Energy demands can be particularly high in arctic-nesting birds that face harsh, unpredictable conditions during the breeding season. Consequences of these demands, particularly energy-partitioning during egg laying and incubation, are fundamentally important for arctic nesters. This study investigated differences in breeding strategies between Long-tailed Duck (<i>Clangula hyemalis</i>) and King Eider (<i>Somateria spectabilis</i>) in the central Canadian arctic. The focus was on ecological variables and influences of variation in nutrient resources used during incubation and egg production. Research was done at Karrak Lake, Nunavut, where both species nest sympatrically at relatively high densities, permitting comparative research about breeding strategies.<p>This study used stable-carbon (d13C) and nitrogen (d15N) isotope analysis to investigate origins and allocation of endogenous (stored) and exogenous (external) nutrients used in egg production. Remote temperature sensors were placed in nests to estimate and compare incubation rhythms and gain insight into capital and income incubating strategies of both species. Results suggest that breeding Long-tailed Ducks and King Eiders used a mixed breeding strategy, that is they relied on both exogenous and endogenous resources for reproduction. Close correspondence between d13C and d15N values of egg components and potential diet items indicated that King Eiders allocated exogenous nutrients for egg production (albumen 98.1%, yolk protein 96.8%, whole yolk 98.4%, and yolk lipids 84%). Female King Eiders relied on endogenous nutrients for incubation, as evidenced by high incubation constancy (96%). Conversely, the range of d13C values in components of Long-tailed Duck eggs and d13C values of diet items suggested that although some females allocated endogenous reserves for egg production, most females allocated exogenous resources for egg production (albumen 98.5%, yolk protein 78.3%, whole yolk 84.9%, and yolk lipids 38.3%). Long-tailed Duck females had an 84% incubation constancy, suggesting less reliance on endogenous nutrients for incubation than was estimated for female King Eiders. Knowledge about the relative importance of endogenous reserves and exogenous nutrients for egg production and incubation may help direct management decisions to specific winter/staging and or breeding areas used by King Eiders and Long-tailed Ducks.

Energy demands can be particularly high in arctic-nesting birds that face harsh, unpredictable conditions during the breeding season. Consequences of these demands, particularly energy-partitioning during egg laying and incubation, are fundamentally important for arctic nesters. This study investigated differences in breeding strategies between Long-tailed Duck (<i>Clangula hyemalis</i>) and King Eider (<i>Somateria spectabilis</i>) in the central Canadian arctic. The focus was on ecological variables and influences of variation in nutrient resources used during incubation and egg production. Research was done at Karrak Lake, Nunavut, where both species nest sympatrically at relatively high densities, permitting comparative research about breeding strategies.<p>This study used stable-carbon (d13C) and nitrogen (d15N) isotope analysis to investigate origins and allocation of endogenous (stored) and exogenous (external) nutrients used in egg production. Remote temperature sensors were placed in nests to estimate and compare incubation rhythms and gain insight into capital and income incubating strategies of both species. Results suggest that breeding Long-tailed Ducks and King Eiders used a mixed breeding strategy, that is they relied on both exogenous and endogenous resources for reproduction. Close correspondence between d13C and d15N values of egg components and potential diet items indicated that King Eiders allocated exogenous nutrients for egg production (albumen 98.1%, yolk protein 96.8%, whole yolk 98.4%, and yolk lipids 84%). Female King Eiders relied on endogenous nutrients for incubation, as evidenced by high incubation constancy (96%). Conversely, the range of d13C values in components of Long-tailed Duck eggs and d13C values of diet items suggested that although some females allocated endogenous reserves for egg production, most females allocated exogenous resources for egg production (albumen 98.5%, yolk protein 78.3%, whole yolk 84.9%, and yolk lipids 38.3%). Long-tailed Duck females had an 84% incubation constancy, suggesting less reliance on endogenous nutrients for incubation than was estimated for female King Eiders. Knowledge about the relative importance of endogenous reserves and exogenous nutrients for egg production and incubation may help direct management decisions to specific winter/staging and or breeding areas used by King Eiders and Long-tailed Ducks.

