Brooding Period Research Articles

Kinematics of mouthbrooding in Oreochromis niloticus (Cichlidae).

Many species from several different families of fishes perform mouthbrooding, where one of the sexes protects and ventilates the eggs inside the mouth cavity. This ventilation behaviour differs from gill ventilation outside the brooding period, as the normal, small-amplitude suction-pump respiration cycles are alternated with actions including near-simultaneous closed-mouth protrusions and high-amplitude depressions of the hyoid. The latter is called churning, referring to its hypothetical function in moving around and repositioning the eggs by a presumed hydrodynamic effect of the marked shifts in volume along the mouth cavity. We tested the hypothesis that churning causes the eggs located posteriorly in the mouth cavity to move anteriorly away from the gill entrance. This would prevent or clear accumulations of brood at the branchial basket, which would otherwise hinder breathing by the parent. Dual-view videos of female Nile tilapias (Oreochromis niloticus) during mouthbrooding showed that churning involves a posterior-to-anterior wave of expansion and compression of the head volume. Flow visualisation with polyethylene microspheres revealed a significant inflow of water entering the gill slits at the zone above the pectoral fin base, followed by a predominantly ventral outflow passing the ventrolaterally flapping branchiostegal membranes. X-ray videos indicated that particularly the brood located close to the gills is moved anteriorly during churning. These data suggest that, in addition to mixing of the brood to aid its oxygenation, an important function of the anterior flow through the gills and buccal cavity during churning is to prevent clogging of the eggs near the gills.

Hatching and growth performances of guinea fowl under intensive management system

Present study was carried out to evaluate the hatching and growth performances of guinea fowls (Numida meleagris) kept under intensive rearing system at the Bangladesh Agricultural University Poultry Farm, Mymensingh. To develop a base population of guinea fowls at BAU Poultry Farm, a good number of hatching eggs were collected from different regions of the country. In first phase, the physical features of hatching eggs, their incubation period, care and handling of eggs during incubation, their fertility and hatchability were investigated. Eggs were hatched in a home incubator incubator at BAU Poultry Farm. In second phase, brooding management of the keets, growth performances, prevention and control of diseases and mortality of the birds were observed. All the activities were performed at the Laboratory of Poultry Science and the Poultry Farm of Bangladesh Agricultural University. Brooding of keets was performed under full intensive system in a littered floor. Broiler starter feed was supplied during the brooding period. Results showed that the shape of egg was top like and both white and spotted cream color shell was found. The average egg weight was 38g per egg and shell thickness was 0.52 mm. The incubation period was 28 days. Fertility and hatchability on set eggs were 80 and 68%, respectively. Dead in shell and dead in germ were 15 and 4%, respectively. The average day-old keet weight was 25.8 g. Average feed intake per bird per day during 0-4, 5-8 and 9-11 weeks of age were 10.22, 30.91 and 52.6 g with the feed conversion ratios were 3.25, 3.05 and 2.88, respectively. The keet’s mortality up to 11 weeks was 10%. Economic feasibility should be taken into consideration with the observation of egg production and other associated parameters keeping guinea under complete free-range rearing system.Progressive Agriculture 27 (1): 70-77, 2016

From brooding to hatching: new insights from a female Octopus vulgaris in the wild

A brooding Octopus vulgaris female was monitored for 128 days in her natural habitat. The main reproductive events and embryonic development in relation to the temperature inside the spawning den, which was recorded by long-battery-life mini-data loggers, are described in the wild. The den temperature ranged from 12.9 to 19.3°C. The total number of egg strings was 160, and the total number of eggs spawned ranged between 139,040 and 241,760 (mean 190,400). The brooding period, the egg laying interval and the duration of the hatching course lasted 128, 35 and 43 days, respectively. Both egg laying and hatching were intermittent processes. The time taken for embryonic development was variable (85–128 d) and depended on the laying date, temperature and position of the string in the egg cluster and the position of the egg in the egg string. The first hatching observed occurred after a progressive and gradual increase of the temperature from 14.9 to 19.3°C. The 280 min of video recordings taken by scuba divers showed that several times, this female opened and closed a small window in the obstructions of the den entrance to facilitate a way out for the hatchling batches.

