Molt Status Research Articles

Wound-healing ability is conserved during periods of chronic stress and costly life history events in a wild-caught bird

Chronic stress, potentially through the actions of corticosterone, is thought to directly impair the function of immune cells. However, chronic stress may also have an indirect effect by influencing allocation of energy, ultimately shifting resources away from the immune system. If so, the effects of chronic stress on immune responses may be greater during energetically-costly life history events. To test whether the effects of chronic stress on immune responses differ during expensive life history events we measured wound healing rate in molting and non-molting European starlings (Sturnus vulgaris) exposed to control or chronic stress conditions. To determine whether corticosterone correlated with wound healing rates before starting chronic stress, we measured baseline and stress-induced corticosterone and two estimates of corticosterone release and regulation, negative feedback (using dexamethasone injection), and maximal capacity of the adrenals to secrete corticosterone (using adrenocorticotropin hormone [ACTH] injection). After 8days of exposure to chronic stress, we wounded both control and chronically stressed birds and monitored healing daily. We monitored nighttime heart rate, which strongly correlates with energy expenditure, and body mass throughout the study. Measures of corticosterone did not differ with molt status. Contrary to work on lizards and small mammals, all birds, regardless of stress or molt status, fully-healed wounds at similar rates. Although chronic stress did not influence healing rates, individuals with low baseline corticosterone or strong negative feedback had faster healing rates than individuals with high baseline corticosterone or weak negative feedback. In addition, wound healing does appear to be linked to energy expenditure and body mass. Non-molting, chronically stressed birds decreased nighttime heart rate during healing, but this pattern did not exist in molting birds. Additionally, birds of heavier body mass at the start of the experiment healed wounds more rapidly than lighter birds. Finally, chronically stressed birds lost body mass at the start of chronic stress, but after wounding all birds regardless of stress or molt status started gaining weight, which continued for the remainder of the study. Increased body mass could suggest compensatory feeding to offset energetic or resource demands (e.g., proteins) of wound healing. Although chronic stress did not inhibit healing, our data suggest that corticosterone may play an important role in mediating healing processes and that molt could influence energy saving tactics during periods of chronic stress. Although the experiment was designed to test allostasis, interpretation of data through reactive scope appears to be a better fit.

Cannibalism among Lithodes santolla (Molina 1782) juveniles: effect of stocking density, stage and molt condition

Losses of king crabs (deaths) in massive rearing conditions are frequently attributed to cannibalism. As several factors could influence cannibalism intensity during culture, the aim of the present study was to determine the effect of molt condition, stage and density on cannibalism among Lithodes santolla juveniles. Comparisons between intermolt and molt conditions and between C1 and C2 stages during intermolt were performed at three densities (6, 12 and 18 individuals per flask; that is equivalent to 236, 472 and 708 individuals m−2). After 16 days of juvenile coexistence, cannibalism (injured + dead) was higher during molting (33.9 ± 4.5 %) than intermolt (21.7 ± 3.9 %), even though only 36 % of crabs had molted. Although cannibalism was similar in C1 and C2 stages, the proportion of dead animals was higher by a factor of three in C1 stage, probably due to the fact that animals reach the first juvenile stage with low energetic reserves, after the lecithotrophic larval development. Density was the main factor influencing cannibalism in our experiments. Higher densities promoted higher deaths, while agonistic interactions evidenced by injured crabs remained constant. Walking appendages were lost more often than chelipeds during first agonistic encounters. We recommend the use of intermediate densities (450 crabs m−2 at most), the early detection of exuviae and the sorting of crabs after molting, for L. santolla rearing.

Health assessment of free-ranging endangered Australian sea lion (Neophoca cinerea) pups: Effect of haematophagous parasites on haematological parameters

