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Functional characteristics of the jaw apparatus, for example bite force, in vertebrates is a combination of the skeleton and the musculature. In birds, bite force has been measured directly or calculated using various methods including summation of forces generated by the different elements of the jaw musculature. However, there have been no reports of the relationships between body size with the mass of the different muscle groups in a closely related group of birds. This study explored allometry in the different jaw muscle masses from parrot (Psittaciformes) species differing in body mass by 40-fold. It was hypothesised that the different muscle masses would exhibit isometry with body mass and skull size. Parrot heads were dissected and the masses of the individual muscle complexes were recorded. Data were subjected to phylogenetically-controlled regression analysis to document scaling effects with body mass and skull size. Most, but not all muscles, exhibited positive allometry with body mass but most were isometric with skull size. Consequently, as parrots get bigger, their skulls get proportionally longer, but that the muscles within the head isometrically scaled relative to the size of these proportionally larger skulls. The large muscles imply greater bite forces in parrots than have been reported to date, which seems to be associated with an increase in skull size to accommodate more muscles. It is unknown whether this pattern is applicable to other birds within specific orders or even across birds as a whole. There needs to be further investigation into the allometry of the morphological and functional properties of the avian jaw musculature.

Dinosaur embryos cause a lot of excitement in the scientific literature and are often widely reported because of the general public's interest in dinosaur biology. Well-preserved, articulated oviraptorosaur embryos in eggs are usually interpreted as representing a stage of development close to hatching because of their large size and good level of skeletal ossification. Based on this evidence, a recent report suggested that the position of the one embryo's head was reminiscent of an avian-like hatching position. Here we explore how the developmental stage of well-preserved oviraptorosaur embryos can be estimated, rather than assumed. This will help in our understanding of their developmental biology and its evolutionary consequences. Using quantitative methods and comparison with modern crocodilian embryos, we show that all articulated oviraptorosaur embryos are small relative to the egg and most likely at a stage of development equivalent to around 50%–60% of the developmental period, that is, not even close to hatching. This conclusion is supported by the fact that many elements of the crocodilian skeleton are well ossified many weeks before hatching and the position of oviraptorosaur embryos’ heads was also comparable to a crocodilian embryo many days before hatching. Misunderstandings about the stage of the developmental biology of these well-preserved oviraptorosaur embryos hampers our understanding of the true nature of their reproductive biology. We urge a more conservative approach to their interpretation. This is important, because misunderstandings in the minds of the public about dinosaur biology are hard to counter once poorly evidenced ideas have been reported around the world.

Interpretation of fossil material using comparative anatomy often relies on relationships predicted from data collected from extant species. Some years ago, it was suggested that femur length of birds could be predicted from egg mass but this relationship was counter-intuitive because egg mass is usually related to a measure of body size. The original analysis was also not phylogenetically controlled. This study used the same data to determine phylogenetically controlled relationships for body mass versus egg mass, and egg mass versus femur length. Further analysis showed that order was important in the prediction of egg mass from either body mass or femur length. For some orders, the single regression estimate through all data significantly over-, or under-estimated egg mass. This problem was more pronounced for femur length compared with body mass. Extrapolation of the relationship between femur length and egg mass for large extinct birds seemed to be provide useful data for the Gastornithidae but under-estimated egg mass for other large bird species of a variety of families. Use of equations derived from extant birds to gain insight into the reproductive biology of extinct species needs to be undertaken with great care.

Nest construction by Common Redstarts Phoenicurus phoenicurus is affected by localized habitat.This study investigated whether variation in nest construction observed over a wide geographical regio...

There is increasing concern about the burgeoning effects of discarded plastic on the earth's biodiversity. Quantifying the presence of plastic and other anthropogenic waste in the environment can be logistically and financially challenging, although it is possible that bird' nests can be used as bioindicators. Many birds in heavily modified terrestrial ecoystems, such as urban environments, incorporate plastic and other anthropogenic materials into their nests but our understanding of the presence of discarded plastic in nests in rural woodlands remains poor. Here, we show that plastic and other anthropogenic materials were present in 35 % of 325 pied flycatcher (Ficedula hypoleuca) nests from 17 rural woodlands throughout Great Britain, although the woodlands did vary in the amount of material incorporated into nests. Then, in an experimental test at one study site, where flycatchers were provided with a choice of two types of natural and two types of anthropogenic nest materials, they preferentially selected one natural and one anthropogenic material. In another test, the flycatchers were provided with plastic of four colours and overwhelmingly selected white and avoided orange, blue and yellow plastic. Although the flycatcher's selectivity for certain material types and colours preclude their nests being a reliable indicator of plastic in the environment, our study nonetheless demonstrates that bird species incorporate anthropogenic materials, such as plastic, into their nests in rural woodlands.

