Flexibility in the timing of post‐breeding moult in passerines in the UK

Higher temperatures resulting from climate change have led to predictions that the duration of the breeding season of many temperate bird species may be changing. However, the extent to which breeding seasons can be altered will also depend on the degree of flexibility in processes occurring at other points in the annual cycle. In particular, plasticity in the timing of post‐breeding moult (PBM) could facilitate changes in the timing of key events throughout the annual cycle, but little is known about the level of within‐ and between‐species plasticity in PBM. As part of the British Trust for Ornithology (BTO) Ringing Scheme, many ringers routinely record moult scores of flight feathers, and these can be used to provide information on the annual progression of PBM for a range of species. Here we use ringing data to investigate patterns of PBM in 15 passerines, as well as data from the BTO Nest Record Scheme to relate these differences to the timing of breeding of these species across the UK. We find considerable variation in both the mean start (19 May–29 July) and duration (66–111 days) of PBM between species, but find no evidence that species starting PBM later in the season complete it any faster. However, there is considerable within‐species variation in PBM, particularly for multi‐brooded species; PBM starts later and is completed in less time when the duration of the breeding season (difference between first and last nests) is longer. This implies that a later end to breeding can be compensated for by faster PBM, and that advances in breeding could lead to earlier and slower PBM. Our findings suggest that adaptation of PBM in response to climate‐mediated changes in the timing and duration of the breeding season is possible. However, the requirement to complete PBM prior to migration or the onset of winter might constrain the extent to which breeding seasons can lengthen, especially for later nesting species.     

When to start and when to stop: Effects of climate on breeding in a multi‐brooded songbird

Climate warming has been shown to affect the timing of the onset of breeding of many bird species across the world. However, for multi‐brooded species, climate may also affect the timing of the end of the breeding season, and hence also its duration, and these effects may have consequences for fitness. We used 28 years of field data to investigate the links between climate, timing of breeding, and breeding success in a cooperatively breeding passerine, the superb fairy‐wren (Malurus cyaneus). This multi‐brooded species from southeastern Australia has a long breeding season and high variation in phenology between individuals. By applying a “sliding window” approach, we found that higher minimum temperatures in early spring resulted in an earlier start and a longer duration of breeding, whereas less rainfall and more heatwaves (days > 29°C) in late summer resulted in an earlier end and a shorter duration of breeding. Using a hurdle model analysis, we found that earlier start dates did not predict whether or not females produced any young in a season. However, for successful females who produced at least one young, earlier start dates were associated with higher numbers of young produced in a season. Earlier end dates were associated with a higher probability of producing at least one young, presumably because unsuccessful females kept trying when others had ceased. Despite larger scale trends in climate, climate variables in the windows relevant to this species’ phenology did not change across years, and there were no temporal trends in phenology during our study period. Our results illustrate a scenario in which higher temperatures advanced both start and end dates of individuals’ breeding seasons, but did not generate an overall temporal shift in breeding times. They also suggest that the complexity of selection pressures on breeding phenology in multi‐brooded species may have been underestimated.     

Roosting behaviour is related to reproductive strategy in brood parasitic cowbirds

Shiny Cowbirds Molothrus bonariensis and Screaming Cowbirds Molothrus rufoaxillaris are closely related brood parasites but the former is socially polygynous or promiscuous and an extreme host generalist, whereas the latter is socially monogamous and parasitizes almost exclusively one host. Females of both species lay in relative darkness, before dawn, relying for host nest location on previous days’ prospecting activity, or possibly on following better‐informed roost associates. We studied the temporal and spatial patterns of roosting behaviour in these species to test the hypothesis that roosting behaviour of cowbirds is related to their breeding strategy (brood parasitism) and reflects differences in strategies between species. We recorded fidelity to a roost, location fidelity within a roost, inter‐individual spatial associations and timing of roost departures and parasitic events, using tagged individuals. Female Shiny Cowbirds and both sexes of Screaming Cowbirds showed marked fidelity in roosting location, and roost departures occurred both during and after the known time window for parasitism, with earlier departures probably corresponding to laying days. Screaming Cowbird females and males that were trapped together and showed high levels of association during the day, also showed high levels of association in the roost. We describe the spatial and temporal patterns of a relatively poorly known aspect of avian ecology in general and the behaviour of brood parasites in particular.     

