Coordination in parental effort decreases with age in a long‐lived seabird

Biparental care is widespread in avian species. Individuals may match the contribution of their partner, resulting in equal parental effort, or may exploit their partner, to minimise their own investment. These two hypotheses have received much theoretical and empirical attention in short‐lived species, that change mates between seasons. However, in species with persistent pair bonds, where divorce is rare and costly, selective pressures are different, as partners share the value of future reproduction. In such species, coordination has been suggested to be adaptive and to increase early in life, as a consequence of the importance of mate familiarity. However, as birds age, an increase in re‐pairing probability occurs in parallel to a decline in their survival probability. At the point when partners no longer share future reproductive success, exploitation of a partner could become adaptive, reducing selection for coordinated effort. As such, we suggest that coordination in parental effort will decline with age in long‐lived species. Using incubation bout duration data, estimated from salt‐water immersion bio‐loggers, deployed on black‐browed albatrosses Thalassarche melanophris, we examined the correlation in incubation bout durations for sequential bouts, as a measure of coordination. Our results show that coordination is highest in inexperienced pairs (early in reproductive life) and declines throughout the lifetime of birds. This suggests that both cooperation, indicated by coordinated effort, and conflict over care occurs in this species. We find no change in individual bout duration with increasing breeding experience, and hence no support for the hypothesis that aging leads to changes in individual incubation behaviour. This is, to our knowledge, the first study to demonstrate strong coordination in parental care when pairs share future reproductive success, but a decline in coordination with age, as sexual conflict increases

Flight Initiation Distance and Starting Distance: Biological Effect or Mathematical Artefact?

In many studies, flight initiation distance (FID, the distance at which a prey starts to flee at the approach of a walker) is positively related to starting distance (SD, the distance at which the walker begins to approach) and alert distance (AD, the distance at which the focal individual becomes alert to the threat). In spite of the fundamental differences between SD, a covariate that may not have any biological effect, and AD, a measure related to the behaviour of the animal, it is common to use SD as a proxy for AD when AD is hard to measure (e.g. in species that do not exhibit distinguishable alert postures). However, the relationship between SD and AD or FID may not have any biological reasons, but may instead simply result from a mathematical artefact because of the constraints SD = AD = FID. Under such constrains, the homoscedasticity assumption is violated, and thus, the classical null hypothesis of linear regression (slope = 0) is invalid. In this study, we first show that using SD as a proxy for AD can strongly affect the results on FID. Using data from FID tests on alpine marmots (Marmota marmota), a linear mixed model with AD as a covariate, suggested that the interaction between previous activity and AD had an effect on FID, while this effect was not detected when SD replaced AD as the covariate in the analysis. We then propose that the actual statistical test of the relationship between SD, AD and FID should be based on a null hypothesis that incorporates the constraint SD = AD = FID = 0 and generate 95% CI of simulated slopes obtained from random values under this constraint. This null hypothesis can be rejected if the observed slope of the relationship between two of these variables is outside the 95% CI. We demonstrated that, for alpine marmots, the observed slope of the relationship between AD and SD was within the 95% CI of the simulated slopes. The absence of a statistically significant biological effect in the relationship between SD and AD raises important questions on the outcome of relationship between SD and FID. In Alpine marmot flight, decision should be studied separating the effect of SD on AD and the effect of AD on FID

Personalities influence spatial responses to environmental fluctuations in wild fish

Although growing evidence supports the idea that animal personality can explain plasticity in response to changes in the social environment, it remains to be tested whether it can explain spatial responses of individuals in the face of natural environmental fluctuations. This is a major challenge in ecology and evolution as spatial dynamics link individual‐ and population‐level processes. In this study, we investigated the potential of individual personalities to predict differences in fish behaviour in the wild. Specifically, our goal was to answer if individual differences in plasticity of space use to sea surface temperature could be explained by differences in personality along the reactive–proactive axis. To address this question, we first conducted repeated standard laboratory assays (i.e., open‐field test, novel object test and mirror stimulation test) to assess the personality type of 76 wild‐caught Atlantic cod (Gadus morhua). Next, we released the fish back into the sea and monitored their spatial behaviour over large temporal (16 months) and spatial (a whole fjord) scales, using high‐resolution acoustic tracking. We demonstrate that (a) cod personality traits are structured into a proactive–reactive syndrome (proactive fish being more bold, exploratory and aggressive), (b) mean depth use of individuals is mainly driven by sea temperature and (c) personality is a significant predictor of home range changes in the wild, where reactive, but not proactive, individuals reduced their home range as sea temperature increased. These findings expand our understanding of the ecological consequences of animal personality and the mechanisms shaping spatial dynamics of animals in nature.publishedVersio

