Energetics of communal roosting in chestnut-crowned babblers: implications for group dynamics and breeding phenology

For many endotherms, communal roosting saves energy in cold conditions, but how this might affect social dynamics or breeding phenology is not well understood. Using chestnut-crowned babblers (Pomatostomus ruficeps), we studied the effects of nest use and group size on roosting energy costs. These 50 g cooperatively breeding passerine birds of outback Australia breed from late winter to early summer and roost in huddles of up to 20 in single-chambered nests. We measured babbler metabolism at three ecologically relevant temperatures: 5°C (similar to minimum nighttime temperatures during early breeding), 15°C (similar to nighttime temperatures during late breeding) and 28°C (thermal neutrality). Nest use alone had modest effects: even for solitary babblers at 5°C, it reduced nighttime energy expenditures by <15%. However, group-size effects were substantial, with savings of up to 60% in large groups at low temperatures. Babblers roosting in groups of seven or more at 5°C, and five or more at 15°C, did not need to elevate metabolic rates above basal levels. Furthermore, even at 28°C (thermoneutral for solitary babblers), individuals in groups of four or more had 15% lower basal metabolic rate than single birds, hinting that roosting in small groups is stressful. We suggest that the substantial energy savings of communal roosting at low temperatures help explain why early breeding is initiated in large groups and why breeding females, which roost alone and consequently expend 120% more energy overnight than other group members, suffer relatively higher mortality than communally roosting group mates.

Interannual variation in pup production and the timing of breeding in benthic foraging Australian fur seals

¯Large interannual variations in reproductive success caused by fluctuations in oceanography and prey availability are common to many species of air breathing epipelagic predators. In contrast, little is known about variation in benthic foragers such as Australian fur seals (Arctocephalus pusillus doriferus). Between 1997 and 2007, pup production was assessed in 9 yr, while the timing of breeding and adult female condition was assessed in 5 yr at Kanowna Island in Bass Strait, southeastern Australia. Pup production was variable ( ¯x = 1,726 ± 42, range = 1,386–2,301), but without temporal trend, as was median birth date ( ¯x = 23 November±1, range = 21–25 November) and pupping synchrony (period of 90% births: ¯x = 28 ± 2 d, range = 23–31 d). Pup production was negatively correlated with median birth date and positively correlatedwith female condition,winter sea-surface temperature (SST) and zonal wind strength within Bass Strait. Pup production was also negatively correlated with SST in the previous summer within Bass Strait and in the eastern Great Australian Bight upwelling region. The results suggest that the reproductive success of Australian fur seals is influenced by oceanography but less so than in otariids foraging epipelagically in major upwellings. Despite spanning several El Niño events, no correlation between pup production and the Southern Oscillation Index was observed.

Effects of Spring Temperatures on the Strength of Selection on Timing of Reproduction in a Long-Distance Migratory Bird

Climate change has differentially affected the timing of seasonal events for interacting trophic levels, and this has often led to increased selection on seasonal timing. Yet, the environmental variables driving this selection have rarely been identified, limiting our ability to predict future ecological impacts of climate change. Using a dataset spanning 31 years from a natural population of pied flycatchers (Ficedula hypoleuca), we show that directional selection on timing of reproduction intensified in the first two decades (1980-2000) but weakened during the last decade (2001-2010). Against expectation, this pattern could not be explained by the temporal variation in the phenological mismatch with food abundance. We therefore explored an alternative hypothesis that selection on timing was affected by conditions individuals experience when arriving in spring at the breeding grounds: arriving early in cold conditions may reduce survival. First, we show that in female recruits, spring arrival date in the first breeding year correlates positively with hatch date; hence, early-hatched individuals experience colder conditions at arrival than late-hatched individuals. Second, we show that when temperatures at arrival in the recruitment year were high, early-hatched young had a higher recruitment probability than when temperatures were low. We interpret this as a potential cost of arriving early in colder years, and climate warming may have reduced this cost. We thus show that higher temperatures in the arrival year of recruits were associated with stronger selection for early reproduction in the years these birds were born. As arrival temperatures in the beginning of the study increased, but recently declined again, directional selection on timing of reproduction showed a nonlinear change. We demonstrate that environmental conditions with a lag of up to two years can alter selection on phenological traits in natural populations, something that has important implications for our understanding of how climate can alter patterns of selection in natural populations.