Blood oxygen-carrying capacity is shaped both by the ambient oxygen availability as well as species-specific oxygen demand. Erythrocytes are a critical part of oxygen transport and both their size and shape can change in relation to species-specific life-history, behavioural or ecological conditions. Here, we test whether components of the environment (altitude), life history (reproductive mode, body temperature) and behaviour (diving, foraging mode) drive erythrocyte size variation in the Lepidosauria (lizards, snakes and rhynchocephalians). We collected data on erythrocyte size (area) and shape (L/W: elongation ratio) from Lepidosauria across the globe (N = 235 species). Our analyses show the importance of oxygen requirements as a driver of erythrocyte size. Smaller erythrocytes were associated with the need for faster delivery (active foragers, high-altitude species, warmer body temperatures), whereas species with greater oxygen demands (diving species, viviparous species) had larger erythrocytes. Erythrocyte size shows considerable cross-species variation, with a range of factors linked to the oxygen delivery requirements being major drivers of these differences. A key future aspect for study would include within-individual plasticity and how changing states, for example, pregnancy, perhaps alter the size and shape of erythrocytes in Lepidosaurs.

The size and shape of red blood cells (erythrocytes) is determined by key life history strategies in vertebrates. They have a fundamental role to deliver oxygen to tissues, and their ability to do so is shaped by the tissue's need and their shape. Despite considerable interest in how other components of blood are shaped by ecology and life history, few studies have considered erythrocytes themselves. We tested how erythrocyte size and shape varied in relation to energetically demanding activities using a dataset of 631 bird species. We found that in general, birds undergoing greater activities such as long distance migration had smaller and more elongated cells, while those with greater male-male competition had smaller and rounder cells. Smaller, more elongated erythrocytes allow more rapid oxygenation/deoxygenation and support greater aerobic activity. The rounder erythrocytes found in species with strong male–male competition may stem from younger erythrocytes deriving from androgen-induced erythropoiesis rates. Finally, diving species of bird had larger erythrocytes, indicating that erythrocytes are acting as a vital oxygen store. In summary, erythrocyte size and shape in birds are driven by the need to deliver oxygen during energetically costly activities.

Sexual selection theory has proven to be fundamental to our understanding of the male-female 15 (sperm-egg) interactions that characterise fertilisation. However, sexual selection does not operate 16 in a void and abiotic environmental factors have been shown to modulate the outcome of pre17 copularory sexual interactions. Environmental modulation of post-copulatory interactions are 18 particularly likely because the form and function of primary reproductive traits appears to be acutely 19 sensitive to temperature stress. Here we report the effects of developmental temperature on female 20 reproductive architecture and the interaction between male and female developmental 21 temperature on the outcome of sperm competition in the bruchid beetle Callosobruchus maculatus. 22 When females were reared at developmental temperatures above and below typical temperatures 23 the bursa copulatrix (site of spermatophore deposition) were smaller and, were either shorter and 24 broader (high temperatures) or longer and thinner (low temperatures) than those reared at 25 intermediate temperatures. Males and females reared at low developmental temperatures were 26 less likely to mate than those reared at higher temperatures. Where copulation occurred, females 27 reared at the highest temperature copulated for longest, whilst males reared at the lowest 28 temperature spent longer in copula. Male developmental temperature had a significant impact on 29 the outcome of sperm competition: males reared at 17oC were largely unsuccessful in sperm 30 competition against control (27oC) males, although some of the variation in the outcome of sperm 31 competition was a product of the interaction between male and female developmental 32 temperature. Our results demonstrate that male-female interactions that characterise pre- and post33 copulatory outcomes are sensitive to developmental temperature and that plasticity in cryptic 34 female preferences could lead to heterogeneous selection on the male reproductive phenotype.

A corrugated bituminised roofing felt ‘tree tin’ originally provided to serve as a bat roost was adopted on a regular basis by Eurasian Treecreepers as nest sites. Data on nest construction under ‘...

Avian nests provide a location for incubation, and in many cases rearing of nestlings. These energetically demanding activities have meant that nest insulation has been the subject of many studies but few to date have dealt with how variation among species in nest construction materials could affect nest insulation. This study investigated the insulation of nests constructed by three species of Old Word warblers (Sylviidae), which vary in size and composition. Insulatory values, i.e. difference in cooling rate of temperature loggers placed inside and outside a nest, and internal cooling rates within the nest cup were determined using temperature loggers under still-air and moving-air conditions. Insulatory values determined in still-air conditions of a laboratory were significantly different among nests of the different species but not when the values were determined within the smaller volume of a wind tunnel. Moving-air increased insulatory values by an order of magnitude but also increased internal cooling rates in all species. Insulatory values were positively correlated with the nest base thickness. Moving-air increased the cooling rate of the external temperature logger much more than the internal logger, which inflated the insulatory value of a nest wall in moving-air. Reasons for these results may reflect the thermal properties of the materials individually or in combination. Future testing of nest insulation should be under standard conditions that limit air movement but the role of the nest location in situ should be investigated in future research.

