Pre-breeding Period Research Articles

Large scale climate affects the timing of spring arrival but local weather determines the start of breeding in a northern Little Tern (Sternula albifrons) population

In migratory birds, the timing of arrival to the breeding grounds can be affected by weather on the migration routes and breeding sites at arrival. Timing of breeding can be affected by arrival dates but also by local weather conditions during the pre-breeding period. Because long-distance migrants arrive and breed late in the season, weather is thought to be less important, but more information is needed especially from seabirds that are vulnerable to climatic effects. I used observation data from the Little Tern (Sternula albifrons), a long-distance migrant, made by bird watchers during 2006–2016 to examine whether their spring arrival to the breeding grounds in Finland is associated with the large-scale weather pattern (the North Atlantic Oscillation; NAO index) or local weather. In addition, I used breeding data to examine whether the start of egg laying is associated with the annual first arrival dates, local weather or the NAO index. Spring arrival was associated with large scale weather patterns rather than local weather conditions.

Analysis of feeding behaviour and gastro-somatic index (GaSI) during different phases of breeding cycle of Monopterus cuchia (Hamilton, 1822) from Meghalaya, India

Fresh water mud eel (Monopterus cuchia) is considered as a highly nutritious food fish having therapeutic value. Therefore, a study has been conducted to acquire information on the food and feeding habit of this species in relation to reproductive cycle. Relative Length of the Gut (RLG), Gastro-Somatic Index (GaSI) and Analysis of gut content have been studied. It was observed that insect larvae and zooplankton comprised the major part of Gut content. GaSI values of 2.70 (Spent), 3.14 (Pre-Breeding), 2.13 (Breeding) and 2.56 (Post-Breeding) was observed to be different from all the four stages. Moreover, GaSI value was lowest during breeding period and highest during pre-breeding period. Lowest GaSI value of 2.13 indicates period of low feeding intensity which coincides with breeding period. Based on the obtained results, Monopterus cuchia was considered as a carnivorous fish since the RLG value is less than 1.

Body condition of Eiders at Danish wintering grounds and at pre-breeding grounds in Åland

Breeding Eiders Somateria mollissima in the Baltic/Wadden Sea population have declined in recent decades, and several causes have been suggested. A recent study showed a modest increase in body mass from 2.20 kg by ca. 100 g during winter in Denmark, the main wintering area of the flyway population. This raises the question of whether Eiders could increase their body mass by an additional 200 g during pre-breeding to reach the average body mass of ca. 2.50 kg needed for successful reproduction. We analyzed this question by collecting Eiders at the Danish wintering grounds and pre-breeding grounds at Aland, Finland. Female Eiders increased their body condition (defined as scaled body mass index) from winter to the pre-breeding period, whereas males concurrently decreased in weight. The mean body mass of adult female Eiders was 2.23 kg in late winter, when they initiated spring migration. The mean female body mass at the pre-breeding grounds was 2.44 kg, an increase of 9.4% compared with females at the wintering grounds, while adult males decreased in weight by 3.4%. A decrease in gizzard mass was accompanied by a change in diet from large blue mussels Mytilus edulis at the wintering grounds to the small but more abundant mussels in the gizzard during pre-breeding. We conclude that female Eiders can reach a body mass of ca. 2.50 kg before breeding. Building up body condition for breeding is feasible at Aland; thus, difficulty in acquiring adequate resources for reproduction is unlikely to restrict local population size.

Changes in processes downstream of the hypothalamus are associated with seasonal follicle development in a songbird, the dark-eyed junco (Junco hyemalis)

