Severe inbreeding depression in a wild wolf (Canis lupus) population

The difficulty of obtaining pedigrees for wild populations has hampered the possibility of demonstrating inbreeding depression in nature. In a small, naturally restored, wild population of grey wolves in Scandinavia, founded in 1983, we constructed a pedigree for 24 of the 28 breeding pairs established in the period 1983-2002. Ancestry for the breeding animals was determined through a combination of field data (snow tracking and radio telemetry) and DNA microsatellite analysis. The population was founded by only three individuals. The inbreeding coefficient F varied between 0.00 and 0.41 for wolves born during the study period. The number of surviving pups per litter during their first winter after birth was strongly correlated with inbreeding coefficients of pups (R2=0.39, p<0.001). This inbreeding depression was recalculated to match standard estimates of lethal equivalents (2B), corresponding to 6.04 (2.58-9.48, 95% CI) litter-size-reducing equivalents in this wolf population.     

青海海晏县热水滩和乌兰脑滩喜马拉雅旱獭的繁殖生物学特征

研究喜马拉雅旱獭(Marmota himalayana)繁殖生物学特征,对阐明其种群数量变动,进行数量监测以及探索动物流行病学有着实践和理论意义。国内赵中石(1982)对天山旱獭(Marmota baibacina)有过研究,而喜马拉雅旱獭尚无报道。作者于1982-1984年对青海湖东北岸热水滩地区(下称研究区,该区于1960-1979年进行了持续地灭獭工作)进行了连续3年的调查,并与未经人群干扰的乌兰脑滩地区(下称对照区)作对比,研究了喜马拉雅旱獭繁殖生物学特征。     

THE FOUNDING OF A NEW POPULATION OF DARWIN'S FINCHES

We report the natural colonization of the small Galápagos island Daphne Major by the large ground finch (Geospiza magnirostris). Immigrants of this species were present in every year of a 22-yr study, 1973–1994. Typically they arrived after a breeding season and left at the beginning of the next one. Geospiza magnirostris bred on the island for the first time in the exceptionally wet El Niño year of 1982–1983, and bred in all subsequent years except drought years. In agreement with theoretical expectations the frequency of inbreeding was unusually high. Pronounced fluctuating asymmetry in tarsus length, together with slightly reduced breeding success of inbreeding pairs, suggests a low level of inbreeding depression. Despite this, the population increased from 5 breeding individuals in 1983 to 20 breeding individuals in 1992, and probably more than twice that number in 1993, largely through recruitment of locally born birds.     

Population response to environmental productivity throughout the annual cycle in a migratory songbird

Environmental factors affect migratory animal populations in every phase of their annual cycle and have significant impacts on breeding success and survival. The Breeding Bird Survey provides a long-term database for examining population trends in North American birds, allowing us to examine large-scale environmental factors that influence population abundance. We examined plant productivity as measured by normalized difference vegetation index (NDVI) over a 24-year period from 1983–2006 in bird conservation regions (BCRs) that overlapped Bullock's oriole (Icterus bullockii) breeding, moult, and wintering ranges to ask whether plant productivity in 1 year influences population abundance in the subsequent breeding season. Bullock's orioles have a moult-migration strategy, with a stopover moult in the Mexican monsoon region, which necessitates examining each stationary phase of the bird's annual cycle to understand the impacts of environmental factors on population abundance. Our results show increased breeding abundance in three (Great Basin, Coastal California and Shortgrass Prairies) of the six BCRs in which the species breeds following years with high NDVI values. We did not detect a response of breeding abundance to high NDVI values in the previous year in either the moulting region or in their primary over-wintering area in central Mexico. Our results demonstrate that large-scale annual variation in primary productivity on the breeding grounds can have an impact on breeding abundance in the following season, but further studies on migratory connectivity and on ecological mechanisms during the non-breeding seasons are needed to understand why we did not detect an influence of productivity during these periods.     

