Variation In Nest Size Research Articles

Natal philopatry is associated with smaller nest size in a cavity-nesting bird with consequences for nest box temperature

Considerable within-population variation in nest size exists among cavity nesters. We sought to explain this by studying a multi-brooded population of Eastern Bluebirds (Sialia sialis) breeding in nest boxes. We examined seasonal change in nest weights and compared the weights of nests built by immigrant and resident females. We further investigated whether nest weight correlated with maternal condition or breeding success. Nest weight measured after broods fledged was correlated with nest height at the start of incubation. Breeders spent fewer days building and built successively smaller, lighter nests in later nesting attempts. Female bluebirds performed the majority of nest construction. Nests built by immigrant females were significantly larger on average than those built by female recruits hatched on site, and the seasonal decline in nest weight was more pronounced for natally philopatric females. For the first time, we present evidence that the weights of philopatric females’ first nests were significantly positively correlated with the weights of the nests they were raised in, suggesting an effect of natal memory. Contrary to expectation, neither maternal condition nor reproductive success (clutch size, hatching success, brood size, and fledging success) was related to nest weight. To investigate whether smaller nests provided a thermal advantage in summer nest attempts when afternoon box temperatures can exceed 41°C, we measured the temperature within nest boxes using programmable data loggers. Mean daily maximum box temperatures during incubation were significantly positively related to nest weight and significantly negatively related to the volume of free space above the nest. Increased air circulation above the nest likely contributed to cooling the boxes when ambient temperatures were high. Reducing nest size was therefore advantageous, especially in later nesting attempts when ambient temperatures were warmest. Seasonal decline in nest weights and differences between immigrant and natally philopatric females merits further investigation.

Nest construction, ambient temperature and reproductive success in a cavity-nesting bird

Nest construction is a widespread behaviour that is a critical fitness investment in many taxa. Nests provide stable environments for offspring production, development and at times adult survival. Avian nest structure and composition has been linked to insulative properties and the reduction of energetic requirements for incubating females. However, it is unclear how and why nest structure varies across landscapes within and between species, especially in cavity-nesting species. Here we examined nest size in a secondary cavity nester, the mountain chickadee, Poecile gambeli. Nests were measured across two years at two elevations varying in ambient temperature to test whether variation in nest size was associated with local ambient temperatures and internal nest cavity microclimate. Despite both elevations having high variation in ambient temperature during nest building in both years, there were no significant relationships between multiple nest measurements and temperature. Nest size was highly consistent between years within females, suggesting that individual females are the best predictor of nest size. Large variation in nest size, internal nest cavity microclimate temperature and ambient temperature during development in one year was not associated with significant differences in reproduction; but fluctuating asymmetry, a measure of developmental stress, was significantly lower in fledglings at the higher-elevation site independent of temperature. However, there were no significant differences between elevations in the second year for any reproductive parameter. Overall, our results suggest that chickadees do not adjust nest size in response to large differences in ambient or microclimate temperature and that large variation in nest size, both across and within sites, is a result of consistent individual preferences, which do not seem to have clear fitness consequences.

Diverse reproductive patterns of Bluehead Chub (Nocomis leptocephalus) and their relationships with nest size and interactions with an associate, Yellowfin Shiner (Notropis lutipinnis)

Nest construction by males is a common reproductive strategy in fishes, but little is known about intra-specific variation in nesting behavior and reproductive interactions with other species. In the southeastern USA, reproductive interactions between bluehead chub (Nocomis leptocephalus) and their nest associate, such as yellowfin shiner (Notropis lutipinnis), are mutualistic because the shiner requires chub nests to spawn but the chub also benefits from additional shiner eggs by reducing predation risk on their own eggs (i.e., dilution effect). As proxies for reproductive success of bluehead chub, we studied factors affecting their nest size variation and utilization by yellowfin shiner in three streams in the upper Piedmont region of South Carolina, USA. A total of 92 nests (71 spawned and 21 abandoned) were located, and we recorded spawning activity, nest size, number and size of male bluehead chub, number of yellowfin shiner, and environmental variables for 89 consecutive days in 2016. Path analysis showed that larger males spawned earlier in the season than smaller males, and instances of pebble re-use for nest construction increased through the spawning season, which extended from April to June. Larger males more likely shared the same nest with each other than smaller males, and larger or more males constructed larger nests and attracted more yellowfin shiner. Nest size also increased when males re-used substrate materials from old nests, and nests built in this manner (36 nests) were equally prevalent as newly constructed nests (35 nests). This study suggests that complex mechanisms mediate host nest size and interactions with nest associates, and individual variation likely shapes dynamics of the mutualistic reproductive interaction.

