Chicks In Broods Research Articles

Isolation time of brooding chicks play an important role in the control of Marek's disease

This work reported the use of a combination of measures for the control of an outbreak of Marek’s disease (MD). Post- introduction vaccinations of young chickens in a farm that had an outbreak over a period of six years did not yield good result. The disease was therefore controlled by brooding new birds in isolated pens far away from the other one, use of biosecurity measures and brooding birds during the rainy season when the environment was damp with minimal dust in the air. Result showed marked reduction of infection during the first one year of trial. By the second and third years of trial, no infection was detected in the birds. This study therefore recommends isolation brooding, biosecurity measures, brooding during the rainy period and completely avoiding brooding during the harmattan period as good methods of controlling cases of MD outbreaks in Nigeria. Key words: Marek’s disease, isolation brooding, vaccination, biosecurity measures, young chickens, Nigeria.

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

Adoption and infanticide in an altricial colonial seabird, the Blue-footed Booby: the roles of nest density, breeding success, and sex-biased behavior

We aimed to elucidate the factors that influence the frequency of adoption and infanticide in the Blue-footed Booby (Sula nebouxii), a seabird with biparental chick care and high chick-rearing costs. We obtained data from two colonies during four breeding seasons. In addition, we removed parents from their nests for short periods of time (10 min) and fitted their chicks with polyethylene foam protectors, in order to record chick behavior, particularly interactions with neighboring adults. Adoption and infanticide occurred mostly in zones of high nest density and during years of high breeding success. The chicks adopted were 20–40 days of age, the age at which they acquire mobility and parents still experience a certain inability to recognize them. Adopted chicks were slightly younger than chicks in the broods into which they were adopted. In most cases, adoptees were younger than their siblings in their natal broods. We also recorded short-term (lasting only a few hours) alloparental care for chicks older than 40 days. When we excluded parents from nests and their chicks were attacked, it was female neighbors that physically attacked them, whereas males were more prone to brood or preen them; therefore, the sex with certainty of parenthood was more prone to practice infanticide, presumably to avoid adoption. The lack of aggressiveness by males might be due to the possibility of paternity, given the occurrence of extra-pair copulations in this species.

Protective mother hens: cognitive influences on the avian maternal response

We previously demonstrated that domestic hens, Gallus gallus domesticus, show behavioural and physiological responses when witnessing mild chick distress, and possess the underlying foundations of emotional empathy. However, no studies have determined how cognitive influences affect empathic processes in birds. A fundamental question is whether a mother hen's response to chick distress is mediated by her knowledge about the situation or by chick distress cues. We therefore investigated how manipulating hen and chick knowledge influences hens' responses to chick distress. Each hen's brood of chicks was split into three groups, based on whether they had the same, opposite or no knowledge about a potentially threatening situation (environmental cues signalling air puff administration). We compared hens' behavioural, vocal and physiological responses (heart rate, heart rate variability and surface body temperature) to actual and perceived threat to their chicks. Hens increased maternal vocalizations and walking, and decreased preening, when they perceived their chicks to be threatened, regardless of the chicks' reactions to the situation. Hens exhibited signs of stress-induced hyperthermia only when their perception of threat was in accordance with that of their chicks. Chick behaviour was influenced by the hens' expectations, with all chick groups spending more time distress vocalizing and less time preening when in the environment that the hen associated with threat. We conclude that the protective maternal response of domestic hens is not solely driven by chick distress cues; rather, hens integrate these with their own knowledge to produce a potentially adaptive, flexible and context-dependent response.

