Breeding Sex Ratios, Territoriality, and Reproductive Success in the Red‐Winged Blackbird (Agelaius Phoeniceus)

Nest Site Selection in Zenaida Dove (Zenaida aurita) in Puerto Rico

-Nest site selection was analyzed for a Mountain Bluebird (Sialia currucoides) population using two different types of nest box in southcentral Washington. The majority of adult females successful in fledging young during the previous year either returned to the same territory and nest box or selected the same type of nest box if they changed territories. If they were unsuccessful, adult females tended to change territories and box types. Most male and female bluebirds breeding for the first time selected the same type of box as housed their natal nest even though none of these birds returned to its natal territory. Nest site selection and breeding area fidelity were influenced by age, sex, previous breeding experience, and natal nest type. Recently, Cink (1976) examined the degree to which nestling House Sparrows (Passer domesticus) imprinted on the type of structure housing their natal nest. Although he found no evidence that early learning or imprinting had any effect on nest site selection, females tended to choose hole-type nests over open nests. Other studies have shown that some species prefer a larger to a smaller nest box (Jiirvinen 1978) and that floor dimensions of a box can influence clutch size (Karlsson and Nilsson 1977). Jackson and Tate (1974) analyzed selection of artificial nest sites by Purple Martins (Progne subis), House Sparrows, and Starlings (Sturnus vulgaris) and found only slight differences related to interior and exterior colors, location, and materials from which the boxes were constructed. Lumsden (1976) reported that Starlings preferred small entrance holes and dark interiors. Bluebirds, like all cavity-nesting species, are limited by availability of suitable nest sites. Many studies (e.g., Miller 1970, Power 1974) have shown that bluebird populations can be increased by placement of nest boxes in suitable habitat. Although much is known about the reproductive biology of bluebird populations (Power 1966, Peakall 1970, White and Woolfenden 1973, Pinkowski 1977a, 1979a), little has been published concerning nest box selection and breeding area fidelity (the tendency for birds to return to the territory used the previous breeding season). Pinkowski (1979b) analyzed breeding data for Eastern Bluebirds (Sialia sialis) using artificial and natural nest cavities and found that age and nesting success seemed to be the most important factors influencing nest site selection. Additionally, he concluded that imprinting on the natal type of nest site was not important. I theorized that imprinting on the natal type of nest site would be important for secondary cavity-nesting species because of the scarcity of natural cavities and that species-specific differences could influence nest site selection. To test these theories, I examined breeding data for a Mountain Bluebird (Sialia currucoides) population using two different types of nest box and analyzed the influences of age, sex, previous breeding experience, and natal nest type on nest site selection. STUDY AREA AND METHODS The study area was located south of Bickleton and Cleveland, Klickitat County, Washington. Elevation ranges from 915 m near Bickleton on the north to 701 m in valleys running north-south. The northern edge of the study area is on the ecotone between ponderosa pine-Oregon white oak (Pinus ponderosa-Quercus garryana) forest and big sagebrush-bluebunch wheatgrass (Artemisia tridentata-Agropyron spicatum) steppe. Much of the land south of Bickleton and Cleveland is farmed with winter and spring wheat and with barley. Areas not cultivated are moderately grazed by cattle. The two types of nest box were designated as either old or indicating how long they had been present on the study area. The old boxes were first erected in 1966 and new boxes were added each year (J. Brinkerhoff, pers. comm.). These boxes resembled a small house with a peaked roof. The inside dimensions of the floor were 30 x 15 cm with an entrance hole diameter of 4.4 cm; the entrance hole was approximately 10 cm above the floor. The outside of these boxes had a blue roof and white sides; the interiors were not painted. All of the boxes had inside floor dimensions of 12.7 x 12.7 cm with a 3.8-cm diameter entrance hole, the bottom of which was 14 cm from the floor. The boxes were not painted. Both old and boxes were made of wood. The number of old box types available was usually 50 (except for 41 in 1976) and box types numbered 30-31. Old type boxes were placed on top of wooden fence posts and type boxes were nailed to the

