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Photoperiodic control of reproduction in birds is based on two processes, a positive effect leading to gonadal maturation and an inhibitory effect subsequently inducing regression. Nonphotoperiodic cues can modulate photoperiodic control, particularly the inhibitory process. In previous studies of common starlings (Sturnus vulgaris), (1) restriction of food availability to 8 h after dawn had little effect on testicular maturation but dramatically delayed subsequent regression and (2) lower ambient temperature also had little effect during maturation but delayed regression. Could the effects of food restriction and temperature share a common underlying mechanism? Four groups of starlings were kept on a simulated natural cycle in photoperiod in a 2 x 2 factorial experimental design. Two groups were held under an ambient temperature of 16°C, and the other two were held under 6°C.One of each of these groups had food provided ad lib., and in the other two groups access to food was denied 7 h after dawn. In both the ad lib. food groups and the food-restricted groups, lower temperature had little effect on testicular maturation but delayed subsequent regression and molt. In both the 16°Cgroups and the 6°Cgroups, food restriction had no effect on testicular maturation but delayed regression and molt. The daily cycle in body temperature was recorded in all groups when the photoperiod had reached 12L∶12D, the photoperiod at which regression is initiated. In both 6°C groups, nighttime body temperature was lower than in the 16°C groups, a characteristic of shorter photoperiods. In the two ad lib. food groups high daytime temperature was maintained until dusk, whereas in the two food-restricted groups body temperature began to decrease after food withdrawal. Thus, both lower temperature and food restriction delayed regression, as if the photoperiod was shorter than it actually was, and both resulted in daily cycles in body temperature that reflected cycles under shorter photoperiods. This implies that the daily cycle in body temperature is possibly a common pathway through which nonphotoperiodic cues may operate. [ABSTRACT FROM AUTHOR]

Although it is well known that body temperature (Tb) is higher during the day in diurnal birds than at night, no data are available regarding exactly how Tb varies during a 24-h period, how this differs under different photoperiods, and how it responds to a change in photoperiod. This study used implanted temperature loggers in starlings (Sturnus vulgaris) to address these questions. The duration of elevated Tb was directly related to photoperiod, but the amplitude of the daily cycle was significantly greater under shorter photoperiods. Under all photoperiods, Tb started to increase before dawn and continued to increase after dawn; there was no sudden change associated with dawn. In contrast, Tb decreased immediately and rapidly at dusk (significantly by 15 min). The daily cycle in Tb rapidly adjusted to a change in photoperiod. Following an acute increase in photoperiod, Tb increased immediately at the new earlier dawn but did not decrease until the new later dusk. Following a decrease in photoperiod, Tb did not increase after the time of the missed dawn; it only increased after the new later dawn. It decreased at the new earlier dusk. Following transfer to constant darkness, there was a moderate increase in Tb around the missed dawn, but then Tb gradually decreased before the missed dusk to lower values than during the previous night. The results suggest that the daily cycle in Tb is weakly circadian and may be entrained by dusk rather than dawn. [ABSTRACT FROM AUTHOR]

Breeding periodicity allows organisms to synchronise breeding attempts with the most favourable ecological conditions under which to raise offspring. For most animal species, ecological conditions vary seasonally and usually impose an annual breeding schedule on their populations; sub-annual breeding schedules will be rare. We use a 16-year dataset of breeding attempts by a tropical seabird, the sooty tern (Onychoprion fuscatus), on Ascension Island to provide new insights about this classical example of a population of sub-annually breeding birds that was first documented in studies 60 years previously on the same island. We confirm that the breeding interval of this population has remained consistently sub-annual. By ringing >17000 birds and re-capturing a large sample of them at equivalent breeding stages in subsequent seasons, we reveal for the first time that many individual birds also consistently breed sub-annually (i.e. that sub-annual breeding is an individual as well as a population breeding strategy). Ascension Island sooty terns appear to reduce their courtship phase markedly compared with conspecifics breeding elsewhere. Our results provide rare insights into the ecological and physiological drivers of breeding periodicity, indicating that reduction of the annual cycle to just two life-history stages, breeding and moult, is a viable life-history strategy and that moult may determine the minimum time between breeding attempts. [ABSTRACT FROM AUTHOR]

From August to December, thousands of Black-necked Grebes Podiceps nigricollis concentrate during the flightless moult period in salt ponds in the Odiel Marshes, southern Spain, where they feed on the brine shrimp Artemia parthenogenetica. We predicted that because Black-necked Grebes moulted in a food-rich, predator-free environment, there would be no net loss of body mass caused by the use of fat stored to meet energy needs during remigial feather replacement (as is the case for some other diving waterbirds). However, because the food resource disappears in winter, we predicted that grebes moulting later in the season would put on more body mass prior to moult because of the increasing risk of an Artemia population crash before the moult period is completed. Body mass determinations of thousands of birds captured during 2000-2010 showed that grebes in active wing-moult showed greater mass with date of capture. Early-moulting grebes were significantly lighter at all stages than late-moulting birds. Grebes captured with new feathers post-moult were significantly lighter than those in moult. This is the first study to support the hypothesis that individual waterbirds adopt different strategies in body mass accumulation according to timing of moult: early-season grebes were able to acquire an excess of energy over expenditure and accumulate fat stores while moulting. Delayed moulters acquired greater fat stores in advance of moult to contribute to energy expenditure for feather replacement and retained extra stores later, most likely as a bet hedge against the increasing probability of failing food supply and higher thermoregulatory demands late in the season. An alternative hypothesis, that mass change is affected by a trophically transmitted cestode using brine shrimps as an intermediate host and Black-necked Grebes as final host, was not supported by the data. [ABSTRACT FROM AUTHOR]