Patterns of roost site selection and use by Southern Ground-Hornbills in north-eastern South Africa

Different habitats may be used for the needs of various aspects of an animal’s life. Southern Ground-Hornbill Bucorvus leadbeateri groups announce their presence within year-round territories by calling at dawn from their overnight roost sites. Knowledge on ground-hornbill roosting habits is limited. Groups roost in large trees, apparently close to where they end up after daily foraging. We investigated patterns of roost site selection and use for four Southern Ground-Hornbill groups in the Associated Private Nature Reserves, north-eastern South Africa, based on data from GPS-satellite transmitters. The number of roost sites used per month averaged 15.4 ± 4.7 across all groups, indicating little evidence of strong preferences for specific sites. This number was least when groups were breeding, decreasing throughout the early wet season (October–December) and was lowest during the late wet season (January–March) when actively breeding groups frequently roosted close to the nest (54–83% of roosts <1 000 m of the nest). As might be expected, the mean monthly number of nights per roost peaked during the breeding season (December–January). Riparian habitats were preferred for roosting during the breeding season, whereas disturbed areas, as well as Combretumand mopane-dominated habitats were preferred during the dry non-breeding season. Adequate large trees not only for nesting, but also for roosting, particularly in riparian habitats, may therefore be an important and potentially limiting factor for the successful reproduction of Southern Ground-Hornbills.     

Getting the timing right: antler growth phenology and sexual selection in a wild red deer population

There has been growing interest in the determinants of the annual timing of biological phenomena, or phenology, in wild populations, but research on vertebrate taxa has primarily focused on the phenology of reproduction. We present here analyses of the phenology of the annual growth of a secondary sexual characteristic, antlers in red deer (Cervus elaphus) males. The long-term individual-based data from a wild population of red deer on the Isle of Rum, Scotland allow us to consider ecological factors influencing variation in the phenology of growth of antlers, and the implications of variation in antler growth phenology with respect to the phenotype of antler grown (antler mass) and annual breeding success. The phenology of antler growth was influenced by local environmental conditions: higher population density delayed both the start date (during spring) and the relative end date (in late summer) of antler growth, and warmer temperatures in the September and April prior to growth advanced start and end dates, respectively. Furthermore, there was variation between individuals in this phenotypic plasticity of start date, although not in that of end date of growth. The phenology of antler growth impacted on the morphology of antlers grown, with individuals who started and ended growth earliest having the heaviest antlers. The timing of antler growth phenology was associated with breeding success in the following mating season, independently of the mass of antlers grown: an earlier start of antler growth was associated with siring a higher number of the calves born the following spring. Our results suggest that the phenology of traits that are not directly correlated with offspring survival may also regularly show correlations with fitness.     

Communal roosting,thermoregulatory benefits and breeding group size predictability in cooperatively breeding sociable weavers

Extreme temperatures impose energy costs on endotherms through thermoregulation and different adaptations help individuals to cope with these conditions. In social species, communal roosting and huddling are thought to decrease the energetic requirement of thermoregulation under low temperatures. This is likely to represent an important mechanism by which individuals save energy during the coldest parts of the year and hence to represent a non‐breeding benefit of sociality. Here, we investigate the potential thermoregulatory benefits of group living in roosting groups of sociable weavers Philetairus socius, a colonial cooperatively breeding passerine that builds communally a massive nest structure with several independent chambers wherein individuals breed and roost throughout the year. To investigate the benefits of sociality during the non‐breeding season, we studied the thermal environment during roosting in relation to group size. In addition, to understand the link between non‐breeding and breeding sociality in this species we studied group size stability between the pre‐breeding and breeding periods. As expected, we found that the nest chamber's night‐time temperature is strongly related to the number of birds roosting together, especially during cold nights. Specifically, birds in larger groups spent less time below the critical thermal minimum temperature (i.e. the temperature below which energy expenditure increases substantially). They were less exposed to external temperature variations. We also found a positive relationship between the number of birds roosting during winter and the breeding group size, indicating breeding group size predictability. In cooperative breeders such as the sociable weaver, the costs and benefits of sociality are usually studied during the breeding period. This study shows that a better understanding of non‐breeding benefits of group membership and group dynamics between the non‐breeding and breeding periods are necessary for a comprehensive understanding of the benefits of sociality.     