Temporal Relationships Exist Between Cecum, Ileum, and Litter Bacterial Microbiomes in a Commercial Turkey Flock, and Subtherapeutic Penicillin Treatment Impacts Ileum Bacterial Community Establishment

Gut health is paramount for commercial poultry production, and improved methods to assess gut health are critically needed to better understand how the avian gastrointestinal tract matures over time. One important aspect of gut health is the totality of bacterial populations inhabiting different sites of the avian gastrointestinal tract, and associations of these populations with the poultry farm environment, since these bacteria are thought to drive metabolism and prime the developing host immune system. In this study, a single flock of commercial turkeys was followed over the course of 12 weeks to examine bacterial microbiome inhabiting the ceca, ileum, and corresponding poultry litter. Furthermore, the effects of low-dose, growth-promoting penicillin treatment (50 g/ton) in feed on the ileum bacterial microbiome were also examined during the early brood period. The cecum and ileum bacterial communities of turkeys were distinct, yet shifted in parallel to one another over time during bird maturation. Corresponding poultry litter was also distinct yet more closely represented the ileal bacterial populations than cecal bacterial populations, and also changed parallel to ileum bacterial populations over time. Penicillin applied at low dose in feed significantly enhanced early weight gain in commercial poults, and this correlated with predictable shifts in the ileum bacterial populations in control versus treatment groups. Overall, this study identified the dynamics of the turkey gastrointestinal microbiome during development, correlations between bacterial populations in the gastrointestinal tract and the litter environment, and the impact of low-dose penicillin on modulation of bacterial communities in the ileum. Such modulations provide a target for alternatives to low-dose antibiotics.

Reproductive constraints influence habitat accessibility, segregation, and preference of sympatric albatross species.

BackgroundThe spatiotemporal distribution of animals is dependent on a suite of factors, including the distribution of resources, interactions within and between species, physiological limitations, and requirements for reproduction, dispersal, or migration. During breeding, reproductive constraints play a major role in the distribution and behavior of central place foragers, such as pelagic seabirds. We examined the foraging behavior and marine habitat selection of Laysan (Phoebastria immutabilis) and black-footed (P. nigripes) albatrosses throughout their eight month breeding cycle at Tern Island, Northwest Hawaiian Islands to evaluate how variable constraints of breeding influenced habitat availability and foraging decisions. We used satellite tracking and light-based geolocation to determine foraging locations of individuals, and applied a biologically realistic null usage model to generate control locations and model habitat preference under a case–control design. Remotely sensed oceanographic data were used to characterize albatross habitats in the North Pacific.ResultsIndividuals of both species ranged significantly farther and for longer durations during incubation and chick-rearing compared to the brooding period. Interspecific segregation of core foraging areas was observed during incubation and chick-rearing, but not during brooding. At-sea activity patterns were most similar between species during brooding; neither species altered foraging effort to compensate for presumed low prey availability and high energy demands during this stage. Habitat selection during long-ranging movements was most strongly associated with sea surface temperature for both species, with a preference for cooler ocean temperatures compared to overall availability. During brooding, lower explanatory power of habitat models was likely related to the narrow range of ocean temperatures available for selection.ConclusionsLaysan and black-footed albatrosses differ from other albatross species in that they breed in an oligotrophic marine environment. During incubation and chick-rearing, they travel to cooler, more productive waters, but are restricted to the low-productivity environment near the colony during brooding, when energy requirements are greatest. Compared to other albatross species, Laysan and black-footed albatrosses spend a greater proportion of time in flight when foraging, especially during the brooding period; this strategy may be adaptive for locating dispersed prey in an oligotrophic environment.Electronic supplementary materialThe online version of this article (doi:10.1186/s40462-015-0063-4) contains supplementary material, which is available to authorized users.

Preconditioning in the reef-building coral Pocillopora damicornis and the potential for trans-generational acclimatization in coral larvae under future climate change conditions.