Nest site selection can have important fitness consequences in birds. I analysed the habitat characteristics of 392 nests of two sympatric raptor species (common buzzard Buteo buteo and goshawk Accipiter gentilis ) in Germany and their relation to nest occupation rate and nest reproductive success. For common buzzard, multivariate models explained only small proportions of the variance in nest occupation rate and nest reproductive success (13–19%). Important variables related to nest occupation rate were human disturbances, intra‐ and interspecific neighbour density, the amount of forested area and nest tree crown cover. Variables related to nest site reproductive success also included human disturbance, intra‐ and interspecific neighbour density and nest tree crown cover as well as nest distance to the nearest forest edge. In contrast, models for the goshawk explained a much higher proportion of the variation in nest occupation rate and nest reproductive success (41–43%). Important variables related to nest occupation rate were the remoteness of the nest site and direct human disturbance. Variables related to nest site reproductive success were remoteness of the nest site and good hunting habitat. Goshawks seem to be more sensitive to human disturbance than buzzards. A multiple discriminant analysis showed that nest site characteristics substantially overlapped between the species and there is a good evidence that competition for optimal nest sites occurs. Thus, buzzards might be constrained by the dominant goshawk in their nest site selection.

Simple SummaryThe size of primate ‘harems’ varies considerably, both inter- and intra-specifically. Previous studies have shown that females prefer high-quality males and that high-quality males are superior in inter-male competition, leading to them having a larger harem size. Based on eleven years of observations of Yunnan snub-nosed monkeys (Rhinopithecus bieti), we documented longitudinal stability in the distribution of harem sizes between 2010 and 2020. These demographic properties are the outcome of male and female social investment decisions that affect their reproductive performance and success. Male reproductive success was positively related to harem size, while constraints on individual social benefits and social investments limited harem size. Our findings advance our understanding of the socioecological determinants of harem size variation in polygynous primates.We used long-term data on the variation in harem size in Yunnan snub-nosed monkeys to research the effects of harem size on reproductive success and the ratio of grooming received to given (RGRG). The results suggest that harem holders derive reproductive benefits commensurate with harem size, whereas the females’ reproductive success is unaffected by harem size. Males of larger harems groomed less and had higher RGRG than males of smaller harems. In the case of females, grooming given increased, and RGRG decreased with an increase in harem size. The males’ reproductive success seems to be a driver of harem size maximization. From the females’ perspective, dwindling social benefits appear to set the upper limit for harem enlargement. We also showed that males of monogamous units (‘single-female harems’) invested more into grooming their female, presumably to prevent unit disintegration and loss of mating privileges.

Nest-Site Selection of American Oystercatchers (Haematopus palliatus) in Salt Marshes

Nest-site selection is an important determinant of individual fitness in birds. Understanding what information individuals use to choose nest sites is therefore important for understanding the evolution of nest-site selection, the dynamics of populations, and the conservation of species. We used five years of mark-recapture data for Mountain Bluebirds (Sialia currucoides) to examine how dispersal probability and nest-site selection vary with potential cues of nest-site quality. Dispersal distance between breeding seasons and nest-site selection were modeled as a function of personal reproductive success, conspecific density, conspecific reproductive success, and habitat type. Between years, the dispersal probability was related to personal reproductive success, not conspecific information, and individuals fledging fewer young dispersed longer distances. For dispersing individuals, the probability that a nest site was selected in year i was negatively related to distance from the nest site selected in year i - 1 for all age and sex classes, and positively related to conspecific density and reproductive success in year i - 1 for both second-year (SY) and after-hatch-year (AHY) females. However, nest-site selection in year i was more strongly related to conspecific density in year i- 1 for hatch-year (HY) females and was much more strongly related to the reproductive success of conspecifics in year i - 1 for AHY females. Nest-site selection of HY and AHY males was not consistently related to the metrics of conspecific information, but we suspect that relationships were obscured by competitive interactions. We found no evidence indicating that individuals respond differently to conspecific information at longer distances, suggesting that individuals limit dispersal to areas where they have prior knowledge. We predict that these patterns of nest-site selection will allow birds to loosely track nest-site quality and maintain an ideal free distribution, where average fitness is equal in all habitat types.