Timing of prenuptial molt as a sexually selected indicator of male quality in superb fairy-wrens (Malurus cyaneus)

Seasonally dichromatic male superb fairy-wrens (Malurus cyaneus)solicit extra-group fertilizations through displays of theirbrightly colored nuptial plumage during visits to females inneighboring territories. This ornamental plumage is lost atthe end of the breeding season, and reacquired before the nextbreeding season after a highly variable period spent in a cryptic,female-like, "eclipse" plumage. Individuals start visiting femalesas soon as they return to nuptial plumage, often several monthsbefore the start of breeding.We examine variation in the timingof acquisition of nuptial plumage in relation to environmentalconditions and the age, social status, and condition of males.We show that males undergo the prenuptial molt earlier as theyage and when in superior condition, and that molt is delayedin years of more adverse winter weather conditions. We proposethat the purpose of male displays may be to advertise theirquality, and that females use this variation in the timing ofacquisition of nuptial plumage to assess the relative qualityof prospective extra-group mates. Molting earlier is apparentlycostlier, so this handicap would appear to be a reliable reflectionof male quality.     

Quantifying long-term phenological patterns of aerial insectivores roosting in the Great Lakes region using weather surveillance radar

Organisms have been shifting their timing of life history events (phenology) in response to changes in the emergence of resources induced by climate change. Yet understanding these patterns at large scales and across long time series is often challenging. Here we used the US weather surveillance radar network to collect data on the timing of communal swallow and martin roosts and evaluate the scale of phenological shifts and its potential association with temperature. The discrete morning departures of these aggregated aerial insectivores from ground-based roosting locations are detected by radars around sunrise. For the first time, we applied a machine learning algorithm to automatically detect and track these large-scale behaviors. We used 21 years of data from 12 weather surveillance radar stations in the Great Lakes region to quantify the phenology in roosting behavior of aerial insectivores at three spatial levels: local roost cluster, radar station, and across the Great Lakes region. We show that their peak roosting activity timing has advanced by 2.26 days per decade at the regional scale. Similar signals of advancement were found at the station scale, but not at the local roost cluster scale. Air temperature trends in the Great Lakes region during the active roosting period were predictive of later stages of roosting phenology trends (75% and 90% passage dates). Our study represents one of the longest-term broad-scale phenology examinations of avian aerial insectivore species responding to environmental change and provides a stepping stone for examining potential phenological mismatches across trophic levels at broad spatial scales.     

European Swallows Hirundo rustica in Botswana during three non-breeding seasons: the effects of rainfall on moult

van den Brink, B., Bijlsma, R.G. & van der Have, T.M. 2000. European swallows Hirundo rustica in Botswana during three non-breeding seasons: the effects of rainfall on moult. Ostrich: 71 (1): 198–204.

The rate of moult of European Swallows spending the non-breeding season in Botswana was studied during December-January of 1992/93,1993/94 and 1994/95 to investigate the effects of variability in rainfall and roosting habitat availability. In January 1994, 2–3 million European Swallows were counted at a traditional roost along the Boteti River. The rate of moult was relatively slow, about one feather (primary, secondary or tail feather) was replaced every two weeks in both adults and juveniles. The speed of moult in juveniles was generally lower than in adults, in particular of secondaries and tail feathers. Moulting rate of both primaries and tail feathers was lowest in 1994/95 during a period of drought and coincided with the almost complete destruction of roosting habitat. In 1992/93, moulting rate was highest when rainfall was moderate and roosting habitat abundant. Moulting rate was intermediate in 1993/94 when rainfall was frequent but roosting habitat reduced because of the low water level in the Boteti River. The combined effect of reduced food availability during droughts and higher densities and longer foraging flights when roosting habitat is scarce might explain the annual variation in moulting rate. From the second week of January onwards many adults started moulting the outermost tail feather before the penultimate feathers. This phenomenon could indicate the importance of long tail streamers in aerial manoeuvring when foraging during the return migration to the breeding grounds.     