Mechanisms related to seasonal reproductive timing in vertebrates have received far more study in males than in females, despite the fact that female timing decisions dictate when rearing of offspring will occur. Production and release of gonadotropin-releasing hormone (GnRH) by the hypothalamus stimulates the pituitary to secrete gonadotropins, initiating the beginning stages of gonadal recrudescence and production of the sex steroids, testosterone and estradiol, which are necessary to prime the liver for secretion of yolk precursors in breeding female birds. While stimulation by the hypothalamus can occur during the pre-breeding period, egg development itself is likely regulated downstream of the hypothalamus. We used GnRH challenges to examine variation in breeding-stage-specific patterns of pituitary and ovarian responsiveness in free-living female dark-eyed juncos (Junco hyemalis) and also examined the ovary and liver for variation in mRNA expression of candidate genes. Baseline LH levels increased during the transition from pre-breeding to egg-development, however no significant difference was observed in post-GnRH injection levels for LH or sex steroids (testosterone and estradiol). Interestingly, a stage by time-point interaction was observed, with post-GnRH LH levels increasing over baseline during the pre-breeding stage, but not during the egg-development stage. We observed a decrease in liver mRNA expression of estradiol receptor-alpha, and glucocorticoid and mineralocorticoid receptors and a decrease in glucocorticoid receptor expression levels in the ovary. A decline in FSH receptor expression across stages was also observed in the ovary. Combined, our data suggest seasonal variation in female’s sensitivity to signals of HPG activity and energetic or stress signals. These data provide additional insight into the physiological mechanisms regulating onset of clutch initiation.

Climate change and functional traits affect population dynamics of a long-lived seabird.

Recent studies unravelled the effect of climate changes on populations through their impact on functional traits and demographic rates in terrestrial and freshwater ecosystems, but such understanding in marine ecosystems remains incomplete. Here, we evaluate the impact of the combined effects of climate and functional traits on population dynamics of a long-lived migratory seabird breeding in the southern ocean: the black-browed albatross (Thalassarche melanophris, BBA). We address the following prospective question: "Of all the changes in the climate and functional traits, which would produce the biggest impact on the BBA population growth rate?" We develop a structured matrix population model that includes the effect of climate and functional traits on the complete BBA life cycle. A detailed sensitivity analysis is conducted to understand the main pathway by which climate and functional trait changes affect the population growth rate. The population growth rate of BBA is driven by the combined effects of climate over various seasons and multiple functional traits with carry-over effects across seasons on demographic processes. Changes in sea surface temperature (SST) during late winter cause the biggest changes in the population growth rate, through their effect on juvenile survival. Adults appeared to respond to changes in winter climate conditions by adapting their migratory schedule rather than by modifying their at-sea foraging activity. However, the sensitivity of the population growth rate to SST affecting BBA migratory schedule is small. BBA foraging activity during the pre-breeding period has the biggest impact on population growth rate among functional traits. Finally, changes in SST during the breeding season have little effect on the population growth rate. These results highlight the importance of early life histories and carry-over effects of climate and functional traits on demographic rates across multiple seasons in population response to climate change. Robust conclusions about the roles of various phases of the life cycle and functional traits in population response to climate change rely on an understanding of the relationships of traits to demographic rates across the complete life cycle.

The effects of periparturient events, mastitis, lameness and ketosis on reproductive performance of Holstein cows in a hot environment

The aim of this study was to determine the association among periparturient events such as mastitis, lameness (infectious and non-infectious) and ketosis and the reproductive performance of high producing Holstein cows in a hot environment. The health status and reproductive data variables were recorded from 6,566 completed lactations in a large dairy operation. A logistic regression model with the stepwise procedure was used, considering the occurrence of the health problems during the pre-breeding period as fixed effect risk factors and reproductive variables as dependent variables. Pregnancy rate of cows contracting clinical mastitis (CM) around the period of first inseminations was five percentage points lower than cows without this disease. Cows with CM shortly before or after the first service had twice the risk of requiring more than three services per pregnancy than cows with healthy udders. Cows experiencing abortion, laminitis or metritis were two times more likely to require >3 services per pregnancy than cows not experiencing these reproductive disorders. Cows experiencing lameness, mastitis and metritis presented a significantly longer interval between calving and pregnancy compared to healthy cows. Ketosis and lameness increased the odds of a cow of being inseminated for the first time after 70 days in milk. In conclusion, these results suggest that abortion, ketosis, CM, retained placenta (RP), metritis, and lameness are associated with decreased reproductive performance in high producing Holstein cows subjected to thermal stress.