Chestnut mannikin (Lonchura malacca), an Estrildine finch recently introduced in Puerto Rico, is a widespread Southeast Asian species. In its native habitat it frequently nests in vegetation over water, but in Puerto Rico it usually nests in dense sugar cane. In a marsh ecosystem in Humacao, mannikins nest in clumps of Cyperus spp. growing on top of stumps in a lagoon (depth = 50 cm). Their nests are in sedge clumps that are in shallower water and on higher stumps, and that are taller, wider and denser than clumps without mannikin nests. Nests were usually placed on the south side of the clump, with the entrance facing open water. The predator protection offered by nesting over water may account for nests being placed in relatively open sites. SPECIES THAT EXPAND THEIR BREEDING RANGE, with or without human assistance, into new geographical areas may expand their nesting sites either by nesting in entirely new habitats (i.e., moving from forests to fields), by nesting in different sites within preferred habitats, or both. Presumably constraints from predation pressures, nest site competition, and environmental factors shape nest site choices in the newly-colonized breeding range. In this paper we examine nest site selection in a population of chestnut mannikin (or munias Lonchura malacca) in a marsh in Puerto Rico. Factors affecting nest site selection include social and physiognomic features of the environment (Burger 1985). Social factors include attraction to conspecifics that provide antipredator or information transfer advantages (Fuchs 1977, Nuechterlein 1981, Burger 1981), or avoidance of other species because of predation (Greig-Smith 1982). Physiognomic aspects of nest site selection include factors such as structural stability (Coon et al. 1981), foliage density (Furrer 1980), vegetation height (Cody 1985), orientation relative to the sun (Reynolds & Knapton 1984), and perch site availability (Gochfeld 1979). Some species appear to have very strict nest site requirements or preferences, whereas others tolerate a wide variety of sites. The chestnut mannikin, munia, or black-headed nun is one of several recently introduced Estrildine finches which has become common in Puerto Rico (Raffaele 1983). It naturally ranges from India through southern China and Southeast Asia to the Philippines and Indonesia (Delacour & Mayr 1946, Smythies 1960, Long 1981, Ali & Ripley 1983). The recentness of its establishment in Puerto Rico is reflected by the fact that Long (1981) did not include it in his compendium of feral exotic bird species. The genus Lonchura is a popular cagebird, and eight species within the genus have successfully established feral populations in regions remote from its natural range (Long 1981). This suggests that the genus is either adaptable with respect to habitat selection, or cosmopolitan with respect to habitat requirement. We wished to examine qualitatively whether chestnut mannikin in Puerto Rico used habitats similar in physiognomy to those in its native habitat, and examine quantitatively whether its choice of nest sites differed from the available habitat. Our general approach to nest site selection is to contrast nest sites with sites that are available but not used (Burger & Gochfeld 1985). We interpret these findings in the light of Skutch's (1976) concept that nest sites should be invisible, inaccessible, impregnable. STUDY AREA AND METHODS We studied chestnut mannikin in Frontera Palmas Lagoon of the Humacao Rufuge (operated by the Puerto Rico Departamento de Recursos Naturales) in June 1987 and February 1988. The Humacao Refuge contains 600 ha of brackish coastal marshes created by hurricanes in the late 1970's, and presently maintained by dikes and management. The palmas lagoon once supported a coconut palm plantation (Cocos nuciferos), but as the trees have died since the flooding, the rotting stumps support a growth of grasses (e.g., Paspalum spp.), Cyperus sedges, and ferns. Small stumps often had no vegetation, whereas wide stumps usually had one dominant plant. ' Received I I April 1988, revision accepted 24 August 1988. 364 BIOTROPICA 21(4): 364-368 1989 This content downloaded from 157.55.39.46 on Mon, 13 Jun 2016 05:24:06 UTC All use subject to http://about.jstor.org/terms

Reproductive success is a critical factor affecting avian demographics and can be influenced by many factors including nesting chronology, predation risk, and fine-scale nest site selection. We modeled the relative influences of habitat-related covariates at six spatial scales (nest site: 15-, 40-, 80-, 120-, 160-, and 200-m radii) on Eastern wild turkey (Meleagris gallopavo silvestris) nest site selection in two pine savannas managed by frequent prescribed fire (≤3 years) in southwestern Georgia during 2011–2013. Nest site (15-m scale) habitat metrics (mean visual obstruction [cm] and canopy closure [%]) had the greatest influence on nest site selection relative to covariates measured at larger spatial scales. Scaled odds ratios suggested that nests were 26.8 % more likely to occur for every 10 cm increase in mean vegetation height with a range of 7.5 to 150.0 cm and 18.5 % less likely to occur for every 10 % increase in canopy closure with a range from 0.0 to 97.8 %. Total ground cover, canopy closure, edge density, and percent land cover type (e.g., mature pine, mixed pine/hardwood, shrub/scrub) had minimal influence on nest site selection. Management of pine savannas for turkey nest sites should focus on creating early-successional vegetation to conceal nests from potential predators. Additionally, we suggest that future studies consider evaluating the influence of spatial scale on turkey nest site selection.