Coral reefs are globally threatened by climate change-related ocean warming and ocean acidification (OA). To date, slow-response mechanisms such as genetic adaptation have been considered the major determinant of coral reef persistence, with little consideration of rapid-response acclimatization mechanisms. These rapid mechanisms such as parental effects that can contribute to trans-generational acclimatization (e.g. epigenetics) have, however, been identified as important contributors to offspring response in other systems. We present the first evidence of parental effects in a cross-generational exposure to temperature and OA in reef-building corals. Here, we exposed adults to high (28.9°C, 805 µatm P(CO2)) or ambient (26.5°C, 417 µatm P(CO2)) temperature and OA treatments during the larval brooding period. Exposure to high treatment negatively affected adult performance, but their larvae exhibited size differences and metabolic acclimation when subsequently re-exposed, unlike larvae from parents exposed to ambient conditions. Understanding the innate capacity corals possess to respond to current and future climatic conditions is essential to reef protection and maintenance. Our results identify that parental effects may have an important role through (1) ameliorating the effects of stress through preconditioning and adaptive plasticity, and/or (2) amplifying the negative parental response through latent effects on future life stages. Whether the consequences of parental effects and the potential for trans-generational acclimatization are beneficial or maladaptive, our work identifies a critical need to expand currently proposed climate change outcomes for corals to further assess rapid response mechanisms that include non-genetic inheritance through parental contributions and classical epigenetic mechanisms.

Embryo oxygenation in pipefish brood pouches: novel insights

The pipefish brood pouch presents a unique mode of parental care that enables males to protect, osmoregulate, nourish and oxygenate the developing young. Using a very fine O2 probe, we assessed the extent to which males of the broad-nosed pipefish (Syngnathus typhle) oxygenate the developing embryos and are able to maintain pouch fluid O2 levels when brooding in normoxia (100% O2 saturation) and hypoxia (40% O2 saturation) for 24 days. In both treatments, pouch fluid O2 saturation levels were lower compared with the surrounding water and decreased throughout the brooding period, reflecting greater offspring demand for O2 during development and/or decreasing paternal ability to provide O2 to the embryos. Male condition (hepatosomatic index) was negatively affected by hypoxia. Larger males had higher pouch fluid O2 saturation levels compared with smaller males, and levels were higher in the bottom section of the pouch compared with other sections. Embryo size was positively correlated with O2 availability, irrespective of their position in the pouch. Two important conclusions can be drawn from our findings. First, our results highlight a potential limitation to brooding within the pouch and dismiss the notion of closed brood pouches as well-oxygenated structures promoting the evolution of larger eggs in syngnathids. Second, we provide direct evidence that paternal care improves with male size in this species. This finding offers an explanation for the documented strong female preference for larger partners because, in terms of oxygenation, the brood pouch can restrict embryo growth.

Brood Habitat Selection of Chinese Grouse (Tetrastes sewerzowi) at Lianhuashan, Gansu, China

ABSTRACT We studied habitat selection in Chinese Grouse (Tetrastes sewerzowi) hens with dependent broods at Lianhuashan, Gansu, China in 2010–2012. We divided the dependent brood period into four stages (weeks 1–2, 3–4, 5–8, and beyond 8 weeks post hatching) and compared used with available habitat, and found that hens with broods chose sites with significantly less canopy cover (0.28 ± 0.01 vs 0.49 ± 0.02), greater willow cover (0.31 ± 0.02 vs 0.14 ± 0.01), and greater herb height (21.36 ± 1.05 vs 14.43 ± 0.59). Broods used a variety of vegetation types at different stages of chick development. They used more early successional deciduous forests and shrubs during stages 2 and 3 (weeks 3–8, Kruskal-Wallis Test: χ2 = 13.918, df = 3, P = 0.003). Sites with more invertebrates were used in Stage 1 compared to available sites (54.5 ± 7.2 vs 36.4 ± 4.4), but not in Stage 2. Compared to sites used during stage 4, chicks in stage 2–3 used sites of earlier successional stages, greater herbaceous vegetation h...

