Hunting and the fate of French breeding waterbirds

Capsule French breeding populations of hunted waterbirds have more negative long-term population trends than closely related non-hunted species.

Aims To assess the relative fate of breeding populations of hunted and non-hunted waterbird species in France.

Methods We compared long-term population growth rates of hunted versus non-hunted waterbirds using two large-scale and long-term national surveys.

Results Waterbirds globally displayed long-term increases in population sizes most likely driven by their positive response to the implementation of numerous protected areas over remnant wetlands across the country since the early 1970s. In contrast, hunted species revealed more negative trends compared to non-hunted species.

Conclusion A causal relationship between hunting and population dynamics is not demonstrated here, but the results are consistent with species' breeding populations being negatively affected, on average, if they are hunted.     

Nest-site selection of the Long-eared Owl Asio otus in northwestern Switzerland

Capsules Sites are selected as part of an antipredator strategy.

Aims To assess if site choice depends on habitat variables at nest sites and if habitat quality influences reproduction.

Methods Breeding density was explored in northwestern Switzerland from 1992 to 1996. Habitat variables were examined at 38 breeding sites and were compared with data collected from random sites. Habitat quality was estimated using the discriminant function scores of the nesting sites.

Results Breeding density was found to vary between years; more pairs bred and raised more young in 1993, a year of high vole abundance. Long-eared Owls tended to avoid the vicinity of buildings; they occupied sites with denser forest edges, greater canopy cover, and with more conifers than random sites. I found no statistical evidence that they used less optimal sites when the population was high. The number of fledglings increased with habitat quality, but did not vary with any of the habitat variables taken separately.

Conclusion Long-eared Owl selects nesting habitat as part of an anti-predator strategy, but the measures of territory quality did not seem to be a limiting factor for the population.     

Population dynamics of Common Sandpipers Actitis hypoleucos in the Peak District of Derbyshire – a different decade

Capsule A report of the failure of a population to recover from a catastrophic snow storm.

Aims To examine why our study population of Common Sandpipers failed to recover from a sharp drop in 1989, caused by a severe late April snowstorm, when it had recovered from a similar event in 1981.

Methods Populations were censused weekly, with extra visits to ring adults and chicks. Hatching was assumed to have occurred if adults alarmed, and fledging if alarming continued for three weeks. Data from 1989–99 and 1979–88 were compared.

Results The recruitment of new adults to the population was much lower, but these recruits mostly came from other breeding areas, and the local recruits appeared to go elsewhere. Median dispersal distance is estimated as 3.3 km, sufficient to take most locally produced young adults outside the study area.

Conclusions We do not know if poorer breeding in the source populations for our birds, or poorer survival of first year birds over winter in West Africa, is the cause of the failure of this population to recover in the 1990s.     

A real‐time eco‐evolutionary dead‐end strategy is mediated by the traits of lineage progenitors and interactions with colony invaders

Evolutionary dead‐end strategies are characterized by short‐term productivity benefits and long‐term evolutionary costs. Here, I detail a real‐time dead‐end strategy associated with the behavioural traits of lineage progenitors in the social spider Anelosimus studiosus. Specifically, colony lineages founded by docile spiders were eight times more likely to suffer extinction, despite their superior reproductive output. However, when inquilines were experimentally removed from progenitor colonies, differences in extinction probability among lineages vanished. Similarly, among lineages founded by purely docile or aggressive individuals, the descendants of lineages with the highest reproductive output suffered the lowest survivorship, whereas lineages founded by a mixture of docile/aggressive lacked such a trade‐off. Finally, lineages with shorter progenitor‐descendant distances gained more inquilines and their descendants had lower survivorship, relative to more diffuse lineages. Overall, this study demonstrates how the traits of lineage progenitors and species interactions can unite to determine the fates of entire lineages.     