The effects of seasonality and precipitation in the avifauna of the Argentine Southern Chaco Serrano

In subtropical regions like the Chaco Serrano (33° S), rainfall has a marked seasonality, and water flood, caused by heavy rains, may have important consequences for dependent ecosystems. Conversely, the high pressure on available resources during dry periods can also affect the fauna diversity and distribution. Even though birds have shown to be excellent ecological indicators of these shifts in the environment, currently little is known about the avifauna of the Argentine Chaco Serrano phytogeographic district. Our aim was to study the resident bird population status in the Southern Chaco Serrano, its fluctuations in richness and abundance, and its relationship to seasonal variations, in monthly and annual hydroperiods. In order to assess the resident bird status over a two year period (2011 Mar.-2013 Feb.) we carried out 18 sampling surveys during pre-breeding (spring), breeding (summer) and non breeding periods (autumn-winter), in the Northeastern part of the Valle Fertil Natural Park, San Juan province, Argentina. During each site survey, we recorded bird assemblages found in six transects, and obtained bird abundance and species diversity. A mixed general linear model was employed to evaluate relationships between the studied variables. We found a total of 98 species of birds belonging to 33 families (44 resident species, 23 spring visitors, six summer visitors, two winter visitors and 23 with scarce registers). We also registered 68 of these species in both hydroperiods, 28 only during rainy periods and only two during the dry period. Both richness and abundance showed the highest values during the pre-breeding and rainy seasons, while different tendencies were detected during the isolated monthly rainfalls. These changes in bird densities were associated with the arrival of migratory species, mainly spring visitors, and probably in relationship with their reproductive activity, and to seasonal fluctuations in food resources. The Southern Chaco Serrano is a subtropical semiarid place that seems to be an important breeding habitat for many migrant bird species, which in turn promoted seasonal changes in species density and diversity, mainly during rainy years. This work contributed to our understanding on the causes of richness and abundance variations on birds, and will contribute to this important group management and conservation in this area.

Efecto de la estacionalidad y lluvias en la avifauna del Chaco Serrano Austral, Argentina

In subtropical regions like the Chaco Serrano (33° S), rainfall has a marked seasonality, and water flood, caused by heavy rains, may have important consequences for dependent ecosystems. Conversely, the high pressure on available resources during dry periods can also affect the fauna diversity and distribution. Even though birds have shown to be excellent ecological indicators of these shifts in the environment, currently little is known about the avifauna of the Argentine Chaco Serrano phytogeographic district. Our aim was to study the resident bird population status in the Southern Chaco Serrano, its fluctuations in richness and abundance, and its relationship to seasonal variations, in monthly and annual hydroperiods. In order to assess the resident bird status over a two year period (2011 Mar.-2013 Feb.) we carried out 18 sampling surveys during pre-breeding (spring), breeding (summer) and non breeding periods (autumn-winter), in the Northeastern part of the Valle Fértil Natural Park, San Juan province, Argentina. During each site survey, we recorded bird assemblages found in six transects, and obtained bird abundance and species diversity. A mixed general linear model was employed to evaluate relationships between the studied variables. We found a total of 98 species of birds belonging to 33 families (44 resident species, 23 spring visitors, six summer visitors, two winter visitors and 23 with scarce registers). We also registered 68 of these species in both hydroperiods, 28 only during rainy periods and only two during the dry period. Both richness and abundance showed the highest values during the pre-breeding and rainy seasons, while different tendencies were detected during the isolated monthly rainfalls. These changes in bird densities were associated with the arrival of migratory species, mainly spring visitors, and probably in relationship with their reproductive activity, and to seasonal fluctuations in food resources. The Southern Chaco Serrano is a subtropical semiarid place that seems to be an important breeding habitat for many migrant bird species, which in turn promoted seasonal changes in species density and diversity, mainly during rainy years. This work contributed to our understanding on the causes of richness and abundance variations on birds, and will contribute to this important group management and conservation in this area.