The vulnerable Osprey breeding population of the Al Hoceima National Park,Morocco: present status and threats

In the Mediterranean, most areas belonging to the initial distribution range of the Osprey Pandion haliaetus have been lost and local populations have disappeared in recent decades because of persecution. Even though direct management actions have allowed local partial recovery, the Mediterranean population currently only holds a few tens of breeding pairs and is still exposed to local extinction risks. One of the last Mediterranean Osprey breeding areas lies along the North African coast between Morocco and Algeria. In this paper, we report new information on the Osprey population within the Al Hoceima National Park, Morocco. The status of the population for 2012 and 2013 is reported and compared with data collected during the period 1983–1990. A reduction in number of nests and breeding pairs was observed and a 35.7% decrease in the population size recorded. In addition, we discuss the main identified threats to Osprey habitats (e.g. dynamite and poison fishing) that affect the Osprey breeding population in this area. In this context, we stress the necessity for urgent measures to be adopted at the local scale for the protection of this vulnerable population in the light of a sound conservation strategy also at the scale of the Mediterranean.     

Reinforcing the native Otter Lutra lutra population in East Anglia: an analysis of the behaviour and range development of the first release group

The British population of the Eurasian Otter Lutra lutra has shown a serious decline since 1957–1958. In England the surviving population is broken into small fragments which may not be viable. One way to strengthen the population to enable it to recover would be to insert breeding units into the gaps. A practical methodology using captive-bred Otters in groups of three is described. This was tested successfully in 1983–1985 in East Anglia, with the first two release groups now breeding. The male in the 1983 group was tracked using a radio harness to be sure of survival and to monitor behaviour and use the environment. Data were obtained on die development of a home range in the new environment. Also, useful information was gathered on swimming and hunting speeds, time of emergence, distance travelled each night, activity periods and time spent in each habitat. This behaviour is compared to that of previously tracked wild Otters in Scotland. The very close similarity of many features is encouraging and results may be taken as indicative of the behaviour of wild Otters in lowland Britain.     

Growth and decline of a penguin colony and the influence on nesting density and reproductive success

Colonial breeding is characteristic of seabirds but nesting at high density has both advantages and disadvantages and may reduce survival and fecundity. African penguins (Spheniscus demersus) initiated breeding at Robben Island, South Africa in 1983. The breeding population on the island increased in the late 1990s and early 2000s before decreasing rapidly until 2010. Before the number breeding peaked, local nest density in the areas where the colony was initiated plateaued, suggesting that preferred nests sites were mostly occupied, and the area used by breeding birds expanded. However, it did not contract again as the population decreased, so that nesting density varied substantially. Breeding success was related positively to the prey available to the breeding birds and negatively to local nest density, particularly during the chick-rearing period, suggesting a density-dependence operating through social interactions in the colony, possibly exacerbated by poor prey availability when the breeding population was large. Although nest density at Robben Island was not high, nesting burrows, which probably reduce the incidence of aggressive encounters in the colony, are scarce and our results suggest that habitat alteration has modified the strength of density-dependent relationships for African penguins. Gaining a better understanding of how density dependence affects fecundity and population growth rates in colonial breeders is important for informing conservation management of the African penguin and other threatened taxa.     

Long term changes in the breeding biology of the woodpigeon Columba palumbus in eastern England

Changes in agricultural practice in eastern England have been shown to have had marked effects upon the winter population size of the woodpigeon Columba palumbus This study examines whether changes in the breeding success of the woodpigeon have also occurred Data were gathered between 1962 and 1983 on the breeding activities of woodpigeons within a wood near Newmarket in eastern England The number of nests monitored each year varied between 16 and 122 with a mean of 45 Agricultural changes resulted in a steep decline in the winter population size in the late 1960's and the breeding population snowed a similar fall Before this decline, productivity was on average 2 8 young per pair, but afterwards it was only 1 8 young per pair This drop in productivity resulted from greater egg predation, which increased steadily over the study period Increased egg predation and variation in seasonal patterns of breeding behaviour are discussed in relation to likely predator numbers and changes in both agricultural and shooting practices In the 1960 s. overwinter starvation was the major limiting factor on the woodpigeon population, but after the mid-1970's low productivity has increasingly become the most important factor     

Population dynamics of an outbreak of house mice (Mus domesticus) in the mallee wheatlands of Australia—hypothesis of plague formation

