Evidence of a Minimum Patch Size Threshold of Reproductive Success in an Endangered Songbird

2010 ◽  
Vol 74 (1) ◽  
pp. 133-139 ◽  
Author(s):  
Jerrod A. Butcher ◽  
Michael L. Morrison ◽  
Dean Ransom ◽  
R. Douglas Slack ◽  
R. Neal Wilkins
Keyword(s):  
Reproductive Success ◽  
Patch Size ◽  
Minimum Patch Size ◽  
Size Threshold

scholarly journals Satellite mapping of gorse at regional scales

2002 ◽  
Vol 55 ◽  
pp. 95-98 ◽  
Author(s):  
J.D. Shepherd ◽  
W.G. Lee
Keyword(s):  
Spatial Distribution ◽  
Patch Size ◽  
Percent Cover ◽  
Error Assessment ◽  
Mapping Accuracy ◽  
Spectral Bands ◽  
Random Samples ◽  
Minimum Patch Size ◽  
Target Management ◽  
Landsat Satellite

The spatial distribution of gorse in the Wellington Region was mapped using Landsat satellite imagery This satellite is capable of mapping at regional scales (150 000) with a large spatial extent (180 km x 180 km) and has spectral bands in both the visible and infrared parts of the spectrum (6 bands in total) A spring Landsat image distinguished flowering gorse enabling mapping of gorse as a separate scrub type We chose a minimum patch size of 05 ha with a boundary precision of 15 m An error assessment using 1200 stratified random samples across the Wellington region compared the satellite classified result with colour aerial orthophotography and found the mapping accuracy of gorse to be 95 Gorse area by catchment was calculated using an existing GIS of catchment boundaries The area and percent cover of gorse within a catchment is a potential way to target management at regional scales

scholarly journals The cheek plumage patch is an amplifier of dominance in great tits

2007 ◽  
Vol 4 (1) ◽  
pp. 12-15 ◽  
Author(s):  
Ismael Galván ◽  
Juan José Sanz
Keyword(s):  
Reproductive Success ◽  
Empirical Evidence ◽  
Patch Size ◽  
Laying Date ◽  
Large Patch ◽  
High Quality ◽  
Aggressive Interactions

Amplifiers are signals that enhance the perception of other signals or cues, but no studies to date provide empirical evidence for the role of these signals in a reproductive context. Here we use the white cheek patch of great tits as a model for studying this issue. Aggressive interactions decrease patch immaculateness, so patch size may be an amplifier of dominance, that is, more clearly reveal status. If so, in high-quality individuals patch size should correlate positively with reproductive success (here estimated by laying date, assuming that the earlier the better), whereas low-quality individuals with a large patch should only more clearly reveal their low quality and thus suffer low reproductive success, which is exactly the pattern found in males. In contrast, the cheek patch does not seem to function as an amplifier in female great tits.

Landscape attributes determine bobcat (Lynx rufus escuinapae) presence in Central Mexico

Mammalia ◽  
2017 ◽  
Vol 81 (1) ◽  
Author(s):  
María Eugenia Espinosa-Flores ◽  
Carlos A. López-González
Keyword(s):  
Patch Size ◽  
Camera Traps ◽  
Lynx Rufus ◽  
Tree Cover ◽  
Central Mexico ◽  
Anthropogenic Pressure ◽  
Landscape Characteristics ◽  
Breeding Populations ◽  
Minimum Patch Size

AbstractCentral Mexico has experienced a decline of its natural vegetation due to anthropogenic pressure. In 12 sites in the southeastern portion of Guanajuato, we deployed camera traps and analyzed landscape characteristics. We recorded the presence of bobcats in four sites. Their presence was explained by a combination of patch size and tree cover. Because bobcats are sensitive to fragmentation and habitat loss, it is essential to increase sampling and conservation efforts to define the minimum patch size and maximum area of human development that can limit their long-term persistence and the establishment of breeding populations.

scholarly journals Environmentally mediated reproductive success predicts breeding dispersal decisions in an early successional amphibian