In vertebrates, reproductive output often increases with age. Unlike older birds, first-year photoperiodic birds lack experience with the reproductively stimulatory effects of long day lengths (photostimulation). We examined whether age-related differences in annual reproductive development could be partially attributed to previous experience with photostimulation in the photoperiodic house finch (Carpodacus mexicanus). By manipulating photoperiod, we generated 2 groups of first-year females: a photo-experienced group that underwent 1 photoperiodically induced cycle of gonadal development and regression and a photo-naïve group exposed to long days since hatch. We transferred both groups from long to short days and then photostimulated and exposed them to male birdsong prior to sacrifice. Following concurrent photostimulation, both groups exhibited similar plasma luteinizing hormone surges and hypothalamic vasoactive intestinal polypeptide immunoreactivity. In contrast, hypothalamic gonadotropin-releasing hormone immunoreactivity and circulating vitellogenin levels were higher in photo-experienced birds, and yolk deposition occurred in only 2 females, both of which were photo-experienced. Our results demonstrate that photo-experience enhances some aspects of early photo-induced reproductive development and raise the hypothesis that photo-experience may account for at least some age-related variation in reproductive output. [ABSTRACT FROM PUBLISHER]

We measured deuterium isotope ratios (δ Df) in primary feathers to distinguish first-year from older Pectoral Sandpipers Calidris melanotos captured in Barrow, Alaska, during the breeding season. δ Df showed a distinct bimodal distribution, and model-based clustering placed the δ Df values into two non-overlapping groups. More negative δ Df corresponded to Arctic areas, probably identifying first-year birds with Arctic-grown juvenile feathers retained from the previous year. The more positive values corresponded to lower latitudes, possibly identifying older birds that grew their feathers at non-Arctic latitudes. [ABSTRACT FROM AUTHOR]

Selection pressures due to parasitism play an important role in driving the evolution of life history traits of birds in general and of behaviour at the nest in particular. Eggshell bacterial load has been shown to predict hatching failure (i.e. the probability of embryo infection) but the relationships between the bacterial environment of the nest and life history characteristics of birds remain poorly investigated. We explored interspecific variation in eggshell bacterial load of mesophilic bacteria, Enterococcus spp., Staphylococcus spp. and Enterobacteriaceae groups across 24 bird species and assessed whether bacterial load is associated with breeding traits. Interspecific variation was much higher than intraspecific variation for all measures of bacterial load even after controlling for annual variation. Thus, we were able to assess the correlation between bacterial community characteristics and life history traits. After correcting for phylogenetic effects, we found that nest type, the use of feathers or plants as lining material, and incubation behaviour explained a significant proportion of the variance in bacterial communities on eggshells. The strength of these associations depended on study year, suggesting an important role of environmental conditions for eggshell bacterial load or community. Overall, these results suggest that bacteria on eggshells are associated with bird species traits, probably because birds are mediating the deleterious effect of eggshell microbes through behavioural traits that modify bacterial load. [ABSTRACT FROM AUTHOR]

Corticosterone has received considerable attention as the principal hormonal mediator of allostasis or physiological stress in wild animals. More recently, it has also been implicated in the regulation of parental care in breeding birds, particularly with respect to individual variation in foraging behavior and provisioning effort. There is also evidence that prolactin can work either inversely or additively with corticosterone to achieve this. Here we test the hypothesis that endogenous corticosterone plays a key physiological role in the control of foraging behavior and parental care, using a combination of exogenous corticosterone treatment, time-depth telemetry, and physiological sampling of female macaroni penguins (Eudyptes chrysolophus) during the brood-guard period of chick rearing, while simultaneously monitoring patterns of prolactin secretion. Plasma corticosterone levels were significantly higher in females given exogenous implants relative to those receiving sham implants. Increased corticosterone levels were associated with significantly higher levels of foraging and diving activity and greater mass gain in implanted females. Elevated plasma corticosterone was also associated with an apparent fitness benefit in the form of increased chick mass. Plasma prolactin levels did not correlate with corticosterone levels at any time, nor was prolactin correlated with any measure of foraging behavior or parental care. Our results provide support for the corticosterone-adaptation hypothesis, which predicts that higher corticosterone levels support increased foraging activity and parental effort. [ABSTRACT FROM AUTHOR]