Dependencies in the timing of activities weaken over the annual cycle in a long-distance migratory bird

Migrating birds have to incorporate migration into their annual cycle, next to breeding and moult. This presents the challenge to arrive at the right place at the right time at any given moment during the year to maximize fitness. Although many studies have investigated the timing of specific (life-history) activities of migrating birds, it is poorly studied how the timing and duration of these activities depend on each other and, ultimately, how they affect fitness. Therefore, we investigated variability and dependencies in the timing and duration of successive activities throughout the annual cycle and assessed their fitness consequences in hoopoes (Upupa epops), a long-distance migratory bird, using geolocator and breeding phenology data of five consecutive years. We found that the timing and duration of seasonal activities generally depended on the timing and duration of the preceding activity; yet, the strength of these dependencies and the degree of variability varied between activities. The strongest dependencies were found between the end of breeding and departure from the breeding grounds as well as between the arrival in the breeding grounds and the onset of breeding. We also found fitness consequences of timing and duration but only for specific activities: spring migration and particularly the duration of the pre-breeding period influenced the quality of the territory acquired as well as the total number of fledglings. Consequently, we suggest that our study species has the flexibility to adjust the timing and duration of activities but to varying degrees. This is a step forward in understanding the time-constraints that migratory animals face and in identifying their fitness consequences. To date, few studies have investigated the timing and dependencies of seasonal activities in migrating birds throughout the annual cycle and their fitness consequences. However, understanding temporal constraints and identifying sensitive—fitness-relevant—periods within the annual cycle is crucial to understand the population dynamics of migrating species. We investigated the timing and duration of life-history activities in a long-distance migratory bird and assessed their fitness consequences. Our results clearly show that seasonal activities were generally linked to the previous activities but that this dependency ceased relative to activities further in the past. We also found clear fitness consequences but only for the timing and duration of specific activities. Thus, our study shows that migrants can adjust the timing and duration of activities to a certain degree but also that this flexibility is more constrained for specific activities.

Ranging Behaviour of Verreaux's Eagles during the Pre-Breeding Period Determined through the Use of High Temporal Resolution Tracking.

Information on movement ecology is key in understanding the drivers and limitations of life history traits and has a potential role in indicating environmental change. Currently we have a limited understanding of the parameters of movement of territory-bound raptors, which are sensitive to environmental change. In this study we used GPS tracking technology to obtain spatially (within 3 m) and temporally (c. 3 mins) high-resolution movement data on a small sample of Verreaux’s eagle Aquila verreauxii during the pre-laying period (n = 4) with one additional example during the chick rearing period. We present GPS-derived home range estimates for this species and we examine temporal (timing, duration, frequency and speed) and spatial (total path length and maximum distance from nest) patterns of trips away from the nest. For eagles tagged in the agriculturally developed Sandveld region (n = 3), which is made up of a mosaic of land use types, we also undertook a habitat selection analysis. Home ranges were small and largely mutually exclusive. Trip activity was centred around midday, which is likely to be related to lift availability. Our habitat selection analysis found that eagles selected for near-natural and degraded habitat over natural or completely modified areas, suggesting that these eagles may have benefitted from some of the agricultural development in this region. Although our sample sizes are small, the resolution of our tracking data was essential in deriving this data over a relatively short time period and paves the way for future research.

Experimentally provided conspecific cues boost bird territory density but not breeding performance

Decision-making during different life-history stages requires information, which is obtained through own or others’ experience and interaction with the environment. In birds, song is important for territory defense and mate attraction. Although song has evolved to purposely convey information, it can be inadvertently exploited by conspecifics. Experiments attempting to attract focal species by playing back their song are numerous, yet the consequences for reproductive performance remain little understood. In 2013 and 2014, settlement, reproduction, and extrapair paternity of Phylloscopus sibilatrix were assessed in a randomized experiment. We hypothesized that territory number, reproductive performance, and extrapair paternity would be higher on song plots (wood warbler song playbacks during prebreeding periods) than on control plots (no wood warbler song playback). On song plots, 3 times more territories were established, settlement occurred faster, and maximum plot occupancy was higher compared with control plots. Pairing rate, daily nest survival rate, mean clutch size, mean number of nestlings and fledglings, rates of extrapair young, nest abandonment, and nest predation did not differ between treatments, but fledging success was lower on song plots compared with control plots. This study shows the important role social cues can play for territory selection of birds, but also exemplifies the necessity for postattraction evaluation of reproduction to rule out negative effects of artificial attraction. Decreased fledging success on song plots and ambiguity about consequences of artificial attraction for distribution and settling dynamics of the species give reason to further evaluate whether acoustic attraction represents a suitable method for songbird conservation.