ROCK inhibitor (Y-27632) disrupts somitogenesis in chick embryos

In chick embryos, administration of cadmium (Cd) induces ventral body wall defects (VBWD) similar to human omphalocele. It has been shown that failure of proper VBW formation may be due to disruption of somite development during early embryogenesis. In the VBWD chick model, Cd causes abnormal cell death in the somitic region resulting in improperly developed somites and tortuosity of the neural tube. However, the exact molecular mechanisms leading to VBWD still remain unclear. Wnt signaling is crucial during embryogenesis and plays a key role in normal somite formation. The Rho-associated coiled-coil containing protein kinase (ROCK) is involved in the non-canonical Wnt pathway which controls actin cytoskeleton assembly and cell contractility, and contributes to several developmental processes including somitogenesis. ROCK gene expression levels have recently been reported to be significantly decreased in the Cd-induced VBWD chick model. We designed this study to investigate the hypothesis that administration of ROCK inhibitor (Y-27632) in the absence of Cd disrupts somitogenesis and could contribute to the development of VBWD during early embryogenesis. After 60h of incubation chick embryos were transferred from eggs to culture dishes containing 20μM of Y-27632 for experimental group (Y-27, n=22) or chick saline for controls (n=14). Following 24h in the incubator they were assessed for stage development and gross abnormalities in morphology using the dissecting microscope. Western blot was performed to confirm Y-27632 inhibition of ROCK downstream signaling using an antibody against phosphorylated cofilin-2. 20 (90.9%) embryos from Y-27 group and all controls were alive at examination. Morphological abnormalities were detected in 14 (70%) Y-27 embryos. Somites appeared improperly developed, flattened in the cranio-caudal direction, and elongated in transverse direction in relation to controls. Chick embryos in Y-27 also presented with tortuosity of the neural tube in the lumbosacral region. Western blot analysis showed inhibition of cofilin-2 phosphorylation in affected embryos in comparison to controls. Our study provides evidence that ROCK inhibitor results in the disruption of normal somitogenesis in chick embryos which may contribute to the failure of fusion of the anterior abdominal wall causing VBWD.

Asymmetric contests at the nest

Hatching asynchrony of nestling birds leads to weight asymmetries, which in turn affect the nestlings’ relative success when competing for feedings brought to the nest. We present a game theoretic model that predicts how weight asymmetry influences the nestlings’ energy on securing feedings, thus determining the caloric value remaining for weight gain as well as the distribution of feedings obtained. The model has a unique Evolutionary Stable Strategy (ESS) profile, in which nestlings in more asymmetric nests exhibit less aggression and hence achieve larger weight gain per feeding. The impetus for this model was data from a long-term study of Arabian babblers (Turdoides squamiceps) that showed a surprising negative correlation between the number of feedings that a nest received and the overall weight gain in the nest. This finding is, however, entirely consistent with our model—in more symmetric nests, the individuals fight more and are consequently hungrier and beg for additional food, are fed more, but still gain less weight due to the higher energetic costs of fighting. The model provides a fundamental explanation also for related findings in other species, in which chicks in asynchronous broods were found to be heavier than those from synchronous broods. In addition, it supports the sibling rivalry hypothesis by which brood asynchrony may diminish aggressive interactions among nestlings, leading to more efficient use of resources.

Competition with a host nestling for parental provisioning imposes recoverable costs on parasitic cuckoo chick's growth

Chicks of the brood parasitic common cuckoo (Cuculus canorus) typically monopolize host parental care by evicting all eggs and nestmates from the nest. To assess the benefits of parasitic eviction behaviour throughout the full nestling period, we generated mixed broods of one cuckoo and one great reed warbler (Acrocephalus arundinaceus) to study how hosts divide care between own and parasitic young. We also recorded parental provisioning behaviour at nests of singleton host nestlings or singleton cuckoo chicks. Host parents fed the three types of broods with similar-sized food items. The mass of the cuckoo chicks was significantly reduced in mixed broods relative to singleton cuckoos. Yet, after the host chick fledged from mixed broods, at about 10-12 days, cuckoo chicks in mixed broods grew faster and appeared to have compensated for the growth costs of prior cohabitation by fledging at similar weights and ages compared to singleton cuckoo chicks. These results are contrary to suggestions that chick competition in mixed broods of cuckoos and hosts causes an irrecoverable cost for the developing brood parasite. Flexibility in cuckoos' growth dynamics may provide a general benefit to ecological uncertainty regarding the realized successes, failures, and costs of nestmate eviction strategies of brood parasites.

Hatching asynchrony and offspring sex: an experiment on maternal effects in the yellow-legged gull

Maternal effects may allow parents to increase their own fitness by adjusting progeny phenotype to pre- and post-natal conditions depending on the sex of individual offspring. In birds, sex-specific maternal effects can be mediated by predictable gradients of rearing conditions due to hatching asynchrony, egg laying date, order and mass, and brood sex ratio. In this study, we analysed the growth and survival consequences of experimentally reduced hatching asynchrony and order per se and in conjuction with other maternal effects (laying date, egg mass and sibling sex ratio) in yellow-legged gull (Larus michahellis) chicks of either sex. Survival of male chicks in synchronised broods was reduced compared to that of their sisters and that of male chicks in control broods, whereas survival of females but not that of males declined with hatching order independently of hatching synchronisation treatment. Survival of female but not male chicks declined with egg mass. In addition, survival of individual chicks, independently of their sex, was positively predicted by the proportion of females among their siblings. Hatching synchronisation resulted in larger average body size and in a weaker dependence of body mass on hatching order, suggesting that by modulating hatching asynchrony parents can effectively tune the size hierarchy among the offspring. Thus, survival of yellow-legged gull chicks of either sex was differentially affected by maternal effects as mediated by hatching asynchrony, hatching order as well as egg mass, which constitute predictable gradients of pre- or post-natal environmental conditions potentially under parental control.