Large nested melanoma: a clinicopathological, morphometric and cytogenetic study of 12 cases

A group of melanomas characterised by predominant growth as large nests within the epidermis has been described. These cases present a diagnostic challenge, as many traditional architectural criteria for the recognition of melanoma are absent. We report the clinical, histological, immunohistochemical, morphometric and cytogenetic features of a series of 12 cases of large nested melanoma. In this series, large nested melanoma accounted for 0.2% of cases of melanoma. The majority occurred on the trunk of middle aged patients with absent or minimal solar elastosis and 42% were associated with a component of benign intradermal melanocytic naevus, speaking to classification of these melanomas as falling within the spectrum of lesions developing in skin with low cumulative sun damage. In 67% of cases invasive melanoma was present. Criteria such as asymmetry, variation in nest size and intraepidermal nests with an underlying rim of junctional keratinocytes appear to be highly specific, and are strongly predictive of typical cytogenetic abnormalities of melanoma, which were identified in 92% of cases. Conversely, in addition to features which are definitionally absent or limited, features such as solar elastosis and cytological atypia do not appear to be particularly helpful in recognition of this variant.

Geographical location affects size and materials used in the construction of European Pied Flycatcher (Ficedula hypoleuca) nests

BackgroundNest construction is a key element of avian reproductive behaviour and the result is often a complex structure that is used for incubation of eggs, which represents an extended phenotype. It is known that nest construction is a plastic behaviour but the extent to which plasticity is observed in a single species with a wide geographical distribution is largely unknown. This study sought to better understand variation in nest size and composition across a very wide geographical area. The hypothesis suggested that location would affect size but not composition of nests of the European Pied Flycatcher (Ficedula hypoleuca).MethodsNests and reproductive data were collected from seventeen study sites, spread over 6° of latitude and 3.3° of longitude on the island of Great Britain. Dimensions of nests were measured before they were deconstructed to determine the masses and types materials used in the outer nest and the cup lining.ResultsGeographical variation was observed in base thickness of nests but not many other dimensions. Nests varied in composition but were mainly made of leaf, moss, bark, grass, root and fern. Moss was used more to the north and east of the study area compared with more leaf mass towards the south and west. The species of leaf and bark used in the nests varied between geographical locations. Additionally, the use of leaves or bark from a particular tree species did not reflect the incidence of the tree species in the immediate territory.ConclusionsThis study showed that nest composition was affected by geographical location over a wide area. Variation between nests at each location was high and so it was concluded that differences in nest composition reflect individual selection of materials but evidence is such that it remains unclear whether this is deliberate to fulfil a specific role in the nest, or simply opportunistic with birds simply picking up materials with the appropriate characteristics as they find them outside their nestbox.

Monitoring large and complex wildlife aggregations with drones

Abstract Recent advances in drone technology have rapidly led to their use for monitoring and managing wildlife populations but a broad and generalised framework for their application to complex wildlife aggregations is still lacking. We present a generalised semi‐automated approach where machine learning can map targets of interest in drone imagery, supported by predictive modelling for estimating wildlife aggregation populations. We demonstrated this application on four large spatially complex breeding waterbird colonies on floodplains, ranging from c. 20,000 to c. 250,000 birds, providing estimates of bird nests. Our mapping and modelling approach was applicable to all four colonies, without any modification, effectively dealing with variation in nest size, shape, colour and density and considerable background variation (vegetation, water, sand, soil, etc.). Our semi‐automated approach was between three and eight times faster than manually counting nests from imagery at the same level of accuracy. This approach is a significant improvement for monitoring large and complex aggregations of wildlife, offering an innovative solution where ground counts are costly, difficult or not possible. Our framework requires minimal technical ability, is open‐source (Google Earth Engine and R), and easy to apply to other surveys.

