This thesis investigates the ecology, taxonomic affinities and conservation management in Sierra Leone of a threatened West African forest bird, the White-necked Picathartes Picathartes gymnocephalus, which has not been previously studied in detail. The incubation and nestling periods (20 and 25 days) respectively were longer than is usual for most tropical passerines. In most cases, one clutch of two eggs was laid between June and December, immediately followed by moult between January and May (the dry season). Peaks in egg laying occurred 1-2 months after the maximum monthly rainfall. Both parents cared for the young and fed nestlings disproportionately more earthworms, frogs, millipedes and earwigs in relation to their abundance in the environment. Nestlings fledged when still as much as 30% below adult size. Food abundance peaked in both forest and farmbush (forest regrowth) habitat at the start of the wet season and in the early part of the dry season; coinciding with the period immediately prior to egg-laying and with dispersing fledglings respectively. Potential Picathartes prey were more abundant in farmbush than forest habitat. The proportion of eggs laid that resulted in fledged young was 22.9% and productivity was 0.22 chicks per adult. Nest predation was the main cause of nest failure but infanticidal behaviour played a significant role. A substantial number of non-breeding birds were apparently present in populations and infanticidal behaviour may have been a consequence of competition for limited nest sites. Population density was estimated as 0.37 individuals km-' and the total population in Sierra Leone as about 1100. Local populations in forest reserves are close to the theoretical minimum for long-term viability in all cases but populations are apparently stable or declining only very slowly. Abandonment of colonies was associated with habitat degradation but there was also evidence that Picathartes may be fairly tolerant to disturbance in some areas. Phylogenetic analysis using mitochondrial DNA of the cytochrome b gene suggests that Picathartes is more closely related to the thrush-babbler assemblage than the crows.

published_or_final_version / Ecology and Biodiversity / Doctoral / Doctor of Philosophy

Abstract I studied the structure of European breeding forest bird communities on several spatial scales focusing on heterospecific attraction among birds (i.e., the attraction of individuals to the company of interspecifics). Namely, I examined how heterospecific attraction affects habitat selection in migrant birds and the potential role of predation risk in enhancing heterospecific attraction during breeding with particular emphasis regarding the interaction between resident and migrant birds. Geographically, low densities and low relative proportions of resident titmice (Parus and Aegithalos spp.) were associated with harsh winter conditions. The densities of northern European titmice populations are suggested to be lower than expected on the basis of summer productivity potentially causing geographical variation with respect to the interactions between resident and migrant birds. As expected, the associations between titmice and migrants appear stronger and more positive in northern Europe than elsewhere. Heterospecific attraction in habitat selection among migrant species was studied both experimentally and theoretically. An increased density of titmice resulted in a higher number and abundance of migrant species than the removal treatment, suggesting that resident birds are used as cues for locating profitable breeding sites. From a theoretical perspective and under most conditions, the use of heterospecific cues proved to be a better habitat selection strategy than selection of sites based on direct assessment of the relative quality of habitat patches. Only when interactions (both positive and negative) between migrants and residents were weak and sampling costs of both strategies were about equivalent, did individuals using direct sampling gain in fitness. Heterospecific attraction during breeding in relation to predation risk was assessed by examining the spatial distribution of birds. Both experimentally increased perceived predation risk and naturally occurring predation risk created by the presence of sparrowhawk (Accipiter nisus) i.e., relative to the vicinity of nesting hawk, resulted in more clumped distribution of birds than areas of lower risk. Around sparrowhawks nest, however, clumping was apparent for only one forest type and only among study plots including both large (≥ 20 g, preferred prey) and small birds (< 20 g). To conclude, heterospecific attraction of migrants to resident birds contributes to the structure of local avian communities in forest landscapes. Heterospecific attraction among birds is strengthened by increased predation risk causing variation in species interactions when considered in a landscape perspective.