2018 ◽  
Author(s):  
Laurent Boualit ◽  
Julian Pichenot ◽  
Aurélien Besnard ◽  
Rémi Helder ◽  
Pierre Joly ◽  
...  
Keyword(s):  
Reproductive Success ◽  
Environmental Conditions ◽  
Breeding Success ◽  
Patch Size ◽  
Negative Influence ◽  
Ecological Succession ◽  
Structured Populations ◽  
Breeding Dispersal ◽  
Capture Recapture ◽  
Context Dependent

AbstractDispersal is a central mechanism in ecology and evolution. Dispersal evolution is driven by a trade-off between costs and benefits, which is influenced by inter-individual variability and local environmental conditions (context-dependent dispersal). Many studies have investigated how dispersal decisions may be influenced by environmental factors, including density, predation, and interspecific competition. Yet few have attempted to examine how habitat disturbance may affect the dispersal process in spatially structured populations. In early successional species, one might expect individuals to adjust their dispersal decisions based on two main factors that potentially have an influence on reproductive success: patch size and the level of patch disturbance. In this study, we examined how these two factors affect breeding success and dispersal decisions in an early successional amphibian, the yellow-bellied toad (Bombina variegata). To this end, we used capture–recapture data collected on a spatially structured population occupying 28 breeding patches. We took advantage of recent developments in multievent capture–recapture models to detect signs of context-dependent dispersal. The results revealed that the probability of successful reproduction and the number of newly metamorphosed individuals increased with both the size and the proportion of disturbance of a patch. In addition, our results showed that the factors affecting breeding success also influenced breeding dispersal probability. Large patch size negatively influenced emigration probability; in contrast, it positively influenced immigration probability. Equally, higher disturbance (in terms of the proportion of the patch’s surface area disturbed each year) had a strong negative influence on emigration probability and slightly positively affected immigration probability. These findings strongly suggest that individuals make context-dependent dispersal decisions, adjusted to maximize future fitness prospects in a patch, allowing them to better cope with rapid changes in environmental conditions resulting from the ecological succession process. This opens new areas of potential research into the role of dispersal in organism specialization along an ecological succession gradient.

Conditional persistence in logistic models via nonlinear diffusion

2002 ◽  
Vol 132 (2) ◽  
pp. 267-281 ◽  
Author(s):  
Robert Stephen Cantrell ◽  
Chris Cosner
Keyword(s):  
Diffusion Process ◽  
Nonlinear Diffusion ◽  
Patch Size ◽  
Logistic Models ◽  
Threshold Effect ◽  
Small Population ◽  
Process Models ◽  
Logistic Equations ◽  
Minimum Patch Size ◽  
Parameter Ranges

A nonlinear diffusion process modelling aggregative dispersal is combined with local (in space) population dynamics given by a logistic equation and the resulting growth-dispersal model is analysed. The nonlinear diffusion process models aggregation via a diffusion coefficient, which is decreasing with respect to the population density at low densities. This mechanism is similar to area-restricted search, but it is applied to conspecifics rather than prey. The analysis shows that in some cases the models predict a threshold effect similar to an Allee effect. That is, for some parameter ranges, the models predict a form of conditional persistence where small populations go extinct but large populations persist. This is somewhat surprising because logistic equations without diffusion or with non-aggregative diffusion predict either unconditional persistence or unconditional extinction. Furthermore, in the aggregative models, the minimum patch size needed to sustain an existing population at moderate to high densities may be smaller than the minimum patch size needed for invasibility by a small population. The tradeoff is that if a population is inhabiting a large patch whose size is reduced below the size needed to sustain any population, then the population on the patch can be expected to experience a sudden crash rather than a steady decline.

ESTIMATES OF MINIMUM PATCH SIZE DEPEND ON THE METHOD OF ESTIMATION AND THE CONDITION OF THE HABITAT

Ecology ◽  
2007 ◽  
Vol 88 (6) ◽  
pp. 1401-1407 ◽  
Author(s):  
Earl D. McCoy ◽  
Henry R. Mushinsky
Keyword(s):  
Patch Size ◽  
Minimum Patch Size
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