In most of colonial avian species, central parts of the colonies offer higher safety in terms of predatory pressure. However, in heterogeneous habitats, nest sites of high physical quality are likely to offer effective protection against predators or adverse weather conditions regardless of their location within the colony. The aim of this paper was to investigate whether nest site selection in a tree-nesting waterbird, the Great Cormorant Phalacrocorax carbo sinensis, depends on the within-colony location of sites, their physical quality or a combination of these components. The study was conducted during 2010–2011 in a cormorant colony in central Poland. We found that early-breeding individuals preferred nest sites in the central parts of the colony and located high off the ground. The high quality of pairs nesting in these locations was confirmed with good body condition of nestlings, measured by their body masses and plasma concentrations of glucose and urea. A similar spatial pattern was found for the daily nest survival rate and reproductive success. It was found that the central nesting sites associated with high nesting densities were better protected against predators, while the physical quality of nesting sites determined the probability of nest collapse before the conclusion of breeding activities. The two-way process of assessing nest site attractiveness (nest site location vs. physical quality) suggests that, under the limitation of the most attractive nesting sites (good-quality central sites), tree-nesting waterbirds may trade central nesting locations for the high-quality sites at the peripheries of the colony.

Urbanization has resulted in changes in bird life histories, and some species have successfully adapted to urban environments, resulting in synurbization. Nest site selection in urban areas challenges cavity nesters because natural nest sites are often replaced by artificial holes. This study was conducted to identify the nest site selection and nest characteristics of the Eurasian tree sparrow (Passer montanus) living in an urban environment. This species inhabits artificial structures and tree holes around human settlements. We surveyed nests of tree sparrows on the Chonnam National University campus, located in Gwangju, Republic of Korea, during the first clutch from March to May 2020. We categorized nest types into natural and artificial nest sites. The tree sparrows selected natural nest sites such as woodpecker's holes and cracks in trees, and selected artificial nest sites which included holes in concrete buildings, under roofs, and in steel frames and nesting boxes. No significant differences were found in breeding schedules and reproductive success between birds nesting in artificial and natural holes. The results suggest that tree sparrows can successfully adapt to an urban environment by selecting nest sites regardless of nest hole type, and can reproduce successfully when nesting in both natural and artificial holes.

IntroductionUnderstanding the birds’ breeding strategies in urban habitats is vital for ensuring their continued existence. Therefore, more research must be conducted on bird breeding and urban adaptation strategies in urban green spaces. This study aimed to address this gap by investigating the influence of landscape factors on the selection of bird nest sites. MethodsData on the presence and absence of magpie (Pica pica) and gray magpie (Cyanopica cyana) nests were collected through field surveys conducted in the campus of Nanjing Forestry University during the 2023 breeding season. Generalized additive models (GAMs) incorporating landscape variables were employed to assess the effects of these predictors on nest occurrence. The model with the lowest Akaike’s information criterion value was selected among the candidate GAMs.ResultsBelow is a summary of the main results. Nest tree height (TH), distance from the central lawn (D), and tree coverage (TC) within the sampled area were identified as the primary landscape factors influencing nest site choice. Conversely, factors such as the shortest distance to the water source, herb coverage, shrub coverage, percentage of buildings, and percentage of hard pavement did not significantly impact on nest site selection. Furthermore, the nesting potential of magpies and grey magpies initially increased with tree height, reaching a maximum at ca. TH=25 meters after which it began to decline. The nesting occurrence rate showed an initial decrease tendency with increasing distance from the central lawn, reaching a minimum at D=400 meters, and then increased with further distance. Additionally, nesting potential decreased initially with increasing of TC in the range of 0–20%, fluctuated evenly between 20–60% TC, and decreased rapidly when TC exceeded 60%.DiscussionThis study provides valuable insights into the selection of nest sites by birds in urban habitats, specifically with respect to landscape factors. The understanding of the impact of urban green spaces on urban birds and the underlying mechanisms of their behavior contributes to the conservation of wild birds and promotes the harmonious development of urban areas.