Differential Maternal Testosterone Allocation among Siblings Benefits Both Mother and Offspring in the Zebra Finch Taeniopygia guttata

Parents are selected to preferentially invest in the offspring with highest reproductive value. One mechanism for achieving this is the modification of competitive asymmetries between siblings by maternal hormones. In many organisms, offspring value varies according to birth position in the brood, which determines survival chances and competitive advantage over access to resources. In birds, variation in yolk androgen allocation over the laying sequence is thought to modulate dominance of senior chicks over junior brood mates. We tested this hypothesis in zebra finches, which show a naturally decreasing pattern of within-clutch testosterone allocation. We abolished these within-clutch differences by experimentally elevating yolk testosterone levels in eggs 2-6 to the level of egg 1, and we assessed fitness measures for junior offspring (eggs 2-6), senior offspring (egg 1), and their mothers. Testosterone-injected eggs hatched later than control eggs. Junior, but not senior, chicks in testosterone-treated broods attained poorer phenotypic quality compared to control broods, which was not compensated for by positive effects on seniors. Mothers were generally unaffected by clutch treatment. Thus, naturally decreasing within-clutch yolk testosterone allocation appears to benefit all family members and does not generally enhance brood reduction by favoring senior chicks, in contrast to the widely held assumption.

Sex‐specific differences in Sand Martin Riparia riparia nest attentiveness

Capsule Nest attentiveness during the night is significantly lower in males but varies with the activities of the breeding cycle. Male nest attentiveness shows minima during the burrowing and egg‐laying phases, and also during the brooding of chicks in second or re‐nest broods.

Effect of Deposition Time on the Optical Characteristics of Chemically Deposited Nanostructure PbS Thin Films

Abstract PbS thin films are good materials for antireflection coatings and for solar thermal applications in flat-plat collectors, house heating for solar chick brooding, etc. Nanocrystalline PbS thin films were deposited on glass substrates with various deposition times using chemical bath deposition technique. The study was carried out for thicknesses in the range (500-660 nm). The crystalline size of these films was studied by atomic force microscope AFM. A dense surface composed of multilayered grains of films was obtained with the crystal size around 37.67 nm. The optical properties of these films have been studied and show that PbS thin films have allowed direct transition and the values of energy gap varied between (1.88-1.55 eV) with increasing film thickness, The large optical band gap in the films is attributed to the quantum coefficient effect. Influences of thermal treatments under various annealing temperatures on the optical properties for some deposition films were studied.

Female Zebra Finches (Taeniopygia guttata) Are Chronically but Not Cumulatively “Anemic” during Repeated Egg Laying in Response to Experimental Nest Predation

Recently it has been recognized that reproduction itself, or the regulatory processes controlling reproduction, might contribute to physiological costs of reproduction. Reproductive anemia, a decrease in hematocrit and hemoglobin concentration, might provide one such mechanism underlying the costs of egg production in birds. In this study, we investigated the effect of repeated cycles of egg production in response to experimental nest predation (egg removal) on hematological traits in female zebra finches (Taeniopygia guttata). We predicted that if the negative effect of egg production on hematocrit and hemoglobin concentration was cumulative, with anemia being proportional to reproductive effort, then females laying more clutches, or laying successive clutches without recovery during incubation, would show greater reproductive anemia. In contrast, if females maintain hematocrit and hemoglobin concentration at some minimum functional level independent of reproductive effort, then there should be no difference in hematological traits among females laying two or more successive clutches. Our results supported the second of these hypotheses: egg-laying females had reduced hematocrit (-7.5%) and hemoglobin concentrations (-10%), but the extent of reproductive anemia did not differ among females laying either two or three successive clutches, with or without recovery during incubation, or in females laying 7-21 eggs. Females maintained low hematocrit and hemoglobin for 20-35 d, and we suggest that prolonged periods of anemia might be common and functionally important in free-living birds, for example, where females produce multiple successive clutches in response to high levels of nest predation or where they initiate a second clutch while still rearing first brood chicks.