Timing of reproduction in temperate-zone birds is strongly correlated with spring temperature, with an earlier onset of breeding in warmer years. Females adjust their timing of egg laying between years to be synchronized with local food sources and thereby optimize reproductive output. However, climate change currently disrupts the link between predictive environmental cues and spring phenology. To investigate direct effects of temperature on the decision to lay and its genetic basis, we used pairs of great tits (Parus major) with known ancestry and exposed them to simulated spring scenarios in climate-controlled aviaries. In each of three years, we exposed birds to different patterns of changing temperature. We varied the timing of a temperature change, the daily temperature amplitude, and the onset and speed of a seasonal temperature rise. We show that females fine-tune their laying in response to a seasonal increase in temperature, whereas mean temperature and daily temperature variation alone do not affect laying dates. Luteinizing hormone concentrations and gonadal growth in early spring were not influenced by temperature or temperature rise, possibly posing a constraint to an advancement of breeding. Similarities between sisters in their laying dates indicate genetic variation in cue sensitivity. These results refine our understanding of how changes in spring climate might affect the mismatch in avian timing and thereby population viability. [ABSTRACT FROM AUTHOR]

Many seasonal breeders adjust the timing of reproduction in response to year-to-year variations in supplementary environmental cues, amongst which ambient temperature is thought to be most influential. However, it is possible that for species such as the great tit (Parus major L.), phenological cues from sprouting vegetation and the consequent abundance of invertebrate prey, although dependent on temperature, may provide supplementary environmental cues per se. This hypothesis was investigated in breeding pairs of great tits kept in outdoor aviaries. In spring, experimental pairs were provided with access to leafing birch branches and caterpillars as a visual food cue, while control pairs were provided with non-leafing branches. Observations were made on the onset of laying and on concentrations of plasma luteinizing hormone (LH) at regular intervals to monitor changes in reproductive function. The onset of egg laying was not advanced by the presence of leafing branches and caterpillars. LH concentrations increased during the course of the study, but phenological cues did not affect plasma LH levels in females and males. Early spring vegetation, such as the leafing of birch branches, and the appearance of caterpillar prey do not appear to play a significant role in fine-tuning the onset of egg laying in great tits. [ABSTRACT FROM AUTHOR]

Hormones mediate major physiological and behavioural components of the reproductive phenotype of individuals. To understand basic evolutionary processes in the hormonal regulation of reproductive traits, we need to know whether, and during which reproductive phases, individual variation in hormone concentrations relates to fitness in natural populations. We related circulating concentrations of prolactin and corticosterone to parental behaviour and reproductive success during both the pre-breeding and the chick-rearing stages in both individuals of pairs of free-living house sparrows, Passer domesticus. Prolactin and baseline corticosterone concentrations in pre-breeding females, and prolactin concentrations in prebreeding males, predicted total number of fledglings. When the strong effect of lay date on total fledgling number was corrected for, only pre-breeding baseline corticosterone, but not prolactin, was negatively correlated with the reproductive success of females. During the breeding season, nestling provisioning rates of both sexes were negatively correlated with stress-induced corticosterone levels. Lastly, individuals of both sexes with low baseline corticosterone before and high baseline corticosterone during breeding raised the most offspring, suggesting that either the plasticity of this trait contributes to reproductive success or that high parental effort leads to increased hormone concentrations. Thus hormone concentrations both before and during breeding, as well as their seasonal dynamics, predict reproductive success, suggesting that individual variation in absolute concentrations and in plasticity is functionally significant, and, if heritable, may be a target of selection. [ABSTRACT FROM AUTHOR]

Summary 1. Annual variation in the timing of avian reproduction is associated with predictive cues related to ambient temperature. Understanding how these cues affect timing, and estimating the genetic variation in sensitivity to these cues, is essential to predict the micro-evolutionary changes in timing which are needed to adapt to climate change. 2. We carried out a 2-year experiment with great tits Parus major of known genetic background, which were kept in pairs in climate-controlled aviaries with simulated natural photoperiod and exposed to a seasonal change in temperature, where the two treatments differed by 4 °C. We recorded the dates of laying the first and last eggs and timing of moult, as well as physiological proxies associated with reproduction: plasma luteinizing hormone (LH), prolactin, and gonadal size at four-weekly intervals. 3. The temperature treatments did not affect first-egg dates, nor gonadal growth or plasma LH and prolactin concentrations. However, birds terminated egg laying, regressed their testes and started their moult earlier at higher temperatures. 4. There were marked family differences in both the start of egg laying, with sisters from early laying maternal families laying early, and in the termination of laying, indicating that there is heritable variation in sensitivity to cues involved in timing. 5. Our experiment, the first to use genetically related individuals in an experimental design with a natural change in photoperiod and biologically realistic temperature differences, thus shows that genetic adaptation in cue sensitivity is possible, essential for species to be able to adapt to a warming world. [ABSTRACT FROM AUTHOR]