Folliculogenesis, onset of puberty and fecundity of mink (Mustela vision Schreb) selectively bred for docility or aggressiveness

It has been suggested that selective breeding of animals for docile behavior is correlated with early onset of puberty and improved fertility. We wished to test the hypothesis that mink bred for docility would show earlier onset of puberty and greater fecundity than mink bred for aggressiveness. We used farm-raised, 7-mo-old mink females that had been selectively bred for 7 to 10 generations on the basis of behavior towards humans. Onset of puberty was estimated once (between 15 and 20 December) by vaginal smears and was said to start wtih preponderance of cornified epithelial cells in the cytological specimen. Fecundity was measured by litter size and rate of folliculogenesis, with and without hCG stimulation, by histomorphometric examination of ovaries and uteri. A total of 43/100 (43%) docile females achieved proestrus and estrus as compared to 16/136 (12%) of the aggressive ones. Overall pregnancy rate, survival to 5 d after whelping and litter size did not differ between the docile and aggressive females. Docile females showed significantly higher numbers (P < 0.05 and < 0.001) of growing, maturing and atretic follicles than the aggressive ones, however the latter showed a highly significant (P < 0.001) folliculogenic response to hCG. The response of the ovary of aggressive females to hCG is particularly dramatic because in most aggressive females the ovaries contained none or only few follicles of any kind. The inhibition of folliculogenesis in aggressive mink is similar to that reported in Silverblue and Sapphire mink homozygous for the Stuart factor. The paradoxical response to hCG may be an indication that selective breeding for aggression may be correlated with the disturbance at the early stages of folliculogenesis which creates a deficiency of follicles that are sensitive to LH-type stimulation.     

Habitat associations of Eurasian Skylarks Alauda arvensis breeding on Irish farmland and implications for agri-environment planning

Capsule Skylarks breeding in Ireland prefer extensive grassland habitats and almost completely avoid tillage habitats.

Aims To describe the distribution and habitat use of breeding Skylarks in Ireland, particularly in lowland agricultural habitats, and to use this information to inform conservation measures for this species.

Methods Countryside Bird Survey (CBS) and Farmland Bird Project (FBP) data were examined to determine large-scale (national) distribution and habitat selection, in addition to smaller-scale (farm- and field-level) habitat use. The CBS is a national breeding bird monitoring scheme involving 397 1-km squares. The FBP collected detailed bird and habitat data from 122 farms.

Results CBS and FBP data both showed significant regional differences in breeding Skylark densities, with the highest relative abundances in the northwest and west. Dry grassland/grass moor habitats supported the highest densities of breeding Skylarks in the CBS, which were significantly higher than in improved grassland or tillage. At the farm-level, Skylark numbers were positively related to wetland habitats but negatively associated with trees in field boundaries, dense ground vegetation and overall density of farm boundaries. At the field-scale, larger fields and unimproved grasslands were preferred.

Conclusion Agri-environment measures tailored to region-specific requirements and to the relatively local habitat preferences of target species are required if population declines of species of conservation concern, including Skylarks, are to be reversed.     

Drivers of low breeding success in the Lesser Spotted Woodpecker Dendrocopos minor in England: testing hypotheses for the decline

Capsule The breeding success of Lesser Spotted Woodpeckers Dendrocopos minor is now lower in England than previously reported and also lower than found in studies elsewhere in Europe.

Aims To quantify the breeding success and identify the causes of nest failure. To test the hypotheses that breeding success is related to aspects of food limitation and parental care, and inclement weather during the nesting period, or to interactions with Great Spotted Woodpeckers.

Methods Nests were monitored in three regions of England, recording survival and causes of failure. We measured aspects of food limitation and parental care, rainfall and Great Spotted Woodpecker interactions at nests, to explore whether there was any evidence that these factors were related to breeding success. We compared results to other studies from the UK and continental Europe.

Results Nest survival was 52%. The average number of chicks produced from successful nests was 2.8. Chick-stage daily nest survival was positively related to provisioning rates, indicating that food supply may be limiting. The most common cause of nest failure was presumed starvation of chicks after the disappearance of an adult. Some females ceased visiting nests, leaving provisioning solely to the male. This behaviour has been reported elsewhere in Europe, but in the present study males were unable to compensate fully by increasing their provisioning rates, leading to poor nest survival. Provisioning rates and chick-stage daily nest survival were negatively associated with rainfall. Nest predation by Great Spotted Woodpeckers occurred but was a less frequent cause of failure. Aggressive interactions were recorded between the two woodpecker species but these were unrelated to breeding parameters.