Evaluation of the health status of free-ranging populations is important for understanding the impact of disease on individuals and on population demography and viability. In this study, haematological reference intervals were developed for free-ranging endangered Australian sea lion (Neophoca cinerea) pups within the context of endemic hookworm (Uncinaria sanguinis) infection and the effects of pathogen, host, and environment factors on the variability of haematological parameters were investigated. Uncinaria sanguinis was identified as an important agent of disease, with infection causing regenerative anaemia, hypoproteinaemia, and a predominantly lymphocytic–eosinophilic systemic inflammatory response. Conversely, the effects of sucking lice (Antarctophthirus microchir) were less apparent and infestation in pups appears unlikely to cause clinical impact. Overall, the effects of U. sanguinis, A. microchir, host factors (standard length, body condition, pup sex, moult status, and presence of lesions), and environment factors (capture-type and year of sampling) accounted for 26–65% of the total variance observed in haematological parameters. Importantly, this study demonstrated that anaemia in neonatal Australian sea lion pups is not solely a benign physiological response to host–environment changes, but largely reflects a significant pathological process. This impact of hookworm infection on pup health has potential implications for the development of foraging and diving behaviour, which would subsequently influence the independent survival of juveniles following weaning. The haematological reference intervals developed in this study can facilitate long-term health surveillance, which is critical for the early recognition of changes in disease impact and to inform conservation management.

Lack of seasonal and moult-related stress modulation in an opportunistically breeding bird: The white-plumed honeyeater (Lichenostomus penicillatus)

This article is part of a Special Issue “SBN 2014”.In most vertebrate species, glucocorticoid levels and stress sensitivity vary in relation to season and life-history stage. In birds, baseline corticosterone (CORT) and stress sensitivity are typically highest while breeding and decrease substantially during moult. Because elevated CORT adversely affects protein synthesis, moult-related CORT suppression is thought to be necessary for forming high-quality feathers. Surprisingly, some passerine species lack moult-related CORT suppression, but these are distinguished by having slow rates of moult and being opportunistic breeders. We examined baseline and stress-induced CORT levels in an opportunistically breeding Australian passerine, the white-plumed honeyeater (Lichenostomus penicillatus). Although this species has a slower moult rate than high-latitude breeders, it differs little from north-temperate passerines. Neither baseline nor stress-induced CORT levels varied with season (winter, spring or summer), sex or moult status in adult birds. While breeding tended to be highest in early spring through late summer, laparotomies revealed only limited reduction in testicular size in males the year round. In all but one sampling period, at least some females displayed follicular hierarchy. Breeding usually coincides with outbreaks of phytophagous insects, which can happen at any time of the year. This results in moult/breeding overlap when infestations occur in late spring or summer. The ability of this species to moult and breed at the same time while having breeding-levels of CORT demonstrates that CORT suppression is not a prerequisite for synthesis of high-quality feathers. An experimental design incorporating moulting and non-moulting phenotypes is suggested to test the functional significance of CORT suppression in other species.

Does sugar content matter? Blood plasma glucose levels in an occasional and a specialist avian nectarivore

Nectar composition within a plant pollinator group can be variable, and bird pollinated plants can be segregated into two groups based on their adaptations to either a specialist or an occasional bird pollination system. Specialist nectarivores rely primarily on nectar for their energy requirements, while occasional nectarivores meet their energy requirements from nectar as well as from seeds, fruit and insects. Avian blood plasma glucose concentration (PGlu) is generally high compared with mammals. It is also affected by a range of factors including species, gender, age, ambient temperature, feeding pattern, reproductive status, circadian rhythm and moult status, among others. We examined whether sugar content affected PGlu of two avian nectarivores, a specialist nectarivore the Amethyst Sunbird Chalcomitra amethystina, and an occasional nectarivore the Cape White-eye Zosterops virens, when fed sucrose–hexose sugar solution diets of varying concentrations (5%–35%). Both species regulated PGlu within a range which was affected by sampling time (fed or fasted) and not dietary sugar concentration. The range in mean PGlu was broader in Amethyst Sunbirds (11.52–16.51mmol/L) compared with Cape White-eyes (14.33–15.85mmol/L). This suggests that these birds are not constrained by dietary sugar concentration with regard to PGlu regulation, and consequently selective pressure on plants for their nectar characteristics is due to reasons other than glucose regulation.