Considering the high rate of endemism in Madagascan organisms, which are mostly restricted to forest ecosystems, and the accelerating rate of deforestation affecting the island, it is critical to understand the effects of forest fragmentation on Malagasy biota to allow for better management of species within ecosystems. Ecological and human-induced changes have led to the disappearance of forest from vast areas of the island, including on the central High Plateau. The Ambohitantely Special Reserve, located on the central High Plateau at 1500 m asl, was selected as the study site for research on the effects of forest fragmentation on forestependent bird species in Madagascar. The Ambohitantely special Reserve covers 5600 ha of which 50% are natural forest, 35% are anthropogenic grassland savannah and 15% are exotic plantations. The forest, described as East Malagasy moist montane forest, is 2737 ha in area, of which 1487 ha are comprised of 513 forest fragments scattered around the largest block totalling 1250 ha. To investigate the effects of forest fragmentation on forest-dependent bird species, seven forest fragments were selected, ranging from 0.64 ha to 136 ha, in addition to the largest block, referred to as the control site. The bird species composition and relative abundance in different-sized fragments were assessed in reference to the control site, by using a combination of two standardized sampling methods: mistnetting and point-counts. A total of 1804 mistnet-days were accrued, 1026 in the control site and 778 in the seven forest fragments, leading to the capture of 491 birds of 26 species. A total of 160 point-counts was made at 39 different sample plots totalling 53 h 29 min of censusing, and a record of 30 species. A total of 72 bird species including 54 breeding forest affinities of the avifauna of Ambohitantely were defined with reference to 32 forest sites scattered across Madagascar. The species composition in all fragments are fully nested subsets of the control site and the species distribution in the fragments does not represent random subsets of the control site. The analysis of the bird communities in different size fragments indicates that the occurrence of bird species reflects a regular pattern of species extinction in relation to decreasing size of forest fragment. Species composition is discussed in reference to Ambohitantely's long history of isolation that may have led to extirpation of bird species from this site. The higher bird taxa decrease in number or totally disappear as a result of their ecological specialization. Equally, they are the most affected by edge effects (e. g. Atelornis pittoides). The main ecological trends in disappearance or extinction of species is a decrease in the number of small-bodied insectivorous understorey species and mid- and upper-stratum small-bodied insectivorous and nectarivorous species. Insectivorous species are particularly affected by forest fragmentation and three forest-dependent species found in Ambohitantely Forest are particularly sensitive to forest fragmentation: Newtonia amphichroa, Calicalicus madagascariensis, and Cyanolanius madagascarinus. The biological (flora species composition and forest structure) and the physical (temperature, moisture, and light) changes generated by the fragmentation of the forest have a greater impact on highly specialized foraging guilds and this explains the pattern of current bird species composition in Ambohitantely Forest. The influence of forest fragmentation on the altitudinal migration process is debated and conservation measures such as the establishment of forest corridors are proposed to improve the protection of biota found in the Ambohitantely Special Reserve. / Thesis (M.Sc.)-University of Natal, Pietermaritzburg, 1995.

I examined impacts of thinning on bird population densities and habitat use in Appalachian mixed-hardwood forests during 1984 and 1985 at three thinned and three unthinned stands in the Jefferson National Forest, southwestern Virginia. Densities of shrubs, saplings, trees, and snags, canopy and ground cover, and foliage volume were the structural variables most influenced by thinning. Populations of shrub/understory birds were higher in thinned stands than unthinned stands. Canopy-dwelling species showed variable population responses to thinning. Habitat use similarities were used to group 13 bird species into three categories: (1) shrub/conifer species included the tufted titmouse, blue-gray gnatcatcher, wood thrush, ovenbird, and hooded warbler, (2) generalist species included the eastern wood-pewee, red-eyed vireo, black-and-white warbler, and scarlet tanager, and (3) mature/deciduous species included the white-breasted nuthatch, solitary vireo, blackburnian warbler, and worm-eating warbler. Shrub, snag, and conifer density and ground cover were the four habitat variables most important in separating used from unused sites. Foraging behavior and resource use of seven bird species were examined in two thinned and two unthinned stands. No differences in foraging methods or niche breadth were found between the stands for all species. Differences in foraging and tree heights were due to tree height differences between the stands. For most species, foraging resource use was equal to availability. Short, small diameter trees were rarely used. Oaks were used most often, and red maple and conifers were rarely used for foraging. The opportunistic nature of avian foraging behavior and the vegetative differences between thinned and unthinned stands led to the foraging differences noted. / Master of Science