Conclusions Low breeding success is most probably related to food shortages in the breeding period. Simple population modelling using parameters from the present study and from published work shows that if the low productivity that we have observed is replicated throughout Britain, it would be sufficient to account for the observed population decline. However, the possibility that survival rates are also low cannot be ruled out.     

Breeding success and nest-site characteristics of Red-breasted Flycatchers Ficedula parva in a primeval forest

Capsule Predation is a major factor influencing the breeding success of Red-breasted Flycatchers under natural conditions.

Aims To examine the breeding success of Red-breasted Flycatchers in relation to nest-site characteristics and time of breeding.

Methods Data were collected during seven breeding seasons under natural conditions in Bia?owie?a National Park. We used survival time analysis to estimate changes in survival probability over time and breeding success in relation to first-egg date and nest-site characteristics.

Results Offspring fledged successfully from 51% of clutches, but the Kaplan–Meier estimate of survival was lower at 0.43. Of the unsuccessful clutches, 82% were lost to predators. The highest probability of loss was during egg-laying and in the second half of incubation. Breeding success was influenced by the height of the nest above the ground, but no relation to other nest-site characteristics was found.

Conclusion To avoid predation Red-breasted Flycatchers build nests in various sites that are more open than most cavity-nesting species. The position of the nest-sites allows the sitting female to observe her surroundings and to escape rapidly from the nest, giving the chance for a replacement clutch.     

Population changes of breeding waders on farmland in relation to agri-environment management

Capsule Population response of breeding waders to agri-environment management varied between management options and species; implementation has been on too small a scale to reverse national population declines.

Aims To test whether numbers of five breeding wader species have shown a more positive response between 1992 and 2005, at sites with appropriate agri-environment management, than at sites that have remained outside such schemes.

Methods Using data from 60 pairs of farmland study areas in Scotland first surveyed in 1992/93, before agri-environment scheme (AES) implementation, and again in 2005, after scheme implementation, we tested at both site and field scales whether changes in the abundance of five breeding wader species were associated with AES management options designed to benefit these species.

Results Changes in breeding wader abundance were more positive on sites in AES, especially for Northern Lapwings Vanellus vanellus and Common Redshanks Tringa totanus, even though management had not been targetted specially at breeding waders on those sites. However, AES management was associated only with modest population increase for Common Redshanks, and a reduction in the magnitude of decline for Northern Lapwings. At the field scale, there was evidence for Northern Lapwings, Common Redshanks and Common Snipe Gallinago gallinago that options which limited grazing and other agricultural activity were associated with more positive outcomes than those which also manipulated water levels.

Conclusions AES management for breeding waders slowed, and in some cases reversed, breeding wader decline at field and farm scales. These benefits were from options that limited grazing and agricultural operations during the breeding season, but not those that also aimed to raise water levels. A possible explanation is that when wetland options are applied to agriculturally marginal fields, grazing reduction or abandonment, and succession to rank vegetation cover then occur over the course of 5-year agreements, with detrimental effects for breeding waders. Verification arrangements need to be robust enough to guard against this. Levels of agri-environment provision in 2005 were too limited and too poorly targeted at remaining key areas for breeding waders to be able to halt or reverse national population declines.     

The impact of livestock on Lapwing Vanellus vanellus breeding densities and performance on coastal grazing marsh

Capsule Even at very low stocking densities, livestock reduce breeding densities of adult Lapwings and increase the risk of nest loss due to predation.

Aims To assess the effects of livestock on Lapwings breeding on coastal grazing marshes.

Methods Densities of breeding adults, clutch sizes, laying dates, incubation schedules, clutch and chick survival were compared between marshes grazed at low stocking densities (0.2–0.51 livestock units/ha) and marshes where livestock had been excluded. Repeated measurements of sward heights were also made.

Results. Breeding densities in 1995 and 1997, but not 1996, were negatively correlated with the presence of livestock. Though few nests were trampled, livestock disrupted incubation schedules and increased the risk of nest predation. Clutches were smaller on grazed marshes than on ungrazed marshes, while more clutches were also laid later on grazed marshes. Grazed swards remained shorter, and more suitable for nesting, longer than ungrazed swards but clutches laid later in the season were more likely to be predated.