Pollutants as endocrine disrupting chemicals (EDCs) are of worldwide concern, due to their detrimental effects on the physiology and behaviour of wildlife. One major source of EDCs is sewage treatment works which serve as foraging grounds for many bird species. However, the risks of consuming EDCs to wild birds at these sites have been largely overlooked. We have previously quantified contamination levels of invertebrates from within filter beds of sewage treatment works and the intake rates of these invertebrates by wild European starlings feeding at these sites. Our work to date has shown that environmentally-relevant EDC exposure results in reduced immunocompetence, increased song behaviour and neural development in adult starlings. In the present study, we hypothesized that nestling starlings exposed to similar EDC levels from contaminated prey, from parental feeding at sewage treatment works, would show altered growth and physiology. Our findings show that EDC exposure results in reduced growth and immunocompetence in nestling birds. However, there was no effect on corticosterone or haematocrit levels. As growth rates and immunocompetence are likely to be related to survival rates, we suggest that these exposure levels are likely to adversely affect recruitment into the adult population. Synthesis and applications. These results highlight the potential transfer of EDCs between semi-aquatic or aquatic organisms and terrestrial organisms up the food chain at sites of sewage treatment works, broadening the scope of potential routes of exposure. Our findings suggest that birds foraging in these sites are at risk of physiological manipulation from EDCs and reduced body condition as a result. We advocate further work to evaluate the potential for EDCs from sewage treatment works to bioaccumulate and modulate the condition of wild organisms feeding on contaminated prey. Our results suggest that changes in management practices of sewage treatment works are required. We support measures to reduce EDC levels in sewage treatment works and that these sites should be designed to exclude or deter wildlife from foraging on contaminated prey. The management implications of such policy - oriented steps will ensure the health of wildlife foraging at sewage treatment works. [ABSTRACT FROM AUTHOR]

Birds use change in daylength during the year to time events during their annual cycles. Individual Eurasian siskins Carduelis spinus can breed and winter in widely separated areas in different years. Birds at different latitudes will experience different changes in photoperiod. So how does latitude affect photoperiodic control? Our aim in this study was to find whether Siskins caught from the wild in Britain and exposed to different photoperiodic regimes, typical of widely separated latitudes, would differ in the subsequent timing and duration of their moults and associated processes. Siskins were caught in late February and early March, and initially kept outside on natural photoperiods. From the spring equinox (21 March), they were divided into three groups kept under photoperiodic regimes that simulated latitudes 40°, 55° and 70°N respectively. All three groups showed highly significant subsequent changes in body mass, fat scores and cloacal protuberance size. Moult of the primary feathers started during June - August (mean 9 July), and lasted 61-99 days (mean 75 days). Birds that started to moult late in the season had shorter moult durations. All individuals showed lower mass and fat levels during moult than before or after moult. Crucially, there were no significant differences in the timing of these events between the three photoperiodic groups. Apparently these birds did not use prevailing absolute photoperiod or the prevailing rate of change in photoperiod to time moult-related seasonal events, but used instead some other feature of the annual photoperiod cycle or some form of interval timer linked to photoperiod. [ABSTRACT FROM AUTHOR]

Recent changes in the seasonal timing (phenology) of familiar biological events have been one of the most conspicuous signs of climate change. However, the lack of a standardized approach to analysing change has hampered assessment of consistency in such changes among different taxa and trophic levels and across freshwater, terrestrial and marine environments. We present a standardized assessment of 25 532 rates of phenological change for 726 UK terrestrial, freshwater and marine taxa. The majority of spring and summer events have advanced, and more rapidly than previously documented. Such consistency is indicative of shared large scale drivers. Furthermore, average rates of change have accelerated in a way that is consistent with observed warming trends. Less coherent patterns in some groups of organisms point to the agency of more local scale processes and multiple drivers. For the first time we show a broad scale signal of differential phenological change among trophic levels; across environments advances in timing were slowest for secondary consumers, thus heightening the potential risk of temporal mismatch in key trophic interactions. If current patterns and rates of phenological change are indicative of future trends, future climate warming may exacerbate trophic mismatching, further disrupting the functioning, persistence and resilience of many ecosystems and having a major impact on ecosystem services. [ABSTRACT FROM AUTHOR]

Where life-history stages overlap, there is the potential for physiological conflicts that might be important in mediating carryover effects. However, our knowledge of the specific physiological mechanisms underlying carryover effects remains rudimentary, and specific examples remain rare. Here we show that female macaroni penguins (Eudyptes clirysolophus) initiate vitellogenesis and yolk formation while at sea during return migrations to breeding colonies; yolk formation takes approximately 16 days, but females lay only 714 days after their return. Once on land, Eudyptes penguins show a unique reproductive pattern of extreme egg size dimorphism in which the smaller, first-laid A-egg is 55%-75% of the size of the larger B-egg. We show that the degree of egg size dimorphism is inversely correlated with time between arrival and laying; that is, females that begin reproductive development well in advance of their return produce more dimorphic eggs. Furthermore, late-arriving females that produce the most dimorphic eggs have lower plasma levels of the yolk precursor vitellogenin on arrival; that is, they show lower reproductive "readiness." These data support the hypothesis that extreme egg size dimorphism in Eudyptes penguins is due to a physiological constraint imposed by a migratory carryover effect and argue against small A-eggs having a specific, adaptive function. [ABSTRACT FROM AUTHOR]