A plague of mice ( Mus domesticus ) in the Victorian mallee wheatlands of south-eastern Australia in autumn 1984 appeared to be generated by a sequence of rainfall events: high autumn (March), mid winter and late winter rainfall in 1983, and high summer rainfall in 1983/84. The March rainfall in 1983 ended a drought; mice began to breed and bred until the end of May. Relatively high survival of mice for 12 months after March 1983, together with early onset of breeding and high reproductive performance throughout the 1983/84 breeding season, including summer, were key demographic processes during the formation of the plague. Temporal differences in mouse abundance and breeding performance between habitats highlighted the relevance of specific habitats to the dynamics of mouse populations in the wheatlands. Fencelines were the most important habitat of mice because they were foci for breeding at the start of the breeding season, good nesting sites which were rarely disturbed, and widespread and in close proximity to crops. Cereal crops were colonized in spring 1983 and in autumn 1984; they became important habitats in 1983 when mice dispersed and bred there in early spring. Redhead's (1988) model was sufficient to explain the 1984 plague, but not the magnitude of the decline of mouse numbers in 1984, nor the absence of a further outbreak in 1985. A new model is proposed based on a sequence of rainfall events beginning at least 10 months prior to a plague.     

Long-term changes in population size,distribution and productivity of skuas (<Emphasis Type="Italic">Stercorarius</Emphasis> spp.) at Signy Island,South Orkney Islands

In this study, we investigate the numbers, productivity and territory distribution of the two species of skuas (brown Stercorarius lonnbergi and south polar Stercorarius maccormicki) breeding at Signy Island, South Orkneys, and compare the results with trends elsewhere. Comparison with previous counts indicates a biphasic increase in brown skuas at Signy Island; much faster from 1958/1959 to 1982/1983 (3.3 % per annum), than in subsequent years (0.4 % per annum from 1983/1984 to 2013/2014). Relative distribution of territories has changed little over time. The reduced rate of population growth in recent years was broadly coincident with a decrease in numbers of penguins (and therefore potential prey), which may also explain recent reductions in skua numbers at other Antarctic sites. As prey have become limiting, breeding success of brown skuas at Signy Island is now slightly lower than in the 1950s/early 1960s, but timing of breeding does not appear to have changed. Brown skuas at Signy Island may still have enough resources to start breeding, but as the season progresses and availability of resources declines, chick survival is reduced. South polar skuas have declined from ten pairs in 1982/1983 to one pair in 2013/2014, and mixed pairs have increased from one to three pairs. A review of the literature indicated that although population trend data are available for relatively few sites elsewhere in the subantarctic and Antarctic, numbers of brown skuas appear to be generally decreasing or stable, and of south polar skuas to be stable or increasing.     

Combined impacts of longline fisheries and climate on the persistence of the Amsterdam Albatross Diomedia amsterdamensis

Incidental capture of seabirds in longline fishing gear is a central issue in the conservation of many long-lived marine species. Despite growing evidence of climate-induced effects on population trends of long-lived species, climate change remains generally overlooked in most risk assessments of seabirds. Because variation in climate may interact with the detrimental effects of bycatch, considering climate is of great importance, especially in the context of ongoing global warming. This paper examines the combined effects of bycatch and climate change on the persistence of one of the world's rarest birds, the Amsterdam Albatross Diomedea amsterdamensis , which has a single population in the upland plateau of Amsterdam Island (Southeast Indian Ocean). Using continuous monitoring from 1983 onwards, we first estimated the relationship between climate and the species' demographic parameters. We then built a stochastic matrix population model to estimate the population growth rate and the probability that the population declines below the level recorded in 1983 of nine breeding pairs under different scenarios involving the joint effects of additional mortality caused by longline fisheries and climate change. The results suggest that the demography of the Amsterdam Albatross is influenced by climate in both breeding and wintering grounds and that these relationships may to some extent compensate for the impact of additive bycatch mortality. However, these compensatory effects would be negligible if the annual additional mortality exceeds around six individuals per year, suggesting that the resumption of longline fishery in the foraging range of the Amsterdam Albatross would rapidly put this species at risk of extinction.     