Conclusion The exclusion of livestock from selected areas to increase the nesting success of lapwings is a desirable option on coastal grazing marshes where the rate of grass growth is slow in spring. Grazing regimes are suggested that would maintain relatively short swards, provide refuge to Lapwings from livestock during the peak nesting period, and allow grazers to exploit all of their marshes.     

Nestbox orientation: a species-specific influence on occupation and breeding success in woodland passerines

Capsule Nestbox orientation has species-specific influences on nestbox occupation and breeding success for woodland passerines.

Aims To determine if nestbox orientation had an influence upon nestbox selection or breeding success for three co-occurring woodland passerines.

Methods We analysed 15 consecutive years of breeding data (1990–2004) from 295 nestboxes in the UK using circular statistical analyses to examine the influence of orientation upon nestbox occupation and breeding success for three species, Blue Tit Cyanistes caeruleus, Great Tit Parus major and Pied Flycatcher Ficedula hypoleuca.

Results The three species used nestboxes of all orientations during the 15-year period. The frequency of nestbox occupation by Great Tits correlated with orientation (the mean number of nests in boxes oriented south-southwest was lower than the mean number of nests in boxes facing other directions). There was no such relationship for Blue Tits or Pied Flycatchers. Nestbox orientation influenced the breeding success of Pied Flycatcher (the mean number of young to fledge from boxes oriented south-southwest was lower than from boxes facing other directions). There was no such relationship for Blue or Great Tits.

Conclusion Nestbox orientation can be an important influence on occupation and breeding success, but this differed between species. Intriguingly, although the directionality reduced nestbox occupation (Great Tit) and breeding success (Pied Flycatcher) was the same (south-southwest), there was a disparity in the influence of orientation for Great Tit (orientation influenced the frequency of occupation but not success) and Pied Flycatcher (orientation did not influence occupation but did affect success). We discuss these disparities, considering the possible influences of mating strategy, breeding phenology, nestbox microclimate and offspring quality.     

Hen Harrier Circus cyaneus population trends in relation to wind farms

Capsule: The data presented here demonstrate a considerable spatial overlap between wind farms and the breeding distribution of Hen Harriers in Ireland, but evidence for a negative impact of wind farms on their population is weak.

Aims: To assess the extent of the overlap between wind farms and breeding Hen Harriers and to investigate their potential impact on Hen Harrier population trends.

Methods: Data on Hen Harrier breeding distribution in 10?km?×?10?km survey squares from national surveys were used in conjunction with information on the location of wind farms to examine whether, and to what extent, changes in Hen Harrier distribution and abundance between 2000 and 2010 were related to wind energy development.

Results: Of the 69 survey squares holding Hen Harriers during the 2010 breeding season, 28% also overlapped with one or more wind farms. Data from 36 of the squares with breeding Hen Harriers during the 2000 survey revealed a marginally non-significant negative relationship between wind farm presence and change in the number of breeding pairs between 2000 and 2010.

Conclusions: A considerable overlap exists between Hen Harrier breeding distribution and the location of wind farms in Ireland, particularly in areas between 200 and 400?m above sea level. The presence of wind farms is negatively related to Hen Harrier population trends in squares surveyed in 2000 and 2010, but this relationship is not statistically significant, and may not be causal. This is the first study to assess the influence of wind energy development on Hen Harriers at such a large geographic and population scale.     

Age structure and reproduction in feral New Zealand populations of the house mouse (Mus musculus), in relation to seedfall of southern beech

Abstract

After good seedfalls by southern beech (Nothofagus spp.), density indices for mice increased, the breeding season for adult females was brought forward, and winter breeding was observed. The end of the breeding season of the following summer was brought forward only slightly if the maximum density achieved was not great; incomplete data on 2 very high-density populations suggested a much earlier end to breeding. In early winter following a good seedfall the recruitment of juveniles was temporarily increased. After spring, few young mice entered the population, though breeding continued. The distribution of age classes shifted steadily upwards as population density rose. The peak population of 1976–77 comprised mainly old mice, still breeding, but without significant recruitment. No effects of density on sex ratio, litter size, or body weight could be detected from these data. In all populations studied, density decreases were ultimately due to failure of recruitment and the disappearance of ageing, non-breeding mice. The proximate causes of this mortality were probably the onset of cold weather in 1976–77 and predation by stoats in 1979–80.     