Differences between species in breeding seasons are thought to be mediated through differences in their reproductive physiology. Little is known about how the timing and duration of gonadal maturation varies between raptor species, how the timing of moult relates to the gonadal cycle, whether the timing and degree of sexual maturation varies between juveniles and adults or whether body condition has a significant effect. To address these questions, data on gonadal size and moult for adults and juveniles of both sexes of three raptor species were extracted from the Predatory Bird Monitoring Scheme (based on birds found dead by members of the public). The three species, Sparrowhawk Accipiter nisus, Kestrel Falco tinnunculus and Barn Owl Tyto alba, have different ecologies – diurnal bird predator, diurnal mammal predator and nocturnal mammal predator, respectively. All are single-brooded but have different breeding seasons. The duration of gonadal maturation was markedly different between the species. Barn Owls showed the earliest maturation and the latest gonad regression, and Sparrowhawks the latest maturation and earliest gonad regression. Kestrels were intermediate. In males of all species, the testes remained fully mature throughout their respective breeding seasons. In females, the ovaries remained partially mature throughout the breeding season. Moult started slightly earlier in Sparrowhawks than in Kestrels and coincided with gonadal regression in the two species. Although females of the two species started to moult earlier than males, moult duration was similar between the sexes. Barn Owls showed no distinct annual pattern of moult. In juveniles of all three species, the gonads were smaller than in adults throughout spring and started to mature later. Gonad size in birds that had starved tended to be smaller than in birds dying from other causes, but did not influence the difference in gonad mass between adults and juveniles and between seasons. Body condition had no effect on moult. Whilst ecology has led to the evolution of different breeding seasons, differences between species, and between adults and juveniles, are mediated through adaptive differences in their reproductive physiology. [ABSTRACT FROM AUTHOR]

Photorefractoriness is the insensitivity of gonadal development to the stimulatory effects of long photoperiods in birds and to the inhibitory effects of short photoperiods in small mammals. Its molecular mechanism remains unknown. Recently, it has been shown that reciprocal expression of thyroid hormone-activating enzyme [type 2 deiodinase (Dio2)] and -inactivating enzyme [type 3 deiodinase (Dio3)] genes in the mediobasal hypothalamus is critical for photoperiodically induced gonadal growth. Since thyroid hormones are required not only for photoinduction, but also for the induction of photorefractoriness, we examined the expression of these genes in relation to photorefractoriness in birds and mammals. Transfer of birds to long photoperiods induced strong expression of Dio2. This was maintained in tree sparrow when they later became photorefractory, but decreased somewhat in quail. In hamsters, transfer to long photoperiods also induced strong expression of Dio2. High values were not maintained under long photoperiods, and, indeed, expression decreased at the same rate as in animals transferred to short photoperiods. There was no renewed expression of Dio2 associated with testicular growth as animals became refractory to short photoperiods. Expression of Dio3 was high under short photoperiods and low under long photoperiods in all the animals examined, except for the short photoperiod-refractory hamsters. Our present study revealed complex regulation of deiodinase genes in the photoinduction and photorefractory processes in birds and mammals. These gene changes may be involved in the regulation of photorefractoriness, as well as photoinduction. [ABSTRACT FROM AUTHOR]

Exposure to organophosphate (OP) pesticides can occur in free-living mammals in treated areas. Risk to nontarget animals from OPs usually is assessed with acute exposure data, but exposure of wild animals is likely to be intermittent and chronic. We compared the effects of single or repeated (hourly and daily) exposure to dimethoate on acetylcholinesterase (AChE) activity in laboratory mice to assess the suitability of standard laboratory tests for assessing risk. Mice were exposed either to a single dose (10 or 30 mg/kg) or to short-term repeated (three hourly doses of 10 mg/kg) intraperitoneal doses of dimethoate, and brain and serum AChE activity were measured. No significant difference was found in the degree of inhibition of AChE activity following acute and short-term repeated exposure. In a second experiment, mice were given three daily doses of 10 or 20 mg/kg of dimethoate, and both AChE activity and hepatic cytochrome P450 enzyme activity were measured. Daily exposure resulted in a dose-dependent decline in brain and serum AChE activity, and inhibition increased progressively with successively repeated exposures. However, this effect was relatively small compared to the effect of dose. Cytochrome P450 enzyme activity (CYP2B) was inhibited in the dimethoate-dosed mice. Our results indicate that acute dose-response toxicity studies are suitable models for predicting the likely occurrence of adverse effects from either short- or longer-term exposure of wild mammals to anticholinesterase compounds. Likely differences in exposure pattern between the laboratory and the natural environment are unlikely to bias the predictive power of these studies significantly. [ABSTRACT FROM AUTHOR]

We previously reported evidence of West Nile virus (WNV) circulation in UK birds, probably introduced by migratory birds from overseas. We now demonstrate WNV-specific seroconversion in sentinel chickens raised on an English farm. Maternal neutralizing antibodies to WNV in hatchlings declined within three weeks. During the following months, healthy chickens developed WNV neutralizing antibodies that were confirmed by immunoblotting and indirect immunofluorescence tests using WNV antigens. The proportion of seropositive chickens was higher for WNV than for Usutu virus or Sindbis virus. Attempts to isolate infectious virus or to detect viral RNA in the sera, failed. [ABSTRACT FROM AUTHOR]