Breeding performance of the red-throated diver Gavia stellata in Shetland

Breeding red-throated divers Gavia stellata were studied in Shetland during 1981-1983. The overall probabilities of nest success were 0.35 in 1981 and 0.25 in 1982, as calculated by the Mayfield method. Productivity was shown to be at least 0.51 chicks fledged per breeding pair in 1981 (n = 100) and 0.36 in 1982 (n = 91), and a review of all field studies for Shetland gave a mean value of 0.45 per year (n = 1104) with no detectable trends in productivity since 1918; this was considered probably sufficient to maintain a stable population. Nests at lochs smaller than one hectare experienced the greatest hatching success. The majority of known breeding lochs wore used in three consecutive years, with a significantly greater re-use of lochs which had previously supported successful pairs. Breeding success declined with season in 1981 and 1982 largely due to reduced hatching success of late nesters, and a slight seasonal decline in egg volume was found in 1983.     

Breeding ecology of a suburban population of Woodpigeons Columba palumbus in northwest England

Capsule Between 1981 and 2008 population size was stable, but there were negative trends in breeding parameters.

Aims To determine the current status and long‐term population trend of an isolated breeding population of Bearded Vultures Gypaetus barbatus (Corsica, Mediterranean).

Methods The total Bearded Vulture population was monitored between 1981 and 2008.

Results The current effective breeding population size of Bearded Vultures in Corsica is ten pairs/trios with a slight increase of one to two pairs since 1983. The population is currently estimated at 25 individuals. Breeding parameters (laying rate, breeding success and productivity) have decreased significantly over the full 28‐year study period, although the decrease was not significant when the data set was restricted to 1988–2008. A mean of 60.3% (n = 204) of pairs have laid, but this proportion is highly variable between years. Productivity has been very low (0.16 young/pair/year, n = 233). Breeding parameters of the Corsican population of Bearded Vultures are very low compared with those of other western European populations in the Pyrenees.

Conclusions This isolated insular population is of small size (eight to ten pairs/trios) but shows a stability of distribution and numbers, but low (and decreasing) breeding rates, making this insular population one the most threatened in Europe.     

Selection against large size in the Sand Martin Riparia riparia during a dramatic population crash

In 1984 breeding Sand Martins declined to 27% of their 1983 numbers at a large colony in Scotland. A population crash of similar magnitude occurred over much of central Scotland and over Britain as a whole. The decline in numbers was probably attributable to severe drought conditions experienced overwinter in the Sahel zone of Africa. There was a significant reduction in the mean keel-length of Sand Martins captured at the main study colony in 1984 compared with individuals measured in both 1982 and 1983, suggesting that selection for small body-size had occurred during the period of high overwinter mortality.     

Serologic study on the prevalence of murine viruses in a population of wild meadow voles (Microtus pennsylvanicus)

The demography and serology of a population of wild meadow voles (Microtus pennsylvanicus) were monitored from 1982 to 1984 near Pinawa, Manitoba, Canada. Serologic tests were performed on 486 samples to detect the presence of viral antibodies to 11 common murine viruses. Meadow voles showed evidence of infection with Theiler's encephalomyelitis, reovirus-type-3, ectromelia, lymphocytic choriomeningitis, adenovirus, and mouse hepatitis viruses. At times of good survival and breeding performance the population was nearly free of evidence of viral infection. During a period of severe mortality in the winter of 1982-1983, evidence of infection by Theiler's encephalomyelitis virus and reovirus-type-3 was obtained. A high prevalence of antibodies and high titers to these two viruses were characteristic of voles that were captured late in the decline in density in the spring of 1983. This association of mortality with a viral outbreak is consistent with the hypothesis that vole population declines are sometimes related to opportunistic pathogens present in the voles' biotic and social environment.     

A Polygamous Social System of the Fan-tailed Warbler Cisticola juncidis

The social system of an individually-marked population of the fan-tailed warbler Cisticola juncidis was studied in Japan, over six breeding seasons from 1978 to 1983. More than 127 males established territories, some 50–70% were polygynists each year. Territorial males were replaced frequently within seasons. Females were less faithful than males to their first breeding sites. Perennial or seasonal pair bonds were rare, maintained over two successive breeding attempts, by only 13.6% of females. Half the females left the area after one breeding attempt. Frequent divorce, rapid and multiple remating of females, multiple breedings, and female movement over a wide area all combine to skew breeding sex ratio from unity and favor polygyny.     