Revisiting reproduction and population structure and dynamics ofProcambarus clarkiieight years after its introduction into Lake Trasimeno (Central Italy)

Key-words: red swamp crayfish, Procambarus clarkii, reproduction, population structure and population dynamics, invasive species Understanding population dynamics and regulation is fundamental for predicting establishment and spread of invasive alien species. In addition, the population biology of invasive alien species offers an opportunity to study basic ecological processes. In this context, we investigated reproductive and growth plasticity in the invasive crayfish Procambarus clarkii in Lake Trasimeno (central Italy). In total, 3153 crayfish were collected monthly from June 2007 to July 2009. The molt status was assessed by evaluating the exoskeleton hardness. To assess the reproductive cycle, the gonado-somatic and wet hepato-somatic indices were calculated for females. The reproductive status of males was appraised as well. We estimated growth and longevity using the von Bertalanffy growth function, and calculated the total, natural and fishing mortality indices. We then compared our present data with those obtained from the same population eight years before. Our results indicate some changes in population dynamics and in both molting and reproductive periods since the initial invasion of the shallow lake investigated. Long-term differences in the life history of the Trasimeno population may be the result of selective pressures different from those of the native range, but may also result from colonization events and human interference caused by professional fishing activities.

Moult and body condition in Long-tailed Tits Aegithalos caudatus

Moult is a key life-cycle event associated with reduced flight performance and high energetic demands. Juvenile Long-tailed Tits Aegithalos caudatus have a complete post-juvenile moult so that both adults and juveniles will be undergoing a full moult at similar times of year. Given lower foraging experience and developmental immaturity of juveniles, we might predict differences between adults and juveniles in moult parameters and the effect of moult progression on body mass. The aim of this study was to test these predictions by analysing moult data for Long-tailed Tits in the northeast of England. Juveniles started moult 12 days later than adults but the duration of moult was similar. The timing of moult varied between years; correlations between year-to-year change in moult timing and spring temperatures suggest that the timing of moult and breeding are linked. Raggedness scores, a measure of moult speed, remained relatively constant during the central phase of moult and were independent of moult score. Although wing length made the greatest contribution to body mass, the best statistical model included raggedness as a factor contributing to variation in body mass, suggesting that faster moulting may be associated with lower body mass. The analysis did not support the prediction that age is a significant factor affecting body mass during moult.

Epibiotic bacterial community of Sphaeroma serratum (Crustacea, Isopoda): relationship with molt status

Sphaeroma serratum is a marine isopod species that inhabits seashores from Europe to West Africa. The individuals live under stones in direct contact with reduced sediments and harbour a diverse bacterial community on the cuticle of their pleopods. We investigated the diversity of these epibiotic bacteria on male (pubescent and senescent) and female specimens with electron microscopic obser vations and molecular tools. The microbial community of S. serratum was shown to be composed of at least 5 bacterial morphotypes observed on the pleopodal cuticle in all male specimens. Using fluorescence in situ hybridization, we identified 5 major phylogenetic groups (α-, β-, γ- and δ-Proteobacteria and Archaea) whereas denaturing gradient gel electro - phoresis (DGGE) of PCR-amplified 16S rRNA gene fragments of epibiotic bacteria revealed 50 bands. The bacterial community associated with S. serratum seems more diverse than in other marine crustaceans, such as Rimicaris. The relative diversity of this bacterial community was also studied in relation to the molt cycle. The comparison of DGGE band patterns of several individuals from female, pubescent male and senescent male groups revealed that the bacterial community diversity was dependent on the sex and the age of the individuals and more generally on the molt status.

Age structure and age-related differences in molt status and fuel deposition of Dunlins during the nonbreeding season at Chongming Dongtan in east China

Although most shorebirds exhibit deferred migration and deferred breeding during their first summer, Dunlins (Calidris alpina) migrate to breeding areas and breed during their first summer. First-year and adult Dunlins should, therefore, have similar fueling and molt patterns if energetic and physiological constraints are responsible for deferred migration. From 2006 to 2008, we examined the age structure of Dunlins during the nonbreeding season at Chongming Dongtan, an estuarine wetland in the Yangtze River estuary in east China, and examined the effects of date, age, and molt status on fuel deposition during migration and during the winter. The Dunlin population at Chongming Dongtan was composed primarily of first-year birds. Most adults and first-year birds arrived together in late August. Regression analyses indicated that age, date, and molt status affected fuel deposition (as indicated by body mass) of Dunlins. Adults had significantly greater fuel deposits than first-year Dunlins near the end of northward migration (May: adults 70.8 ± 6.4 g, first-year 63.8 ± 8.0 g) and at the start of southward migration (September: adults 50.2 ± 6.1 g, first-year 47.2 ± 4.9 g). Adults also had significantly higher fuel deposition rates than first-year Dunlins during northward migration. Nonetheless, first-year Dunlins migrate and breed in their first summer. Thus, other factors, such as migration distance and body size, may be more important in determining if first-year shorebirds defer migration during their first spring and summer. During boreal spring and autumn, first-year Dunlins in active body molt had greater body mass than those that had not initiated body molt or those in suspended molt, and premigratory fuel deposits for northward migration were greatest after prealternate molt was completed. These results suggest that body molt requires additional fuel deposits and imposes a constraint on fuel deposition for migratory flights. ©2011 The Authors. Journal of Field Ornithology