We note the recurrence of errors in specifying an econometric proxy for short-run uncertainty of outcome in sporting fixtures. This research note aims to prevent the spread of these errors because they are becoming embedded in a growing literature. The note also suggests how investigators might more usefully define uncertainty of outcome. [ABSTRACT FROM AUTHOR]

The mass and length of each primary flight feather was measured in 120 species of birds (347 individuals) representing 37 families and 15 orders. The scaling relationship between mass and length was determined using the mass of each primary as a proportion of total primary feather mass for that individual and, similarly, length as a proportion of total length. This eliminated errors due to intra- and interspecific differences in absolute size. In every species there was a highly significant constant scaling relationship (log mass/log length) for all of the primary feathers proximal to the feather that formed the wing tip. This relationship was allometric and varied between 1.80 in RooksCorvus frugilegusand 4.87 in Winter WrensTroglodytes troglodytes. The mean scaling relationship for 120 species was 2.41 ± 0.42 sd, which was significantly less (P < 0.0001) than isometry (i.e. 3.00). In most species (117 of 120) the primary feather forming the wing tip and all feathers distal to it had a different scaling relationship, and had a greater mass than expected from their length. The greater relative mass of the outer primaries may reflect a protective role against physical abrasion, or an aerodynamic role in that each of these feathers provides a leading edge to the wing. Thus, there were two scaling relationships that pivoted about the feather forming the wing tip, resulting in a characteristic‘signature’ for each species. Scaling relationships can be related to flight characteristics and habitat, rather than to phylogeny. Closely related species often had widely varying scaling relationships. In general, species exploiting dense vegetation had greater scaling relationships than more aerial species. However, species with a high scaling relationship did not have a greater mean feather mass, so the increased relative mass of the distal primaries was at the expense of proximal primary feather mass. [ABSTRACT FROM AUTHOR]

In many species of birds there is a close relationship between the end of breeding and the start of moult. Late-breeding birds therefore often start to moult late, but then moult more rapidly. This is an adaptive mechanism mediated by decreasing day lengths that allows late-breeding birds to complete moult in time. This study asked how these birds complete moult of the primary feathers more rapidly, and the consequences of this on the mass of primary feathers. Common StarlingsSturnus vulgariswere induced to moult rapidly in one of two ways. In the first experiment, one group was exposed to artificially decreasing photoperiods from the start of moult, whereas the control group remained on a constant long photoperiod. The second experiment was a more realistic simulation. Two groups were allowed to moult in an outdoor aviary. One group started to moult at the normal time. In the other, the start of moult was delayed by 3 weeks with an implant of testosterone. The duration of moult was significantly reduced in both the group experiencing artificially decreasing photoperiods and the group in which the start of moult was delayed. The faster moult rate was achieved by moulting more feathers concurrently. The rate of increase in length of each of the primary feathers, and their final length, did not differ between groups. The rate at which total new primary feather mass was accumulated was greater in more rapidly moulting birds, but this was insufficient to compensate for the greater numbers of feathers being grown concurrently. Consequently, the rate of increase in mass of individual feathers, and the final feather mass, were less in the rapidly moulting birds. A 3-week delay in the start of moult is not an unrealistic scenario. That this caused a measurable decrease in feather mass suggests that late-breeding birds are indeed likely to suffer a real decrease in the quality of plumage grown during the subsequent moult. [ABSTRACT FROM AUTHOR]

During moult, the rate that protein can be synthesized and used to grow new feathers must be a critical factor influencing the quality of new plumage. However, the rate that new feather mass accrues during moult has not been assessed in detail. To estimate this, the increase in length of each of the nine primary feathers (P1–P9) in 16 captive Common Starlings Sturnus vulgaris was measured at weekly intervals throughout moult. The rate of increase in length was similar for all primary feathers except P9, which increased more slowly. After completion of moult, these feathers were plucked, accurately measured and weighed. The distribution of mass along the length of each primary was assessed. Using these data, I estimated the rate that mass had increased for each feather during moult. For each individual primary, mass increased at a steady rate until almost fully grown. The rate of increase in mass was least for P1 and greatest for P9. The number of feathers growing concurrently decreased as moult progressed. The net result was that total new primary feather mass increased at a steady rate throughout most of moult (linear regression between start of growth of P2 and end of growth of P8; r 2 = 0.991). Retrospective conversion of feather lengths into moult score showed that the increase in score was not linear. It was greatest early in moult and decreased as moult progressed. A scoring system that factors in distribution of mass within and between feathers may provide a more physiologically relevant measure of the progress of moult. [ABSTRACT FROM AUTHOR]

The article presents a study investigating the timing and rate of post-nuptial moult in relation to wood size in two single-brooded species, Blue Tit and Great Tit. In the study, the timing and rate of post-nuptial moult in Blue Tits and Great Tits was assessed using primary moult, recorded using the standard method of the British Trust for Ornithology. It was found that moult in Great Tits and Blue Tits in small woods was delayed on average by about 8 days compared to birds in large woods.