Status and abundance of the African Black Oystercatcher Haematopus moquini at the eastern limit of its breeding range

From 1983 to 2004 the breeding population of African Black Oystercatchers along the East London coast has more than trebled. The population increase is probably due to immigration as local breeding success is low. There are three classes of birds: breeding pairs, tenants and visitors, and birds may change status during the breeding season. In the winter, birds aggregate into groups and some birds may disperse from the East London coast. The presence of African Black Oystercatchers in all months of the year shows that they are resident, but may only be resident in the general sense, and at a local level appear to be nomadic, wandering along the coast in search of resources and, in the summer, opportunities to breed. The birds remain at any locality only for as long as conditions are suitable, suggesting that the birds along the East London coast are mostly visitors that have dispersed from their natal areas in the south.     

Asymmetrical competition between the bell miner (Manorina melanophrys,Meliphagidae) and other honeyeaters: evidence from Southeastern Victoria,Australia

Summary The Bell Miner (Manorina melanophrys, Meliphagidae) is a medium-sized, colonial and co-operatively breeding honeyeater. Recent works show that the Bell Miner presents clear patterns of interspecific competition involving aggressive behaviour against many honeyeaters (Meliphagidae) and other bird species (Loyn et al. 1983; Clarke 1984). Nevertheless, those works have been based on short-term (1 year or less) studies only, and none of them have studied the effect territorial defence has on Bell Miners' fitness. We show how the population of honeyeaters decreased over 7 years at the Sir Colin Mackenzie Zoological Park (Southeastern Victoria, Australia). The decrease of honeyeaters in the study site was correlated with a local increase in the Bell Miner population which has been expanding since at least 1983. This process presumably led to the spatial zonation of Bell Miners and honeyeaters observed at present, while other passerine species show no sensitivity to either the invasion of Bell Miners in the recent past or to the present spatial distribution of the Bell Miner population. Finally, we show that Bell Miner reproductive activity is not affected by their interaction with competitors, which leads us to conclude that the interaction between the Bell Miner and other honeyeaters would be better described as asymmetrical competition.     

The breeding performance of the Gentoo Penguin Pygoscelis papua at the northern edge of its range

Gentoo Penguins Pygoscelis papua on the Crozet Islands have a unique timing of breeding, which occurs in winter and is considerably protracted, differing greatly from that of other populations breeding south of the antarctic convergence. Their breeding biology was intensively studied in 1983–1989, involving daily observations in 1983–1985. Winter breeding is associated with an extension of laying, chick rearing, foraging trips and premoult periods, a lower breeding success and a high weight loss. Annual variations in breeding performances were less pronounced than for southern populations. Variations in breeding success were closely associated with variations in feeding frequencies, fledging and breeding weight, and timing of laying. Early breeders were at an advantage over late breeders in terms of breeding success, growth patterns, fledging weight, duration of foraging trips and premoult period. The unusual winter breeding coincides with a time when food is most readily available for chick rearing in restricted foraging conditions at the edge of the species' breeding range.     

Changing female spacing behaviour and demography in an enclosed breeding population of Clethrionomys glareolus

The social organization of Clethrionomys glareolus Schreber was studied by live trapping in an enclosure of 0.8 ha in Central Finland between the years 1982–1986. The enclosure consisted of three habitats: abandoned field, brushwood, and moist spruce heath forest.
The population density increased from 50 voles ha⁻¹ in 1982 and 1983 to 150 ha⁻¹ in 1984 and 1985. In the summer of 1986 the population crashed to almost zero. In the summer of 1984 after winter breeding the number of breeding females grew to 22 compared with 6–7 in previous years. In 1984 the mature females changed from territorial to group behaviour.
During the high population density in 1984 and 1985 breeding stopped already in late July – early August, thus preventing any fence effect.
The present study supports the hypothesis stating that microtine social organization is an opportunistic strategy reacting phenotypically to changing environmental – especially food – conditions.