Diet and growth of chicks of the Great Cormorant, Phalacrocorax carbo, at Ramsar, northern Iran (Aves: Phalacrocoracidae)

The diet of Great Cormorant (Phalacrocorax carbo Linnaeus, 1758) chicks was studied using regurgitated fish prey in a colony at Ramsar, northern Iran, in the 2003 breeding season. The development of young was analysed in terms of body mass and wing length growth. The regurgitated prey items belong to Gobiidae, Mugilidae, Atherinidae and Clupeidae, with approximately 90% of the regurgitated prey mass belonging to Gobiidae and Mugilidae. The growth rate, expressed as body mass increment per day during the period 1–30 days, ranged from 58.7 to 112.2 g/d and was independent of age ranking and brood size. The growth rate of wings was 5.5 to 8.2 mm/d and did not vary between broods of different sizes and chicks of different ages.

Predation of a brood of European Shag Phalacrocorax aristotelis chicks by a Honey- buzzard Pernis aviporus

Predation of a brood of European Shag Phalacrocorax aristotelis chicks by a Honey- buzzard Pernis aviporus

Interspecific offspring killing in owls

In Baranya County (Southern Hungary), tawny owls (Strix aluco) and barn owls (Tyto alba) sequentially use the same nest boxes in a significant number of cases. A total of 460 broods were observed between 1996 and 2003 and, in 12 cases, whole broods of dead tawny owl chicks were registered that had apparently been killed. On investigating the reproductive life characteristics, population sizes, and frequency of killing in these two species, it was concluded that: (1) with growing barn owl population, the number of sequential broods increases but changes in tawny owl population size have no effect on the frequency of sequential broods; (2) the number of killings depends on the number of sequential broods; and (3) with growing barn owl population, the number of killings also grows and this change is unaffected by the size of the tawny owl population. However, no killing occurs as long as 50–60% of the nest boxes are unoccupied. There is no killing either until the percentage of nest boxes occupied by barn owls reaches 40%, although a threshold value like this cannot be shown for the tawny owl. In the cases when a barn owl breeding follows the tawny owl's, the percentage of killing is significantly higher compared to that when barn owls do not breed in the same box. These results indicate that barn owls kill the offspring of tawny owls. By these means, they obtain a breeding place earlier than without killing the chicks of the other species, and this results in higher reproductive success. © 2008 The Linnean Society of London, Biological Journal of the Linnean Society, 2008, 95, 488–494.

Shared parental care is costly for nestlings of common cuckoos and their great reed warbler hosts

Obligate avian brood parasitism typically involves one of 2 strategies: parasite chicks are either 1) virulent and evict all other eggs and nest mates to be raised alone or 2) more tolerant and share foster parental care with host chicks for some or the entirety of the nestling period. We studied the consequences of experimentally forced mixed broods of age-matched one common cuckoo (Cuculus canorus) and 2 great reed warbler (Acrocephalus arundinaceus) chicks. In these broods, both cuckoo and host chicks grew slower than did either individual cuckoos or great reed warblers in broods of 1 parasite or 3 host chicks, respectively. Video records showed that in mixed broods, cuckoo chicks received feedings less frequently than the 33% predicted by chance at 4 days of age but parental food allocations increased to chance levels at 8 days of age. The consistent patterns of lower growth rates arose even though chicks in broods of 1 parasite and 2 hosts received the largest prey items per feeding. In addition, several other measures of parental provisioning also did not predict species and brood-specific differences in nestling growth rates across the different treatments. However, variation in begging displays and its specific costs on host and parasite chicks in the different nest treatments were not quantified in this study. We conclude that young of nest mate-evictor common cuckoos benefit from the sole occupancy of host nests in part owing to an initial competitive disadvantage for parental care in broods with age-matched great reed warbler chicks.

Parental behaviour of Spanish Imperial Eagles Aquila adalberti: sexual differences in a moderately dimorphic raptor

Capsule The sexes make significantly different contributions in the tasks of nest-building, incubation and food provisioning to chicks. Aims To determine the division of parental activities during breeding (nest-building, incubation, brooding, food provisioning and feeding). Methods Between 1991 and 1998 focal observations were made at nests using 20–60× telescopes. During the incubation period, 11 pairs were studied involving a total of 2812 observation hours over 269 days. During the chick-rearing period, seven pairs were studied involving a total of 5499 observation hours spread over 503 days. The birds were sexed and identified individually on the basis of size, position during copulation, vocalization and plumage differences. Results Significant differences were found between the sexes in parental behaviour. Males scarcely participated in incubation and contributed significantly more than the females only in food provisioning, both during incubation (food transfers to feed the female) and during chick-rearing (to feed the chicks). Females were responsible for most of the incubation, nest-building (during incubation and chick-rearing), brooding, shading and feeding of chicks. Nest attendance by females decreased over time. In both sexes, food provisioning increased with brood size. Conclusion Intersexual differences are discussed in the context of the reversed sexual size dimorphism and parental investment strategies. We suggest that in Spanish Imperial Eagles reversed sexual size dimorphism is best explained by the prey capture difficulty hypothesis, than by parental role division during reproduction.