“THE BIRDS OF SOUTH AFRICA”

Jones, P. J. 1980. The timing of wing moult in the Greyhooded Kingfisher in Nigeria. Ostrich 51:99-106.

The post-nuptial and post-juvenile moults of the Greyhooded Kingfisher Halcyon leucocephala took place in northern Nigeria between May and November (the rainy season) after migration from the southern breeding areas. Moult of individual birds lasted between 92 and 176 days, those starting moult latest (mostly juveniles) moulting fastest. This variation may be related to food availability during moult; those starting early do so before the rainy season begins in the north and before insect numbers increase, whereas those moulting later do so during the full flush of rainy season insect availability. This variability appears to be adaptive in allowing the complete moult to be fitted into the period remaining between the end of the breeding season, which is variable, and the southward migration in the early dry season, whose timing is relatively fixed.     

Effects of consecutive,contrasting, winters on the bird population of an Anglesey pine plantation

Capsule European Nightjars Caprimulgus europaeus breeding in southern England were found to over-winter in the Democratic Republic of Congo.

Aims To ascertain the wintering areas and migration routes of European Nightjars breeding in southern England.

Methods The wintering areas of three Nightjars were mapped using light geolocation tags (two in 2008 and one in 2010). For one of these birds, details of the timing and route of migration were determined. The impact of the birds' behaviour on location accuracy was measured and data on the timing of emergence and roosting was collected.

Results All three Nightjars were found to be wintering in the south and east of the Democratic Republic of Congo, in an area not previously considered to be part of the wintering range of this species. The route of migration differed in each period. Autumn migration was across central Sahara, whereas in spring the route was to the west of the Sahara. Aberrations in the light curve caused by the roosting and emergence of the birds were found to affect the estimated location of the wintering areas, shifting them approximately 1° south, and reducing the estimated accuracy of the locations. The timing of these aberrations showed that roosting and emergence roughly follow the timing of dawn and dusk.

Conclusions Current distribution maps for the wintering areas of Nightjars in Africa probably under-represent the true distribution of the species in the continent. The wide dispersal of birds from the same breeding area in the UK may be an indication of mixing of breeding populations during the wintering period. Further study is needed to understand how these results fit into the larger picture of Nightjar migration both from the UK and the wider Eurasian breeding range, and to determine locations of stopovers.     

Marked reduction in demographic rates and reduced fitness advantage for early breeding is not linked to reduced thermal matching of breeding time

Warmer springs may cause animals to become mistimed if advances of spring timing, including available resources and of timing of breeding occur at different speed. We used thermal sums (cumulative sum of degree days) during spring to describe the thermal progression (timing) of spring and investigate its relationship to breeding phenology and demography of a long‐distant migrant bird, the northern wheatear (Oenanthe oenanthe L.). We first compare 20‐year trends in spring timing, breeding time, selection for breeding time, and annual demographic rates. We then explicitly test whether annual variation in selection for breeding time and demographic rates associates with the degree of phenological matching between breeding time and thermal progression of spring. Both thermal progression of spring and breeding time of wheatears advanced in time during the study period. But despite breeding on average 7 days earlier with respect to date, wheatears bred about 4 days later with respect to thermal spring progression. Over the same time period, selection for breeding time changed from distinct within‐season advantage of breeding early to no or very weak advantage. Furthermore, demographic rates (nest success, fledgling production, recruitment, adult survival) and nestling weight declined markedly by 16%–79%. Those temporal trends suggest that a reduced degree of phenological matching may affect within‐season fitness advantage of early breeding and population demographic rates. In contrast, when we investigate links based on annual variation, we find no significant relationship between either demographic rates or fitness advantage of early breeding with annual variation in the degree of phenological matching. Our results show that corresponding temporal trends in phenological matching, selection for breeding time and demographic rates are inconclusive evidence for demographic effects of changed phenological matching. Instead, we suggest that the trends in selection for breeding time and demographic rates are due to a general deterioration of the breeding environment.     

