94-106
Author(s):  
Björn Ferry ◽  
Johan Ekenstedt ◽  
Martin Green
Keyword(s):  
Population Density ◽  
Home Range ◽  
Large Scale ◽  
Montane Forest ◽  
Northern Sweden ◽  
Montane Forests ◽  
Density Estimates ◽  
Species Specific ◽  
Different Parts

Species-specific tracks animals can be an effective way of mapping species that are hard to find even if they are present. We used observations of sap rows on trees to calculate densities of Eurasian Three-toed Woodpeckers Picoides tridactylus. We surveyed 14 fixed routes in northern Sweden below the montane forest for sap rows during the autumn of 2020. We used our observations of fresh sap rows together with average home range and proportion of active territories per year derived from the literature, to calculate large-scale woodpecker population density. The density based on sap rows was 0.19 pairs per km2. Densities from fixed route bird observations for different parts of Västerbotten County below the montane forests were 0.13–0.14 pairs per km2, in relative agreement with the estimates from sap rows. We also calculated the population density from fixed route observations in the montane forests, and these were almost three times higher. Our density calculations correspond to 7,900 pairs in Västerbotten County. These results indicate that systematic counts of sap rows can quickly provide credible population density estimates of Eurasian Three-toed Woodpeckers.

Sign in / Sign up

Export Citation Format

Share Document