Aggressive behavior of adult meadow voles (Microtus pennsylvanicus) towards young

Summary Field evidence indicates that adult microtines, especially females, may be a major cause of poor juvenile survival and this may be instrumental in their population regulation. This suggests that males and females behave differently towards young animals. To examine how adult males, nonlactating females, and lactating females behave towards strange young, I introduced young animals into the home cage of the adults. Lactating females were most aggressive towards young; most males investigated them; most nonlactating females ignored them. However, discriminant function analysis indicated a great deal of overlap in the behavior of the classes. None of the classes behaved differently towards young of either sex. Females did not vary their behavior during lactation. Behavior varied among lactating females, with 55% showing little aggression and 20% showing a great deal. Most lactating females showed similar behavior in each of their bouts: docile females remained docile, aggressive females remained aggressive. I conclude that lactating females are most aggressive towards strange young. These results are consistent with the field evidence, which suggests that adult females depress juvenile survival and recruitment and that the main culprits are breeding females.     

Comparative population dynamics of Common Sandpipers Actitis hypoleucos: living at the edge

Capsule Common Sandpiper populations at the edge of their range do not recruit so well.

Aims To compare the survival rates, breeding success and recruitment of a population near the edge of its range (Peak District) with one more centrally placed (Borders).

Methods Populations were censused weekly; adults and chicks were ringed, and apparent survival of adults determined by resighting colour-ringed birds. Breeding success was assessed from ringing chicks and the guarding behaviour of their parents over 3–4 weeks post-hatching.

Results Survival rates of adults and their breeding success were similar in the two sites. Recruits were rarely ringed chicks returning to near their natal site; they were usually newly recruited adults. In both, natal dispersal took returning chicks away from their natal site, by 3–6 km, but far more potential recruits returned to the Borders (51% compared with 4%). The population in the Borders was more variable, but recovered better from declines.

Conclusions There is no obvious difference in survival or reproductive rates that would explain the different recent fates of the two study populations. Differential survival over winter in West Africa (the presumed wintering grounds) is unlikely to explain the recent decline of the Peak District population, because conditions there should have affected the Borders population too. The Peak District population is exposed at the edge of the species' range, and it seems to be poorer breeding success across its general range that has caused the poorer recruitment there, and hence the decline.     

The importance of observer effort on the accuracy of breeding success estimates in the Common Guillemot Uria aalge

ABSTRACT

Capsule: A data-thinning approach was used to assess the effects of reducing the frequency of nest-checks on estimates of breeding success of Common Guillemots Uria aalge. Inter-year and inter-colony differences in fledging age and their implications for setting a minimum age after which a chick could be assumed to have fledged were evaluated.

Aims: To assess the consequences of reducing sampling frequency on the estimation of breeding success, and on the robustness of the assumption that breeding has been successful if a chick survives to 15 days old.

Methods: Breeding success, ages at fledging and loss of chicks were estimated from daily checks at two Scottish colonies over a six-year period. Data-thinning was used to assess the consequences of reducing checks from daily to every two or three days. Breeding success was recalculated assuming that all chicks surviving to 15 days fledged.

Results: Reducing the frequency of checks from daily to every second or third day resulted in a small but statistically significant increase in the estimate of success. Between 20% and 25% of chick losses occurred when chicks were ≥15 days old. Assuming that these chicks had fledged resulted in significant increases in breeding success.

Conclusion: Assumptions about whether or not a chick fledged had a greater impact on the estimate of breeding success than reducing the frequency of nest-checks from daily to every second or third day. There was no threshold age after which a chick could be assumed to have fledged. These findings are relevant to other monitoring schemes where there is pressure to reduce input. Sampling methods used in monitoring schemes need to be clearly stated and changes in protocols documented so that sampling effects can be incorporated into future analyses.     

