Orientation behaviour of toads (Bufo bufo) displaced from the breeding site

Summary The sensory basis and spatial range of orientation to the breeding site were studied in the toadBufo bufo, during two breeding seasons. Toads were displaced passively from their breeding pond and fitted with a tracking device to record the path of migration in individuals. The directional choice and the straightness of trails after release were used to quantify the effect of experimental treatments. In both years, control (untreated): toads headed to the breeding site with the same precision at all release sites. The initial orientation of toads blinded by opaque tape over their eyes. did not differ from controls, but the return paths were not as direct. The directional choice of anosmic toads was apparently random, however, individuals followed a straight path in a chosen direction. Anosmic toads also blinded were completely disoriented, moving in cycloid trails. Bar magnets glued to the head caused an increase in dispersion of toads. However, in some individual releases a directional bias without increased dispersion was observed. Sky conditions (clear or overcast) did not influence the initial orientation or the dispersion of toads. Nevertheless, the breeding site component was significantly correlated with wind direction in relation to the breeding site. Wind blowing from the breeding site improved the initial orientation, whereas wind from the opposite direction reduced the breeding site component. The spatial range for the ability to relocate the breeding pond after displacement exceeded 3 km, but the time taken to select the correct direction increased with the displacement distance. The results indicate that after displacement the initial orientation ofB. bufo is based mainly on olfactory and magnetic cues, with visual control of straightness.     

The straight and narrow path: the evolution of straight-line dispersal at a cane toad invasion front

At the edge of a biological invasion, evolutionary processes (spatial sorting, natural selection) often drive increases in dispersal. Although numerous traits influence an individual''s displacement (e.g. speed, stamina), one of the most important is path straightness. A straight (i.e. highly correlated) path strongly enhances overall dispersal rate relative to time and energetic cost. Thus, we predict that, if path straightness has a genetic basis, organisms in the invasion vanguard will exhibit straighter paths than those following behind. Our studies on invasive cane toads (Rhinella marina) in tropical Australia clearly support this prediction. Radio-tracking of field-collected toads at a single site showed that path straightness steadily decreased over the first 10 years post-invasion. Consistent with an evolved (genetic) basis to that behavioural shift, path straightness of toads reared under common garden conditions varied according to the location of their parents'' origin. Offspring produced by toads from the invasion vanguard followed straighter paths than did those produced by parents from long-established populations. At the individual level, offspring exhibited similar path straightness to their parents. The dramatic acceleration of the cane toad invasion through tropical Australia has been driven, in part, by the evolution of a behavioural tendency towards dispersing in a straight line.     

Temporal spacing of breeding activity in the natterjack toad,Bufo calamita

Summary The reproductive behaviour of the toad Bufo calamita was studied in a large population in the northern Rhineland, Germany. Toads bred at four spatially separated but neighbouring areas including 34 breeding ponds. Three methods were applied to monitor quantitatively the intensity of breeding and migratory activity: capture-mark-recapture, a mechanical tracking device, and radio-telemetry. In 1987 a twofold temporal spacing of breeding activity was observed: (1) division of the reproductive period into early, main, and late breeding periods; (2) subdivision of each breeding period into several short calling periods. Since weather conditions were favourable during most of the reproductive period, environmental factors contributed little (23.4%–41.0%) to the temporal variation in breeding intensity as shown by multivariate statistics. The period of vocalization (April to August) included the activity of three distinct male groups. The first group called from April to mid-May (2 calling periods), the second from May to early July (5 calling periods) and the third from mid-July to August (2 calling periods). Within a calling period most males stayed near their calling sites and migratory activity was low. Extensive movements were detected when a new group of males immigrated from the feeding regions to the breeding areas and males that had been calling previously emigrated, at least partly. However, exchange of males among the neighbouring breeding choruses were clearly audible. It is suggested that the energetic costs of vocalization impeded continuous calling activity in individuals and accounted for the periodical variations in chorus size. The short-time variations of breeding activity therefore probably reflect the physiological limits of toads in a situation where the weather permits continuous reproductive activity.     

