A comparative study of breeding ecology in Parakeet Auklets (Cychlorrhynchus psittacula (Pallas)), Crested Auklets (Aethia cristatella (Pallas)), and Least Auklets (A. pusilla (Pallas)) was conducted on St. Lawrence Island, Alaska, in 1966 and 1967. Emphasis was placed upon the climatic conditions which prevailed throughout the breeding seasons and their effects on timing of breeding in auklets. The pre-egg stage, egg-laying and incubation, hatching, growth of young, and departure of chicks were studied in both seasons; 1966 was a late year and 1967 was an early year. It was found that (1) Parakeet Auklets appear to have a more extensive migration than Aethia spp. , (2) arrival of adults back on the breeding grounds in spring occurs at approximately mid-May each year, (3) the pre-egg stage is prolonged but the post-breeding dispersal of adults and young from the nesting slope is rapid, (4) breeding does not take place at the same time each year, (5) Cychlorrhynchus breeds a few days later than Aethia spp., (6) a change in diet accompanies the onset of the chick-rearing period in Aethia spp. but not in Cychlorrhynchus, (7) patterns and rates of growth of A. pusilla chicks and possibly chicks of Cychlorrhynchus and A. cristatella differ according to time of hatching, (8) chicks of these auklets are well-adapted to early life, (9) predation upon auklets is low in the Sevuokuk colony, and (10) molt of adults overlaps the breeding effort in Aethia spp. but not in Cychlorrhynchus. Ecological and behavioral specializations in the annual cycles of these auklets revealed close synchronization and shortening of breeding events necessary for breeding in the short Arctic summer. It appears that these auklets are faced with two problems in timing their breeding cycles. Breeding must take place within a period which is largely dictated by climate and they must make best use of the food supply. / Science, Faculty of / Zoology, Department of / Graduate

Male and female Papilio glaucus were released in pairs in a flight cage to study courtship behavior and mate choice. The study was designed to test the hypothesis that females select the natural color pattern, an important aspect of the theory of the evolution of mimicry. Males were unpainted or were painted either yellow as a control or black to resemble a newly arisen mimetic pattern. Painted males were permitted three courtships to achieve a mating. Failure to mate was followed by the release of the other color of male to the same female. The courtship flight was divided into four stages for analysis of sexual selection. Females directed solicitation flights more often to natural color than to black males, and these solicitation flights increased the number of interactions and courtships by males. Naturally colored males were rejected less frequently than the black ones in the early stages of courtship. Once the later stages were attained, there was no difference. The higher mating success and increased female solicitation which favored the yellow painted males over color-altered ones suggest that female-limited mimicry in P. glaucus is the result of selection by females for the non-mimetic pattern. / M.S.