Studies on Rhabdionvirus oryctes: III. Incidence in the Oryctes rhinoceros population of Western Samoa

The viral pathogen Rhabdionvirus oryctes [ROV] was found to be widespread in the population of Oryctes rhinoceros in Western Samoa. About 3% of the larvae and 35% of the adults were infected with ROV. Larval breeding sites more frequently contained ROV-infected insects if the sites were occupied by two broods instead of one and if there was a high density of breeding in the area. Females infected with ROV visited the breeding sites less frequently for egg-laying than healthy females. The male adults, as they increased in age, were found to be more frequently infected with ROV, but the young female adults were more frequently infected than very young or old females. The ROV-infections in adults apparently play a more important role in suppressing the O. rhinoceros population than those of larvae.     

Breeding ecology of Kentish Plover Charadrius alexandrinus in an extremely hot environment

Capsule Hot environments are associated with more biparental care, high nest‐site fidelity and low mate fidelity.

Aims To investigate the breeding ecology and parental behaviour of Kentish Plovers in an extremely hot environment. Kentish Plovers have an unusually diverse breeding system in which the frequencies of biparental, female‐only and male‐only care vary between populations. A common, but rarely tested, explanation for such a variation is local adaptation: birds exhibit social traits that are adaptive to their breeding environment. In particular, we investigated the effect of a hot environment on breeding success, distribution of care types, and mate and site fidelity.

Methods A breeding population of approximately 200 pairs of Kentish Plovers was investigated in 2005 and 2006 at Al Wathba Wetland near Abu Dhabi in the United Arab Emirates.

Results We found high nest‐site fidelity, low mate fidelity and more biparental care in Al Wathba than in most temperate zone populations of Kentish Plovers.

Conclusions Our results are consistent with the argument that a harsh environment can select for biparental care. However, further studies are warranted to distinguish between alternative hypotheses for the different distribution of social behaviours of breeding populations.     

Status of breeding Dotterel Charadrius morinellus in Britain in 1999

Capsule A minimum of 220 male Dotterel nested in Britain in 1999, which after correction for missed birds led to an estimated 630 breeding males.

Aims To provide a reliable population estimate of Dotterel against which past and future estimates could be compared.

Methods Over half of the potential breeding habitat in Britain, selected randomly and to cover protected sites and former breeding sites for Dotterel, was surveyed through a single visit when Dotterel had young chicks.

Results After correcting for missed birds, 750 males were estimated to be breeding in Britain in 1999. An alternative method led to an estimated 510 males. Both methods had their drawbacks – 630 males probably represented the best estimate. Almost 93% of males bred in three regions: central, east and north Highlands. Around a third of surveyed sites were occupied by breeding birds. The national population estimate was significantly higher in 1987/88 but numbers were probably greatest in 1989 and declined in the 1990s. In 1999 Dotterel distribution had contracted to those sites with the highest densities in the late 1980s.

Conclusion It is unlikely that changes in numbers between surveys were due to changes in the British breeding grounds. They may be due to adverse influences away from the breeding grounds or, because Dotterels can move across large distances between breeding attempts, a redistribution of birds away from Scotland to breeding sites elsewhere in the Palearctic.     

Road to Royalty – Transition of Potential Queen to Queen in the Primitively Eusocial Wasp Ropalidia marginata

Ropalidia marginata, a primitively eusocial wasp, is different from typical primitively eusocial species in having docile queens who cannot be using dominance to maintain reproductive monopoly and instead appear to use a pheromone from the Dufour's gland to do so. When a docile queen is removed from her colony, one of the workers (potential queen, PQ) becomes highly aggressive, and if the queen is not returned, gradually loses her aggression and becomes the new docile queen within a few days. We hypothesized that the decrease in aggression of the PQ with time since queen removal should be correlated with her change in ovaries and pheromone profile. Because the Dufour's gland hydrocarbon composition in R. marginata can be correlated with fertility, this also gave us an opportunity to test whether PQ is different from workers in her Dufour's gland hydrocarbons. In this study, we therefore trace the road to royalty in R. marginata, that is, the transition of the PQ during queen establishment, in terms of her ovaries, aggression, and Dufour's gland hydrocarbons. Our study focuses on queen establishment, which is important for understanding how reproductive conflict can be manifested and resolved.