Two closely-related, different-sized species of geese nest sympatrically south of the Queen Maud Gulf (QMG) in Canadas central arctic. Following a period of high population growth rate in both species within the QMG, the population growth rate of larger-bodied lesser snow geese (Chen caerulescens caerulescens; hereafter snow geese) has slowed most recently to roughly half that observed in smaller-bodied Rosss geese (Chen rossii). I focused on factors that influence productivity and recruitment in these two species, to improve our understanding of life history variation associated with interspecific differences in body size, and to test for density-dependent population responses. I used long-term data (1991 to 2008) to compare spring nutrient reserves, breeding strategies, clutch sizes, nest success, and juvenile survival in Rosss and snow geese breeding at Karrak Lake, Nunavut; a large breeding colony located within the QMG.<p> Long-term patterns of spring body condition (i.e., fat and protein reserves) diverged in prospective breeding female Rosss and snow geese implying that differences in food acquisition ability had become more acute. Snow geese displayed larger reductions in protein and fat reserves through time compared to Rosss geese thereby suggesting a differential density-dependent response in the ability to store nutrient reserves, a prerequisite for breeding in both species. Decreased per capita food availability influenced the timing of reproduction in both species. Nesting phenologies of Rosss and snow geese, adjusted for variation in phenology of local spring climate, have become later by 6.5 and 5.0 days, respectively, since 1991. Nutritional strategies (i.e., reliance on reserves versus local food) used for clutch formation differed between species. Rosss geese displayed greater reliance on stored reserves (i.e., capital breeding) than did snow geese, though both used endogenous reserves (> 62% of yolk protein, > 48% of albumen, and > 73% of yolk lipid) for clutch formation. Rosss and snow geese experienced declines of 28% and 23% in body masses from arrival to post-laying and also until hatch demonstrating that endogenous reserves are the main nutrient sources for incubation. Still, constraints of small size forced Rosss geese to use a mixture of local food plants and reserves for incubation metabolism.<p> I then examined differences in clutch size, nest success, and juvenile survival to understand of the role of recruitment in the interspecific divergence of population trajectories. I did not find strong interspecific differences in clutch size and nest success. Overall, snow geese had a larger mean clutch size, which was expected based on benefits of a larger-body size. Clutch sizes decreased with delays in breeding and decreasing protein reserves of arriving females, although Rosss geese displayed larger declines with decreasing protein reserves. Mean apparent nest success for Rosss geese was 4.5% higher compared to snow geese. Nest success showed large declines (11%) in both species with increasing population size at the breeding colony. However, nest success of snow geese decreased twice as fast with delays in breeding compared to Rosss geese. Last, I found no evidence of negative density dependence in juvenile survival over time. Juvenile survival was higher in snow geese (48%) compared to Rosss geese (38%), consistent with a life history prediction based on body size differences. Despite lower juvenile survival, recruitment by Rosss geese is likely greater than that of snow geese because of earlier sexual maturity, higher breeding probability and/or greater nest success.<p> Ultimately, small body size of Rosss geese may produce an ideal life history schedule under resource limitation at this colony i.e., one that maximizes fitness compared to larger snow geese. Life history characteristics of Rosss geese (e.g., absolutely lower energy requirement, have a flexible breeding strategy, higher reproductive effort, an earlier age of sexual maturity, a shorter breeding cycle allowing delayed arrival and nest initiation on arctic breeding areas, and shorter time required by goslings to attain adult size), in addition to their smaller bill morphology may allow exploitation of a wider niche space (i.e., one that includes marginal quality and low quantity vegetation) relative to snow geese. Because there were no large differences in components of recruitment considered here, other components of recruitment (age of sexual maturity, breeding probability) may be affected more strongly by diminished spring nutrition in snow geese and thus have a larger influence on local population dynamics.