Platypus (Ornithorhynchus anatinus) body size, condition and population structure in Tasmanian river catchments: variability and potential mucormycosis impacts

Context Despite widespread interest in platypus (Ornithorhynchus anatinus) conservation, it is unclear how their fundamental morphometric and demographic characteristics differ over a range of scales. This hampers impact assessments and understanding of platypus ecology. Although the ulcerative fungal disease mucormycosis has infected platypuses in Tasmania for three decades, its population level impacts and conservation significance remain unknown. Aims This study examined morphometric and demographic patterns in Tasmanian platypuses to provide a basis for investigating impacts of mucormycosis or other anthropogenic disturbances. It also sought to identify important spatial scales of natural variability and the magnitude of seasonal variation in platypus body size, condition and population structure. The hypothesis of higher mucormycosis prevalence and mortality in adult males was also investigated. Methods Extensive live-trapping surveys were conducted from January 2008 to July 2009 in 75 streams and 18 river catchments across Tasmania including King Island. The sex, age, body size, tail volume index, health and moult condition of 195 individuals were assessed, and population age and sex structures characterised. Sampling focussed on assessing variability within and between river catchments and compared populations in river catchments with contrasting disease status. Key results Differences in platypus morphometrics within and between catchments and seasonal moulting patterns were detected. Adult males had higher fat stores than adult females, especially during winter. This study also provided the first evidence of population level consequences of disease in platypuses. The demographic group most commonly affected by mucormycosis was confirmed to be adult males. Differences in male age structure among catchments of varying disease status were consistent with the hypothesis of higher adult male mortality rates and turnover in currently affected catchments. Conclusions More than 25 years after mucormycosis was first detected in Tasmanian platypuses, the disease continues to play a low-level, ongoing role in affected populations. Implications The present study provides the first systematic multi-scale spatial investigation of platypus mucormycosis, which contributes to unravelling the epidemiology of the disease and detecting its impacts. By identifying the magnitude and important scales of morphometric and demographic differences in Tasmanian platypuses the study also assists researchers choose comparable demographic groups and spatial scales for meaningful comparisons in future impact studies.

Biochemical Reference Intervals for the Resting State in the Adult LobsterHomarus americanus

Clinical biochemistry is the measurement of body fluid constituents, and is considered an integral component of disease diagnosis in human and veterinary medicine. Biochemical reference intervals are the ranges of values of specific analytes at the population level that are expected to encompass 95% of “normal” individuals. However, how do we define a “normal” lobster? Homarus americanus (H. Milne Edwards, 1837) is a sublittoral ectotherm with a limited homeostatic ability to adapt to rapid environmental changes. An experiment was designed to measure the changes that may occur in selected analytes as wild lobsters “acclimate” to captivity. Biological variation was minimized by the maintenance of strict environmental conditions, uniform life stages, nutrition, and molt status. The results of this experiment suggest that elevations in hemolymph levels of glucose, L-lactate, crustacean hyperglycemic hormone, ammonia, ionic calcium, and a decrease in ionic potassium may be indicative of the stress associated with capture, handling, and emersion hypoxia. Although the data demonstrate a considerable intraspecific variation in most analytes during the acclimation process, these reference intervals may be useful in the interpretation of clinical findings in lobsters held in captivity for research or exhibition in public aquaria.