The high northern latitudes of North America are undergoing rapid climatic change with acute impacts to the ecosystems in which millions of songbirds breed each year. The goal of this dissertation is to improve understanding of how concurrent and interacting changes in environmental and land surface conditions influence annual movements and habitat selections of long distance migratory birds who must navigate the mosaic of changing North American ecosystems. Chapter 1 presents novel automated bioacoustic methods for estimating arrival dates of the songbird community to their arctic breeding grounds. Automated acoustic networks could vastly expand the spatiotemporal coverage of wildlife observations. However, the enormous datasets that autonomous recorders typically generate demand automated analyses that remain largely undeveloped. Chapter 1 demonstrates novel machine learning and signal processing techniques for estimating songbird community arrival dates near Toolik Field Station which agreed well with traditional survey estimates and were strongly related to the landscape’s snow free dates. Daily variations in vocal activity were more strongly influenced by environmental conditions prior to egg-laying dates. The success of the approaches presented in Chapter 1 indicate that variation in songbird migratory arrival can be detected autonomously. Widespread deployment of this advance could provide avian monitoring on a scale large enough to enable global-scale understanding of how climate change influences migratory timing of avian species. Chapter 2 examines potential future changes in habitat suitability for for two songbirds breeding throughout North America’s high northern latitudes – a tundra-nesting species (Lapland Longspurs (Calcarius lapponicus)) and a shrub-nesting species (White-crowned Sparrows (Zonotrichia leucophyrs)). By the late 21st century, models based on both climate and vegetation projected habitat suitability for Lapland Longspurs decreased across nearly all of the study domain (54-96%), while that for White-crowned Sparrows decreased in 69% of North America’s high northern latitudes. For both species, currently unsuitable habitats in northern Canada and Alaska are projected to provide suitable breeding habitat in the future. In contrast, models based solely on climate showed more drastic declines in habitat suitability for both species (Lapland Longspur, ~100% and White-crowned Sparrow ~80%). This discrepancy between model projections demonstrates that the future availability of suitable songbird breeding habitat for both species will be strongly dependent on how both the vegetation and climate– as opposed to climate alone - of northern ecosystems respond to ongoing climate change. Chapter 3 investigates the environmental and ecological drivers of migratory movements of songbirds breeding at high northern latitudes. For North America alone, there is overwhelming evidence of major shifts in seasonality of meteorological conditions, snow cover, and vegetation phenology. Few studies have focused on how this suite of changes impacts long distance migratory species that annually navigate throughout the spatially and temporally dynamic mosaic of ecosystems because of technological constraints in animal tracking. However, recent advances in GPS technology have generated units small enough to be placed on songbird species. In 2016-2018 a total of 55 American robins (Turdus migratorius) were tracked during their spring migration through the Canadian boreal forest en route to their breeding grounds. We found a significant trend towards earlier arrival of robins to the Canadian boreal forest over the past quarter-century, consistent with advances in spring environmental conditions. Robin stopover timing at our tagging site was delayed in response to later seasonal snowmelt, but triggered by adverse environmental conditions. Individuals breeding in regions with shorter snow-free seasons moved faster than individuals breeding in areas with longer snow-free seasons and selected locations with less favorable environmental conditions. Overall, arrival timing to breeding grounds was negatively related to snow depth and positively related to snowmelt timing. Migratory movements and timing of American robins are highly tied to seasonal environmental dynamics en route to their breeding grounds. Our findings present a unique, mechanistic understanding of how migratory birds navigate highly dynamic ecosystems. In light of rapid global change, the use of multi-disciplinary, spatially explicit approaches similar to the ones used in this dissertation will be critical for understanding how avian taxa breeding at high northern latitudes may respond to ongoing and future change. This is important for investigating both regional and global impacts because species breeding in arctic-boreal zones perform key ecosystem services around the globe.

No description available.

Lanner Falcons Falco biarmicus are the commonest large falcons in Africa and this study in the coastal area of the Eastern Cape Province, South Africa investigated their ecology from 1984 to 2000. Lanners have recently been categorised as near-threatened and this study was initiated to ascertain if the population was stable. Breeding success of a small population, in different habitat types, was monitored intensively from 1997 to 2000, and the factors that inhibited breeding were investigated. The earliest onset of incubation was 17 July and the latest 16 August, with 2.2 young fledged per breeding pair over the four-year period. Incubation lasted 32 days and young fledged after 42-45 days. All nest sites were on cliffs with a mean height of 114 m, a mean vertical face of 53 m; 45% of the nests were in ravens’ nests. The aspect of cliff sites also influenced breeding success. Radio tracking was used to determine home range, habitat use and hunting methods, with prey species identified. Home ranges were between 66 km² and 249 km². Preferred prey was domestic chickens, pigeons and small birds during the breeding season. Foraging ranges were smaller in intensively cultivated areas with seed crops. Data obtained from ringing returns showed that no long distance movements occurred in this region, but two juveniles dispersed 152 km and 127 km. Conservation aspects with possible threats to Lanner Falcons such as poisons, electrocutions and direct persecution are discussed with some recommendations made for future research. Evidence from this study indicates that Lanner breeding success is not limited by nest site availability, but by rainfall timing and prey availability. Lanners foraged more in open areas than areas with tall vegetation, and benefited from intensive agriculture. This population appeared to be healthy and in no danger of declining in the near future.

Sociality represents one of the major evolutionary transitions in life: a transition from individuality to societies as complex as our own. Animals exhibit a wide variety of societies, from temporary aggregations, such as schools of fish, to complex organizations where individuals maintain stable relationships, such as cooperative groups in birds, mammals, and eusocial ants. However, the diversity of social systems and the mechanisms driving the formation of complex societies remain unclear. In this dissertation, I aim to understand a less known complex social system, a colonial cooperatively breeding bird on the African savannah, grey-capped social weavers (Pseudonigrita arnaudi). I monitored daytime and nighttime relationships among more than 600 birds in over 100 colonies across three subpopulations for five breeding seasons using an auto-tracking system. In Chapter 1, I examine the social organization of this species and test the role of kinship in the organization of the society. In Chapter 2, I focus on the inter-annual variation in the fission-fusion process of colonies and test how social factors (i.e., group membership and colony membership) and ecological conditions (i.e., rainfall) may underlie individual and group decisions about settlement of colonies. In Chapter 3, I investigate the conflict in the form of infanticide behavior (i.e., egg tossing) in this social system and test nest predation as an alternative hypothesis against a presumed hypothesis that group conflict is the cause of the tossing behavior. In sum, my dissertation provides the first detailed study of a colonial and cooperatively breeding bird with high resolution of movement at the individual level. Understanding a new social system will not only expand our knowledge of the variety of animal societies, but will also give insight into how social complexity has evolved, including our own.

