To robustly predict the effects of disturbance and ecosystem changes on species, it is necessary to produce structurally realistic models with high predictive power and flexibility. To ensure that these models reflect the natural conditions necessary for reliable prediction, models must be informed and tested using relevant empirical observations. Patternoriented modelling (POM) offers a systematic framework for employing empirical patterns throughout the modelling process and has been coupled with complex systems modelling, such as in agent-based models (ABMs). However, while the production of ABMs has been rising rapidly, the explicit use of POM has not increased. Challenges with identifying patterns and an absence of specific guidelines on how to implement empirical observations may limit the accessibility of POM and lead to the production of models which lack a systematic consideration of reality. This review serves to provide guidance on how to identify and apply patterns following a POM approach in ABMs (POM-ABMs), specifically addressing: where in the ecological hierarchy can we find patterns; what kinds of patterns are useful; how should simulations and observations be compared; and when in the modelling cycle are patterns used? The guidance and examples provided herein are intended to encourage the application of POM and inspire efficient identification and implementation of patterns for both new and experienced modellers alike. Additionally, by generalising patterns found especially useful for POM-ABM development, these guidelines provide practical help for the identification of data gaps and guide the collection of observations useful for the development and verification of predictive models. Improving the accessibility and explicitness of POM could facilitate the production of robust and structurally realistic models in the ecological community, contributing to the advancement of predictive ecology at large.
Passerines are especially vulnerable to predation at the pre-independence stage. Although the role of nest success in British farmland passerine declines is contentious, improvement in nest success through sympathetic management could play a role in their reversal. Because habitat is known to interact with predation, management options for mitigation will need to consider effects of nest predation. We present results from an observational study of a population of Common Blackbird Turdus merula on a farm which has experienced a range of agri-environment and game-management options, including a period with nest predator control, as a case study to address some of these issues. We used an information theoretic model comparison procedure to look for evidence of interactions between habitat and nest predation, and then asked whether habitat management and nest predator abundances could explain population trends at the site through their effects on nest success. Interactions were detected between measures of predator abundance and habitat variables, and these varied with nest stage -habitat within the vicinity of the nest appeared to be important at the egg stage, and nest-placement characteristics were important at the nestling stage. Although predator control appeared to have a positive influence on Blackbird breeding population size, the non-experimental set-up meant we could not eliminate other potential explanations. Variation in breeding population size did not appear to be influenced by variation in nest success alone. Our study demonstrates that observational data can only go so far in detection of such effects, and we discuss how it might be taken further. Agri-environment and game-management techniques are likely to influence nest predation pressure on farmland passerines, but the patterns, mechanisms and importance to population processes remain not wholly understood.
Changes of bat species composition over altitudinal gradients on northern and southern aspects of the Soutpansberg mountain range, South Africa DOI 10.1515/mammalia-2015-0055 Received March 24, 2015 accepted December 16, 2015 Abstract: In order to gain insight into the pattern of bat species composition over altitude and the environmental variables driving the observed pattern, we compared data from moist southern and drier northern aspects of the Soutpansberg range in northern South Africa. Acoustical monitoring and additional capturing of bats was used for analysis of species distribution patterns and comparisons of community composition. Bat activity generally followed a linear decline with increasing altitude, possibly related to reproductive females preferring lower altitudes. Species richness followed a hump-shaped distribution on the northern aspect and across the transect, whereas a pattern of a linear decline was observed on the southern aspect. Our study strongly supports a previously published climate model for insectivorous bats which assumes that water availability linked with temperature determines the shape of altitudinal distribution in bat species.Step-wise selection from multiple regression models retained habitat type and/or measures of habitat structure in all final models, supporting several other studies in that vegetation correlated to altitude is a primary determinant of bat species distribution over altitude. This study also supports that the Soutpansberg is a biodiversity hotspot for bats and emphasises that conservation efforts should by no means ignore the lower altitudes.
Predation pressure on many threatened species, including European farmland songbirds, may have increased over recent decades. Predator reduction to protect declining bird populations is a controversial but potentially important tool for managers. Its effects require measurement before its consideration in conservation. Game management typically combines sympathetic habitat management measures with reduction of nest predators. It has been proffered as additionally benefiting farmland songbirds, but little is known about the effects on their demography. We analyzed 11 years of nest data from 6 songbird species on 3 lowland farms. The different game management regimes on the farms enabled us to test the hypotheses that systematic predator reduction (mammals and corvids) and sporadic corvid reduction improve nest success in songbirds. We detected a positive effect of systematic predator reduction on common blackbird (Turdus merula), common chaffinch (Fringilla coelebs), dunnock (Prunella modularis), song thrush (T. philomelos), and yellowhammer (Emberiza citrinella) but not common whitethroat (Sylvia communis). For the 5 species that demonstrated an effect, systematic predator reduction improved the odds of nests surviving a day within the nest cycle by a factor of between 1.59 and 1.89. For common blackbird, the effect occurred at the egg (laying and incubation) stage of the nest cycle, whereas for other species it occurred across stages. Sporadic corvid reduction had a positive effect on nest survival only for common blackbird (at the nestling stage only) and a negative effect only for yellowhammer (across both stages). The extent to which predator reduction might influence populations may depend on mechanisms such as re‐nesting compensation and overwinter mortality. Where habitat management is in place to assist threatened songbirds, intensive, systematic nest predator reduction may provide a useful conservation tool for improvement of nest success. © 2014 The Wildlife Society.
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