The selection of nest sites and nesting material may have important implications for avian reproductive behaviour and performance. Nest construction may involve costs arising from transporting material that may be reduced considerably if nest materials are located close to the nest site. Eurasian Nuthatch Sitta europaea nests in our nest box study area are mainly composed of pine bark flakes or alternatively of strips of bark of the widespread shrub Cistus laurifolius, with variable amounts of mud being used for plastering the entrance. Several small streams run through the area — an oak Quercus pyrenaica forest with a few scattered pines Pinus sylvestris. Here we show that Nuthatches collected pine bark only when nest sites were situated close to pines, used more mud when breeding close to streams and selected nest sites closer to streams than a sympatric species not using mud, the Pied Flycatcher Ficedula hypoleuca. Nuthatches used pine bark only when there was a pine tree less than 100 m away from the nest box and selected Cistus bark when transport distance was greater. We suggest that the selection of nest sites and nest materials in this species may be constrained by the costs of transporting nest material.

We collected 354 blood samples from territorial and nonterritorial male Redwinged Blackbirds (Agelaius phoeniceus) to determine plasma levels of testosterone (T) and corticosterone (B) of a polygynously breeding bird, and to determine the potential influences of steroid hormone levels on obtaining breeding territories. In contrast to monogamous species, we found no peak in average T levels early in the breeding season and a five-weeklong high plateau in T levels during the period when most nests were initiated. These endocrinologic characteristics may result from the long breeding season and resource defense polygyny of Red-wings. Territory owners had higher T levels during the breeding season than adult floaters. Subadult floaters had the lowest levels. Also, territory owners generally had the highest circulating levels of corticosterone during most of the breeding season. This implies greater energetic demands and stress on owners than on floaters. During early April the T levels of males for which we had complete breeding and territorial history information correlated significantly with their annual fledging success, and males with more breeding experience tended to have higher peak T levels. There was also a positive correlation between B levels in early April and eventual fledging success. Circulating levels of steroid hormones may affect territory ownership and reproductive success in this species.

Personality-dependent nest site selection and nest success during incubation in wild chestnut thrushes

Hole nesting birds, due to the long lasting nature of cavities, use their nest sites for many years. Therefore, they may face the problem of the presence of nest material from previous breeding seasons. For a long time, the problem of old nest presence was not addressed in studies of this group of birds because nestboxes, a useful tool in studies of hole nesters, were cleaned by investigators, with old nests removed before each breeding season. In this review, the available results of experiments related to the effects of old nests on hole nesting birds are collected, recapitulated and discussed. The possible effects of old nests on nest site choice and breeding parameters, such as phenology, clutch size, fledging condition, as well as on ectoparasite numbers in a new nest, are presented. The findings show that studies on the problem of old nests started to be conducted mainly in the early 1990's, and to date more then thirty papers have been published related to this topic. The most frequent subjects of such studies in Europe were the Pied Flycather Ficedula hypoleuca, Blue and Great Tits Cyanistes caeruleus, Parus major, and European Starling Sturnus vulgaris, while in North America — the House Wren Troglodytes aedon and Eastern Bluebird Sialia sialis. The analysis of existing papers reveals that a majority of studies did not find any significant effect of old nest presence on nest site selection. In most papers, the presence of old nests did not influence birds' breeding parameters. Worse reproductive output in nestboxes containing old nests was found very rarely, and in particular seasons or study areas. Data on ectoparasite occurrence in relation to the presence of old nest material were presented only in a few papers. Fewer fleas were found in new nests built in artificially cleaned sites compared to sites containing old nests. The abundance of mites and blow fly larvae was not related to nestbox treatment. The results of this review suggest that there is no clear pattern of effects of old nest presence on hole nesters' breeding. It seems that the location of the study area, which influences the time available for birds' reproduction, is especially important for migratory species, and the impact of the ectoparasites dominating in a given study area may influence obtained results. This paper also suggests the direction of future work in this topic. Of most importance are studies carried out in natural tree holes, as the decomposition rate of old nest material could be much higher in such cavities than in nestboxes, and studies providing detailed descriptions of the costs and benefits of nest site cleaning behaviour of the birds themselves.