Temporal variation in circulating concentrations of organochlorine pollutants in a pelagic seabird breeding in the high Arctic.

The present study explored short-term temporal variations in circulating concentrations of 3 legacy organochlorines with different physicochemical properties (polychlorinated biphenyl 153 [PCB-153], p,p'-dichlorodiphenyldichloroethylene [DDE], and hexachlorobenzene [HCB]) in breeding kittiwakes (Rissa tridactyla) in a colony in Svalbard (78°N), Norwegian Arctic. Concentrations were measured in blood of a large number (n = 412-521 blood samples, depending on the data analyses) of prebreeding, incubating, and chick-rearing birds over a period of 5 yr (2007-2011). The PCB-153 concentrations were equal in male and female blood in the prebreeding period, whereas females had significantly lower concentrations during incubation and chick rearing, probably because of their ability to eliminate organochlorines through egg laying. A similar temporal pattern was observed with DDE, although the lower concentrations in incubating females were not significant. Males and females had similar concentrations of HCB over all reproductive stages. The concentrations of all 3 compounds varied greatly between years. The concentrations of PCB-153 tended to decline over the study period, whereas concentrations of HCB showed an increasing trend, especially among chick-rearing males late in the season. Concentrations of PCB-153 increased approximately 2.5 times from the prebreeding to the chick-rearing period, concurrent with mobilization of body lipids (reduced body mass). A similar, but less pronounced trend was found for HCB. For DDE, however, kittiwakes had the highest concentrations in the prebreeding period, suggesting relatively high exposure in their winter areas. The present study documented large variations in circulating concentrations of legacy organochlorines among and within breeding seasons in kittiwakes, but the alterations within seasons were relatively consistent from year to year. Environ Toxicol Chem 2017;36:442-448. © 2016 SETAC.

Increased mammalian predators and climate ch1ange predict declines in breeding success and density of Capercaillie tetrao urogallus, an old stand specialist, in fragmented Scottish forests

Low breeding success has been associated with declines in population and range of the re-introduced Capercaillie Tetrao urogallus in Scotland. Annual breeding success from 26 Scottish forests surveyed between 1991 and 2009 averaged only 0.6 chicks per female, the lowest rate recorded in 16 previous studies. Reduced breeding success was due to proportionally fewer females rearing chicks rather than a reduction in brood size. Birds bred less well in Perthshire at the southern edge of the range, where declines in indices of female and male density were highest. Only at the core of the range (Strathspey), where birds bred better, were female densities stable. Two weather variables, April temperature in the pre-breeding period (APRTEMP), and temperature at chick hatch in June (HATCHTEMP), increased over the study period. Indices of Pine Marten Martes martes increased 3.9-fold since 1995, and those of Red Fox Vulpes vulpes by 2.2-fold, whereas those of Carrion Crow Corvus corone, raptors and forest floor vegetation showed no change. Neither forest type nor forest ground vegetation appeared to influence breeding success. Instead, females reared more chicks in years when hatch time in June was drier, and in forests with lower marten and crow indices. In addition, more females reared broods in years when Aprils were cooler. Brood size was unaffected by any of the measured variables. Densities of adult birds were lower in forests with higher fox indices. Increased predation of clutches and chicks by martens and crows within these small, fragmented forests, as well as changes in climate, may explain reductions in breeding success and hence contribute to continued declines. Successful conservation of Capercaillie in remaining Strathspey strongholds may require better predator management, including a licensed removal of martens to test the hypotheses that martens contribute to reduced breeding success. This short-medium term approach will inform longer-term predator management policies and complement aspirations to increase the area and connectivity of forest habitat to benefit Capercaillie in-part through mitigating against any impact of increasing forest-edge predators.

Is individual consistency in body mass and reproductive decisions linked to individual specialization in foraging behavior in a long‐lived seabird?