The lack of suitable nest sites may be a limiting factor for Western Bluebird populations inhabiting the upper Willamette Valley. Nest box trails have been established on the hills surrounding the Portland metropolitan area. Since their placement, approximately 25% of the boxes available have been used by Western Bluebirds as nest cavities. This study was undertaken to identify factors which might determine the selection of a nest box by Western Bluebirds and the subsequent nest success or failure. The breeding biology of Western Bluebirds using the nest box trail located on Parrett Mountain, Oregon in 1979 was investigated. Breeding season, mean clutch size, average incubation and nestling periods, and level of nest success were determined. Nest box dimensions, placement, and surrounding habitat features were quantified. Potentially important nest site characteristics were examined and tested for association with Western Bluebird nest box use and reproductive success. Western Bluebird nest box selection was random with regard to all of the characteristics studied except Solar Index and Nest Box Density. No correlation was seen between nest box characteristics and bluebird nest success.

Cooperatively breeding societies, in which one or more non-parental individuals (“alloparents”) care for young alongside the parents, show considerable variation in social structure. Traditionally, such societies have been thought to comprise small, kin-based family groups where offspring from previous broods delay dispersal and help raise closely-related offspring to gain indirect fitness benefits when independent breeding opportunities are unavailable or yield lower fitness outcomes. However, genetic evidence is increasingly revealing cooperatively breeding species whose social groups comprise unrelated individuals as co-breeders or alloparents or both (for e.g., 45% of all avian cooperative breeders). Such social groups exhibit complexity in social structure such as large group size, multiple breeders, and low and varied group kin structure. To understand why such complex societies form and how are they maintained when the opportunity to gain indirect benefits via kin selection is low and variable, I investigated the direct and indirect benefits driving a key demographic process, dispersal, and the resulting variation in group social structure on the individual, group, and population levels in an obligate, avian cooperative breeder, the superb starling (Lamprotornis superbus). I used a combination of long-term, individual-level data spanning 15 years from nine groups monitored at the Mpala Research Centre in Kenya and fine-scale genetic and environmental data sampled across 22 social groups that included the long-term study population. In Chapter 1, I show that (i) dispersal decisions in superb starling males are driven by temporal environmental variation experienced by their parents pre-laying, (ii) both dispersal and philopatry result in equivalent lifetime inclusive fitness outcomes, and (iii) oscillating selection due to high temporal variability in the environment likely maintains the two alternative dispersal tactics, resulting in the formation of mixed-kin groups. In Chapter 2, I show that (i) immigrants are vital to the stability of superb starling social groups in light of low and variable offspring recruitment in a harsh, unpredictable environment, (ii) plural breeding likely arises as a result of reproductive concessions provided by group members as joining incentives to recruit immigrants, and (iii) despite smaller groups providing more reproductive concessions, immigrants gain higher fitness in larger social groups and thus prefer to immigrate into larger groups which are found in higher-quality territories. Finally, in Chapter 3, I find genetic signatures of directional dispersal from social groups in low- to high-quality territories across an environmental gradient which likely generates considerable within-population variation in group social structure. Overall, my dissertation underscores the importance of direct benefits derived from group augmentation in the formation and maintenance of cooperative social groups with a complex social structure in a harsh and unpredictable environment.