Influence of Cover and Food Resource Variation on Post-Breeding Bird Use of Timber Harvests With Residual Canopy Trees

We investigated avian use of clearcuts and two-age harvests during the post-breeding period in 2006 in the central Appalachians, West Virginia, USA with an information-theoretic approach to model selection. Cover variables appeared to be most important; e.g., vegetative vertical complexity had a strong positive relation with capture rates of mature forest birds and molting adults, as well as physical condition which supports a predator-avoidance hypothesis for habitat use. Basal area was a poor predictor of captures; residual trees near nets tended to depress capture rates. Food variables best explained capture rates for some species groups (e.g., early-successional insectivores and granivores, mature forest nesting adults, molting birds), but post-breeding habitat quality was based primarily on vegetative cover. Habitat use may depend on the bird's physical condition and molt status, and we found evidence for age-specific differences which may impact survival. Our study suggests important links between post-breeding habitat quality, molt status, physical condition, and bird age, and indicates a variety of response variables (relative abundance, survival, body condition) should be measured to assess avian habitat quality during the post-breeding period.

Bill color, not badge size, indicates testosterone-related information in house sparrows

The honesty of ornamental signals of quality is often argued to be enforced via costs associated with testosterone. It is still poorly understood, however, how seasonal variation of testosterone within individuals is related to the timing and extent of ornament development. Here, we studied inter- and intra-individual variability of plasma testosterone levels in a population of 150 captive male house sparrows (Passer domesticus) through the course of a full year. We further analyzed the relationship between plasma testosterone levels and two sexually dimorphic ornaments: badge size and bill coloration. Also, because of a known negative relation between molt and circulating testosterone levels, we analyzed the relationship between ornamentation and molt status during the fall. We found that testosterone levels increased towards the breeding season and decreased before the onset of annual molt. However, within individuals, relative testosterone titers demonstrated low repeatability between seasons. Plasma testosterone levels were not correlated with badge size in any season but were correlated strongly with bill coloration during all periods, except the breeding season when variation in bill color was low. Finally, we found that bill coloration strongly correlated with molt status during fall. Our results indicate that bill coloration, not badge size, is the best ornamental indicator of a “running average” of male testosterone in house sparrows and therefore the best potential indicator of qualities and/or behavioral strategies associated with testosterone.

Infestation rates of the pedunculated barnacle Octolasmis lowei (Cirripedia: Poecilasmatidae) on the spider crab Libinia spinosa (Decapoda: Majoidea)

The prevalence and infestation intensities of Octolasmis lowei in the branchial chambers of Libinia spinosa were evaluated according to the host's sex, size, and moult condition. Epibionts were classified as cyprid larvae, non-ovigerous or ovigerous according to their developmental stage. A median intensity of infestation of 21 epibionts/host was found (range = 1–644; Q3 = 81). Epibiont prevalence values (88%) were higher on ovigerous female hosts than on males (55%) or on non-ovigerous females (31%). Intensity of infestation was positively correlated with host size in both sexes for non-ovigerous and ovigerous epibionts. No preference between host sex by cyprid larvae was observed, nor any correlation between cyprid abundance and host size. Cyprid larvae abundance was positively correlated with settled epibionts on both host sexes. The duration of the intermoult phase was the main factor linked to the establishment of sessile epibionts. These observations are important in relation to crabs that have a terminal moult, because these animals cannot eliminate their epibionts in future moults, thus increasing the importance of density-dependent mechanisms on epibiont establishment; in that way, prevalence of infestation alone can underestimate the real impact of infestation on the host's life cycle.