The role of trained winning in a broodmate dominance hierarchy

We tested the hypothesis that stability of a linear dominance hierarchy is due to each individual being trained to a different level of general aggressiveness. This mechanism, combined with assessment of aggressiveness, is particularly likely when individual recognition is absent, as may be the case in young broods of altricial chicks. Dominance relationships in broods of blue-footed boobies involve trained winning and trained losing, and broods of three chicks form stable linear dominance hierarchies. To test the prediction that chicks of intermediate rank in broods of three express an intermediate level of general aggressiveness, we pitted intermediates against similar sized bottom rank chicks from broods of two (equivalent to bottom rank chicks from broods of three). Contrary to expectation, intermediates failed to outperform bottom rank chicks by attacking first, attacking more, or submitting less. This failure suggests that general aggressiveness of intermediate chicks is not enhanced by the experience of attacking their younger broodmates and does not determine their intermediate rank in the brood hierarchy. Differential training of general aggressiveness may well be important in linear hierarchies of broods, but in dyads that do not differ in their training effects, stable dominance may depend on responsiveness to relative size.

Reproduction of Bali starlings Leucopsar rothschildi at Durrell Wildlife Conservation Trust, Jersey

The Critically Endangered Bali starling Leucopsar rothschildi is the only endemic avian species on the island of Bali, Indonesia. In 1998 the wild population comprised c. 25 birds, of which only eight to ten were wild born. An international captive‐breeding programme to restore a viable and self‐sustaining population in Bali was established in 1987. In order to understand better the reproductive activity of Bali starlings at the Durrell Wildlife Conservation Trust, Jersey, small cameras were placed inside the nestboxes of six pairs. Details of egg production and egg turning were recorded for 16 clutches, and incubation data were recorded for 14 clutches. Mean clutch size was 2·8±0·20 SE eggs. Females incubated eggs significantly more than ♂♂ (median 143‐6 hours vs 46·8 hours, ♀vs♂). During the day (0500–2100 hours) eggs were turned every c. 13 minutes. At night eggs were incubated by ♀♀ while ♂♂ roosted in the nestbox. The median duration of incubation was 15·5 ± 0·24 SE days. Behaviour of parents and chicks during hatch and rearing was recorded for seven broods. Hatching success was 68% and for each pair the mean brood size was two chicks. Females carried out significantly more brooding (t= 7·08, df=6, P<0·001), preening (t= 2·94, df=6, P= 0·025) and manipulation (t= 2·50, df=6, P= 0·046) of chicks than ♂♂. Males provided significantly more feeds (62%) than ♀♀ (38%) (t= 4.035, df=6, P= 0·006). Only five birds survived > 30 days, of which three were parent‐reared and two hand‐reared. All parents assisted chicks during hatching. Synchronous hatching was recorded for 45% of chicks. Nutritional requirements of chicks were higher during the first 9 days post‐hatch. Chick survival was compromised by parents feather plucking the chicks.

Consequences of biparental care for begging and growth in zebra finches, Taeniopygia guttata

Although most (>90%) species of birds have biparental care, little is known about the consequences of such care for offspring behaviour and fitness-related traits. We examined the effect of biparental care on chick growth and begging behaviour in zebra finches, by comparing biparental broods with uniparental broods in which the male parent was removed and the brood size halved to control for potential parental workload. Differences in patterns of growth and begging behaviour between treatments therefore resulted from the difference in (1) the number of parents providing care and/or (2) the number of chicks per brood. Collaborating parents did not appear to act in concert and fed chicks independently of each other's feeding bouts. Broods reared by two parents were fed more frequently than those fed by one, and because biparental feeding bouts were less predictably spaced in time with less food available for each chick per feeding bout, competition was greater than in broods reared by single parents. Furthermore, chicks in biparental broods sustained an additional cost of begging: they had to beg almost twice as hard as chicks reared by single parents to receive a given amount of food, and they received less food per chick. Despite these effects, they grew faster. Growth rate may depend not just on the amount of food available but also on the frequency and predictability with which it is delivered, and, in particular, it reflects an adaptive response to competition for the available resources.