Climate change and the risks associated with delayed breeding in a tropical wild bird population

There is growing evidence of changes in the timing of important ecological events, such as flowering in plants and reproduction in animals, in response to climate change, with implications for population decline and biodiversity loss. Recent work has shown that the timing of breeding in wild birds is changing in response to climate change partly because individuals are remarkably flexible in their timing of breeding. Despite this work, our understanding of these processes in wild populations remains very limited and biased towards species from temperate regions. Here, we report the response to changing climate in a tropical wild bird population using a long-term dataset on a formerly critically endangered island endemic, the Mauritius kestrel. We show that the frequency of spring rainfall affects the timing of breeding, with birds breeding later in wetter springs. Delays in breeding have consequences in terms of reduced reproductive success as birds get exposed to risks associated with adverse climatic conditions later on in the breeding season, which reduce nesting success. These results, combined with the fact that frequency of spring rainfall has increased by about 60 per cent in our study area since 1962, imply that climate change is exposing birds to the stochastic risks of late reproduction by causing them to start breeding relatively late in the season.     

Differences in circadian phase and weekday/weekend sleep patterns in a sample of middle-aged morning types and evening types

Factors contributing to sleep timing and sleep restriction in daily life include chronotype and less flexibility in times available for sleep on scheduled days versus free days. There is some evidence that these two factors interact, with morning types and evening types reporting similar sleep need, but evening types being more likely to accumulate a sleep debt during the week and to have greater sleep extension on weekend nights. The aim of the present study was to evaluate the independent contributions of circadian phase and weekend-to-weekday variability to sleep timing in daily life. The study included 14 morning types and 14 evening types recruited from a community-based sample of New Zealand adults (mean age 41.1 ± 4.7 years). On days 1–15, the participants followed their usual routines in their own homes and daily sleep start, midpoint and end times were determined by actigraphy and sleep diaries. Days 16–17 involved a 17 h modified constant routine protocol in the laboratory (17:00 to 10:00, <20 lux) with half-hourly saliva samples assayed for melatonin. Mixed model ANCOVAs for repeated measures were used to investigate the independent relationships between sleep start and end times (separate models) and age (30–39 years versus 40–49 years), circadian phase [time of the dim light melatonin onset (DLMO)] and weekday/weekend schedules (Sunday–Thursday nights versus Friday–Saturday nights). As expected on weekdays, evening types had later sleep start times (mean = 23:47 versus 22:37, p < .0001) and end times (mean = 07:14 versus 05:56, p < .0001) than morning types. Similarly on weekend days, evening types had later sleep start times (mean = 00:14 versus 23:07, p = .0032) and end times (mean = 08:56 versus 07:04, p < .0001) than morning types. Evening types also had later DLMO (22:06 versus 20:46, p = .0002) than morning types (mean difference = 80.4 min, SE = 18.6 min). The ANCOVA models found that later sleep start times were associated with later DLMO (p = .0172) and weekend-to-weekday sleep timing variability (p < .0001), after controlling for age, while later sleep end times were associated with later DLMO (p = .0038), younger age (p = .0190) and weekend days (p < .0001). Sleep end times showed stronger association with DLMO (for every 30 min delay in DLMO, estimated mean sleep end time occurred 14.0 min later versus 10.19 min later for sleep start times). Sleep end times also showed greater delays on weekends versus weekdays (estimated mean delay for sleep end time = 84 min, for sleep start time = 28 min). Comparing morning types and evening types, the estimated contributions of the DLMO to the mean observed differences in sleep timing were on weekdays, 39% for sleep start times and 49% for sleep end times; and on weekends, 41% for sleep start times and 34% of sleep end times. We conclude that differences in sleep timing between morning types and evening types were much greater than would be predicted on the basis of the independent contribution of the difference in DLMO on both weekdays and weekend days. The timing of sleep in daily life involves complex interactions between physiological and psychosocial factors, which may be moderated by age in adults aged 30–49 years.     