Identifying anatomical sites of carotenoid metabolism in birds

Carotenoid metabolism has long interested plant and animalbiochemists (Goodwin 1986; Lu and Li 2008). Identifyingtissue sites and enzymes responsible for carotenoid trans-formations (e.g., β-carotene to vitamin A) has beenchallenging. Colorful birds have recently become a modelfor studying carotenoid nutrition and metabolism, in thecontext of sexual selection and honest signaling (McGraw2006). In a recent paper published in Naturwissenschaften,del Val et al. (2009) described carotenoid profiles in tissuesof male common crossbills (Loxia curvirostra), with theaim of localizing metabolic site(s) for a ketocarotenoidpigment—3-hydroxy-echinenone (3HE)—present in redfeathers. They found 3HE in blood and liver, unlikeprevious studies of colorful songbirds where metabolizedintegumentary carotenoids were found only at peripheraltissues (e.g., beak, legs; McGraw 2004). Thus, the authorsconcluded that the liver was the site of ketocarotenoidsynthesis in crossbills. Here, I outline the limitations ofsuch descriptive pigment analyses, when carotenoid typesare present in various tissues, and discuss fruitful directionsfor future lines of research in this area.Because carotenoids are dietary in origin in animals butcan be modified in body tissues enzymatically, careful foodand physiological studies allow for accurate identificationof pigment origins and transformations. Traditional rigor-ous methods for identifying carotenoid metabolic sites,processes, and products in animals include direct enzymeidentification (Wyss 2004), isotope labeling of precursors(Burri and Clifford 2004), and by inference from ex vivochemical reactions (Khachik et al. 1998) or where caroten-oid types exist in no other tissue type (McGraw 2004).del Val et al. (2009) undertook none of these types ofinvestigation. The first step in such research is to rule out adietary source to the pigment, but the authors did not studyfood carotenoids in crossbills; they sampled only liver,skin, and feathers from accidentally field-killed animals anddrew blood from molting birds. While red carotenoids arenot currently thought to be common in diets of herbivorousland birds (e.g., rubixanthin in rose hips, rhodoxanthin inTaxus berries), this is a key assumption to biochemicallyvalidate for any species, given the paucity of informationon avian food carotenoids.del Val et al. (2009) based their assertion that 3HE wasmetabolized in the liver of crossbills on the observation that3HE was the most proportionally concentrated (and mostvariably occurring) carotenoid in liver. However, data onother types of body carotenoids were not presented in thispaper, the molt status of dead birds was not given, and withsmall sample sizes (n=7) no statistics were performed.Thus, we have no context for understanding which and howcertain carotenoid pigments occurred in different crossbilltissues. Follicles actually contained proportionally more3HE than liver (61% vs. 35% of total carotenoids,respectively), and while the authors argue that this isexpected (given that “maturing follicles would just accu-mulate this red derivative until the pigment would beincorporated finally into growing feathers during moult”;p. xxx), this makes the non-null assumption that folliclespreferentially retain 3HE over other circulating carotenoids.Even if we assume that 3HE is not dietary in origin,alternate tissues with carotenoidmetabolismcapabilitieswerenot studied. The oxygenase enzyme that cleaves β-carotene

To what extent do environmental factors affect the long-distance nocturnal post-fledging movements of the Reed Warbler?

We studied the effects of weather and the lunar cycle on long-distance nocturnal pre-migratory flights of Reed Warblers (Acrocephalus scirpaceus). Noturnal tape luring was used to capture the birds, and the study was carried out in a habitat atypical of this species on the Courish Spit (southeastern Baltic) between1999 and 2002. A total of 443 juvenile Reed Warblers were captured during 120 nights of trapping. Based on data on the moult and body condition of the birds, it was possible to identify 163 individuals as being on post-fledging movements. More than half of the birds (54.0%) were captured at the end of night during the nautical and civil twilight period; the remaining individuals were caught during the astronomical twilight period and darkest periods of night. Many birds performed pre-migratory flights in the middle of the night, the period during which a large part of the moon was visible. We suggest that the increased visibility under the full moon may provide conditions in which Reed Warblers increase the distance or intensity of nocturnal post-fledging movements. During the entire course of the night, the birds generally preferred to fly under rainless conditions, limited cloud cover and/or in still air. The birds performed flights under winds stronger than 2 m s−1 when the wind was blowing along the axis of the spit. We also suggest that the birds generally fly along the spit. We found a weak but significant relationship between the numbers of Reed Warblers captured during post-fledging movements and the individual weather parameters and their interaction. Our data suggest that endogenous stimuli rather than weather parameters or lunar cycle phase determine the decision of Reed Warblers to undertake pre-migratory long-distance flights at night.

Moulting reduces freeze susceptibility in the Antarctic mite Alaskozetes antarcticus (Michael)

Abstract The effect of moulting on the cold hardiness of the oribatid mite Alaskozetes antarcticus (Michael) is investigated. Non moulting animals show clear seasonal patterns of cold hardiness with high supercooling points (SCPs) at the peak of summer and an increasing proportion of low SCPs with declining environmental temperatures. By contrast, both field‐fresh and laboratory acclimated (5 °C) mites in the moult state are consistently found to have low SCPs regardless of environmental temperature.