Experimental manipulation of Blue Tit nest height does not support the thermoregulation hypothesis

Birds show immense variation in nest sizes within species. At least siz different hypotheses have been forwarded to explain intraspecific variation in nest size in cavity nesting species, but very few of those hypotheses have been tested experimentally. In our study, when nestlings were 2 days old, we manipulated the height of 182 Blue Tit (Cyanistes caeruleus) nests to either 5 cm or 11 cm while standardizing their ectoparasite load and genetic and maternal background. In line with the the hypothesis that larger nests to show increased growth of nestlings compared to shallow nests, or to imrove female somatic condition. We found that the nest height manipulation affected the tail length of 16-day old nestlings, but did not affect any other morphometric measure (tarsus length, body mass, head size and wing length). In addition, nest height manipulation had no impact on nestling survival and did not affect female body condition. Our results do not therefore provide strong support for the thermoregulatory hypothesis and suggest regional differences in the relationship between nest size and reroductive success.

Fitness in invasive social wasps: the role of variation in viral load, immune response and paternity in predicting nest size and reproductive output

Within any one habitat, the relative fitness of organisms in a population can vary substantially. Social insects like the common wasp are among the most successful invasive animals, but show enormous variation in nest size and other fitness‐related traits. Some of this variation may be caused by pathogens such as viruses that can have serious consequences in social insects, which range from reduced productivity to colony death. Both individual immune responses and colony‐level traits such as genetic diversity are likely to influence effects of pathogen infections on colony fitness. Here we investigate how infections with Kashmir Bee Virus (KBV), immune response and intracolony genetic diversity (due to queen polyandry) affect nest size in the invasive common wasp Vespula vulgaris. We show that KBV is highly prevalent in wasps and expression of antiviral immune genes is significantly increased with higher viral loads across individuals. Patriline membership within a nest did not influence KBV susceptibility or immune response. A permutational MANCOVA revealed that polyandry, viral load and expression of the immune gene Dicer were significant predictors of variation in nest size. High intracolony genetic diversity due to polyandry has previously been hypothesized to improve colony‐level resistance to parasites and pathogens. Consistent with this hypothesis, we observed genetically diverse colonies to be significantly larger and to produce more queens, although this effect was not driven by the pathogen we investigated. Invasive wasps clearly suffer from pathogens and expend resources, as indicated here by elevated immune gene expression, toward reducing pathogen‐impact on colony fitness.

Variation in nesting behavior of eight species of spider mites, Stigmaeopsis having sociality.

Nesting behavior is considered to be an important element of social living in animals. The spider mites belonging to the genus Stigmaeopsis spend their lives within nests produced from silk threads. Several of these species show cooperative sociality, while the others are subsocial. In order to identify the origins of this social behavior, comparisons of nest sizes, nesting behaviors (making nests continuously or separately), and their associated traits (fecal deposition patterns) were made for eight cogeneric Stigmaeopsis species showing various levels of social development. All of these species inhabit bamboo plants (Poaceae). We initially addressed the proximate factor of nest size variation. The variation in nest size of the eight species corresponded well with the variation in dorsal seta sc1 length, suggesting that nest size variation among species may have a genetic basis. The time spent within a nest (nest duration) increased with nest size on the respective host plants. Nest arrangement patterns varied among species showing different sized nests: Large nest builders continuously extended their nests, while middle and small nest-building species built new separate nests, which resulted in different social interaction times among species, and is thought to be closely related to social development. Fecal deposition behaviors also varied among Stigmaeopsis species, suggesting diversity in anti-predatory adaptations. Finally, we discuss how the variation in sociality observed within this genus is likely the result of nest size variation that initially evolved as anti-predator strategies.

Exploring Biotic and Abiotic Determinants of Nest Size in Mediterranean Great Tits (Parus major) and Blue Tits (Cyanistes caeruleus)

AbstractStandardized long‐term multi‐plot investigations of variation in nest size in free‐ranging model species are rare, despite their value for understanding how the environment influences plastic traits such as nest size. Here, we report the results of an 18‐yr descriptive study of nest size in first clutches produced by secondary‐cavity nesting great tits (Parus major) and blue tits (Cyanistes caeruleus) in the Mediterranean, whilst also taking individual (lay‐date, clutch size, age, species) and environmental characteristics (e.g. weather, oak habitat, region) into account. Nests of both species were built in relatively small standardized boxes erected in habitat patches that differed in the presence of the dominant oak species which was either summergreen deciduous or evergreen sclerophyllous. Nest size showed strong differences between species, and also in relation to environmental factors. Great tits built smaller nests than blue tits, Corsican birds had larger nests than mainland ones, nests tended to be larger in evergreen oak‐habitat, and larger nests were built during drier weather. None of the individual‐specific traits most often considered in long‐term studies (lay‐date, clutch size, and female age) were related to nest size in either species. Experimental approaches will be required to identify the underlying mechanisms that caused the observed phenotypic diversity for nest size in our study system.

