Search

The size and shape of the nest are species-specific characteristics that are often associated with environmental factors at the time of breeding. Nests are expected to be larger or thicker in colder environments, although the relationships between nest design and weather differ between species. Here we present the results of an analysis of the external height of the nest wall in Paridae that accepted small standardized nesting boxes for breeding. The study populations were monitored in a relatively cold Mediterranean study area. We found that Coal Tits Periparus ater built higher external nest walls than Great Tits Parus major or Blue Tits Cyanistes caeruleus, after controlling for the first-egg date and clutch size which are assumed to reflect aspects of the quality of the nest builders. Our measures of nest size were not closely associated with the average ambient temperature, but nest walls tended to be shallower when there was more rain. Nest-shape asymmetry, as reflected in the difference in the external height of the nest measured closest to and farthest from the nest-chamber entrance, was observed in all three species, but the average asymmetry was highest in Coal Tits. In asymmetric nests, more nest material was added to the side that was closest to the front wall considered to be the coldest and least protected against harsh weather. Thus, nest size characteristics differ between three ecologically similar species inhabiting the same cavity type in the same coniferous woodland habitat, which would imply that different species do not respond in the same way to the same set of environmental factors. [ABSTRACT FROM AUTHOR]

Standardized 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. [ABSTRACT FROM AUTHOR]

Longitudinal multi-plot studies of nest architecture in non-domesticated birds are rare. Here we report the results of an 18-year multi-plot study that compared heights of fresh female-built nests in Corsican Great Tits (Parus major) and Blue Tits (Cyanistes caeruleus ogliastrae). Boxes with relatively small nest-chambers were erected in a landscape with habitat patches that were either dominated by food-rich broad-leaved deciduous oaks (Quercus humilis) or food-poor evergreen oaks (Quercus ilex). Nest height tended to change with oak habitat type in a species-specific manner. Great Tits built shallower nests than Blue Tits supporting the published findings from other geographic regions (Poland, UK, southern mainland France). Potential impacts of local climate factors and risks related to nest predation on the species-specific expression of the size of nests are discussed. [ABSTRACT FROM AUTHOR]

Comparative studies predicted or reported weaker or stronger positive relationships between nest size and body size both within and across avian species. Here we show that in relatively small nest-chambers, larger Great Tits (Parus major) build shallower nests than smaller Blue Tits (Cyanistes caeruleus). Our results from the Mediterranean region support findings from published studies that were conducted at more northerly latitudes (UK and Poland). Potential impacts of the local climate and predation risks on the species-specific expression of the size of fresh nests are discussed. [ABSTRACT FROM AUTHOR]

An ecological trap occurs when animals prefer to settle in poor-quality habitats even though alternative high-quality habitats are available. Thus, to find evidence of a trap one must show (1) a habitat preference and (2) a mismatch between the settlement decision and reproduction or survival. However, demonstrations of traps in the wild are currently limited because the misleading cues have to be identified and are usually difficult to manipulate experimentally. Places where humans transform habitats, such as urbanized areas, are particularly prone to this ecological phenomenon. Here we tested whether the size of a human-made structure (artificial cavities) can induce maladaptive breeding responses via an ecological trap mechanism in an urban secondary-cavity nesting bird, the great tit, Parus major . Previous studies showed that great tits prefer to breed in large cavities; cavity size is thus used as a cue in nest site selection. Reproductive investment in great tits has also been shown to be influenced by the breeding cavity size. However, this behaviour can only be adaptive if cavity size matches the quality of the breeding habitat. This is not necessarily the case in urbanized environments where natural habitat has been removed or breeding habitat modified. We performed a cavity choice experiment, providing an opportunity for great tits to choose between three cavity size options, and monitored their subsequent breeding attempts. We found that urban great tits preferred the largest artificial cavities for breeding when they could choose between small, medium-sized and large cavities. Individuals from the largest cavities also invested more in egg production, yet had a lower fledging success than those from medium-sized cavities, experimentally showing a trap mechanism in free-living animals. With this study, we shed light on maladaptation associated with human-transformed habitat. [ABSTRACT FROM AUTHOR]