The effect of winter temperatures on the timing of breeding activity in the common toad Bufo bufo

A 19-year study of a common toad population in south Dorset, UK, was carried out between 1980 and 1998. The daily arrival of sexually mature male and female toads at a breeding pond was recorded each year. The timing of the main arrival of toads at the breeding pond was highly correlated with the mean daily temperatures over the 40 days immediately preceding the main arrival. When the temperatures were higher than average, breeding occurred significantly earlier in the year than if they were either average or lower than average. During the study, the toad breeding seasons were early (2–13 February) in 5 years (1989, 1990, 1993, 1995, 1998), late (16–23 March) in 2 years (1986, 1996) and average (25 February–8 March) during the remaining 12 years. Evidence was found suggesting that common toads have a daylength threshold of about 9 h, below which the migration to the breeding pond does not occur. Evidence was also found indicating that common toads in southern England have a threshold temperature for activity of about 6°C and that the onset of breeding activity is highly correlated with the number of days during the 40 days prior to the main arrival at the breeding pond that were at or above this temperature. Predicting the start of the main breeding migration to a pond in any year may be possible by comparing the pattern of the 40-day running mean daily temperatures from 21 December the preceding year with those from previous years when the start of breeding activity is known. Although all five of the earliest recorded toad breeding years occurred during the last 10 years, and were associated with the occurrence of particularly mild winters, a significant trend towards earlier breeding in recent years compared with previous years was not found. Received: 16 July 1998 / Accepted: 14 September 1998     

Changes in the Oscillatory Electric Potential on the Olfactory Epithelium and in Reproductive Hormone Levels during the Breeding Season in the Toad (Bufo japonicus)

A slow transient electric potential change (electro-olfactogram, EOG) can be recorded through an Ag-AgCl electrode placed on the olfactory epithelium in response to stimulation with an air stream to the tissue in toads (Bufo japonicus). During the breeding season, oscillatory potential changes (OSC) superimpose on the EOG. In the present study the OSC amplitude was found to be highly correlated with the migratory behavior. Since toads track the route to and from the breeding pond using olfactory cues along the migration route, the enhanced OSC should be responsible for the breeding migration.A significant positive correlation was found between plasma gonadotropin levels and the OSC amplitude in males captured during the breeding migration. There was no significant relationship between plasma gonadotropin levels and the OSC amplitude in female toads during the breeding season, but there was a significant correlation between plasma progesterone levels and the OSC amplitude. In males, hypophysectomy just before the breeding season decreased the OSC amplitude. And testis weight was also positively correlated with the OSC amplitude in January. These results suggest that the appearance of the OSC is related to the timing of the activation of the reproductive system. However, treatment of toads with hCG (human chorionic gonadotropin), testosterone, estradiol or progesterone in the non-breeding season did not induce a significant change in the OSC amplitude. Other factor or factors may be required in activation of the olfactory system of the toad in a non-reproductive stage together with the hormones of the gonadal axis.     

Long-term investigations of migratory behaviour of asp (Aspius aspius L.) in the middle part of the Elbe River, Germany

The migratory behaviour, habitat use, home range and temporal and spatial variability of migrations of the potamodromous asp (Aspius aspius L.) in the large Elbe River, Germany, were studied in the years 1997–2000. Fifty‐three asp were tagged with surgically implanted radio transmitters and individually hand‐tracked usually once per week for about 1 year; 50% of the asp exclusively inhabited the main channel, 22% moved for short visits into other habitats and 24% changed between winter habitats in a harbour or oxbow and summer habitats in the main channel where they spawned in late March/April. The migratory behaviour of asp was highly variable; 34 asp observed for more than 1 year lived in home ranges of 1 to >100 stream kilometres (skm) mostly near their capture site. Longest observed migration from summer habitat in the Tidal Elbe back to the spawning ground in the Middle Elbe was 166 skm. After the spawning period or the spawning period thereafter, nine of these 34 fish left their home ranges for a long downstream migration without returning during the observation period. From these results we conclude that populations of rheophilic, potamodromous fish use a surprisingly long river section and that weirs have a strong impact on migration patterns and, ultimately, on population dynamics of these species.     

Winter rainfall predicts phenology in widely separated populations of a migrant songbird

Climate change is affecting behaviour and phenology in many animals. In migratory birds, weather patterns both at breeding and at non-breeding sites can influence the timing of spring migration and breeding. However, variation in responses to weather across a species range has rarely been studied, particularly among populations that may winter in different locations. We used prior knowledge of migratory connectivity to test the influence of weather from predicted non-breeding sites on bird phenology in two breeding populations of a long-distance migratory bird species separated by 3,000 km. We found that winter rainfall showed similar associations with arrival and egg-laying dates in separate breeding populations on an east–west axis: greater rainfall in Jamaica and eastern Mexico was generally associated with advanced American redstart (Setophaga ruticilla) phenology in Ontario and Alberta, respectively. In Ontario, these patterns of response could largely be explained by changes in the behaviour of individual birds, i.e., phenotypic plasticity. By explicitly incorporating migratory connectivity into responses to climate, our data suggest that widely separated breeding populations can show independent and geographically specific associations with changing weather conditions. The tendency of individuals to delay migration and breeding following dry winters could result in population declines due to predicted drying trends in tropical areas and the tight linkage between early arrival/breeding and reproductive success in long-distance migrants.     