Contrasting genetic structuring between colonies of the world's smallest penguin, Eudyptula minor (Aves: Spheniscidae)

The Little Penguin, Eudyptula minor, is a seabird that nests in colonies throughout New Zealand and southern Australia. Individuals from different colonies in southeast Australia differ significantly in morphology and ecology, suggesting that some genetic structuring may exist among colonies. In contrast, the marking of individuals with flipper bands has revealed some, albeit infrequent, movement between colonies. To determine the extent of genetic structuring, we tested the null hypothesis of substantial gene flow within southeast Australia by examining patterns of genetic variation across seven colonies separated by up to 1,500 km. Phylogeographic structuring was absent for mitochondrial control region sequences (2–3 individuals per colony). Microsatellite allele frequencies at five loci and mitochondrial haplotype frequencies (50 individuals per colony) were also homogenous among the majority of colonies sampled, although two colonies at the western periphery of the sampling range were distinct from those to the east. The genetic homogeneity among the majority of colonies can be explained by low but consistent contemporary gene flow among them, or a recent founder event in Bass Strait following the last marine transgression. The genetic break towards the western end of the sampling distribution appears best explained by differences in sea surface temperature and, consequentially breeding phenology, the latter hindering genetically effective migration.

Range-wide phylogeography of the Little Penguin (Eudyptula minor): evidence of long-distance dispersal

The Little Penguin (Eudyptula minor), a colonial-nesting seabird that is widespread in New Zealand and southern Australia, has high dispersal potential but exhibits regional variation in morphology, coloration, and breeding phenology. We present a distribution-wide survey of mitochondrial DNA variation in the Little Penguin to document phylogeographic relationships and genetic structuring and to test for concordance with intraspecific taxonomy. Phylogeographic structuring was absent among Australian colonies (27 localities, 94 individuals), but the distribution of haplotypes among colonies was significantly nonrandom (ϕST = 0.110, P < 0.01). The Australian individuals exhibited close phylogenetic relationships with a subset of New Zealand birds (4 localities, 22 individuals), whereas the remaining New Zealand birds (20 localities, 106 individuals) were phylogenetically distinct, with ≥7% sequence divergence, and exhibited greater levels of genetic variation and geographic structuring (ϕST = 0.774, P < 0.05). These patterns are consistent with earlier suggestions of an origin in New Zealand followed by recent colonization of Australia and back-dispersal to New Zealand. Extinction and re-establishment processes may have been important factors in the development of genetic structuring across a range of spatiotemporal scales. The genetic data are consistent with suggestions that a single subspecies exists in Australia, but not with the subspecies distributions within New Zealand that have been suggested on the basis of morphology and coloration.

Determining trends and environmental drivers from long-term marine mammal and seabird data : examples from Southern Australia

Climate change is acknowledged as an emerging threat for top-order marine predators, yet obtaining evidence of impacts is often difficult. In south-eastern Australia, a marine global warming hotspot, evidence suggests that climate change will profoundly affect pinnipeds and seabirds. Long-term data series are available to assess some species' responses to climate. Researchers have measured a variety of chronological and population variables, such as laying dates, chick or pup production, colony-specific abundance and breeding success. Here, we consider the challenges in accurately assessing trends in marine predator data, using long-term data series that were originally collected for other purposes, and how these may be driven by environmental change and variability. In the past, many studies of temporal changes and environmental drivers used linear analyses and we demonstrate the (theoretical) relationship between the magnitude of a trend, its variability, and the duration of a data series required to detect a linear trend. However, species may respond to environmental change in a nonlinear manner and, based on analysis of time-series from south-eastern Australia, it appears that the assumptions of a linear model are often violated, particularly for measures of population size. The commonly measured demographic variables exhibit different degrees of variation, which influences the ability to detect climate signals. Due to their generally lower year-to-year variability, we illustrate that monitoring of variables such as mass and breeding chronology should allow detection of temporal trends earlier in a monitoring programme than observations of breeding success and population size. Thus, establishing temporal changes with respect to climate change from a monitoring programme over a relatively short time period requires careful a priori choice of biological variables. © 2014 Springer-Verlag Berlin Heidelberg.