Cavity Depth, Not Experience, Determines Nest Height In Eastern Bluebirds

The functional consequences of nest size variation in cavity nesting birds have been thoroughly investigated in recent years. However, it is unknown whether recent nest-building experience influences subsequent nest architecture. By providing Eastern Bluebirds (Sialia sialis) with either deep or shallow nest boxes for their initial nest of the breeding season, we tested whether the height of their subsequent nest in the same breeding season reflected the height of their initial nest or whether they built nests to match their current nest cavity regardless of their previous nest height. We found that second nests built in deep boxes were significantly taller than first nests built in shallow boxes by the same females. This difference could be because of nest date, cavity depth, or experience. We tested each possible driver and found that cavity depth better explains variation in nest height than either nest date or prior experience. We conclude that, for this multi-brooded secondary cavity nesting passerine, the roles of learning and experience are secondary to the importance of behavioral plasticity.

Genetic basis of woven nest size in subsocial spider mites

The variation in nest size of social spider mites of the genus Stigmaeopsis is assumed to correspond to their anti-predator strategy and to be a key aspect of their social organization and speciation. It is known that the length of the dorsal setae (sc1, 2nd propodosomal setae) correlates with the nest size. We conducted interspecies cross experiments to determine the heredity of sc1 length and nest size using two closely related species that build different sized nests, Stigmaeopsis saharai Saito et Mori and Stigmaeopsis takahashii Saito et Mori. A cross between a S. saharai female and a S. takahashii male produced several viable F1 females. We measured sc1 length and the nest size of the F1 females and then compared these values with those of their parent species. The sc1 length of F1 females and the nest size constructed by these mites were intermediate with respect to the values of the two parent species. Therefore, the length of the sc1 and nest size are heritable. This result sheds light on the importance of considering the genetic basis for the variations in social organization.

Natural History and Ecological Correlates of Fungus-Growing Ants (Formicidae: Attini) in the Neotropical Cerrado Savanna

AbstractFungus-growing ants (Formicidae: Attini) comprise a diverse and ecologically important group in Neotropical habitats. Compared with leaf-cutters, however, relatively little is known about the biology of less conspicuous attine species. Here, we compare nest size and structure, colony size and demographic composition, and worker size and polymorphism among the genera Cyphomyrmex, Mycetarotes, Mycocepurus, Myrmicocrypta, Sericomyrmex, and Trachymyrmex. In total, 25 ant colonies (one species per genus) were investigated at one site in the Brazilian savanna. Results indicate a consistent variation in nest size and structural complexity (architecture), colony and worker size, and a tendency to polymorphism among the studied genera. In addition, nest mound volume was found to be a good predictor of both worker number and volume of the fungus garden. Based on morphometric analyses, Sericomyrmex and Trachymyrmex together formed a distinct group from the other genera. The transition from the ancestral agricultural system toward the derived leaf-cutting habit also is followed by remarkable changes in nest size and architecture, colony size, and worker size and polymorphism. Our results support other recent studies that consider Sericomyrmex and Trachymyrmex as possessing transitional habits, distinct both from species that cultivate fungus by using mostly nonplant items (insect feces and corpses) as well as from typical leaf-cutters Atta and Acromyrmex. This is the first study to detect correlations of nest traits with worker number and size of fungus garden in the less conspicuous attines. Results highlight the importance of combining data on natural history and morphometry to understand the evolutionary history of fungus-growing ants.

Reproductive Ecology of the Upland Buzzard (Buteo hemilasius) on the Mongolian Steppe

The breeding distribution of the Upland Buzzard (Buteo hemilasius) is restricted to the eastern Palearctic. In comparison to other Buteo species, little is known about this species' breeding ecology. The objectives of our study were to describe nest sites and reproductive success of Upland Buzzards in Mongolia. The average clutch size for 304 breeding attempts in 2001–07 was 3.49 eggs (±1.09 SD; range 2–8; total of 1061 eggs laid). For 215 breeding attempts, the average brood size was 1.95 nestlings (±1.53; range 0–6). We found that the nest materials and nest size varied greatly, probably corresponding to the availability of nesting materials within the territory. However, the variation in nest size may also reflect the fact that some of the smaller nests were built on human-made structures, such as electric pylons or roofs of small buildings.

