Perspectives on “Nest construction and function 2012"

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Perspectives on “Nest construction and function 2015”

The second meeting was held in September 2015 at the University of Lincoln (UK) and was attended by delegates from the UK, from four different countries across Europe, and the USA

Measurement of brood patch temperature of British passerines using an infrared thermometer

Capsule An infrared ear thermometer can be easily used to measure brood patch temperature in passerines caught on the nest or in mist-nets

How does the bird-nest incubation unit work?

The bird-nest incubation unit was proposed as a means of explaining the functionality of incubation in most avian species where the egg is in direct contact with the incubator. Subsequent work resulted in revision of this idea to suggest that large birds act as incubators and the nest is a location for incubation; by contrast, in small species the interaction between the bird and its nest played a key role in ensuring efficiency of incubation. This paper briefly reviews what we know about the incubation environment within nests and considers how small birds can contact-incubate eggs whilst ensuring appropriate levels of respiratory gas exchange. A hypothesis is proposed that the incubating bird does not ‘sit tight’ on its nest to maintain egg temperature at a minimal energy expenditure but, rather, it allows warmed air to escape from the nest cup. This convection flow draws air into the cup from the nest walls, providing oxygen for developing eggs and diluting carbon dioxide that they produce. Evidence supporting this idea of an ‘open’ nest during incubation is presented. Further experimentation is required to understand the environment within the nest cup better and this paper presents a hypothesis that can be tested in future studies. Investigations of how nests interact with their immediate environment should no longer be biased towards the effects of temperature on nest dimensions or composition. Instead, they should address all of the environmental factors that could affect the composition and function of a bird nest

Feathering the nest

Dr Charles Deeming explores the subtle factors that will determine the size and shape of individual bird nests this sprin

How pterosaurs bred

Ninety years have passed since Roy Chapman Andrews returned from his exploration of Mongolia with tales of fossilized dinosaur eggs (1). Fossils interpreted as dinosaur eggs had been described before, but Chapman's crew had found fossils that could only be interpreted as clutches of eggs. Recent fossil evidence of dinosaur reproduction has confirmed that all dinosaurs laid eggs, whereas other Mesozoic groups, such as the aquatic ichthyosaurs, evolved live birth (2). However, the reproductive biology of a key group of extinct Mesozoic species, the flying pterosaurs (see the image), has remained elusive. On page 1197 of this issue, Wang et al. (3) report the largest accumulation of Hamipterus pterosaur eggs found to date. The work is a crucial advance in understanding pterosaur reproduction

Opportunistic use of a wool-like artificial material as lining of Tit (Paridae) nests

The lining material is a key element of bird nests primarily serving as insulation for the adult, eggs and/or chicks but collection of such material will have an energetic cost. This study investigated the nest building effort of four species of tit (Paridae) in an English wood by determining the use of colored, wool-like artificial nest lining material over the period 2000-2010. The distances that birds carried the material from source to nest was recorded for each nest as an indirect measure of the energetic cost of collection of nest material by individual birds. Birds did not always use nest material from the nearest source to their nest and some birds collected material from 2, 3 or 4 well-separated sources. There was no detectable color preference in choice of material and few birds would travel more than 200 m to gather the material. Use of the material appeared to depend on the species. Within defined areas around material dispensers not all individual Great Tits (Parus major) used the artificial material and, for all species examined, the proportion of birds using the material declined with increasing distance between source and nest. Use of artificial material suggested that selection of nest materials was probably opportunistic but also reflected the preference of these species for a wool-like nest-lining

Interspecific and intraspecific spatial separation by birds breeding in nest boxes

Nest boxes can be seen as a conservation tool for improving low-grade nesting habitat but it is unclear how sympatric species using boxes establish a spatial distribution relative to conspecifics and heterospecifics. This study determined the distances between nest boxes occupied by Blue Tits (Cyanistes caeruleus) and Great Tits (Parus major) in two British woodlands to ascertain whether spatial distribution was affected by species and, if it was, whether there were reproductive consequences of this breeding distribution. Occupancy of nest boxes at two woodland sites were recorded on an annual basis between 2010 and 2014, inclusive. Distances between nest boxes, and reproductive activity, were recorded. Even if nest boxes showed a clumped distribution in the woodlands, the occupancy of the boxes was random. Not all boxes were used and the minimum distance between occupied boxes was at least twice the distance between boxes in general. Blue Tits tended to have greater distances between boxes containing conspecifics but distances between boxes containing heterospecifics were generally of comparable lengths. Reproductive output was only affected in relation to clutch size for Blue Tits nesting at one site. Nest boxes that ai

Material Type and Position Determines the Insulative Properties of Simulated Nest Walls

Incubation in birds takes place within a nest that is often assumed to confer a degree of thermal insulation. The range, amounts and organisation of materials used to construct nest walls hampers our understanding of the degree to which they provide insulation during incubation. This experimental study used temperature loggers in a model system to test the insulative properties of materials extracted from bird nests to determine: 1) whether differences existed in terms of insulation, and 2) if the position of a material mattered when two materials were tested in combination. Animal-derived materials offered better insulation than plant-derived materials, whether tested singly or in combination. Halving the mass of each material did not affect insulation conferred by the material proximal to the temperature logger. Differing thermal conductivities of the materials in contact with the temperature logger may explain these results. If a bird strategically places an animal-derived material only into a nest cup lining then it may be sufficient to provide good insulation for the whole nest. More research is needed to generate thermal conductivity data for commonly used nest materials to test this idea more rigorously in finite element heat transfer models.—Deeming, D.C., Griffiths, J.D. & Biddle, L.E. (2020). Material type and position determines the insulative properties of simulated nest walls

A review of the relationship between eggshell colour and water vapour conductance

This review brings together the available literature that examines the effect of variations in pigmentation on the gas conductance of avian eggshells. Pheasant and Houbara bustard eggs provide some evidence that shell abnormalities can impact upon colour and conductance. By contrast, data from wild birds suggest that neither the degree of maculation or intensity of ground colour impact upon gas conductance. Those studies that purport to show variation in rates of water loss in eggs with different degrees of pigmentation may have been confounded by variation in nest humidity. This emerging field of research remains very much in its infancy