Bird nests represent an extended phenotype that is variable among and within species in terms of nest location and construction materials. It has also been suggested that nests indicate niche construction, although empirical evidence to support this is lacking. The nest wall is often considered to confer some insulation because this would help minimize the energetic expenditure by the incubating adult. However, it has been previously suggested that nests are constructed primarily for their structural role rather than for insulation, but to date, studies have used a variety of techniques to investigate the insulation of nest walls but only for relatively few species. This study used temperature loggers to determine insulatory values of nests for 16 previously undescribed species and to replicate values for eight previously described species. In addition, data for nest wall insulation that were determined using temperature loggers have been collated for a total of 32 different passerine species. The effects of nest dimensions, mass, and composition on these values were examined. Base thickness, but not wall thickness, and nest mass significantly positively affected insulatory values. This study found that the proportions of feathers and moss in the nest wall significantly positively correlated with insulatory values. This suggests that there is a key role for nest materials in determining insulation, which provides empirical evidence that nest building constitutes niche construction. The data will also help us interpret data from future studies of the thermal properties of nests. Ultimately, we need to develop our understanding of the role of insulatory values in the evolution of nest function.

Avian incubation relies on maintenance of the appropriate temperature and humidity within the nest. Previous studies suggested that conductance of the nest wall to water vapour was relatively low, albeit greater than the conductance of the eggshell, but no empirical studies confirmed this. In this study hygrometer loggers were used to measure water vapour inside and outside nest cups to determine conductance of the nest wall. Average water vapour conductance values for nine species of passerine ranged from 479 mgH2O·day-1·Torr-1 for Common Chaffinch Fringilla coelebs nests to 712 mgH2O·d-1·Torr-1 for Eurasian Reed Warbler Acrocephalus scirpaceus nests. Generally, water vapour conductance values were two orders of magnitude higher than that of published values for the eggshell for these species, although humidity in the nest cup were comparable to published data for passerine nests. These results indicate that in the study species the nest wall was not an effective barrier to water vapour loss. Reconsideration of high values for nest wall conductance, nest attentiveness and sources of water to create humidity, have led to a new approach that deals with nest humidity as part of the water budget during the incubation period. Over time the amount of water vapour required to raise nest humidity far exceeds that released by the eggs. It is proposed that nest humidity is driven by cutaneous water loss from the incubating bird, rather than water vapour lost from the eggs, in order to counter loss of humidity through the nest wall and during incubation recesses.

Increasing nestbox size affects mass of whole nests and the moss component but not proportions of nest materials except for feathers, which are inversely correlated with nestbox floor area.

Capsule: The use of woody material in the outer nest is significantly associated with heavier passerine species, whereas the use of grass, moss or leaves is unrelated to body mass.

Bird nests can have various roles but all act as the location for incubation, so at least have to serve to hold and support the incubating bird and its clutch of eggs. Nest construction is species specific and the use of materials varies between different parts of the nest. At present we know very little about the role that these materials play in the structural characteristics of the nest. This study examined materials from deconstructed nests from four species of thrush (Turdidae) and two species of finch (Fringillidae) that all constructed nests made of woody stems. It was hypothesised that structural properties would vary within the different regions of a nest, with thicker and stronger materials being found in parts of the nest needing the most support. Secondly, it was predicted that structural properties would vary little between nests of members of the same family, but would be quite different between nests of different families. Nests were deconstructed to quantify the materials used in the cup lining, and the upper and lower parts of the outer nest. The 20 thickest pieces of material were selected from each nest part and for each piece, and their diameter and mass quantified. Each piece was then subjected to a three-point bending test using an Instron universal testing machine to determine its rigidity and bending strength. Placement of materials in the nest was non-random in all species. The materials used in the outer part of the nest were thicker, stronger and stiffer than those materials found in the cup lining. The extent to which these structural properties varied between families depended on where the material was taken from the nest. Both strength and rigidity strongly positively correlated with the diameter of the piece of material. We hypothesise that birds are not directly aware of the structural properties of the material per se but rather assess diameter and mass of the material when they pick it up by the bill. Using this information they decide on whether the piece is suitable for that appropriate stage of nest construction.

Bird nests represent an extended phenotype of individuals expressed during reproduction and so exhibit variability in composition, structure and function. Descriptions of nests based on qualitative observations suggest that there is interspecific variation in size and composition but there are very few species in which this has been confirmed. For these species, data of the amounts of different materials indicate that nest construction behaviour is plastic and affected by a variety of factors, such as prevailing temperature, geographic location, and availability of materials. The lack of data on nest composition is hampering our understanding of how nests achieve their various functions and how different species solve the problem of building a nest that will accommodate incubation and allow successful hatching of eggs. This study deconstructed nests of four species of the Turdidae, four species of the Muscicapidae, and six species of the Fringillidae and quantified the size of the nests and their composition. These data were used to test: (1) whether nest size correlated with adult bird mass; (2) whether it was possible to distinguish between species on the basis of their nest composition; and (3) whether, within a species, it was possible to distinguish between the cup lining and the rest of the nest based on composition. Most but not all nest dimensions correlated with bird mass. Principal component analysis revealed species differences based on nest composition and discriminant analysis could distinguish cup lining from the outer nest based on material composition. Intraspecific variation in composition varied among species and in general fewer types of material were found in the cup lining than the outer nest. These data provide insight into how nests are constructed by the different species and in conjunction with studies of the mechanical, thermal and hydrological properties of a nest, will begin to reveal how and why individual species select particular combinations of materials to build a nest.