A new case of poecilogony from South America and the implications of nurse eggs, capsule structure, and maternal brooding behavior on the development of different larval types.

Poecilogony is the production of different larval types within the same species. Although rare, poecilogonous species are ideal systems for testing the evolutionary and ecological implication of different developmental modes in marine invertebrates. Here, we described a new case of poecilogony, the Southern Hemisphere spionid Boccardia wellingtonensis. We used a combination of common-garden experiments, video recordings, and in vitro manipulations of individuals from three sites to (1) document the type of poecilogony, the brooding behavior of the mother, and the hatching process; (2) experimentally measure the effect of nurse eggs on the growth and type of larvae produced; and (3) document variation in the length of the brooding period, number of capsules, larvae, and nurse eggs of mothers from three sites to explore the potential for plasticity in reproductive traits. These results were compared to the previously reported poecilogonous species B. proboscidea, which resembles B. wellingtonensis in size, morphology, ecology, and reproductive strategy but differs in capsule structure. We found that in contrast to B. proboscidea, B. wellingtonensis produced larvae that, in isolation and in the presence of nurse eggs, developed into a wide range of offspring sizes. Mothers brood and hatch the larvae with frequent partial hatching of the brood during the brooding period. Although larvae could not liberate themselves, larvae crossed to other capsules as interconnections between capsules broke during the developmental period, potentially affecting food availability, sibling competition for nurse eggs, and cannibalism. Variation in brooding time and number of capsules deposited among sites suggest local adaptations.

A high‐resolution panorama camera system for monitoring colony‐wide seabird nesting behaviour

Summary Obtaining accurate and representative demographic metrics for animal populations is critical to many aspects of wildlife monitoring and management. However, at remote animal colonies, metrics derived from sequential counts or other continuous monitoring are often subject to logistical, weather and disturbance challenges. The development of remote camera technologies has assisted monitoring, but limitations in spatial and temporal resolution and sample sizes remain. Here, we describe the application of a robotic camera system (Gigapan) which takes a tiled sequence of photographs that are automatically stitched together to form high‐resolution panoramas. We demonstrate the application of the Gigapan using data collected during field testing at a shy albatross colony on Albatross Island in northwest Tasmania. We took daily panoramas over 5 days to estimate mean incubation shift duration, an indirect measure for foraging trip duration, in an existing study area. Similar numbers of occupied nests could be observed at a distance of approximately 100 m in the Gigapan panoramas compared to ground‐based counts (115 and 117, respectively). Of these, birds on 90% of nests visible in the panoramas could be unambiguously identified as marked or unmarked with a small daub of paint throughout the study period and thus a shift change reliably recorded. Gigapan‐based shift duration was estimated using a novel instantaneous statistical method and were longer than estimates earlier in the egg brooding period, potentially revealing a new pattern in shift duration. This example field application provides proof of concept and demonstration that the relatively low‐cost Gigapan system provides the spatial advantages of aerial photos with the detail and temporal replication of land‐based camera systems. The Gigapan system can extend or enhance traditional data collection methods, particularly for simultaneous observations at distance, of the behaviour of surface nesting colonial seabirds.

Breeding performance of Crested Goshawk Accipiter trivirgatus in urban and rural environments of Taiwan

Capsule A Crested Goshawk population recently colonizing an urban area of Taiwan is characterized by earlier egg-laying dates, a higher ratio of mixed-age pairs and higher nesting success.Aims To compare breeding time, productivity and pairing pattern of Crested Goshawk populations between urban and rural areas.Methods A total of 117 nests, comprising 49 rural and 68 urban ones, were monitored in Taichung, central Taiwan over six years. Age of parents, egg-laying date, clutch size and number of fledglings were recorded from each nest.Results The urban Crested Goshawk bred 34 days earlier on average than the rural population with a significantly higher nesting success. Mixed-age pairs occurred in a higher frequency in urban (30.9%) than in rural (14.3%) areas. Predation (55.6%) and inclement weather (27.8%) were the two main factors causing nesting failures in rural areas, whereas neither occurred in the urban area.Conclusion We conclude that the urban Crested Goshawk population benefits from high food supply and low predation risk. The year-round abundance of prey might increase the breeding success of young adults and advance their breeding schedule, which coincidently shifts the brooding period away from the heavy rainy season.