The breeding behaviour of the Blue-throated Bee-eater was studied at two colonies in Peninsula Malaysia during 3 breeding seasons, with particular emphasis on pair behaviour, mixed reproductive strategies and nestling competition. This is the first study of vertebrate social behaviour and ecology to contain the documentation of a relational database. This was designed to store and manipulate all data obtained from regular captures and biometric measurements of adults and nestlings and from observations of adults. DNA fingerprinting was used to establish the true genetic relationships between nestlings and their social parents: most nestlings were genetic offspring (72%). Nestlings were classified as illegitimate offspring using 95% confidence intervals of the band sharing coefficient and number of unexplained nestling bands as criteria. Very few if any nestlings were sired by an extra-pair male (fewer than 5%). Behavioural evidence of strong cooperation between pair members throughout the breeding season supports the DNA fingerprinting results of no confirmed case of offspring fathered by extra-pair males (extra-pair offspring; EPO). The Blue-throated Bee-eater probably has a near monogamous mating system. Most illegitimate nestlings had been 'dumped'. They were either the result of intra-specific nest parasitism (INP; 7%) or of 'quasi' parasitism (the offspring of the pair-male and an extra-pair female; 7-12%). INP by relatives of the hosts could have explained some intermediate band sharing coefficients. Anti-INP behaviour was demonstrated when experimentally 'dumped' eggs were almost always expelled before the onset of laying, but never afterwards. DNA fingerprinting showed that relatives may roost together and that related males may nest close together. Compared with other colonial Bee-eaters, M. viridis had low levels of helping-at-the-nest and EPO, but similar or higher levels of INP. The high nestling mortality in Blue-throated Bee-eaters was explained by a combination of three hypotheses, some of which were tested by experiment. (1) Insurance: extra-eggs are needed to counter hatch failure. (2) Brood reduction (including resource tracking): in times of food constraint, the laterhatched nestlings in asynchrously hatched broods starve. (3) Anti-INP hypothesis: these later-hatched nestlings are eliminated because they are likely to be illegitimate. Hatching failure was about 1 in 3 eggs overall. Help from the male allows an early onset of incubation which results in asynchronous hatching. Nestling hunger was shown to be a proximate factor affecting runt mortality both directly through competition and indirectly through nestling aggression. The demise of runts was delayed when conditions improved. Blue-throated Bee-eater broods are severely limited by food. Under this severe brood size constraint, breeding females may increase reproductive output by 'dumping' their last egg. This leads to the high frequency of INP observed in Blue-throated Bee-eaters. An early onset of incubation also gives the first-laid egg(s) a temporal developmental advantage over subsequently 'dumped' parasitic eggs. The 'dumped' nestlings are eliminated by starvation and siblicide, which may itself be an adaptation to INP to eliminate of unrelated nestlings.

Thesis (M.S.)--Southern Oregon University, 2005. / "A thesis submitted to ... Southern Oregon University in partial fulfillment of the requirements for the degree of Master of Science ..." Includes bibliographical references (leaves 70-73). Also available via Internet as PDF file through Southern Oregon Digital Archives: http://soda.sou.edu. Search Bioregion Collection.

Thesis (Ph.D.) in Wildlife Ecology--University of Maine, 2003. / Includes vita. Includes bibliographical references (leaves 103-110).

No description available.

Forest birds located by their calls were related to mapping units of different land resource maps using a new method. The method involved computer programs which use mathematical descriptions of landform, forest canopy heights, and the nature of the bird's call to predict the area censused for each bird species from each listening station. Computer programs were also used to display locations made from each station, and to associate the locations and areas censused with different mapping units. Yellow-bellied Sapsucker (Sphyrapicus varius), Chestnut-backed Chickadee (Parus rufeseens), Steller's Jay (Cyanocitta stelleri), Winter Wren (Troglodytes troglodytes), Varied Thrush (Ixoreus naevius), and Swainson's Thrush (hylocichla ustulata) were each related to both serai stages and vegetation taxonomic units; while Hairy Woodpecker (Dendrpcopus villosus), Common Flicker (Colaptes cafer), Red-breasted Nuthatch (Sitta canadensis), and Olive-sided Flycatcher (Nuttallornis borealis) were each related only to seral stages. Most species showed a consistent pattern of selection for mapping types with repeated census. Results for the Steller's Jay indicated some change in the use of seral stages between census periods. However, there was no clear trend in use over time, and the observed changes may include effects of flocking which would violate the statistical assumption that locations were independent. Each species had a unique pattern of selection of seral stages and of vegetation types. Species with similar patterns of selection were grouped to form five groups for seral stages and three groups for vegetation types (groups not mutually exclusive). Only Chestnut-backed Chickadee with Yellow-bellied Sapsucker, Swainson's Thrush with Winter Wren, and Varied Thrush with Winter Wren were grouped together both for seral stages and for vegetation types. A more definite preference among seral stages than vegetation types was detected for most of the species studied. However, the Steller's Jay preferred only two of the vegetation types, while it used all seral stages somewhat equally. Most of the species studied preferred older seral stages. Common Flicker, Steller's Jay, and Olive-sided Flycatcher also used younger stages; while Swainson's Thrush selected for stages of medium age. Of the species related to vegetation types, only Chestnut-backed Chickadee did not show some preference for taxonomic units associated with high soil moisture. The preference was most pronounced for Steller's Jay, which concentrated its use on the two wettest types. The preference by Yellow-bellied Sapsucker may be explained by the older trees and snags that survived logging and fire in wet areas. All of the species also used many of the drier types. The data support the hypothesis that land resource maps can be used to predict the occurrence of wildlife. The results suggest that habitat for a wildlife species can be predicted over vast areas if the areas have been mapped, and if significant differences in the habitat value of different mapping units have been documented. The results indicate that the prediction can be improved by combining the predictions from two or more maps. The predicted area and spatial distribution of high-quality habitat can be compared with management policy objectives for the wildlife species. The predicted change in available habitat with planned forest management activities can provide criteria for habitat management. The same land resource maps may be used for many wildlife species, thereby facilitating multi-species habitat management. / Forestry, Faculty of / Graduate