Diversidade, padrões espaciais e temporais de anfíbios anuros em uma floresta estacional semidecidual atlântica, parque estadual do Morro do Diabo (PEMD)

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Cascading climate effects and related ecological consequences during past centuries

The interface between climate and ecosystem structure and function is incompletely understood, partly because few ecological records start before the recent warming phase. Here, we analyse an exceptional 100-yr long record of the great tit (Parus major) population in Switzerland in relation to climate and habitat phenology. Using structural equation analysis, we demonstrate an uninterrupted cascade of significant influences of the large-scale atmospheric circulation (North-Atlantic Oscillation, NAO, and North-sea – Caspian Pattern, NCP) on habitat and breeding phenology, and further on fitness-relevant life history traits within great tit populations. We then apply the relationships of this analysis to reconstruct the circulation-driven component of fluctuations in great tit breeding phenology and productivity on the basis of new seasonal NAO and NCP indices back to 1500 AD. According to the structural equation model, the multi-decadal oscillation of the atmospheric circulation likely led to substantial variation in habitat phenology, productivity and consequently, tit population fluctuations with minima during the "Maunder Minimum" (∼ 1650–1720) and the Little Ice Age Type Event I (1810–1850). The warming since 1975 was not only related with a quick shift towards earlier breeding, but also with the highest productivity since 1500, and thus, the impact of the NAO and NCP has contributed to an unprecedented increase of the population. A verification of the structural equation model against two independent data series (1970–2000 and 1750–1900) corroborates that the retrospective model reliably depicts the major long-term NAO/NCP impact on ecosystem parameters. The results suggest a complex cascade of climate effects beginning at a global scale and ending at the level of individual life histories. This sheds light on how large-scale climate conditions substantially affect major life history parameters within a population, and thus influence key ecosystem parameters at the scale of centuries.

British container breeding mosquitoes: the impact of urbanisation and climate change on community composition and phenology

The proliferation of artificial container habitats in urban areas has benefitted urban adaptable mosquito species globally. In areas where mosquitoes transmit viruses and parasites, it can promote vector population productivity and fuel mosquito-borne disease outbreaks. In Britain, storage of water in garden water butts is increasing, potentially expanding mosquito larval habitats and influencing population dynamics and mosquito-human contact. Here we show that the community composition, abundance and phenology of mosquitoes breeding in experimental water butt containers were influenced by urbanisation. Mosquitoes in urban containers were less species-rich but present in significantly higher densities (100.4±21.3) per container than those in rural containers (77.7±15.1). Urban containers were dominated by Culex pipiens (a potential vector of West Nile Virus [WNV]) and appear to be increasingly exploited by Anopheles plumbeus (a human-biting potential WNV and malaria vector). Culex phenology was influenced by urban land use type, with peaks in larval abundances occurring earlier in urban than rural containers. Among other factors, this was associated with an urban heat island effect which raised urban air and water temperatures by 0.9°C and 1.2°C respectively. Further increases in domestic water storage, particularly in urban areas, in combination with climate changes will likely alter mosquito population dynamics in the UK.