Avian Habitat Following Grazing Native Warm-Season Forages in the Mid-South United States

Native warm-season grasses (NWSG) currently are being promoted for livestock forage and biofuels feedstock in the Mid-South. However, there are no published data on how NWSG managed with livestock in the Mid-South may affect habitat for wildlife. We conducted a study to evaluate habitat for grassland songbirds and northern bobwhite (Colinus virginianus) in response to two cattle grazing treatments in NWSG pastures across three sites in Tennessee, 2010 and 2011. We evaluated vegetation composition and structure along with invertebrate availability during the primary nesting season for grassland songbirds and the typical brood-rearing season for the northern bobwhite. Grazing treatments included full-season (May to August) grazing and early-season (30 days beginning in May) grazing, after which subsequent growth was taken as a biofuel harvest postdormancy. Forage treatments included big bluestem/indiangrass mixture, switchgrass, and eastern gamagrass. Vegetation composition was dominated by the planted forages in all pastures. All forage types and both grazing treatments provided suitable structure for grassland songbirds and bobwhite during the primary nesting season. Full-season grazing maintained suitable structure through the brooding period, with greater openness at the ground level and angle of obstruction, as well as optimal vegetation height (<60 cm). Structure within early-season grazing treatments became dense after cattle were removed with less openness at ground level than what brooding bobwhites typically use. Invertebrate biomass was sufficient in all forage types and grazing treatments to support bobwhite broods. We recommend livestock producers in the Mid-South use full-season grazing that maintains grass height of approximately 40 cm in production stands of NWSG to maximize benefits for grassland birds and northern bobwhite.

The effect of parental age, experience and historical reproductive success on wandering albatross (Diomedea exulans) chick growth and survival

Growth and survival of altricial young are influenced by their parents’ abilities to invest in a breeding attempt. As a result, chick growth and survival in one breeding season may be indicative of their parents’ long-term reproductive potential. To determine whether variation in long-term reproductive success is driven by differential breeding investment, parental care and chick growth in wandering albatrosses (Diomedea exulans) were correlated with parental historical reproductive success. Effects of age and breeding experience (determined from past breeding attempts) and pre-laying body condition (mass–size indices) on chick growth and survival also were tested. Longer brooding of chicks increased their survival, but length of chick brooding did not differ between historically unproductive and successful breeders. Past reproductive success also was not correlated with chick growth rates or fledging mass or size. Chick brooding period, chick growth rates, final mass and size were independent of parental body condition. Older and more experienced parents brooded chicks for longer and their chicks grew faster, supporting previous findings that breeding competence is a learnt skill. Chick care and growth characteristics differed more between than within pairs, suggesting that differences in these characteristics are driven by variation among pairs.

Deep-Sea Octopus (Graneledone boreopacifica) Conducts the Longest-Known Egg-Brooding Period of Any Animal

Octopuses typically have a single reproductive period and then they die (semelparity). Once a clutch of fertilized eggs has been produced, the female protects and tends them until they hatch. In most shallow-water species this period of parental care can last from 1 to 3 months, but very little is known about the brooding of deep-living species. In the cold, dark waters of the deep ocean, metabolic processes are often slower than their counterparts at shallower depths. Extrapolations from data on shallow-water octopus species suggest that lower temperatures would prolong embryonic development periods. Likewise, laboratory studies have linked lower temperatures to longer brooding periods in cephalopods, but direct evidence has not been available. We found an opportunity to directly measure the brooding period of the deep-sea octopus Graneledone boreopacifica, in its natural habitat. At 53 months, it is by far the longest egg-brooding period ever reported for any animal species. These surprising results emphasize the selective value of prolonged embryonic development in order to produce competitive hatchlings. They also extend the known boundaries of physiological adaptations for life in the deep sea.

