Forest fragmentation is caused by the clearing of patches of indigenous vegetation for agriculture, urban development, and other human land uses. Such action results in patches of remnant natural vegetation being surrounded by altered vegetation. I investigate the effects of forest fragmentation and matrix type on avian diversity and assemblage structure in forest patches of the historically fragmented Karkloof / Balgowan forest range, KwaZulu-Natal, South Africa. This study compares the bird assemblage diversity and composition of indigenous forest patches surrounded by commercial forestry (Gilboa complex) with that surrounded by natural grassland matrix (Balgowan complex). Insularisation of Afromontane Mistbelt forest in KwaZulu-Natal has led to loss of species where forest fragments support fewer bird species than comparably sized patches of mainland forest. Small fragments within natural grassland have fewer bird species per unit area than larger fragments. Forest patch area-dependent density compensation is evident and bird assemblages appear saturated. Bird assemblages are characterised by a non-random species distribution pattern where area-dependent processes are dominant, and the loss of species from fragments follows a deterministic sequence. In forests in the plantation-dominated matrix no island-effect is detectable and it appears that forest patches are converging on the same bird species richness, regardless of forest size. No density compensation is evident and bird assemblages are not saturated. The sequence of species loss from forest patches is not as predictable, where a random yet prominent colonisation process exists. As commercial plantations provide suitable habitat cover for movement of forest birds, colonisation of both distant and small indigenous forest patches has been possible, reducing the effects of area-dependent extinction in the forest patches but also resulting in lower species richness in larger patches. Bird species of the Karkloof / Balgowan forest range appear to be fragmentation adapted, and most species are resilient to further landscape change. Certain species are however more prone to local extinction than others. The major predictors of extinction risk are body size, abundance status, and feeding guild. Patch area is the dominant force governing traits in the natural Balgowan complex where larger species with low natural abundance and an insectivorous diet are most prone to local extinction. In the Gilboa complex the nature of the plantation matrix appears to be masking the species natural responses to fragmentation making it difficult to predict which species are most at risk. In order to preserve maximum bird diversity, including high-risk species, the largest intact forest units (≥302ha) must be conserved. Evidently, the nature of the matrix affects avifaunal diversity and distribution in forest patches, and plantations have the capacity to significantly alter bird assemblage structure and composition in indigenous forest patches. Forest fragments must be considered as integrated parts of a complex landscape mosaic, and this study emphasises the importance of understanding landscape-scale processes. Knowledge of ecological and life history traits proves valuable for predicting community level response to landscape change. / Thesis (M.Sc.)-University of Natal, Pietermaritzburg, 2001.

Thesis (Ph. D.)--University of Hong Kong, 1997. / Includes bibliographical references (leaf 140-163).

No description available.

Thesis (Ph. D.)--Oregon State University, 2008. / Printout. Includes bibliographical references. Also available on the World Wide Web.

Despite intense publicity, habitat loss still remains a serious threat to biodiversity. Forest destruction is its frontrunner, both in terms of physical habitat under threat and potential for biodiversity loss. In the fragmented landscape of the Taita Hills, SE Kenya, several bird species are facing the threat of extinction from forest loss. They are absent from many of the remnant forest patches and/or are showing negative effects with increasing disturbance. Using a relatively common forest-dependent bird species - the whitestarred robin Pogonocichla stellata - as a model, the current status of this ecosystem was examined, and future patterns predicted in view of the unrelenting destruction. As expected, the robin population in the largest and most intact fragment (c35 ha) was the healthiest, suggesting that this was indeed the best quality habitat patch: it had the highest population density, highest productivity (low nest predation and high juvenile to adult ratio) and lowest turnover rates. Effects of forest deterioration were evident from the fact that the medium-sized patch (c95 ha), which is undergoing severe degradation, was a worse habitat for the robin than the tiny patches (c2-8 ha): it had the lowest population density, lowest productivity (highest nest predation rates and lowest juvenile to adult ratio), and highest turnover rates. The explanation for this is twofold. Besides the smallest patches facing lower levels of habitat loss recently, they also had high levels of dispersal between them. They occasionally operated as a finegrained system with individuals moving between them in the space of a few days. In general, the robin metapopulation is demographically (rate of change, λ = 0.996) and genetically (at migration- and mutation-drift equilibrium) stable at present. The populations in the largest and smallest patches were potential sources providing emigrants that were possibly crucial in sustaining the population in the medium-sized patch (given its low productivity and high turnover rates). Overall, these findings underscore the importance of within-patch processes, both for ensuring persistence of subpopulations and providing dispersers, as well as between-patch processes (chiefly dispersal) for ensuring metapopulation persistence. Thus, by furnishing ample sample sizes that enabled work to be carried out in all fragments throughout this landscape, the model species approach was useful for identifying the need for a two-pronged conservation strategy. First, a need to focus within fragments to reduce habitat loss and degradation, and second, to address among fragment issues relating to land-use and maintaining a forested landscape, in order to enhance connectivity between patches. Finally, based on the mechanisms by which disturbance and fragmentation are affecting bird populations e.g. predator influxes from the surrounding matrix, conservation recommendations for the Taita Hills are offered.

Thesis (M.Sc.)--Memorial University of Newfoundland, 1997. / Bibliography: leaves 64-72.

Thesis (doctoral)--Swedish University of Agricultural Sciences, 2006. / Appendix includes reproductions of papers and manuscripts co-written with other authors; abstract of one paper also in Spanish. Includes bibliographical references. Issued also electronically via World Wide Web in PDF format; online version lacks appendix of papers.