Individual specialization in diet or foraging behavior within apparently generalist populations has been described for many species, especially in polar and temperate marine environments, where resource distribution is relatively predictable. It is unclear, however, whether and how increased environmental variability – and thus reduced predictability of resources – due to global climate change will affect individual specialization. We determined the within‐ and among‐individual components of the trophic niche and the within‐individual repeatability of δ13C and δ15N in feathers and red blood cells of individual female southern rockhopper penguins (Eudyptes chrysocome) across 7 years. We also investigated the effect of environmental variables (Southern Annular Mode, Southern Oscillation Index, and local sea surface temperature anomaly) on the isotopic values, as well as the link between stable isotopes and female body mass, clutch initiation dates, and total clutch mass. We observed consistent red blood cell δ13C and δ15N values within individuals among years, suggesting a moderate degree of within‐individual specialization in C and N during the prebreeding period. However, the total niche width was reduced and individual specialization not present during the premolt period. Despite significant interannual differences in isotope values of C and N and environmental conditions, none of the environmental variables were linked to stable isotope values and thus able to explain phenotypic plasticity. Furthermore, neither the within‐individual nor among‐individual effects of stable isotopes were found to be related to female body mass, clutch initiation date, or total clutch mass. In conclusion, our results emphasize that the degree of specialization within generalist populations can vary over the course of 1 year, even when being consistent within the same season across years. We were unable to confirm that environmental variability counteracts individual specialization in foraging behavior, as phenotypic plasticity in δ13C and δ15N was not linked to any of the environmental variables studied.

Sex-specific fitness effects of unpredictable early life conditions are associated with DNA methylation in the avian glucocorticoid receptor.

Organisms can adapt to variable environments by using environmental cues to modulate developmental gene expression. In principle, maternal influences can adaptively adjust offspring phenotype when early life and adult environments match, but they may be maladaptive when future environments are not predictable. One of the best-studied 'maternal effects' is through modification of the offspring's hypothalamic-pituitary-adrenal (HPA) axis, the neuroendocrine system that controls responses to stress. In addition to the direct transfer of glucocorticoids from mother to offspring, offspring HPA function and other phenotypes can also be affected by epigenetic modifications like DNA methylation of the glucocorticoid receptor promoter. Here we examine how among-year variation in rainfall is related to DNA methylation during development and fitness in adulthood in the superb starling (Lamprotornis superbus), which lives in a climatically unpredictable environment where early life and adult environments are unlikely to match. We found that DNA methylation in the putative promoter of the glucocorticoid receptor gene is reduced in chicks - particularly in males - born following drier prebreeding periods. Additionally, DNA methylation is lower in males that become breeders than those that never breed. However, there is no relationship in females between DNA methylation and the likelihood of dispersing from the natal group to breed elsewhere. These results suggest that early life conditions may positively affect fitness in a sex-specific manner through chemical modification of an HPA-associated gene. This study is the first to show that epigenetic modifications during early life may influence the fitness of free-living organisms adapted to unpredictable environments.

Experimental evidence and 43 years of monitoring data show that food limits reproduction in a food-caching passerine.

Several species of birds and mammals overcome periods of scarcity by caching food, but for the vast majority of species, it is virtually unknown whether they are food limited during these periods. The Gray Jay (Perisoreus canadensis) is a boreal-resident, food-caching passerine that breeds in late winter when fresh food is scarce. Using a two-year experiment and 43 years of monitoring data, we examined the food limitation hypothesis in a population of Gray Jays in Algonquin Park, Ontario, Canada, that has declined by over 50% in the last three decades. Breeding pairs that were experimentally food supplemented during the pre-breeding period laid eggs earlier in the season and had larger brood sizes than non-supplemented controls. From the long-term data, we found strong evidence that pairs that were regularly supplemented by the public (park visitors) tended to lay eggs earlier and have larger clutches and brood sizes compared to pairs that were not supplemented. Nestling body condition (mass controlled for body size) was not influenced by either experimental or public food supplementation. Our results support the hypothesis that Gray Jays are food limited during their late-winter breeding period and suggest that warmer fall temperatures, which have been hypothesized to lead to cache spoilage, may have a significant impact on reproductive success in this declining population. Moreover, our results contribute to understanding how public feeding can influence the fitness of wild animals.