There is considerable evidence that reproductive success improves with age in birds. It is often suggested that improved performance of older birds is because they are more experienced. Less consideration has been given to the possibility that improvements may be a consequence of age-related changes in reproductive physiology. One factor that consistently changes with age is laying date – first year birds lay later than older birds. In European starlings Sturnus vulgaris , older males begin reproductive activity earlier than first year males and dominate available nest sites. I monitored changes in testicular volume in captive starlings exposed to natural changes in day length and temperature, from their first autumn through the next two annual cycles. Testicular maturation was advanced by 3–4 weeks in birds during their second year compared to the first, and testicular regression occurred about 2 weeks later. The period of full sexual maturation was 50% longer during the second year. The timing of the post-nuptial moult was the same. A possible physiological mechanism to explain this is discussed. The results show that earlier reproductive activity in older birds can be explained, at least in part, by intrinsic physiological mechanisms. This does not preclude additional effects of experience of an individual in the improvement in reproductive performance between first and second year birds. [ABSTRACT FROM AUTHOR]

Abstract Photoperiodic manipulation of young European starlings suggests that their reproductive physiology is incapable of responding to a short photoperiod until they are fully grown. This study aimed to determine whether the lack of response to a short photoperiod is reflected in the daily profile of plasma melatonin concentrations. Five-day-old starlings taken from nest boxes showed a significant (p < 0.0001) rhythm in plasma melatonin concentrations, with high values during night. In nestlings hand-reared from 5 days of age on a long photoperiod (LD 16:8), equivalent to natural photoperiod at the time, the amplitude of the daily rhythm in melatonin increased significantly (p < 0.01) with age until birds were fully grown (20 days old). In nestlings reared on a short photoperiod (LD 8:16), the daily melatonin profile remained almost identical to that of long photoperiod birds until they were fully grown. However, after 20 days old, the duration of elevated nighttime melatonin began to extend to encompass the entire period of darkness. In contrast, fully grown starlings transferred from a long to a short photoperiod had partially adapted to the short photoperiod after 5 days; by 10 days, the daily melatonin profile was identical to that of birds held chronically on a short photoperiod. Thus, consistent with responses of reproductive physiology, the pineal of young birds appears to be incapable of perceiving, or adapting to, a short photoperiod. [ABSTRACT FROM AUTHOR]

The timing and duration of primary moult were estimated for wild adult Starlings Sturnus vulgaris near Monks Wood in 1977-78, and for captive birds in 1999. The model of Underhill and Zucchini (1988) was modified to allow for a non-linear increase in the moult score, based on scores of captive birds. For wild birds, estimates of moult duration in 1977 and 1978 were 100 days and 98 days, with mean and standard deviation in start dates of 6 June and 7.3 days in 1977, and 2 June and 9.7 days in 1978. For captive birds, moult duration was 85 days, with mean and standard deviation of 31 May and 4.1 days. Differences between these estimates and those reported for other wild and captive Starling populations are discussed. [ABSTRACT FROM AUTHOR]

This review examines how birds use the annual cycle in photoperiod to ensure that seasonal events—breeding, molt, and song production—happen at the appropriate time of year. Differences in breeding strategies between birds and mammals reflect basic differences in biology. Avian breeding seasons tend to be of shorter duration and more asymmetric with respect to changes in photoperiod. Breeding seasons can occur at the same time each year (predictable) or at different times (opportunistic), depending on the food resource. In all cases, there is evidence for involvement of photoperiodic control, nonphotoperiodic control, and endogenous circannual rhythmicity. In predictable breeders (most nontropical species), photoperiod is the predominant proximate factor. Increasing photoperiods of spring stimulate secretion of gonadotropin-releasing hormone (GnRH) and consequent gonadal maturation. However, breeding ends before the return of short photoperiods. This is the consequence of a second effect of long photoperiods—the induction of photorefractoriness. This dual role of long photoperiods is required to impart the asymmetry in breeding seasons. Typically, gonadal regression through photorefractoriness is associated with a massive decrease in hypothalamic GnRH, essentially a reversal to a pre-pubertal condition. Although breeding seasons are primarily determined by photoperiodic control of GnRH neurons, prolactin may be important in determining the exact timing of gonadal regression. In tropical and opportunistic breeders, endogenous circannual rhythmicity may be more important. In such species, the reproductive system remains in a state of "readiness to breed" for a large part of the year, with nonphotic cues acting as proximate cues to time breeding. Circannual rhythmicity may result from a temporal sequence of different physiological states rather than a molecular or cellular mechanism as in circadian rhythmicity. Avian homologues of mammali... [ABSTRACT FROM AUTHOR]

This review examines the evidence for endocrine disruption in birds. It reviews in vitro and in vivo laboratory based evidence for endocrine disruption by (1) agonism or antagonism of gonadal steroid hormones, (2) altering the activity of cytochrome P450 enzymes, (3) altering thyroid hormone function, (4) affecting intrinsic neuroendocrine control mechanisms and (5) activation of the stress response. It also discusses the evidence for the existence of such effects in free-living birds. In vitro studies demonstrate that mechanisms for potential endocrine disruption exist, but in vivo studies suggest that such mechanisms are insufficient to overwhelm endogenous homeostatic control. There are only two phenomena in wild birds where endocrine disruption has been cited as a possible cause: eggshell thinning and supernormal clutches. Evidence suggests that neither of these is caused by endocrine disruption. Despite three decades of concern, there is no evidence that avian wildlife has suffered endocrine disruption. [ABSTRACT FROM AUTHOR]

Identifies some of the theoretical and empirical problems with the conventional economic approaches to the analysis of industrial accidents which use the hedonic pricing approach. Important determinants which the hedonic pricing approach excludes; Formulation of a model which explicitly encompasses a broader range of determinants than hedonic pricing; Test of the model using industry accident data from the United Kingdom.