A global meta-analysis reveals higher variation in breeding phenology in urban birds than in their non-urban neighbours

Cities pose a major ecological challenge for wildlife worldwide. Phenotypic variation, which can result from underlying genetic variation or plasticity, is an important metric to understand eco-evolutionary responses to environmental change. Recent work suggests that urban populations might have higher levels of phenotypic variation than non-urban counterparts. This prediction, however, has never been tested across species nor over a broad geographical range. Here, we conducted a meta-analysis of the avian literature to compare urban versus non-urban means and variation in phenology (i.e. lay date) and reproductive effort (i.e. clutch size, number of fledglings). First, we show that urban populations reproduce earlier and have smaller broods than non-urban conspecifics. Second, we show that urban populations have higher phenotypic variation in laying date than non-urban populations. This result arises from differences between populations within breeding seasons, conceivably due to higher landscape heterogeneity in urban habitats. These findings reveal a novel effect of urbanisation on animal life histories with potential implications for species adaptation to urban environments (which will require further investigation). The higher variation in phenology in birds subjected to urban disturbance could result from plastic responses to a heterogeneous environment, or from higher genetic variation in phenology, possibly linked to higher evolutionary potential

Archiving primary data: solutions for long-term studies

The recent trend for journals to require open access to primary data included in publications has been embraced by many biologists, but has caused apprehension amongst researchers engaged in long-term ecological and evolutionary studies. A worldwide survey of 73 principal investigators (Pls) with long-term studies revealed positive attitudes towards sharing data with the agreement or involvement of the PI, and 93% of PIs have historically shared data. Only 8% were in favor of uncontrolled, open access to primary data while 63% expressed serious concern. We present here their viewpoint on an issue that can have non-trivial scientific consequences. We discuss potential costs of public data archiving and provide possible solutions to meet the needs of journals and researchers

Ressources trophiques et reproduction chez les mammifères et les oiseaux

Problems raised by relationships between food resources and reproduction in mammals and birds are various and imply many theoretical and empirical aspects of biological fields such as physiology, ecology, ethology, population biology and genetics. The study of these relationships reveals ecological or evolutionary consequences of spatial and temporal variation in abundance and quality of trophic resources on reproduction. This paper first reviews and clarifies the main concepts of life history theory and sociobiology/behavioural ecology, generally used in that literature, followed by several recommandations upon their use. Afterwards, several currently developed aspects of birds and mammals reproduction in function of food resources availability are reviewed. Reproductive capacities and fecundity, adjustment in the number of young before or after birth or hatching, sex-ratio adjustment in the progeny and sex-biased investment, parental care, parental expenditure, parental investment and parent-offspring conflict in function of availability in food resources are analysed in details. The consequences of lowering trophic resources on some aspects of the offspring’s ontogeny are also developed.Les problèmes soulevés par les relations entre les ressources trophiques et la reproduction des mammifères et des oiseaux sont variés et font appel à des théories couvrant de nombreux champs de la biologie tels que la physiologie, l’écologie, la biologie ou la génétique des populations. L’étude de ces relations la mise en évidence des conséquences, évolutives ou immédiates, des variations spatiales et temporelles de l’abondance et de la qualité des ressources alimentaires sur la reproduction. Cette synthèse présente, tout d’abord, les deux approches théoriques des histoires de vie et sociobiologique/étho-écologique, couramment utilisées pour l’étude des relations entre ressources et reproduction. Suit une mise au point des concepts employés fréquemment dans la littérature sur le sujet, de même que quelques recommandations quant à leur utilisation. Dans un deuxième temps, un inventaire de certains aspects développés récemment sur la question, chez les oiseaux et les mammifères, est dressé. Les capacités de reproduction et la fécondité, l’ajustement du nombre de jeunes avant ou après la naissance, l’ajustement de la sex-ratio de la progéniture et l’investissement différentiel en fonction du sexe du jeune, les soins parentaux, les dépenses parentales, l’investissement parental et le conflit parent-jeune, sont analysés plus en détails. Les conséquences d’une diminution des ressources sur quelques aspects de l’ontogénèse des jeunes sont également développées.Réale Denis. Ressources trophiques et reproduction chez les mammifères et les oiseaux. In: Revue d'Écologie (La Terre et La Vie), tome 52, n°4, 1997. pp. 369-410