Capsule: Air movement over a nest increases the rate of cooling within the nest cup but the walls provide good thermal insulation. Aims: This study compared nests of six bird species of the families Fringillidae and Motacillidae to investigate the insulative properties in still and moving air treatments. It was hypothesized that differences in nest size and moving air would differ between species and would have a significant effect on insulatory values of the nests. Methods: Nest dimensions were measured for a total of 35 nests from six species. Thermal properties of the nests were recorded using temperature loggers within nests placed in a wind tunnel under still and moving air conditions. Results: Insulatory values and internal nest cooling rates were significantly increased by moving air. There was no significant difference between species for the thermal properties of nests but nest mass correlated with greater insulatory values and a lower rate of cooling within the nest cup. Nest wall thickness had no significant effect on the thermal characteristics of the nests. Conclusion: The use of a constructed nest mitigated the effects of air movement but the differences between species reflected difference in nest mass rather than wall thickness.

The field of comparative psychology has traditionally focussed on investigating the cognitive abilities of a small number of mammal and bird species, but in order to understand the evolution of cognition, it is essential to examine cognitive abilities across a large range of vertebrates. Reptiles are particularly interesting in this context as they represent a key amniotic Class that do not develop under high, stable temperatures, which can produce phenotypic variation in the population. As their patterns of development differ substantially from those of birds and mammals reptiles can be used to investigate fundamental questions relating to factors shaping cognition; questions that cannot be asked in mammals and birds. In this review, we highlight some of these areas of interest and consider how the emerging field of reptile cognition can address crucial questions in cognitive science.

After laying their eggs, oviparous reptiles are reliant on the external environment to provide the required incubation conditions for successful embryonic development. Egg incubation temperature can impact the behaviour of various species of reptiles, but previous experiments have focused on the impact of incubation environment on hatchlings, with only a limited number of studies focussing on the longer-term behavioural consequences of incubation environment. This study investigated the effects of developmental environment on bearded dragon lizards (Pogona vitticeps) that were incubated at different temperatures within the natural range; half of them were incubated at a ‘hot’ temperature (30 ± 3 oC) and half at a ‘cold’ temperature (27 ± 3 oC). The growth and foraging behaviour of the lizards was then compared over 18 weeks of development. Although the lizards incubated at cooler temperatures grew more quickly, those incubated at the hotter temperature completed the foraging task more often and had significantly faster running speeds than those incubated at the cooler temperature. These results show that egg incubation temperature impacts the foraging behaviour of juvenile lizards and suggest a potential trade-off between growth and foraging speed, which could influence an animal’s life history trajectory.

Capsule Pied Flycatchers use different materials to construct their nests according to localised habitat and geographical location. Aims This study tested the hypotheses that birds would use the leaves they normally encountered within their breeding territories and that nest composition varied between geographical locations. Methods In Lancashire, Pied Flycatcher nests were collected from nestboxes built in locations dominated by different tree species and were deconstructed to determine which materials were used. Results Materials found in nests generally reflected the localised habitat around the nest rather than showing evidence of active collection from distant sources of material. Nests from Lancashire were significantly different in composition when compared with published data for nests from north Wales and central Spain. The use of moss was dominated by the use of one species in all but two nests. Conclusion Pied Flycatchers exhibit plasticity in nest construction behaviour because they were opportunistic in their choice of most nesting materials although they may be selective in their choice of moss.

Personality traits, defined as differences in the behavior of individual animals of the same species that are consistent over time and context, such as ‘boldness,’ have been shown to be both heritable and be influenced by external factors, such as predation pressure. Currently, we know very little about the role that early environmental factors have upon personality. Thus, we investigated the impact of incubation temperature upon the boldness on an oviparous reptile, the bearded dragon (Pogona vitticeps). Eggs, from one clutch, were incubated at two different average temperatures within the normal range. After hatching the lizards were raised under the same environmental conditions. Novel object and novel environment tests were used to assess personality. Each test was repeated in both the short term and the long term. The results revealed that incubation temperature did impact upon ‘boldness’ but only in the short term and suggests that, rather than influencing personality, incubation temperature may have an effect on the development of behavioral of oviparous reptiles at different stages across ontogeny.