Necrotic enteritis in a captive mute swan (Cygnus olor) in the breeding season

Abstract A captive mute swan ( Cygnus olor ) in the brooding period was found dead without any specific signs. On necropsy, the entire digestive tract was severely necrotized with loosely adherent pseudomembranes, and Clostridium perfringens (CP) colonies isolated from the intestinal contents were identified as CP type A by polymerase chain reaction. Microscopically, the intestine and the liver were necrotized and intralesional bacterial clusters were observed. In this case, there were no other mortalities, so the con-dition of a single bird, in particular, stress from incubation effort, could act as the predisposing factor for necrotic enteritis. In this study, we report a unique case of necrotic enteritis associated with in-cubation in a captive mute swan. Key words : Cygnus olor , Incubation effort, Mute swan, Necrotic enteritis, Stress factor INTRODUCTION Necrotic enteritis (NE) is a clinically dramatic enteric disease afflicting birds which is characterized by an in-testinal necrotic fibrinous pseudomembrane with a “Turkish towel” appearance (Opengart and Songer, 2013). NE occurs in the presence of predisposing fac-tors, such as feed ingredients, stress or intestinal para-sites (Timbermont et al, 2011) that cause a microbial imbalance favorable for the overgrowth of the causal agent,

Do Introduced Mammals Chronically Impact the Breeding Success of the World's Rarest Albatross?

Introduced mammals may have deleterious effects on avifauna. We investigated whether such species may be affecting the breeding success of the critically endangered Amsterdam Albatrosses Diomedea amsterdamensis on its remote breeding island. Twelve camera-traps deployed near albatross nests during the chick brooding period in 2011 captured 25,000 pictures. Two of them showed Black Rats Rattus rattus, but without revealing evidence of any direct interaction between the two species. Breeding success in 2011 was similar to that in previous years (60%). Our survey suggests that introduced mammals may not currently represent a primary direct threat to this population, but they might amplify the risks of chick mortality in case of disease outbreaks.

Implications of climatic heterogeneity for conservation of the Lesser Prairie‐Chicken (Tympanuchus pallidicinctus)

A geographic range is a heterogeneous matrix where the natural capability to support resident species varies from detrimental to optimal. Given this, the first priority for species conservation should be to determine where optimal environments exist. We used MaxEnt species distribution modeling to distinguish climatic characteristics associated with persistent leks from those at random locations in order to characterize the niche and potential distribution of the imperiled Lesser Prairie‐Chicken (Tympanuchus pallidicinctus). Annual, brood period, and winter precipitation were the most important characteristics of the niche across the entire range, but maximum temperature during nesting was a key characteristic in the southern part of the range. Habitat suitability across the geographic range was multimodal but also consistent with a center‐periphery pattern. Western Kansas and Oklahoma and east‐central New Mexico contributed more than expected, whereas all other areas contributed less than expected, to habitat suitability of the geographic range. Lesser Prairie‐Chickens appear constrained on the western edge of their range by abiotic factors, namely aridity, unfavorable temperatures and sandy soils. Conversely, they appear constrained on the eastern edge by biotic factors, namely transition from mid‐grass to tallgrass prairie that results in dominance by the Greater Prairie‐Chicken (Tympanuchus cupido). Conserving Lesser Prairie‐Chickens will depend on maintaining persistent populations in western Kansas and Oklahoma and east‐central New Mexico, as well as expanding its distribution across Texas. Aridity, unfavorable temperatures, and a paucity of habitat make eastern Colorado and southeastern New Mexico challenging areas for persistence of this species. Climate change may make it more difficult for populations in New Mexico and adjacent parts of Texas to persist, but more favorable for populations in eastern Colorado. The potential difficulties for populations in the southern part of the range will make it increasingly important to conserve populations in western Kansas and Oklahoma.

Coupling instantaneous energy-budget models and behavioural mode analysis to estimate optimal foraging strategy: an example with wandering albatrosses.