Establishment and development of a seabird colony : long-term trends in phenology, breeding success, recruitment, breeding density and demography

Few studies document long-term colony-level metrics from colony establishment to maturity (equilibrium) and few test predictions of general models of colony development. We describe long-term trends in a colony of Australasian Gannets (Morus serrator) which has been monitored from an early stage in its development. The colony at Pope’s Eye, within Port Phillip Bay, Victoria, Australia was established in 1984 on an artificial structure and the first nest count (25 nests) was conducted in the same year. The colony was then studied for 15 of 19 years between 1988 and 2006–2007. During the study, 2,516 eggs were recorded, resulting in 1,694 chicks hatching (67 % of eggs), of which 1,310 (77 % of those hatched) fledged. At least 184 (14 %) of fledged offspring returned to Pope’s Eye as breeding adults. Since establishment, the number and density of nests increased (number of nests increased 8.8 % annually), with density increasing at varying rates in different areas of the colony. Early recruitment involved birds from a nearby colony, but within 5 years post establishment the first natal recruits were breeding at Pope’s Eye and thereafter natal recruitment was the main source of new breeding adults (totalling 81.4 % of all recruits). Age of recruitment varied throughout the study, though not systematically, and there was no difference between the sexes. The pattern of rapid initial growth is typical of patterns reported for other seabird colonies. However, as the colony (and birds within it) aged, there was no increase in breeding success and egg laying did not become earlier, as was expected from general models of colony development.

Flowering phenology, nectary structure and breeding system in Corymborkis flava (Spiranthoideae : Tropidieae), a terrestrial orchid from a Neotropical forest

Flowering phenology, breeding system and nectary structure of Corymborkis flava (Sw.) Kuntze were studied in a fragment of the Atlantic Forest in south-eastern Brazil. The flowering period extended from March (end of rainy season) to early June and seed dispersal occurred from June to September (dry season). Flowering peak occurred mainly in April, with up to 34 open flowers per plant being observed. The yellow, odourless and tubular flowers lasted similar to 7.8 days. The flowers present a perigonal nectary located in the basal lateral parts of the labellum; this is the first report on the nectary location and characterisation in the Tropidieae tribe. At the pre-anthesis stage, cells of both secretory parenchyma and epidermis of the nectary are filled with compound amyloplasts. However, starch grains were not observed in these tissues in senescent flowers, indicating that these starch grains are hydrolysed and used as source of sugars for nectar production. The nectar accumulates between the cuticle and the outer periclinal wall of the epidermal cells before. owing out into the nectar chamber. C. flava is a self-compatible species and spontaneous self-pollination does not occur because of hercogamy. The high pollinia removal (0.80) and insertion (0.82) per flower, as well as the high natural fruit-set indicate an efficient natural pollination system. The present study contributes for the knowledge of the diversity of reproductive strategies and nectary structures in Orchidaceae.

Ecological factors associated with the breeding and migratory phenology of high-latitude breeding western sandpipers

Environmental conditions influence the breeding and migratory patterns of many avian species and may have particularly dramatic effects on long-distance migrants that breed at northern latitudes. Environment, however, is only one of the ecological variables affecting avian phenology, and recent work shows that migration tactics may be strongly affected by changes in predator populations. We used long-term data from 1978 to 2000 to examine the interactions between snowmelt in western Alaska in relation to the breeding or migration phenologies of small shorebirds and their raptor predators. Although the sandpipers' time of arrival at Alaskan breeding sites corresponded with mean snowmelt, late snowmelts did delay breeding. These delays, however, did not persist to southward migration through British Columbia, likely due to the birds' ability to compensate for variance in the length of the breeding season. Raptor phenology at an early stopover site in British Columbia was strongly related to snowmelt, so that in years of early snowmelt falcons appeared earlier during the sandpipers' southbound migration. These differential effects indicate that earlier snowmelt due to climate change may alter the ecological dynamics of the predator-prey system.