Individual variation in nest size and nest site features of the Bornean orangutans (Pongo pygmaeus)

Nest construction is a daily habit of independent orangutans for sleeping or resting. Data on their nests have been used in various ecological studies (e.g., density estimation, ranging behavior, evolution of material culture) because they are the most observable field signs. We investigated nest size and nest site features of Bornean orangutans in the wild during 10 months' fieldwork at three sites in East Kalimantan, Indonesia: Kutai National Park, Birawa, and Meratus. To examine individual variation, we followed 31 individual orangutans and recorded the 92 nests they made for nest size (diameter) and nest site features (height of nest above ground, tree species used for the nest site, the diameter and height of the tree, whether the nest was new or reused, and nest location within the tree). Analyses taking age-sex classes of the focal individuals into consideration showed significant age-sex differences in nest size and location, but not in nest height or nest tree features (diameter, height of tree, and height of lowest branch). Mature orangutans (adult females, unflanged and flanged males) made larger nests than immatures (juveniles and adolescents). Flanged male orangutans with larger nests used stable locations for nesting sites and reused old nests more frequently than immatures. The overall proportion of nests in open (exposed) locations was higher than in closed (sheltered) locations. Flanged males and immatures frequently made open nests, whereas adult females with an infant preferred closed locations. The good correspondence between nest size and age-sex classes indicates that nest size variation may reflect body size and therefore age-sex variation in the population.

Variation in social behavior within a spider mite genus, Stigmaeopsis (Acari: Tetranychidae)

The spider mites belonging to the genus Stigmaeopsis construct extremely dense oval woven roofs (web-nests) over depressions on the lower surface of host leaves and are known to have a kind of sociality. The four species that occur on bamboo plants in Japan show different nest areas. The nest area of Stigmaeopsis longus is the largest, followed by that of S. celarius, S. takahashii, and S. saharai in decreasing order. Smaller nests effectively prevent adults of several predator mite species from intruding. We hypothesized that variation in nest size reflects different anti-intruder adaptations of this mite group in relation to their sociality. The larger nest makers may adopt an alternative anti-intruder strategy, namely, counterattack by a large group, so as to compensate for the disadvantage of large nests. S. longus and S. celarius adults effectively defended their large nests against potential predators, and the effects of nest defense increased with the number of individuals in a nest. S. takahashii and S. saharai revealed no counterattack effect. Counterattack abilities that increase with the adult density, and thus, sociality may compensate for the vulnerability of larger nests. Key words: cooperation, counterattack, group defense, sociality, spider mites, web-nest. [Behav Ecol]

Nest-size variation reflecting anti-predator strategies in social spider mites of Stigmaeopsis (Acari: Tetranychidae)

The social spider mites (Acari: Tetranychidae) of Stigmaeopsis weave dense nests on the underside of host leaves. Four species occur on the leaves of bamboo in Japan: Stigmaeopsis longus, S. celarius, S. takahashii and S. saharai. We initially reconfirmed the occurrence of distinct variation in nest size among the species. Based on the hypothesis that this variation plays a role in protecting the spider mites from predators, we looked at the behavior of the natural enemies that occur on the host plants along with members of Stigmaeopsis. We found considerable variation in the ability of nests to protect the spider-mite eggs. The smallest nests protected the eggs against three predators, whereas the largest nests protected the eggs against only one predator species. So, decreases in nest size increased egg defense. Thus we concluded that nest-size variation reflects a strategy for reducing predation.

Effects of Nest Characteristics on Breeding Success of Great TitsParus major

In this study, nest characteristics (size and proportions of basic components) were not correlated with the timing of breeding. Clutch size was negatively correlated with total nest mass but positively correlated with the proportion of the mass of the lining in the total nest mass. Analyses of hatching and fledging success showed that the quantity and proportion of moss in the nest structure as well as the nest size influenced the performance of eggs and nestlings at the nest. We suggest that variation in nest size and composition may be due to several contradictory pressures associated with the need to keep the moisture and temperature in the nest relatively constant, to protect the brood from predation, and to control sanitary standards.

Geographic Variation in Nest Size Among Species of Peromyscus

Geographic Variation in Nest Size Among Species of Peromyscus