Evaluates several computer software and related material available for use by the economists. "Running the British Economy 1987"; "Macmod"; "Ready Reckoner"; "Chancellor One"; "Chancellor Two."

Presents a study which looked at the effects of varying light intensity on the photoperiodic reproductive response of starlings. Theories on how photoperiodic time measurement occurs; Insight on the methodology used to conduct the study; Discussion based on the results of the study.

The results presented by Attfield, Demery and Duck (1981) in the European Economic Review, 18 p. 367-385 are replicated. The model is re-estimated to take account of the policy switch to floating exchange rates in 1972, with rather less than favourable results, a major problem being misspecification of the monetary growth equation.
Attfield, Demery and Duck (hereinafter ADD)(1981)present a three-equation New-Classical model of the UK, which they suggest is broadly consistent with the postwar evidence. They do however qualify their conclusion, drawing attention to the smallness of the sample size and to the unsatisfactory estimates of the price equation. Finally, they suggest that 'there is clearly scope for much more empirical work in this area' (op. cit. p. 382).
Bearing in mind the criteria of replicability, relevance to the current macropolicy debate and the authors' own comments it seems appropriate to examine whether ADD's conclusions are consistent with their sample data -- a task somewhat eased by their publication not only of the data but of a detailed description of sources.
In section II the authors' least squares results are reproduced and the problem of structural instability in the monetary growth equation is noted. In section III estimates of the model are presented for the period of fixed exchange rates 1949-1971. [ABSTRACT FROM AUTHOR]

The author replicates three wage equations suggested by McCallum (1974a,b), by Henry, Sawyer and Smith (1976), and by Johnston (1972), using quarterly British data 1951 (I)--1977(IV). The latter pair of equations yields fair results when tested by the usual methods. However, the application of a test of post fitting period parameter stability leads to their rejection. (The first equation performs so badly by conventional criteria that the stronger test is not required.)
The results point to the need (a) for more replication and (b) for testing the power of models to predict outside the fitting period. [ABSTRACT FROM AUTHOR]

Sargan's (1964) wage equation is respecified within the feedback control framework to which it belongs and confronted with quarterly British data. The starting point for the work reported in this paper is the interesting and important puzzle that despite over twenty years of fitting wage equations to British post-war data, no great success can be claimed either in explanation or in prediction. Indeed Sargan in the original paper used the model to illustrate the use of autoregressive least squares and instrumental variable estimators. The implication is that the equation is misspecified in some undetected manner. The objective of the research reported herein was to attempt the removal of the specification error by a careful reconsideration of the theory, then to test the appropriateness of the suggested reformulation by econometric methods. Some writers e.g. Sargan (1964) and Johnston (1972) have attempted to break away from the conventional excess demand/expectation models and to take account of bargaining in a labour market characterized by bilateral monopoly. To a Keynesian this appears as a potentially more fruitful conception of the labour market, both for prediction and explanation.

Parkin et all (1976) present a set of results for the post-war Great Britain economy which (they claim) confirm inter alia the role of excess demand for labour in the determination of the rate of change of money wage rates. Their most interesting behavioural hypothesis is that money wage rates are so adjusted by transactors that the change in excess demand, given expectations of price and tax changes, eliminates (in whole or in part) excess demand during some previous period. The disequilibrium framework introduced by Fair and Jaffee (1972) permits the estimation of excess demand quantities, and the method has been applied to the postwar Great Britain labour market by Dawson (1979) in an attempt to identify the Phillips Curve. Independent evidence lends some support to Parkin et al.'s market clearing hypothesis. However, the support is rather weak, since the explanatory power is very low. As one might anticipate, the implied speed of adjustment is slow. Given that economics abounds with unresolved issues (many of them with non-trivial policy implications) rather more effort needs to be applied to model-building in order to obtain identification prior to estimation.

The article focuses on the celebration of the 150th anniversary of the British Ornithologists' Union (BOU) in England. The association was founded in the rooms of Alfred Newton of the Magdalene College in Cambridge, England on November 17, 1858. Another founder member was Henry Baker Tristam, a clergyman. The anniversary of the association will be celebrated in two ways. First, the association will paying for all of the back issues to be scanned and digitized. The other one will be the celebration of its anniversary at the BOU annual conference on April 8-10, 2008.

Reviews the shareware macro-economics simulation software ECONOLAND-2001, developed by Michael C. Lovell.