The world's biodiversity is concentrated in tropical ecosystems, yet tropical forests are being converted for agriculture at a rapid rate. I evaluated the potential of an alternative coffee production system known as Integrated Open Canopy (IOC) to contribute to avian conservation. This study was conducted from 2005-2010 in the Cordillera de Tilarán, Costa Rica. My results indicate that species richness of forest-dependent birds was higher in IOC farms than in shade coffee farms, and was comparable to secondary forest sites. There was no difference in species richness of Neotropical-Nearctic migrants between IOC and shade coffee farms. Overall similarity was higher between IOC farms and primary forest than between shade coffee farms and primary forest. he golden-winged warbler Vermivora chrysoptera is a declining Neotropical-Nearctic migrant bird, yet little is known about its non-breeding season ecology and demographics. I found that golden-winged warbler abundance was highest at intermediate precipitation levels found at middle elevations (1000-1200 m) of the Pacific slope, but they were absent from the dry forests at lower elevations on the Pacific slope. Abundance peaked in forests with canopy heights of 22 m, and was positively related to the quantity of hanging dead leaves. Radio-telemetry data indicated that golden-winged warblers used microhabitat features characteristic of disturbance more frequently than expected by chance. Selection of these microhabitat features was related to their highly specialized dead-leaf foraging behavior, which may also have contributed to their high degrees of site fidelity, mixed-species flock attendance, and territoriality. These behaviors have important conservation implications because they constrain density, and thus could affect carrying capacity. Population dynamics were characterized by estimating plot-level and individual-level apparent survival and recruitment rates within and among non-breeding seasons. Both levels of analysis suggested that recruitment was too low to offset mortalities within this study area. This study indicates that increasing forest cover in tropical agricultural landscapes may be the most effective way of providing habitat for bird species of high conservation concern, including the golden-winged warbler. Integrated open canopy coffee production is one option for achieving this goal because it provides a financial incentive to protect or restore forest.

Montane forests provide habitat for unique assemblages of flora and fauna that contribute significantly to a region’s biodiversity. Previous work indicates that montane forest ecosystems are exceedingly vulnerable to a host of anthropogenic stressors including climate change, atmospheric deposition, and recreation, to name a few. Montane forests and other high elevation ecosystems are considered to be among the first and most severely impacted by climate change. It is therefore, imperative to evaluate anthropogenic impacts on montane ecosystems and maintain reliable monitoring methods that are capable of tracking potential shifts in the distribution of species dependent on these systems. I surveyed birds at various distances from hiking trails in the White Mountain National Forest from 2006 - 2009 to determine whether existing monitoring programs, all of which are based on trail-centered surveys, are accurately reflecting bird abundance, abundance stability and recruitment. Contrary to previous studies, I found that recreational trails generally did not alter estimates of abundance, recruitment, abundance stability, and detection probability for five species of birds considered to be indicators of montane forest ecosystem integrity in northeastern North America. Therefore, trail-based monitoring programs for montane birds appear to accurately reflect dynamics of bird communities undisturbed by hiking trails. These conclusions were supported by my finding that the daily nest survival of a montane spruce-fir indicator species, blackpoll warbler (Steophaga striata), did not vary as a function of distance from trail. I then used data from the White Mountain National Forest’s montane bird monitoring program from 1994 through 2009 to assess potential shifts in the elevational distribution of montane birds in conjunction with documented habitat shifts in the region. My results provide evidence that low elevation forest birds have expanded their upper elevational boundary while high elevation birds have expanded their lower elevation boundary. These results highlight the complicated relationship between habitat, climate, and other anthropogenic stressors such as atmospheric deposition and that even in the face of climate change other stressors may be playing a significant role in shifts of species distributions. Understanding how climate affects the reproductive ecology of montane organisms is an important step toward unraveling the potential mechanisms by which climate change will alter the distribution of these species. I used blackpoll warbler breeding data from the Green Mountains, VT from 1994 to 2003 to determine if temporal variation in climate influenced blackpoll nesting initiation and found that years with warm Mays and typical precipitation lead to earlier nest initiation. I also examined the effect of spatial variation in climate on blackpoll reproductive ecology and demography. I found a gradient in habitat quality associated with the spatial variation in climate along an elevation gradient. Blackpolls were less abundant, younger, had lower pairing success, lower daily nest survival, higher nest predator occupancy, and lower fecundity at lower elevations. The climatic conditions at these lower elevations represent the climatic conditions predicted to encompass increasingly larger portions of montane areas. Collectively, these findings contribute to filling in a dearth of knowledge regarding management and an understanding of how species dependent on montane ecosystems are responding to climate change.