The various roles that birds’ nests play are widely discussed and there is increasing interest in developing a better understanding of how they achieve these roles. The insulatory properties of nests have been investigated in a variety of songbird species and can vary with temperature and latitude. However, data are only available for a limited number of species. Here, we study the variations of the insulatory properties of European Robin ( Erithacus rubecula) nests in conjunction with the morphology of the nests and composition of the materials used in construction. As well as quantifying the materials used to construct these nests for the first time, we test the hypothesis that there is a latitudinal effect on nest insulation. Robin nests have a cup structure that is quite distinct, and easily separated, from the nest's base. Although the cup and nest's base shared similar construction materials discriminant analysis showed that they can be distinguished on the basis of their differing proportions of leaves. Insulatory values correlated with the mass of leaves in the cup but not latitude. Unlike other songbirds of comparable size that nest in nestboxes, European Robins appear to be able to use plant-derived materials rather than animal-derived materials to effectively insulate their nests.

Animals that use materials to build nest structures have long since fascinated biologists and engineers alike. Avian nests are generally composed of collected materials brought together into a cup-like structure in which the bird sits to incubate eggs and, in many cases, it is where chicks are reared. Hence, the materials in a nest can be presumed to be loaded in compression, but relatively few studies have investigated the mechanical role of the nest elements and their position within the structure. However, recent studies on avian and primate nests have used engineering tests to quantify the structural properties of the nest elements to provide insight into how animals arrange the materials they collect and their mechanical role within the nest. In two studies, we deconstructed nests from Common Blackbirds (Turdus merula) and Bullfinches (Pyrrhula pyrrhula) into their component parts. We then used three-point bending tests to investigate regional variation in the structural properties of these elements within the nest. Results indicate that the birds use materials with different physical characteristics in various parts of the nest, thereby providing an indirect indication of nest-building behaviour in these species. We also used a novel cutting test, previously developed to measure the mechanical anisotropy of keratin, to investigate the mechanical behaviour of the mud-cup structure found in Common Blackbird and Song Thrush (Turdus philomelos) nests. This allowed us to determine whether these species utilise and arrange mineralised materials in a particular way to improve the toughness of their nests. The applicability of similar and other mechanical testing methods are discussed in relation to future investigations of the architecture and function of songbird nests.

Several methods have been used to determine the thermal properties of nests and in the last few years small iButton® temperature loggers have been used to determine an insulatory value. A recent study on Common Bullfinch ( Pyrrhula pyrrhula) nests used a different method, namely infrared (IR) thermography, to study nest wall insulation because pushing temperature loggers into the nest wall materials would have destroyed their structural integrity and probably adversely affected the insulatory value. Here, we compared the insulatory values of Common Linnet ( Carduelis cannabina) nests determined using temperature loggers (to record cooling rates in °C 20 s−1) with the temperature differences (ΔT in °C) across the nest wall as measured with IR thermography when the inside of the nest was heated under a steady state. Insulatory values were more variable than ΔT but there was no correlation between these two proxy measures of insulation. Despite being within the same family, Common Linnets build nests with very different materials from Common Bullfinches but ΔT values measured using IR thermography suggested that the nest wall of Common Linnet nests offered better insulation than the walls of Bullfinch nests. Our results suggest that comparative studies need to use the same methodologies but more research is needed to better understand the limitations of different methods in determining nest wall insulation.

Birds’ nests exhibit a considerable amount of plasticity in their size and construction. Indeed, several studies have shown that geographical location can affect this plasticity because local climatic conditions appear to affect nest-construction behaviours. This study examined nests collected in the UK and housed either at the University of Lincoln or at the British National Nest Reference Collection at the Hunterian Museum, University of Glasgow. Our aim was to increase the species diversity and the sample sizes for each species, over and above published studies. Mass and linear dimensions were recorded from nests of five finch species and two thrush species together with longitude and latitude for the nest site locations. An effect of species was shown for all finch nest dimensions measured but only for particular thrush dimensions. Latitude (range from 50.4 to 57.8°N) had no effect on nest measurements taken for thrush or finch species. However, while longitude (range from 6.8°W to 1.1°E) had no effect on thrush nests, it had a significant effect on the nest mass of finches, with nests constructed in the west being lighter in mass than those from the east. Previous studies examining the effects of latitude have used nests collected from different locations and built in a single year, which suggests that climatic conditions will be broadly comparable between locations. We found that museum collections have nests from a range of years and this rather limits their value in studies trying to ascertain the effects of location. Across different years there may be many unknown factors contributing to the patterns observed. We suggest that any future studies of the effects of climate on nest construction will have to rely on materials especially collected rather than using museum collections.

The behaviour of the incubating bird should be linked with the functional characteristics of its nest because they could minimise the incubation period that will reduce the risk of predation. Incubation attentiveness (percentage of daylight hours) in small passerines is a highly variable behaviour that is unrelated to egg mass. The thermal characteristics of nests are known to vary but whether they correlate with attentiveness, i.e. high attentiveness could reflect poorly insulated nests, has yet to be investigated. In this study, insulatory values were determined using temperature loggers for five species of British songbird in order to supplement equivalent data for six species from published sources. Attentiveness values for each species were determined from the literature. There was a significant negative correlation between attentiveness and insulatory values, which was unaffected by phylogeny. By contrast, attentiveness did not correlate with female body mass. That the avian incubation behaviour correlates with the functional properties of bird nests supports the concept of a bird–nest incubation unit, where reproductive success depends on both the bird and the nest structure. Further research should be directed towards a better understanding of this relationship for more species and, given the observed plasticity exhibited in nest composition and function, within species.