Changes in the abundance and distribution of a montane specialist bird, the Dotterel Charadrius morinellus, in the UK over 25 years

Capsule The number of Dotterel breeding in the UK declined by 57% between 1987/88 and 2011, from 980 to 423 breeding males; there has been a contraction of the species’ geographical range as well as declining numbers on core sites.Aims To estimate the number of Dotterel breeding in the UK in 2011, the changes since surveys in 1987–88 and 1999, and to document broad patterns of change in distribution.Methods Two survey visits were carried out at montane sites (protected areas designated for Dotterel; and a stratified random sample of other sites >600 m altitude) across the Dotterel's breeding range using a standardized protocol as used in previous surveys. The first visit was to assess numbers in the pre-breeding period, and the second visit, comparable to those made in previous national surveys, provided data to calculate population estimates through extrapolation to unsurveyed sites and 95% confidence intervals by bootstrapping.Results In 2011, the number of Dotterel in the UK was estimated to be 423 breeding males (95% CI 279–644), a decline of 57% since 1987/88 and 43% since 1999. As in previous surveys, the majority of the population (61%) was found in the East Highlands, but large declines were recorded in this region. Dotterels were largely absent from previously occupied sites in North and West Highlands.Conclusions Numbers of Dotterel breeding in the UK declined by more than half between 1987 and 2011. Long-term monitoring data are rare for montane environments in the UK, but these findings may signify the occurrence of important ecological changes, with possible drivers including land-use/habitat change, nitrogen deposition and climate change.

Sex-specific association between sleep and basal metabolic rate in great tits

Differences in animal behaviour can arise from individual variation in energy resource allocation decisions. Because energy is essential to fuel all processes that permit behaviour, it is necessary to consider metabolism for a more complete understanding of behavioural ecology. Although many studies have explored interspecific relationships between metabolic rate and behaviour, few studies have evaluated within-species relationships between metabolism and sleep. We investigated the relationship between basal metabolic rate (BMR) and components of sleep behaviour measured in wild great tits, Parus major, during winter and the prebreeding period. Individuals with higher metabolic rates may partially offset their costs by using sleep as an energy conservation strategy, where individuals with higher BMR may sleep more. On the other hand, the energetic savings of longer sleep may not be worth the lost foraging opportunities and therefore higher BMR individuals may sleep less. Our results suggest that the relationship between BMR and sleep behaviours may depend on sex. Female great tits displayed a positive relationship between metabolic rate and sleep duration consistent with energy conservation, or protection, while male great tits displayed a negative relationship. Differences in sleep duration came about largely due to a sex-specific interaction between BMR and sleep onset time; we found no relationship between BMR and time of awakening in either sex. Nor did it appear that individuals compensated for changes in duration of sleep with changes to quality of sleep, measured as frequency of night-time awakenings. This suggests that male and female great tits use different sleep strategies based on their metabolic requirements which may contribute to variation in sleep behaviour within a species. Sex-specific differences in metabolic physiology, or fitness-enhancing behaviours throughout the circannual cycle may contribute to variation in energy-balancing strategies within and between the sexes.

Sexual foraging segregation in South American sea lions increases during the pre-breeding period in the Río de la Plata plume