The Cape gannet has undergone considerable population change and redistribution over the past 50 years. This has been linked to shifts in the abundance and distribution of their dominant prey, sardine and anchovy. Five breeding colonies, along the west coast of Southern Africa, have shown rapid population declines as a result of reduced prey availability. In contrast, a single colony (Bird Island, Algoa Bay) on the south coast of South Africa has, over the same period, grown fivefold and now supports approximately two thirds of the total population. Due to its conservation importance, and isolation from other breeding localities, it is important to assess the health of the Bird Island colony, and determine how foraging distribution relates to the environment to evaluate current measures of protection. This was achieved through two related studies; a long-term dietary analysis spanning 34 years, and a spatial foraging study, which related three years of tracking data to estimates of prey availability, oceanographic features and marine protected areas (MPAs). The results of the dietary study showed that the dietary constituents of Cape gannets breeding at Bird Island have remained similar over the last three decades, but the importance of sardine and anchovy has increased significantly. For sardine, in particular, this reflects an increased availability of this species (as deduced from hydroacoustic surveys) within the foraging range of the Bird Island colony. The dietary abundance of anchovy was found to be negatively correlated with that of sardine. Surprisingly,.the dietary abundance of anchovy was also negatively correlated with estimates of its availability based on acoustic surveys. The latter is likely to be due to sardine being a preferred prey item. Recent decreases in the dietary contribution of sardine (since 2005) suggest that this species is becoming less available to gannets, with profound implications in terms of nutrient gain associated with foraging. However, this has been mediated by an increase in the dietary contribution of anchovy, which now accounts for the vast majority of prey taken. Spatially, the foraging range of the Bird Island colony expanded during the three years of study, indicating an increase in effort. This increase was likely in an effort to track a distributional change of sardine and anchovy, which showed an apparent westward shift during the study period. There was, however, no evidence of birds tracking features associated with high productivity. This may have been partly due to anomalously warm conditions during the summer of 2012/2013, in which an absence of coastal upwelling prevented surface cooling. Nonetheless, low sea surface temperatures and high chlorophyll a concentrations do not seem to be reliable indicators of important Cape gannet foragingareas. Foraging effort was largely concentrated outside of MPAs, indicating that the current MPA network provides little protection for foraging gannets. This could change with the additional protection of the proposed Greater Addo Elephant National Park MPA expansion, as prey species are allowed to recover following the removal of fishing pressure. Overall, the colony appears to be in good condition as the diet is still dominated by live prey items, and the foraging range remains smaller than many of the colonies along the west coast. However, it is important that monitoring be continued, in particular with respect to changes in the availability of sardine and anchovy. Long-term shifts of these species out of the colony‘s foraging range could negatively influence the population in the future. This might be worsened by interspecific competition for prey resources. Considering the conservation importance of this population, maintenance of healthy prey stocks within the home range of breeding Cape gannets should be prioritised in order to prevent declines similar to those observed at west coast colonies.

For several decades now, seabirds have been considered to be useful indicators of the state of their prey resources because of how they reflect lower-level trophic variability through proxies such as diet or behaviour. However, collection of appropriate data is often challenging in the marine environment because of logistical or financial constraints. In this study, time-activity budgets were studied in the Cape gannet (Morus capensis), a seabird which has been advocated as a potential bioindicator for local epipelagic prey. VHF transmitters attached to PVC leg-rings were fitted to 50 adult breeding pairs during the 2011/2012 and 2012/2013 breeding seasons at Bird Island, Algoa Bay, to determine whether an automated method of continuously collecting time-activity budget data can replace conventional laborious direct observations. To validate that the foraging trip duration data generated from the automated method was a reflection of foraging effort, Time-Depth Recorders (TDRs) were simultaneously equipped to birds with VHF transmitters for three weeks. In order to assess the influence of factors other than prey availability on parent time-activity budgets, sex, chick age and body condition were measured. Additionally, chick growth and survival were recorded in order to investigate the gender-specific effects of parental time-activity budget variability on these parameters. Attachment of VHF transmitters to leg-rings of adult Cape gannets had no observable negative effects on the adults or their chicks in terms of adult body condition, nest attendance and foraging trip durations, or chick growth and survival. Furthermore, the frequency distribution of behaviour bout (foraging trip and nest attendance) durations was no different between automated and directly observed data. However, the automated method did record shorter behaviour bouts, largely attributed to the increased likelihood of direct observations missing birds returning briefly to their nests during older chick provisioning. Additionally, foraging trip duration was highly correlated to foraging effort in terms of time spent resting on the sea surface, flying and diving. The automated method therefore appears to be a good reflection of direct nest attendance observations and foraging effort. Cape gannet time-activity budgets were related to chick age and parental sex. Especially as chicks neared fledging, females spent significantly longer periods of time foraging than males, with males consequently provisioning their chicks more often. Furthermore, adults departing their nests earlier spent more time away from the nest foraging as more same-day daylight hours were available. Chick growth was a function of parent foraging trip duration and associated prey delivery rates. Chick survival was most strongly affected by the amount of time which chicks were left unattended by both parents and consequently exposed to predation by kelp gulls (Larus dominicanus) or to adverse weather conditions. Additionally, for females (but not males) there appeared to be a trade-off between foraging trip duration and chick survival. The Cape gannet appears to demonstrate a strategy whereby the costs of reproduction to the female are shifted towards male-dominated chick provisioning as the chick nears fledging. Drivers of time-activity budget variability such as chick age and parental sex therefore need to be considered if using data on foraging trip duration as a proxy of foraging effort and prey availability.