Thermal properties of nests have been investigated using a variety of techniques. Infrared (IR) thermography has the advantage of being a non-invasive technique allowing the integrity of the nest wall to be retained during measurement. This study investigated the insulative properties of nests of the Eurasian Bullfinch (Pyrrhula pyrrhula), the Common Blackbird (Turdus merula) and the Song Thrush (Turdus philomelos) using IR thermography. Nests were inverted over a heat source and the temperature of the external nest surface was recorded. Bullfinch nests were less insulated than thrush nests. Including foil inside the nest cup decreased the amount of convection through the open walls of Bullfinch nests. Removal of the outer nest and cup lining of thrush nests only slightly decreased the degree of insulation offered by the nest indicating an important insulative role for the substantial 'mud cup' in these nests. The results suggested that the nest wall is not sealed and convection currents may a play a significant role in nest insulation. In conjunction with a steady-state heat source IR thermography is useful in assessing the insulative properties of bird nests.

Studies investigating nest function in birds show that individual preferences and environmental temperature can affect the type and amount of materials used in their construction and, thus, how well insulated they are. Levels of insulation of bird nests may be important because this could impact on heat loss by adults and eggs during incubation, and by nestlings during rearing, which may in turn affect individual fitness. Here we used infrared (IR) thermography to measure the surface temperature of nests of Great Tits Parus major and Blue Tits Cyanistes caeruleus in situ during incubation to test the hypothesis that nest insulation predicts reproductive success. Previous studies of thermodynamics during incubation have focussed on factors, e.g. egg temperature, which do not directly measure the thermal conditions in the nest itself. Rarely applied to studies of avian incubation, IR thermography has yet to be used to quantify the thermal properties of nests with the incubating bird in situ. The r...

Data collected from wildlife telemetry studies relies on tagging and attachment having minimal impactson behaviour. Though a widespread technique, relatively few studies evaluate the impacts of differingtagging methods on both welfare and behaviour. Here we use tracking data, collected for other aims, toinvestigate the impact of inter-peritoneal surgical implantation of acoustic transmitters on the healthand behaviour of common bream, Abramis brama (L.). In five separate capture events, the behaviour interms of distances moved and linear range of newly tagged fish (n = 61) were compared to previouslytagged fish (n = 55) present in the same river at the same time. In the first 5 days post-tagging, newlytagged fish moved significantly further than previously tagged fish. Despite this difference, the linearranges moved by the two groups of fish were equivalent. During 6–10 days post tagging there was nosignificant differences between the two groups. Thus, the tagging procedure had short term, but not longterm behavioural impacts. In addition, a number of tagged fish were recaptured between 51 and 461days post-surgery. Recaptured fish appeared to have clean, well-healed incisions and exhibited ‘normal’behaviour in that they were caught alongside a large number of conspecifics. Three recaptured taggedfish were translocated ∼35 km downstream, to ascertain how translocation would affect their behaviour.The translocated fish had a greater linear range than control fish, with all three fish returning to the siteof capture within 6 to 24 days, suggesting that common bream can exhibit site fidelity.

Four species of songbird, Great Tits Parus major, Blue Tits Cyanistes caeruleus, Pied Flycatchers Ficedula hypoleuca and Wood Warblers Phylloscopus sibilatrix, have nests that have similar insulatory properties, but are made of widely differing materials. This study used a novel technique to investigate the role of air-gaps between component materials of the nest wall on the insulatory properties of the whole nest. Nests of four passerine species were investigated by measuring the rate of warming of a temperature logger within the wall materials before and after vacuum-packing, which removed the air and compressed the nest. After vaccum-packing nest volume was estimated to have decreased by 90% and the measured insulatory values decreased by an average of 20% irrespective of the nest materials. Nest maintenance behaviors that may serve to ensure that air-gaps are maintained within the nest wall, which perhaps maximises its insulatory properties, are discussed.