This study examined winter habitat use and nesting ecology of greater sage grouse (Centrocercus urophasianus) in Strawberry Valley (SV), Utah located in the north-central part of the state. We monitored sage grouse with the aid of radio telemetry throughout the year, but specifically used information from the winter and nesting periods for this study. Our study provided evidence that sage grouse show fidelity to nesting areas in subsequent years regardless of nest success. We found only 57% of our nests located within the 3 km distance from an active lek typically used to delineate critical nesting habitat. We suggest a more conservative distance of 10 km for our study area. Whenever possible, we urge consideration of nest-area fidelity in conservation planning across the range of greater sage grouse. We also evaluated winter-habitat selection at multiple spatial scales. Sage grouse in our study area selected gradual slopes with high amounts of sagebrush exposed above the snow. We produced a map that identified suitable winter habitat for sage grouse in our study area. This map highlighted core areas that should be conserved and will provide a basis for management decisions affecting Strawberry Valley, Utah.

I conducted demographic and behavioral studies of Western Sandpipers (Calidris mauri) breeding on the Yukon-Kuskokwim River Delta, Alaska (1998-2005). In chapter one, I estimated apparent annual survival (product of true survival and site fidelity) while correcting for the probability of encounter for 237 males and 296 females. Overall return rates (individual returned to the site in a subsequent season) were lower for females (40%) than males (65%), as was apparent annual survival (&#177; SE, females = 0.65 &#177; 0.05, males = 0.78 &#177; 0.03), and encounter rate (females = 0.51 &#177; 0.07, males = 0.74 &#177; 0.04). In chapter two, I examined the effects of mate and site fidelity on nesting success (N = 430 nests). Annual divorce rate ranged between 37-83%, with 17-63% of pairs reuniting annually. Reuniting pairs initiated clutches earlier than newly formed pairs, and clutches that were initiated early in the season had higher nest success rates compared to late-season nests. When I controlled for clutch-initiation date, nests tended by individuals with prior breeding-site experience had higher daily survival rates compared to birds breeding at the site for the first time. The effect of site experience was greater for males than females. In chapter 3, I reported that Western Sandpipers exhibited aggregated breeding behavior on a 36 ha plot. Breeding aggregations occurred when dominant and/or older individuals excluded younger, subordinate individuals from preferred habitat. The pattern of habitat occupancy conformed to an ideal despotic distribution with aggregated nesting birds in less preferred habitat experiencing lower reproductive success. In chapter 4, I described and demonstrated the form and function of parent-chick communication in the Western Sandpiper. Through experimental playback of adult vocalizations to chicks in the field, I demonstrated: (1) chicks respond to the alarm call by vocalizing relatively less often and moving away from the signal source, (2) chicks respond to the gather call by vocalizing relatively more often and moving toward the signal source, (3) and chicks respond to the freeze call by vocalizing relatively less often and crouching motionless on the substrate for extended periods of time. I also describe two distinct chick vocalizations (chick-contact and chick-alarm calls). / Ph. D.

The Wilson’s Plover (Charadrius wilsonia) is a species of concern in most southeastern U.S. coastal states, where it breeds and winters. The U.S. Shorebird Conservation Plan listed this species as a Species of High Concern (Prioritization Category 4), and the U.S. Fish and Wildlife Service has designated it as a Bird of Conservation Concern (BCC). Despite its conservation status, Wilson’s Plover population trends are poorly understood and little research has been conducted examining habitat factors affecting this species’ breeding and foraging ecology. I collected Wilson’s Plover demographic data and explored which habitat characteristics influenced breeding success and foraging site selection among three coastal habitat types (i.e. fiddler crab (Uca spp.) mud flats, beach front, and interdune sand flats) at Onslow Beach, Marine Corps Base Camp Lejeune, North Carolina, 2008-2009. I observed little difference between years in nest success (≥ 1 egg hatched), failure, and overall nest survival. The majority of nest failures were caused by mammalian predators. For those nests that hatched successfully, greater proportions were located in clumped vegetation than on bare ground or sparsely vegetated areas. In-season chick survival for both years was