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 525:261-272 (2015) - DOI: https://doi.org/10.3354/meps11236 Sexual foraging segregation in South American sea lions increases during the pre-breeding period in the Río de la Plata plume M. Drago1,*, V. Franco-Trecu2, L. Zenteno3, D. Szteren4, E. A. Crespo5, F. G. Riet Sapriza2,8, L. de Oliveira6, R. Machado6,7, P. Inchausti1, L. Cardona3 1Department of Ecology & Evolution, Centro Universitario Regional Este (CURE), University of the Republic, C/ Tacuarembó s/n, 20000 Maldonado, Uruguay 2Proyecto Pinnípedos, Sección Etología, Facultad de Ciencias, Universidad de la República, Iguá 4225, 11400 Montevideo, Uruguay 3IRBIO and Department of Animal Biology, Faculty of Biology, University of Barcelona, Av. Diagonal 645, 08028 Barcelona, Spain 4Dpto de Ecología y Evolución, Facultad de Ciencias, Universidad de la República, Iguá 4225, 11400 Montevideo, Uruguay 5Laboratory of Marine Mammals, Centro Nacional Patagonico (CENPAT-CONICET), and National University of Patagonia, Blvd. Brown 3600, 9120 Puerto Madryn, Chubut, Argentina 6Study Group of Aquatic Mammals of Rio Grande do Sul (GEMARS), Av. Tramandaí 976, RS 95625-000, Imbé, Brazil 7Laboratório de Sistemática e Ecologia de Aves e Mamíferos Marinhos (LabSMar), Departamento de Zoologia/IB, Universidade Federal do Rio Grande do Sul (UFRGS), Av. Bento Gonçalves 9500, RS 91509-900, Porto Alegres, Brazil 8Present address: Lab. de Ecología Molecular de Vertebrados Acuáticos (LEMVA), Departamento Ciencias Biológicas, Facultad de Ciencias, Universidad de los Andes, Carrera 1E No 18A - 10, Bogotá, Colombia *Corresponding author: m.drago@ub.edu ABSTRACT: Stable carbon and nitrogen isotopes in skin and bone of South American sea lions from Brazil and Uruguay were analysed to test the hypothesis that trophic overlap between the sexes is lower during the pre-breeding season than throughout the rest of the year. The isotopic values of skin and bone were used to infer the trophic relationships between the sexes during the pre-breeding period and year round, respectively. Prey species were also analysed to establish a baseline necessary for interpreting the stable isotope ratios of skin and bone. Standard ellipse areas, estimated using Bayesian inference in the SIBER routine of the SIAR package in R, suggested that males and females used a wide diversity of foraging strategies throughout the year and that no differences existed between the sexes. However, the diversity of foraging strategies was largely reduced during the pre-breeding period, with all the individuals of each sex adopting similar strategies, but with the two sexes differing considerably in stable isotope values and the ellipse areas of males and females not overlapping at all. Nevertheless, the results revealed a general increase in the consumption of pelagic prey by both sexes during the pre-breeding period. The progressive crowding of individuals in the areas surrounding the breeding rookeries during the pre-breeding period could lead to an increase in the local population density, which could explain the above reported changes. KEY WORDS: Otaria flavescens · Sexual foraging segregation · Skin · Bone · Stable isotope Bayesian ellipses Full text in pdf format PreviousNextCite this article as: Drago M, Franco-Trecu V, Zenteno L, Szteren D and others (2015) Sexual foraging segregation in South American sea lions increases during the pre-breeding period in the Río de la Plata plume. Mar Ecol Prog Ser 525:261-272. https://doi.org/10.3354/meps11236 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 525. Online publication date: April 09, 2015 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2015 Inter-Research.

Pre-breeding energetic management in a mixed-strategy breeder.

Integrative biologists have long appreciated that the effective acquisition and management of energy prior to breeding should strongly influence fitness-related reproductive decisions (timing of breeding and reproductive investment). However, because of the difficulty in capturing pre-breeding individuals, and the tendency towards abandonment of reproduction after capture, we know little about the underlying mechanisms of these life-history decisions. Over 10 years, we captured free-living, arctic-breeding common eiders (Somateria mollissima) up to 3 weeks before investment in reproduction. We examined and characterized physiological parameters predicted to influence energetic management by sampling baseline plasma glucocorticoids (i.e., corticosterone), very-low-density lipoprotein (VLDL), and vitellogenin (VTG) for their respective roles in mediating energetic balance, rate of condition gain (physiological fattening rate) and reproductive investment. Baseline corticosterone increased significantly from arrival to the initiation of reproductive investment (period of rapid follicular growth; RFG), and showed a positive relationship with body mass, indicating that this hormone may stimulate foraging behaviour to facilitate both fat deposition and investment in egg production. In support of this, we found that VLDL increased throughout the pre-breeding period, peaking as predicted during RFG. Female eiders exhibited unprecedentedly high levels of VTG well before their theoretical RFG period, a potential strategy for pre-emptively depositing available protein stores into follicles while females are simultaneously fattening. This study provides some of the first data examining the temporal dynamics and interaction of the energetic mechanisms thought to be at the heart of individual variation in reproductive decisions and success in many vertebrate species.