BackgroundHow foragers move across the landscape to search for resources and obtain energy is a central issue in ecology. Direct energetic quantification of animal movements allows for testing optimal foraging theory predictions which assumes that animals forage so as to maximise net energy gain. Thanks to biologging advances, we coupled instantaneous energy-budget models and behavioural mode analysis to test optimal foraging theory predictions on wandering albatross Diomedea exulans during the brooding period. Specifically, the instantaneous energy-budget model considered the energetic balance (i.e., the difference between empirical energy gain data and modelled energy expenditure via heart rate values) along the trajectory of a given individual. Four stereotypic instantaneous behavioural modes were identified based on trajectory properties (e.g., speed and turning angle) by applying a new algorithm called Expectation Maximization Binary Clustering. Previous studies on this species have shown that foraging-in-flight is the optimal foraging strategy during the incubation period when albatrosses undertake long-distance movements but no specific foraging strategy has been determined for shorter foraging movements (e.g., brooding period).ResultsThe output of our energy-budget model (measured as net energy gain) highlighted the potential optimality of alternative search strategies (e.g., sit-and-wait) during brooding, when birds may be subjected to specific energetic trade-offs and have to adapt their foraging strategies accordingly. However, not all birds showed this pattern, revealing the importance of considering individual variability in foraging strategies, as well as any switching among strategies, before drawing population-level generalizations. Finally, our study unveils the importance of considering fine scale activities to make realistic estimates of trip energy expenditure for flying birds at sea.ConclusionsThe up-scaling of accurately measured fine-scale energy patterns is essential to quantify energy balances, and their fluctuations by season of different activities among individuals or populations. In particular, we offer new insights for the energetic quantification of the effect of changing oceanic winds on the biology of pelagic predators in the southern oceans.Electronic supplementary materialThe online version of this article (doi:10.1186/2051-3933-2-8) contains supplementary material, which is available to authorized users.

Evaluation of a Modified Passive Solar Housing System for Poultry Brooding

A modified passive solar poultry brooding system was tested for its performance at full capacity for a brooding period of four (4) weeks for broiler chicks. Its performance was evaluated through the determination of thermal environmental properties as well as physiological development of brooded chicks for a period of 4 weeks. The temperature levels obtained in the brooding space were in the range of 280C – 350C. The maximum average weight per chick attained at the end of brooding period was 566.5g. Only 6.7% loss was incurred and feed conversion ratio decreased from 1.5 in the first week to 1.1 by the end of the brooding period indicating better performance. The hourly efficiency of the solar brick passive system was estimated at about 78.42% in a day of May and 92.73% in a day of June. The modified solar housing system met the temperature requirements (270C - 350C) for the broiler chicks within the 4 – 5 weeks of brooding period.Keywords: clay bricks, passive solar system, chick brooding, performance evaluation, Nigeria

Environmentally relevant bouts of cooling stimulate corticosterone secretion in free-living eastern bluebird (Sialia sialis) nestlings: Potential links between maternal behavior and corticosterone exposure in offspring

In vertebrates, exposure to stressful stimuli or to elevated glucocorticoids early in development can contribute to phenotypic variation that may have significant fitness consequences. In species with altricial young, offspring may be partially buffered from elevations in glucocorticoids by a period of low glucocorticoid responsiveness to stressors coupled with high levels of parental care. Because altricial young depend heavily on their parents for warmth, parental brooding behavior could buffer offspring from glucocorticoid exposure associated with cooling. We studied eastern bluebirds (Sialia sialis) with two goals: (1) to determine whether an experimental drop in body temperature such as that which might occur when a brooding female is off the nest was sufficient to stimulate glucocorticoid secretion in young chicks, and (2) to examine the extent to which chicks experienced such bouts of cooling in the field. We subjected chicks to treatments simulating nest temperatures while females were brooding or absent from the nest. We also recorded chick surface temperatures and ambient temperatures at nests during the first week of the brood period. Reductions of surface temperature of less than 10°C significantly elevated corticosterone secretion in chicks as young as 5days old, and thermal and hormonal responses of chicks to cooling increased in an age-dependent manner. One quarter of broods experienced repeated, natural bouts of cooling of this magnitude or greater in the nest. Our data suggest that natural variations in maternal brooding patterns can result in differential exposure of offspring to glucocorticoids, and this may have important phenotypic consequences later in life.