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Blackburnian Warblers (Dendroica fusca) were observed in their wintering grounds in a High Andean native secondary forest in Colombia between September 1993 and May 1994. The main objective of the study was to determine the relationships between the Blackburnian Warblers and the habitats where they were found. Size and composition of the mixed-species flocks joined by Blackburnian Warblers were also compared to habitat features. Habitat variables were measured in circular plots centered where a Blackburnian Warbler was first seen. The same set of variables was measured in randomly located paired plots to compare the two sets. The results obtained in Colombia (wintering grounds) were compared to similar data available from North America (breeding grounds). Ninety-six mixed-species flocks with Blackburnian Warblers were detected. Some of the habitat variables measured differed between plots used by the birds and the random plots. Density of trees in all dbh (diameter at breast height) categories, density of snags and density of native trees and shrubs were higher at the bird-centered plots. Percentage vegetation density (understory foliage volume) from O-1m, 1-2m and 2-3m were lower at bird-centered plots. There was no significant difference for maximum and mean canopy height between bird-centered and randomly selected paired plots. At Los Amarillos, Blackburnian Warblers avoided Eucalyptus spp. trees. They preferred the higher part of the trees and trees in the middle and high abh classes. They avoided the smallest dbh size class (3-8cm dbh). Comparisons were made between the data from Los Amarillos and data available from northern central Minnesota (Collins et al. 1982). Percent ground cover, densities of trees 15.1-23, 23.1-38 and 38.1-53 cm dbh and total density of trees were significantly higher in Minnesota. Trees 7.5- 15, 53.1-68 and > 68.1 cm dbh were higher in Los Amarillos. Percent canopy cover was not different between the two Sites. Blackburnian Warblers selected for closed canopy cover (about 75%) and large trees in each individual site. They selected larger trees in Minnesota. This selection may be related to nesting requirements of the species. / Master of Science

7 Abstract Bird nests protect eggs and nestlings, allowing the parents to leave their offspring and subsequently return to them. Their thermoregulatory properties reduce energetic costs of incubation and brooding of nestlings. For all these reasons, nests are key structures for the reproduction of a majority of avian species and as such they should be subject to natural selection. Several hypotheses describing selection pressures which affect the size of nests or some of their parts have been suggested. In my PhD thesis, I investigated some of them in the great reed warbler (Acrocephalus arundinaceus) - an open nesting passerine species with very variable nest size. For this purpose, I used a large dataset of several hundred measured great reed warbler nests, nest enlargement experiments and an experiment with artificial nests. In accordance with previous studies, we did not find that nest size affects the probability of common cuckoo (Cuculus canorus) brood parasitism, while it was influenced by other factors, such as timing of breeding, reed density around the nest and nest visibility from the nearest potential cuckoo perch site. More interestingly, we found that cuckoos adjust their nest-searching strategy in relation to availability of host nests. When host nests were scarce, cuckoos parasitized all of...

Recent global climate change is influencing the behaviour and ecology of species worldwide. Birds are typical systems to study in this context, as they are often migratory and thus subjected to a variety of environmental effects. This thesis employs the use of long-term ringing records, field observations, historical maps and historical volunteer observations with the aim of describing behavioural and ecological responses of birds to the current environmental change. An investigation into the spring arrival, reproduction and autumn departure in willow warblers (Phylloscopus trochilus) breeding at a southern study site in Sweden (65°N 18°E) showed that all three phenological events had advanced in parallel. Thus birds arrive earlier, start breeding earlier and leave Sweden earlier, with the breeding period staying the same in length. By teasing apart the migratory responses of different individuals, it became clear that particularly early arriving males and early departing juveniles had advanced migration. However, willow warblers migrating past a northern study site in Sweden (65°N 23°E) displayed no change in autumn departure. When migration in the two regionally separate populations were analyzed in relation to climatic variables, the results indicated that foremost a combined effect of growing season onset and the North Atlantic Oscillation influenced migratory timing, and only in individuals that had advanced migration. As growing season onset had advanced at both regions, but only elicited migratory change in southern willow warblers, it is proposed that intra-specific difference between populations prepare them differently to climate change. Willow warblers breeding at northern latitudes were also displaying absence of an otherwise common behaviour of the species: philopatry. It is suggested that the climate induced change in onset of the growing season, coupled with an increase in available territories, could have enabled a southern influx of dispersal-prone birds adopting a less philopatric breeding behaviour. Availability of territories was also studied in southern Sweden, in relation to 100 years of land use change and future climate change effects on forestry. The mass-conversion of grazed forest into coniferous sylvicultures that has occurred in Sweden 1900-2013 was shown to have negatively affected territory availability for willow warblers. The second most common bird species in Sweden, the chaffinch (Fringilla coelebs), was however shown to be largely unaffected. In a future scenario where rising temperatures will increase growth rates of trees, harvest rotation will be faster and both sylvicultures and logged areas will increase in coverage, favouring both species. Thus commonness in terms of landscape and species occurrence has altered historically and is dynamically linked. Historic perspectives were also applied to observations of spring arrival of 14 migratory bird species. A relative comparison of two data sets, collected over 140 years, revealed that short-distance migrants have changed their spring arrival more than long-distance migrants in southern Sweden. In conclusion, the results of this thesis provide insights into climate change effects on avian behaviour and ecology, document unique observations and contribute with a great spectrum of knowledge, from exact details on responses by individual birds, through long-term changes in populations to historical perspectives on shifts in entire landscapes / <p>At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 2: Manuscript. Paper 3: Manuscript. Paper 4: Manuscript.</p>