Testudines exhibit considerable variation in the degree of eggshell calcification, which affects eggshell conductance, water physiology of the embryos, and calcium metabolism of embryos. However, the underlying reason for different shell types has not been explored. Phylogenetically controlled analyses examined relationships between egg size, shell mass, and clutch size in ∼200 turtle species from a range of body sizes and assigned by family as laying either rigid- or pliable shelled eggs. Shell type affected egg breadth relative to pelvic dimensions, egg mass, and relative shell mass but did not affect size, mass, or total shell mass of the clutch. These results suggest that calcium availability may be a function of body size and the type of shell may reflect in part the interplay between clutch size and egg size. It was further concluded that the eggshell probably evolved as a means of physical protection. Differences in shell calcification may not primarily reflect reproductive parameters but rather correlate with the acidity of a species’ nesting environment. Low pH environments may have thicker calcareous layer to counteract the erosion caused by the soil and maintain the integrity of the physical barrier. Limited calcium availability may constrain clutch size. More neutral nesting substrates expose eggshells to less erosion so calcification per egg can be reduced and this allows larger clutch sizes. This pattern is also reflected in thick, calcified crocodilian eggs. Further research is needed to test whether eggshell calcification in the testudines correlates with nest pH in order to verify this relationship.

Recent work exploring the relationship between early environmental conditions and cognition has shown that incubation environment can influence both brain anatomy and performance in simple operant tasks in young lizards. It is currently unknown how it impacts other, potentially more sophisticated, cognitive processes. Social-cognitive abilities, such as gaze following and social learning, are thought to be highly adaptive as they provide a short-cut to acquiring new information. Here, we investigated whether egg incubation temperature influenced two aspects of social cognition, gaze following and social learning in adult reptiles ( Pogona vitticeps ). Incubation temperature did not influence the gaze following ability of the bearded dragons; however, lizards incubated at colder temperatures were quicker at learning a social task and faster at completing that task. These results are the first to show that egg incubation temperature influences the social cognitive abilities of an oviparous reptile species and that it does so differentially depending on the task. Further, the results show that the effect of incubation environment was not ephemeral but lasted long into adulthood. It could thus have potential long-term effects on fitness.

The pelvic girdle provides physical support and attachment for the hind limb musculature. In birds there is variability in pelvic morphology across different orders and this has been used as evidence for various types of locomotion. However, the morphological variation of pelvic bones has yet to be studied systematically in birds. Therefore, we investigated basic allometric relationships among female body mass (as a size proxy) and various pelvic measurements in a phylogenetic context. We also examined in detail the inter-relationships among various pelvic measurements. Also considered were the effects of broader taxonomic relationships at the level of order, with further examination of the influence of style of terrestrial locomotion on the allometric relationships. Positive relationships were initially found among all pelvic linear measurements and female body mass (FBM). The relationships among measures of pelvic width and FBM were isometric, whereas those between pelvic length and FBM showed positive allometry. Also, FBM explained more of the variance in pelvic length than in width. Similarly, the angle of the pelvis had a significant negative relationship, but FBM only explained a very low proportion of the variation in pelvic angles. In general terms, ancova showed that the effect of FBM was smaller than the effect of locomotor style in this species set. Both the synsacrum and pelvic girdle play roles in weight support and therefore scale in proportion to body weight accordingly. All three parts of the pelvis (ilium, ischium and pubis) are attached around the acetabulum and also provide muscle attachment points, so it might be expected for them to scale in a similar manner. Increased angulation of the pelvis is linked to orders which employ their hind limbs in feeding, perching and running, although FBM also explains a very low proportion of the variation in pelvic angle. Muscle attachment and the confines on morphology presented by locomotion explain much of the variation exhibited by the relationships among pelvic measurements.

Numerous new fossils have driven an interest in reproduction of early birds, but direct evidence remains elusive. No Mesozoic avian eggs can be unambiguously assigned to a species, which hampers our understanding of the evolution of contact incubation, which is a defining feature of extant birds. Compared to living species, eggs of Mesozoic birds are relatively small, but whether the eggs of Mesozoic birds could actually have borne the weight of a breeding adult has not yet been investigated. We estimated maximal egg breadth for a range of Mesozoic avian taxa from the width of the pelvic canal defined by the pubic symphysis. Known elongation ratios of Mesozoic bird eggs allowed us to predict egg mass and hence the load mass an egg could endure before cracking. These values were compared to the predicted body masses of the adult birds based on skeletal remains. Based on 21 fossil species, we show that for nonornithothoracine birds body mass was 187% of the load mass of the eggs. For Enantiornithes, body mass was 127% greater than the egg load mass, but some early Cretaceous ornithuromorphs were 179% heavier than their eggs could support. Our indirect approach provides the best evidence yet that early birds could not have sat on their eggs without running the risk of causing damage. We suggest that contact incubation evolved comparatively late in birds.

Capsule Common blackbirds select different materials, with varying biomechanical properties, to construct different parts of their nest. Aims This study tested the hypothesis that outer components of a nest have a more structural role and so are stronger than materials used to line the cup. Methods Blackbird nests were measured prior to being dismantled to isolate structural components which were tested for mechanical strength and rigidity. Results Outer nest wall materials were significantly thicker, stronger and more rigid than materials in the inner structural wall or the cup lining. In the vertical plane materials used in the structural wall did not differ. By contrast, lining materials from the bottom of the nest cup were significantly thicker, stronger and more rigid than materials from the top of the cup. Conclusion Blackbirds use different materials in nest construction roles suited to their properties and so may be able to recognise the structural properties of these materials. Materials on the outside of the nest may have a key structural role during construction.