Role of exotic tree stands on the current distribution and social behaviour of Swainson's hawk, Buteo swainsoni in the Argentine Pampas

Aim The Argentine Pampas was extensively and abruptly altered by European colonization. Between 1880 and 1885 the indigenous human inhabitants were completely displaced, and native grasslands were replaced by exotic pasture plants and crops. One of the most important ecological changes in the Pampas landscape, the introduction of tall exotic tree species, has received little attention, and its effect on wildlife has never been assessed. We have made an intensive survey of habitat use of Swainson's hawk, Buteo swainsoni in its most important non‐breeding quarters, the Pampas of Argentina, aiming to characterize the sites used by hawks for communal roosting. Location Pampas grasslands, Argentina. Methods We surveyed 30,000 km of roads by car during the austral summer from 2001 to 2004, covering the main non‐breeding area occupied by Swainson's hawks. Their roost sites were located by direct observation of birds roosting in tree stands close to the roads, by surveying potential roost sites around places where groups of pre‐ and post‐roosting hawks were recorded, and by gathering information from local farmers. Results Swainson's hawks exclusively used stands of exotic tree species for roosting. Eucalyptus viminalis was present in all 34 roosts surveyed, and in 59% of them it was the only species present. The remaining exotic tree species were the Siberian elm, Ulmus pumila, pines (Pinus spp.) and cypress (Cupressus spp.). Flock sizes at roost sites were unusually high for a raptor, with an average of 658 individuals (range 8–5000 hawks, n = 27 flocks). Main conclusions The introduction of exotic trees may have resulted in the expansion of the suitable habitat for Swainson's hawks, permitting a recent colonization of the Argentine Pampas. Tree stands may have also changed the communal roosting behaviour of this raptor, by virtue of their providing new structural elements in a region that almost completely lacked trees prior to European occupation.     

Intraspecific developmental variation in the life cycle of the Andean Treefrog (Boana riojana): A temporal analysis

Intraspecific variation during the anuran larval period has been analyzed mainly in relation to the timing of metamorphosis and body size at metamorphosis. However, other traits may vary as well. We examined two developmental series of Boana riojana from the same population in two consecutive years and describe intraspecific variation in larvae of this species. We discuss how variation, if present, may influence its life cycle. We found that both larval series differed in the larval period length, one twice as long as the other. This variation primarily depended on when breeding occurred, metamorphosis was achieved during late spring in both generations and at similar sizes, and only the rate of larval development during premetamorphosis varied extensively between years. This is consistent with thyroid gland activity because when it became active the developmental trajectory became more canalized. No variation of staging sequence occurred in relation to the different durations of the larval period. However, in the long-lasting series we found two different morphs. Also, integument, thyroid gland, skeleton, and testis differentiation events occurred at the same developing stages. In contrast, ovarian differentiation proceeded at the same absolute age in both series. Sexual dimorphism becomes evident within the year after metamorphosis. The intraspecific heterochrony that we describe for the larval development of B. riojana does not lead to phenotypic variation at the end of metamorphosis. We discuss the importance of analyzing growth and development independently. Each proceeds differently in time, but with an interdependence at some point, because size and shape do not vary at the end of metamorphosis.     

Flexibility and constraints in the molt schedule of long‐distance migratory shorebirds: causes and consequences

Molt is a major component of the annual cycle of birds, the timing and extent of which can affect body condition, survival, and future reproductive success through carry‐over effects. The way in which molt is fitted into the annual cycle seems to be a somewhat neglected area which is both of interest and of importance. Study of the causes of annual variation in the timing of molt and its potential consequence in long‐distance migratory birds was examined using the Curlew Sandpiper, Calidris ferruginea, as a model species. Using the maximum likelihood molt models of Underhill and Zucchini (1988, Ibis 130:358–372), the relationship between annual variability in the start dates of molt at the population level with conditions on the breeding area was explored. Adult males typically started early in years when temperature in June on the Arctic breeding grounds were high compared to cold years while adult females molted later in years of high breeding success and/or warm July temperature and vice versa. When molt started later, the duration was often shorter, indicating that late completion of molt might have fitness consequences, probably jeopardizing survival. Evidence of this was seen in the low body condition of birds in years when molt was completed late. The results indicate that these migratory shorebirds follow a fine‐tuned annual life cycle, and disturbances at a certain stage can alter next biological events through carry‐over effects.     