higher for nests that hatched earlier in the season, and for nests farthest from the broods’ final foraging territory. Productivity estimates (chicks fledged per breeding pair) were not significantly different between years (0.88 ± 0.26 fledged/pair in 2008, 1.00 ± 0.25 fledged/pair in 2009) despite a shift in foraging behavior, possibly related to habitat alterations and availability in 2009. My findings indicate that Wilson’s Plover adults and broods were flexible in establishing final foraging territories; in 2008 all final brood foraging territories were on fiddler flats while in 2009, final foraging territories were sometimes split between fiddler flats, beach front, and interdune sand flats. For those Wilson’s Plovers establishing territories on fiddler flats, area of the flat was the most important feature explaining use versus non-use of a particular flat; area ≥ 1250 m² was preferred. Close proximity to water and vegetative cover were also important habitat features in foraging site selection on fiddler crab mud flats, and in all habitat types combined. My findings will directly contribute to population and habitat research goals outlined in the U.S. Shorebird Plan and will supplement limited data about foraging and habitat use related to Wilson’s Plover breeding ecology. / Master of Science

Made available in DSpace on 2016-06-02T19:29:57Z (GMT). No. of bitstreams: 1 5249.pdf: 4090294 bytes, checksum: 3e43d0f22c6895a3bc1866edf5eafc88 (MD5) Previous issue date: 2012-06-29 / Financiadora de Estudos e Projetos / Nesting is a critical step on bird s life cycle, since nest predation is high all over the world. Predation influences the population dynamics, the community structure and the life history of birds. Birds evolved anti-predatory strategies, which include selection of safer places for nesting. Here we intent to: (i) analyze habitat characteristics selected by adults, and (ii) evaluate the influence of these elements on nests success, and fitness consequences to individuals. We studied the Lesser Elaenia (Elaenia chiriquensis), a migratory bird that breeds in Brazilian Savannas. We conducted the study between 2010 e 2011 in a 100 ha area in the Estação Ecológica de Itirapina, a protected area in São Paulo state, were the Lesser Elaenia is abundant along its breeding season (September to December). We analyzed habitat selection comparing characteristics of used and available patches. We made all tests using chi-square tests, analysis of variance, paired t-tests and permutation tests. We used program MARK to evaluate the influence of all of the parameters on nests success. We created a set of models that included temporal and a set of environmental parameters and used Akaike s Information Criterion to evaluate the adjustment of each model to our data. Adults apparently selected anemochoric plants, with larger crowns and more lichen flakes on stalks, but did not show preference for specific plant species. Individuals also preferred patches with high plant density and high density of Aspidosperma tomentosum, the most used plant as nest substrate. Contrary of our expectations, none of these characteristics influenced nests success. However, some parameters not evaluated for selection, influenced the offspring survival. Vegetation density on nest sites was the most important variable, probably because it helps concealing nests and parental activities. Nest age and time along the breeding season were also important elements and both reduced nests success. Nest predation, habitat selection, and their consequences to the fitness are complex and are related to many variables. The present study contributed with the knowledge on this subject in tropical areas. / A nidificação é uma etapa crítica no ciclo de vida das aves, uma vez que a predação de ninhos é alta em todo o globo. Ela exerce influência na dinâmica das populações, estrutura das comunidades e evolução da história de vida do grupo. Diante disso, evoluíram estratégias antipredação, entre elas, a seleção de hábitats seguros para a nidificação pelos adultos. Assim, nesse trabalho tivemos como objetivos principais (i) conhecer os elementos do hábitat de nidificação selecionados pelos adultos e (ii) avaliar a influência desses elementos no sucesso dos ninhos, de forma a conhecer o valor adaptativo das escolhas dos adultos. Trabalhamos com Elaenia chiriquensis, um Passeriforme migratório que nidifica em áreas de Cerrado no Brasil. Conduzimos o estudo entre 2010 e 2011, em uma área de 100 ha na Estação Ecológica de Itirapina, unidade de conservação localizada no interior paulista, em que E. chiriquensis é abundante na estação reprodutiva (setembro a dezembro). Fizemos as análises de seleção do hábitat de nidificação comparando características das manchas de nidificação às manchas nas imediações, disponíveis aos