Post-natal parental care seems to have evolved numerous times in vertebrates. Among extant amniotes, it is present in crocodilians, birds, and mammals. However, evidence of this behavior is extremely rare in the fossil record and is only reported for two types of dinosaurs, and a varanopid ‘pelycosaur’. Here we report new evidence for post-natal parental care in Philydrosaurus, a choristodere, from the Yixian Formation of western Liaoning Province, China. We review the fossil record of reproduction in choristoderes, and this represents the oldest record of post-natal parental care in diapsids to our knowledge.

Recent fossil finds in China and Argentina have provided startling new insights into the reproductive biology and embryology of pterosaurs, Mesozoic flying reptiles. Nineteen embryos distributed among four species representing three distinct clades have been described and all are assumed to be at, or near, term. We show here how the application of four contrasting quantitative approaches allows a more precise identification of the developmental status of embryos revealing, for the first time to our knowledge, the presence of middle and late developmental stages as well as individuals that were at term. We also identify a predicted relationship between egg size and shape and the developmental stage of embryos contained within. Small elongate eggs contain embryos at an earlier stage of development than larger rounder eggs which contain more fully developed embryos. Changes in egg shape and size probably reflect the uptake of water, consistent with a pliable shell reported for several pterosaurs. Early ossification of the vertebral column, limb girdles and principal limb bones involved some heterochronic shifts in appearance times, most notably of manus digit IV, and facilitated full development of the flight apparatus prior to hatching. This is consistent with a super-precocial flight ability and, while not excluding the possibility of parental care in pterosaurs, suggests that it was not an absolute requirement.

Figure S1: Looking response time for the looking upwards condition. Figure S2: Looking response time for the looking sideways condition

Recent studies are documenting the extent to which the mass and construction of bird nests varies between individuals and locations. In the Blue Tit ( Cyanistes caeruleus) and Great Tit ( Parus major), temperatures experienced by females during nest construction are inversely related to nest mass. Moreover, Mainwaring et al. ( Journal of Biogeography, 2012) showed that nests constructed at high latitude are heavier and better insulated than nests built by conspecifics in the south. Although mean spring temperature was used as a proxy for latitude in the Mainwaring et al. study, it remains untested whether individual birds build nests in response to a narrower range of temperatures experienced at the start of the breeding season. Our study showed that irrespective of latitude nest mass, and in particular nest cup mass, of Blue Tits and Great Tits was significantly affected by the temperature experienced by the birds for the seven days preceding clutch initiation. Similar results were seen with the insulatory properties of nests. The potential impact of variation in nest construction and insulation on subsequent incubation and chick-rearing behaviour is discussed.

Capsule Mortality from egg-laying to fledging is species-dependent with Great Tits exhibiting greater losses of chicks, Coal Tits greater losses of eggs and Blue Tits exhibiting comparable rates of mortality of eggs and chicks. Aims To determine whether reproductive losses during incubation and chick-rearing were different and to ascertain whether there were different effects in three closely related songbirds. Methods Breeding success of Great Tits Parus major, Blue Tits Cyanistes caeruleus and Coal Tits Periparus ater at Treswell Wood, Nottinghamshire, England was examined, selecting only those nests which fledged at least one chick. Mortality during incubation (i.e. loss of eggs) or rearing (i.e. loss of chicks) was recorded per nest and annual means were calculated and used in the analysis, which examined relationships between year, first-egg date and species. Key factor analysis was used to investigate the relative effects of egg or chick losses on the total breeding mortality. Results Timing of repr...

Nest humidity is a function of how water vapour is retained within the nest. Previous analysis suggested that in general, nest humidity was largely unaffected by ambient humidity but there was no consideration of the type of nest involved. This study examined data collected from the literature to test the hypothesis that the relationship between nest and ambient humidity is a function of the type of nest. Data for water vapour pressure for the egg (PE), nest (PN) and ambient air (PA) were collected for 48 examples of nests from 44 species of bird from a range of Orders. Initial egg mass and water vapour conductance of the eggshell was also recorded for each species. Analysis showed that birds on scrape nests are able to raise PN above PA by on average 5 Torr irrespective of PA. By contrast, PN in cup nests was unaffected by PA, such that at low values nests are well insulated against water vapour loss. The balance between the proportion of water vapour lost from the egg to the ambient air that is controlled by the nest varied with the type of nest and PA. For eggs in scrape nests mass specific water vapour conductance showed a positive relationship with PA. By contrast, for eggs in cup nests the relationship was negative and under conditions of low PA the high PN means that mass specific shell conductance values have to be high so as to ensure the appropriate rate of weight loss from the egg. Whilst birds do not control nest humidity directly the inter-relationship between weight loss from an egg, its initial mass, its shell conductance, and the incubation period can now be extended to include the water vapour conductance of the nest wall.