Breeding status influences timing but not duration of moult in the Northern Fulmar Fulmarus glacialis

Seabirds are key marine top predator species that are often used as indicators of the environmental quality of the oceans. Their breeding phenology has been studied extensively, but their pelagic habits mean less is known about the phenology of other events during the non-breeding period. Here, we used miniaturized saltwater immersion light-based geolocators (GLS) to investigate moult phenology in individuals with known breeding histories in a population of Northern Fulmar Fulmarus glacialis in Orkney, Scotland. As seabirds spend more time on the water during moult, moulting periods can be identified from patterns of variation in the amount of time that birds are in contact with saltwater. Estimates of daily variation in this behaviour during the non-breeding period were based upon wet/dry sensors and then modelled to characterize the timing of the moult. Light-based geolocation provided information on the areas used by each individual during its moult period. Inter-individual variability in moult timing was investigated in relation to sex and breeding success in the previous summer. We found a sex difference in the location of the moult, but not in its timing. However, the timing of moult did differ between individuals that had succeeded or failed in their previous breeding attempt, with successful breeders moulting the latest. In contrast, the duration of moult did not depend on prior reproductive success, but there was evidence of inter-annual variation in moult duration. GLS studies have provided a step change in our understanding of the at-sea distribution of pelagic seabirds. Our work highlights how activity data from these devices can add value to such studies by identifying key phases of the annual cycle, and locations at these times, when seabirds may be at particular risk. Furthermore, our findings indicate that individual and inter-annual variation in breeding success may influence phenological patterns in other phases of the Northern Fulmar annual cycle.     

Delayed timing of breeding as a cost of reproduction

Timing of breeding is a trait with considerable individual variation, often closely linked to fitness because of seasonal declines in reproduction. The drivers of this variation have received much attention, but how reproductive costs may influence the timing of subsequent breeding has been largely unexplored. We examined a population of northern wheatears Oenanthe oenanthe to compare three groups of individuals that differed in their timing of breeding termination and reproductive effort to investigate how these factors may carry over to influence reproductive timing and reproductive output in the following season. Compared to females that bred successfully, females that put in less effort and terminated breeding early due to nest failure tended to arrive and breed earlier in year 2 (mean advancement = 2.2 and 3.3 d respectively). Females that spent potentially more effort and terminated breeding later due to production of a replacement clutch after nest failure, arrived later than other females in year 2. Reproductive output (number of fledglings) in year 2 differed between the three groups as a result of group‐level differences in the timing of breeding in combination with the general seasonal decline in reproductive output. Our study shows that the main cost of reproduction was apparent in the timing of arrival and breeding in this migratory species. Hence, reproductive costs can arise through altered timing of breeding since future reproductive success (including adult survival) is often dependent on the timing of breeding in seasonal systems.     

A phenological shift in the time of recruitment of the shipworm,Teredo navalis L., mirrors marine climate change

For many species, seasonal changes in key environmental variables such as food availability, light, and temperature drive the timing (“phenology”) of major life‐history events. Extensive evidence from terrestrial, freshwater, and marine habitats shows that global warming is changing the timings of many biological events; however, few of these studies have investigated the effects of climate change on the phenology of larval recruitment in marine invertebrates. Here, we studied temperature‐related phenological shifts in the breeding season of the shipworm Teredo navalis (Mollusca, Bivalvia). We compared data for the recruitment period of T. navalis along the Swedish west coast during 2004–2006 with similar data from 1971–1973, and related differences in recruitment timing to changes in sea surface temperature over the same period. We found no significant shift in the timing of onset of recruitment over this ~30‐year time span, but the end of recruitment was an average of 26 days later in recent years, leading to significantly longer recruitment periods. These changes correlated strongly with increased sea surface temperatures and coincided with published thermal tolerances for reproduction in T. navalis. Our findings are broadly comparable with other reports of phenological shifts in marine species, and suggest that warmer sea surface temperatures are increasing the likelihood of successful subannual reproduction and intensifying recruitment of T. navalis in this region.