Interactions agonistiques en fonction de la densité et de la structure dans une population insulaire de mouflons (Ovis musimon)

The Haute island (Kerguelen subantarctic archipelago) population of Corsican Mouflon (Ovis musimon) is characterized by a demographic cycle, with periodic die-offs every three to five years. The frequency of displacement from feeding sites between a period of peak population density (1992) and a period of relative low density that followed a winter crash (1993) were compared. Agonistic interactions that occurred in other situations than feeding competition were also investigated. During both years, mouflons did not interact at random, but mainly selected individuals of their own age-sex class. The frequency of displacements decreased for females and lambs between the two years but remained stable for males. Nevertheless, displacements from feeding sites were very infrequent, even at peak population density. This result suggests a low direct competition for food in this population. In contrast, the frequency of agonistic interactions decreased for all the age-sex classes except the adult males. At peak population density, the frequency of agonistic behaviours was much higher among subadult males than among the other classes. This was due to their frequent involvement in huddles (simultaneous interactions of three individuals or more). The high frequency of subadult male aggressive interactions, with associated high energy expenditure and risk of wounding, could reduce their winter survival probability at peak population density.La population de mouflons (Ovis musimon, Pallas, 1 802) introduits sur l’île Haute, dans l’archipel de Kerguelen (TAAF), est caractérisée par un cycle démographique marqué, des épisodes de forte mortalité hivernale survenant tous les trois à cinq ans. Les fréquences de déplacements d’individus par un congénère de sites d’alimentation et les taux d’interactions agonistiques ont été comparés entre une période de forte densité et sex-ratio équilibrée (été 1992) et une période de relative faible densité et forte proportion de femelles succédant à un crash hivernal (été 1993). Les deux années, les animaux des différentes classes d’âge et de sexe ont interagi préférentiellement avec des congénères de leur propre classe. Avec la réduction de densité, la fréquence de déplacements d’un site d’alimentation a diminué pour les femelles et les agneaux, mais est restée stable pour les mâles. Ces interactions sont néanmoins très rares et suggèrent une faible compétition alimentaire directe dans cette population. D’autre part, la fréquence des interactions agonistiques a chuté pour toutes les classes, à l’exception des mâles adultes. A forte densité, les mâles subadultes ont interagi beaucoup plus que les autres classes. La plupart de leurs interactions agonistiques sont survenues à l’occasion de mêlées, interactions impliquant simultanément plus de deux individus. La fréquence des mêlées a fortement chuté à faible densité. L’importante participation des mâles à des interactions agressives, impliquant des coûts énergétiques importants et des risques de blessures, pourrait contribuer à réduire leur probabilité de survie hivernale.Réale Denis, Boussès Patrick. Interactions agonistiques en fonction de la densité et de la structure dans une population insulaire de mouflons (Ovis musimon). In: Revue d'Écologie (La Terre et La Vie), tome 50, n°1, 1995. pp. 49-67

Reconsidering acquisition and allocation in animal nutrition models to better understand efficiency

Reconsidering acquisition and allocation in animal nutrition models to better understand efficiency. 66. Annual Meeting of the European Federation of Animal Science (EAAP