casais. Usamos testes de Qui- Quadrado, análises de variância (ANOVAs), testes de permutação e testes-t pareados para as variáveis amostradas. Para avaliarmos a influência dessas e de outras características, relacionadas aos ninhos, na sobrevivência da prole, usamos o programa MARK. Criamos modelos que incluíam variáveis temporais e nossas variáveis de interesse e avaliamos, usando o critério de informação de Akaike, o ajuste dos modelos ao nosso conjunto de dados. Os adultos aparentemente selecionaram vegetais anemocóricos, com copa de tamanho maior e maior abundância de liquens nos caules como substrato dos ninhos, mas não exibiram preferência pelas espécies usadas como substrato. Elaenia chiriquensis também mostrou preferência por locais com alta densidade de vegetação lenhosa e alta abundância de Aspidosperma tomentosum, a espécie vegetal mais usada como substrato dos ninhos. Contrariando nossas expectativas, nenhuma dessas características teve influência no sucesso dos ninhos. No entanto, características relacionadas aos ninhos, e que não foram avaliadas quanto à seleção, tiveram influência na sobrevivência da prole. A mais importante delas foi a densidade de vegetação nos sítios de nidificação, que provavelmente reduz as chances de encontros com predadores e oculta a atividade dos adultos. A idade dos ninhos e a influência do tempo ao longo das estações também foram variáveis de peso na explicação dos dados e ambos reduziram as chances de sucesso dos ninhos. A predação de ninhos, a seleção do hábitat de nidificação e as consequências para o fitness dos indivíduos são assuntos de grande complexidade biológica e envolvem diversas variáveis. O presente estudo contribui com o conhecimento acerca do assunto em áreas tropicais.

No description available.

Graduation date: 2006 / Habitat loss causes a reduction in available resources for wildlife, alters the configuration of remaining habitat, and may isolate wildlife populations. White-breasted nuthatches (Sitta carolinensis) are experiencing long-term population declines in the Willamette Valley of Oregon, where they are historically associated with oak woodlands. As secondary cavity-nesters, white-breasted nuthatches may be limited by the availability of existing cavities for nesting and roosting. Oak vegetation in the Willamette Valley has changed since European-American settlement times from vast areas of open oak savanna to isolated closed-canopy stands separated by agricultural fields. We examined nuthatch density, nest cavity selection, and nest success in relation to oak woodland structure and landscape context. We conducted point transect surveys in 3 strata: woodland interiors, large woodland edges, and small woodlands. We located and monitored nuthatch nests and sampled vegetation at nest locations and matching random locations around each nest. Woodland structure and edge density were measured at a 178-m radius (home range) scale, and landscape context was measured using vegetation cover within a 1-km radius around point transects and nests. We used program DISTANCE to fit detection functions and calculate nuthatch densities. We used conditional logistic regression to compare nest locations with random locations, and analyzed nest success with Mayfield logistic regression. White-breasted nuthatch density was significantly higher in small woodlands than in edges of large woodlands, which had higher nuthatch density than woodland interiors. Density of nuthatches increased with a combination of oak cover within a 1-km radius of the point, edge density within a 178-m radius, and number of oak trees >50 cm diameter at breast height (dbh) within a 100-m radius. Nest cavities were situated in oak trees containing more cavities than random oak trees that had cavities, and oak trees used as nest trees had a larger dbh than oak trees within random plots. Local woodland structure at nest locations was characterized by larger trees, measured by greater mean dbh, canopy cover, and basal area of oaks than random locations within the home range. Nest success in natural cavities was 71% and was not predicted by attributes of nest cavities, nest trees, local woodland structure at nests, woodland structure at the home range scale, or landscape context. These results suggest that the most suitable habitat for white-breasted nuthatches in the Willamette Valley includes oak woodlands in close proximity to one another with a high proportion of edge and mature oak trees. Managers should preserve trees containing cavities and large oak trees whenever possible. Thinning of small oaks and removal of conifers in oak woodlands to create more open, savanna-like conditions may also promote the development of larger oaks with more spreading branches, providing more opportunities for cavities to form and more foraging surface area for nuthatches.