Pheromone and other chemical communication

This was the first time, as far as we are aware, that the Conference of European Comparative Endocrinologists had included a session devoted specifically to chemical communication. Chemical communication between individuals of the same species has many obvious parallels with the endocrine systems within those individuals. Not only are both involved with specific chemical messengers, often at very low concentrations, that act via specific receptors to evoke specific physiological and/or behavioural effects in the receiver (target tissue) but, also, chemical messengers (pheromones) often evoke their effects by the endocrine and neuro-endocrine systems of the receiver. Many pheromones themselves have been shown to be hormones or their metabolites. Therefore Comparative Endocrinology is the natural home for those working in Chemical Communication. Jelle Atema gave the first State-of-the-Art lectures on ‘Chemical Communication in Decapod Crustacea’. Although Jelle, by his own admission, is not an endocrinologist, he finds himself faced by problems similar to those faced by early endocrinologists—finding, and identifying, the active components amongst the confusing mixture of chemicals that animals release into their (internal or external) environment. However, this lack of knowledge did not prevent Jelle from giving a presentation of how crustaceans, chiefly the American lobster, use chemical signals to recognise sex, dominance, moult state and even individual identity of conspecifics. It seems that lobsters have a good memory of males against which they have previously lost a fight; a useful ability in competitive lobster hierarchies. The second State-of-the-Art lecture by Lynda Corkum discussed ‘Chemical Communication in the Freshwater Environment’. Lynda gave an overview of the ways in which freshwater animals—crustacea, insects, fish and amphibians—use chemical communication and the uses to which they put these systems; specifically mate-finding

Early moult improves local survival and reduces reproductive output in female pied flycatchers

Overlapping moult and reproduction might be crucial for long-distance migratory birds, which are time-constrained to complete these energy-demanding functions before the onset of migration. However, proximate factors modulating the potential trade-off between moult and breeding, such as haemoparasite infection and stress, have not been studied in wild avian populations. We investigated the occurrence of moult-breeding overlap in females of a Spanish population of pied flycatchers (Ficedula hypoleuca) and its association with female age, haemoparasite prevalences, physiological stress, and condition at initial (incubation phase or beginning of the nestling period) and final breeding stages (days11'12 of the nestling period). Late-breeding females were more likely to show a moult—breeding overlap than early-breeding females. Female age was not associated with moult status when taking into account laying date and study year. A higher proportion of females infected by Haemoproteus at initial breeding stages showed a moult—breeding overlap. Haemoproteus prevalences at final breeding stages did not differ according to moult status. Females with a moult—breeding overlap also showed better condition and lower stress levels (HSP60 levels) at the end of the season. A higher proportion of moulting females returned to the breeding grounds in the following season compared with non-moulting ones. Conversely, moulting females showed reduced hatching success and numbers of hatchlings and fledglings. Overlapping moult and breeding might be the expression of a shift in resource allocation between present and future reproduction, towards increased self-maintenance and reduced reproductive investment.

Transition between moult and migration in a long-distance migratory passerine: organ flexibility in the African wintering area

Phenotypic flexibility of organs in migratory birds has been documented for a variety of species of different genera during the migratory period. However, very little is known about phenotypic mass changes of organs with respect to other events within the annual cycle. This seems particularly interesting when birds face different physiological challenges in quick succession. We investigated mass changes of 13 organs from garden warblers (Sylvia borin) during the transition from moult to migration. These long-distance migratory birds perform a complete moult within their wintering area just shortly before the onset of spring migration. Birds were sampled in three successive stages according to their moult status: group I consisted of birds with growing primary or secondary wing feathers, group II consisted of birds with completed wing moult but with still moulting body feathers, and group III consisted of birds that had completed wing moult and body moult. Size-corrected flight muscle, kidney mass, and pancreas mass differed significantly among the three groups. Flight muscle was heaviest in birds that were about to leave their wintering area (group III) compared with birds still in body moult (group II). Kidney and pancreas showed a pattern similar to each other, with the heaviest mass occurring in birds with moulting wing feathers (group I) and significantly reduced mass in birds that had completed wing moult (group II) or both wing and body moult (group III). Mass reductions of kidney and pancreas during the transition from moult to migration are considered to be related to the demands of moult, while increased flight muscle may be due to moult, migration, or both. Phenotypic mass changes of organs in birds occur during their migration, but they also occur during the transition between other phases of the annual cycle such as moult and migration and are not restricted to the flight muscle.