Prolific oak regeneration occurred over past centuries from anthropogenic cutting, grazing, and fire, and has declined over the past century due to decreased disturbance. Mesophication within closed-canopy forests of the eastern deciduous region has resulted. Oaks are a keystone species and provide abundant resources for forest wildlife; the ability of late-successional tree species to provide similar resources is relatively understudied. To determine the importance of oak-hickory stands for forest birds, we examined two habitat-selection hypotheses that influence avian abundance and distribution: (1) Habitat heterogeneity (i.e. differences in forest structure) and (2) Availability and distribution of food resources (i.e. index of arthropod biomass). We examined avian response across a gradient of oak-hickory to non-oak tree-species dominance. Non-oak stands were largely dominated by sugar maple, American beech, and yellow poplar (Liriodendron tulipifera). We predicted that migratory breeding-species of concern would respond positively to oak-dominated stands and associated vegetation (e.g. oaks and hickories) because they provide more heterogeneity and likely more food than non-oak stands and associated vegetation (e.g. yellow poplar, maples and beech). We hypothesized that oak and hickory species contain more arthropod biomass and diversity than late-successional species. We conducted breeding bird surveys from 30-April to 15-July 2013-2014 in the Shawnee National Forest, Illinois at 22 study sites. We characterized study sites by dominant canopy vegetation. We used a modified version of the branch-clipping technique to sample arthropods on tree species that represented a gradient of succession. We used generalized linear mixed models to examine differences in arthropod metrics. We estimated detection probabilities for PIF-concern, breeding species and modeled density as response to a priori habitat models using hierarchical distance sampling in R package unmarked. We compared best-fit habitat models for each species with a model of our derived index of food availability (i.e. mean total arthropod biomass (g/m)) for each study site. Habitat heterogeneity was higher in oak-hickory dominated sites. Aerial foragers and foliage gleaners responded predominantly to forest composition and structure, whereas ground foragers responded largely to microhabitat. Density estimates from five of seven species that included percent oak-hickory composition in top models exhibited positive responses. All species that included canopy tree diversity (n=6) in top models responded positively to increasing canopy diversity, and canopy diversity was significantly higher in oak-hickory sites than non-oak sites. Yellow poplar, oak and hickory species yielded more total arthropod biomass (g/m), Lepidopteran biomass (g/m), and guild diversity and richness than late-successional beech and maples. Heterogeneity and food biomass both influenced avian abundance of aerial foragers and foliage gleaners. Our results imply that oak-hickory stands are ecologically important for migratory forest birds of concern because heterogeneity and food resources increase as oak-hickory canopy composition increases. Oak regeneration is a challenging process to manage because oaks require frequent disturbance to achieve the high levels of light needed by this genus. Therefore, it may be beneficial to manage stands for yellow poplar dominance because this species grows rapidly. Moreover, our results suggest that yellow poplar yields comparable and higher estimates of arthropod biomass and diversity on hickories and oaks, respectively. However, foraging opportunities are likely restricted on yellow poplar because of limited structure, attributed to excurrent branching.

A five-year study was carried out to test a sensitive, nondestructive, new method for determining sublethal and long-term consequences of fenitrothion applications on forest songbirds. I used censuses and territory mapping of singing males to provide indices of relative abundance on sprayed and control plots. Mist-netting was used to colour-band individuals of 3 indicator species (the chestnut-sided warbler, magnolia warbler and white-throated sparrow), to determine "their breeding condition, and to follow their fates after a fenitrothion application. Time-budget observations were made of the behaviour of some marked individuals. Fenitrothion was applied aerially in 1985, and by ground in 1986. I first studied the effect of fenitrothion on the songbird community; comparing treatment and control plots, before and after the application. Data on the bird populations showed that fewer young were caught in 1985, and birds returned at a lower rate the year following treatment; a lower proportion of the 1986 catch in mist nets were males. Nonetheless, other factors (budworm cycles, for example) had a greater influence on population trends than the treatment. Behavioural observations indicated that individuals of the 3 indicator species did not abandon the treated area after either application, although white-throated sparrows and magnolia warblers moved away from foliage regions with higher deposits of spray. There was no significant change in the allotment of time to social, maintenance, or feeding behaviours, for any of the indicator species. This observation is not consistent with the known symptoms of organophosphate poisoning (i.e. increased time spent sitting, bill-wiping, and preening). Chestnut-sided warblers and white-throated sparrows continued to forage actively on sprayed plots or nearby. Magnolia warblers decreased their foraging effort after both applications. In part 2 of the thesis, I studied the effect of fenitrothion on the invertebrate food of forest songbirds. Branch samples were taken as a measure of the food available to foliage-gleaning birds. Drop trays were placed under sample trees to measure the amount of food fallen from the tree after the application. Following treatment, there was a lower density of invertebrates on white birch and balsam fir branches than on control trees. This reduction was not observed until 5 days after the application, although drop tray samples indicated an immediate kill of invertebrates. These techniques sampled different types of invertebrates such that a large proportion of the drop tray samples were not associated with the tree (eg. flying Diptera). In addition to a decreased abundance, a large portion of the remaining invertebrates on white birch treated trees were dead. This suggests a further decrease in food availability to birds like warblers that specialize on moving prey. The depression of food available to birds was probably short-lived, assuming movement of invertebrates into depopulated areas from unsprayed foliage nearby. Behavioural responses of birds to spraying were also short-lived, apparent only within 5 days of the application. At the maximum allowable single dose, fenitrothion appears to have little effect on forest songbirds, even when tested with a highly-sensitive method. / Science, Faculty of / Zoology, Department of / Graduate

Abstract not available