The seasonal phenology of Bactrocera tryoni (Froggatt) (Diptera: Tephritidae) in Queensland

Bactrocera tryoni is a polyphagous fruit fly, originally endemic to tropical and subtropical coastal eastern Australia, but now also widely distributed in temperate eastern Australia. In temperate parts of its range, B. tryoni populations show distinct seasonal peaks driven by changing seasonal climates, especially changing temperature. In contrast to temperate areas, the seasonal phenology of B. tryoni in subtropical and tropical parts of its range is poorly documented and the role of climate unknown. Using a large, historical (1940s and 1950s) fruit fly trapping data set, we present the seasonal phenology of B. tryoni at nine sites across Queensland for multiple (two to seven) years per site. We correlate monthly trap data for each site with monthly weather averages (temperature, rainfall and relative humidity) to investigate climatic influences. We also correlate observed population data with predicted population data generated by an existing B. tryoni population model. Supporting predictions from climate driven models, B. tryoni did show year-round breeding at most Queensland sites. However, contrary to predictions, there was a common pattern of a significant population decline in autumn and winter, followed by a rapid population increase in August and then one or more distinct peaks of abundance in spring and summer. Mean monthly fly abundance was significantly different across sites, but was not correlated with altitudinal, latitudinal or longitudinal gradients. There were very few significant correlations between monthly fly population size and weather variables for eight of the nine sites. For the southern site of Gatton fly population abundance was correlated with temperature. Results suggest that while climate factors may be influencing B. tryoni populations in southern subtropical Queensland, they appear to be having only minor or no influence in northern sub-tropical and tropical Queensland. In the discussion we focus on the role of other factors, particularly larval host plant availability, as likely drivers of B. tryoni abundance in tropical and subtropical parts of its range.

Nest spacing and breeding performance in Short-toed Eagle Circaetus gallicus in northeast Greece

Aims: To describe the phenology and breeding success of one of the densest populations of Short-toed Eagle in Europe. Methods All nests in the Dadia-Lefkimi-Soufli forest in northeast Greece were located and visited regularly throughout the 1996-98 breeding seasons. Data on every stage of the breeding cycle were collected and related to among-year variation in the weather conditions during March to June. Results: A total of 58 pairs were located during the three-year study spread across 22 territories (the same territories are usually occupied each year). The nests were evenly spaced (mean of 2.7 km between nests). Adults arrived between mid-March and mid-April. Only one egg per nest was laid. Nestlings fledged on average after 68.9 days. Eagles departed between 8 September and 2 October. Conclusions: Arrival date determines laying date. The population size appears to be stable but the species has a relatively low reproductive rate and takes three to four years to mature, consequently it may be susceptible to stochastic or human-mediated factors.

Climatic variation and breeding in the Australian magpie (Gymnorhina Tibicen) : a case study using existing data

To anticipate the effects of climate change on Australia’s avifauna, it is first necessary to understand the current effects of climate (including climate variability) on life histories, and to examine the scope and nature of existing data that may provide the necessary historical context to anticipate the effects of climate change. This study examines naturally occurring geographical gradients (altitude, latitude) and the Southern Oscillation Index (SOI) as integrated measures of climate. These are then compared with the timing and ‘amount’ of breeding recorded for the Australian Magpie (Gymnorhina tibicen) using data from Birds Australia’s Nest Record Scheme and Atlas of Australian Birds, the NSW Bird Atlassers Inc.’s NSW Bird Atlas, and the Canberra Ornitholgists Group’s Garden Bird Survey. For this common, easily identified species, these data suggest links between Australian Magpie breeding and all three environmental variables. Breeding became later as altitude increased, the proportion of breeding records increased from north to south, and years of high SOI corresponded to more (and earlier) breeding in this species. That annual climatic fluctuations have a direct, immediate and substantial effect on breeding in the Australian Magpie, particularly on the amount of breeding that occurs, implies that longer term changes in climate will have substantial impacts on populations. Results were not solely temperature-driven, which makes predicting climate change impacts difficult. For rainfall, predictions are far less precise and regional variation is higher. The results also highlight the potential and limitations of current survey techniques for documenting the impacts of climate change on birds; in particular, the Nest Record Scheme does not measure the amount of breeding that occurs, but a useful index of this can be derived from bird atlassing data