北京地区红隼的迁徙路线和活动区域

红隼(Falco tinnunculus)被列为国家二级重点保护野生动物,是能同时适应农村和城市环境的小型猛禽,对维持城市生态系统稳定具有重要意义。2022年4月至7月,为在北京救助的7只红隼佩戴了卫星追踪器,追踪其活动轨迹,依据追踪的动物活动位点数据,采用净平方位移-时间曲线依次对各红隼的迁徙模式进行了判别,深入分析了迁徙红隼的迁徙时间、距离和路线等,并采用核心密度法分别计算了迁徙及留居型红隼95%及50%活动区面积。研究结果表明,在北京地区红隼的迁徙模式为部分迁徙,追踪的7只红隼个体(N01 ~ N07)中,4只为留鸟,1只为迁徙鸟,2只居留类型无法准确判断。N01为迁徙红隼,其度夏地和越冬地分别在内蒙古锡林郭勒盟和河北廊坊,此红隼秋季迁徙速度明显高于春季,其春季迁徙距离551 km,历时25 d,平均迁徙速度为22 km/d,而秋季迁徙距离412 km,历时2 d,平均迁徙速度为203 km/d,河北承德滦平县是其春季迁徙的重要中途停歇地。不同红隼个体间95%及50%活动区面积均存在较大差异,迁徙红隼N01 95%、50%活动区面积在度夏区分别为93.10 km²、17.50 km²,在越冬区分别为7.03 km²、0.99 km²;留居型红隼95%、50%活动区面积均值分别为1 165.34 km²、178.71 km²(n = 4),其中最大95%、50%活动区面积分别为4 320.26 km²(N02)、648.22 km²(N02),最小95%、50%活动区面积分别为2.80 km²(N03)、0.29 km²(N03)。本研究揭示了北京地区红隼的迁徙模式、迁徙路线、重要停歇地及活动区状况,为红隼的针对性保护和管理提供了科学依据。     

Diel pattern of migration in a poisonous toad from Brazil and the evolution of chemical defenses in diurnal amphibians

Most amphibians with biphasic life cycles have aquatic eggs and larvae and terrestrial adults that migrate between terrestrial habitats and aquatic breeding sites. Migration usually occurs at night in order to avoid desiccation and predation. However, some amphibians also migrate during the day, and it has been proposed that this may have evolved as a result of poisonous skin secretions and aposematic coloration that release individuals from visually oriented diurnal predators. Based on this hypothesis and recent observations of 24 h breeding activity in the poisonous, aposematic toad Melanophryniscus cambaraensis, we predicted that migration in this species would occur equally during the day and night. To test our prediction we documented the diel pattern of migratory activity over multiple explosive breeding events from October 2008 to February 2009 (127 nights) at a temporary stream in Rio Grande do Sul state, southern Brazil. We also obtained environmental data to determine if diel activity could be attributed to variation in rainfall, barometric pressure, temperature, and/or relative air humidity. Contrary to our prediction, migratory activity in M. cambaraensis is strongly diurnal. Although temperature and humidity varied significantly between day and night intervals, this variation does not account for the diurnal-only migratory activity of M. cambaraensis. We suggest that the diurnal-only migratory activity of M. cambaraensis is best explained by phylogeny, not contemporary functions or selective pressures. Diurnal activity is primitive for this species and evolved in the common ancestor of Agastorophrynia, prior to the chemical defenses found in toads (Bufonidae) and poison frogs (Dendrobatidae). This suggests that chemical defenses in these groups may have evolved as a result of the diurnal activity that brought them into contact with visually oriented diurnal predators, and not the other way around.     

Behavioural thermoregulation of the Andean toad (Bufo spinulosus) at high altitudes

Summary The body temperature of free-ranging Andean toadsBufo spinulosus was measured either directly or radiotelemetrically during two 15-day periods at 3200 m elevation in the Mantaro Valley, Central Perú. All toads attempted to maintain their diurnal sum of body temperature within a narrow range. Consequently thermoregulatory behaviour differed according to cloud cover and precipitation. If the sky was clear, toads emerged from their hiding place and exposed themselves to solar radiation during 3–5 h in the morning. Core temperature increased up to 15° C above the air temperature in shade and reached maximum values of about 32° C. At air temperatures (in sun) exceeding 29° C, toads maintained body temperatures below 32° C by evaporative cooling. Following heliothermic heating during the moring toads retreated to the shade, thereby decreasing body temperature below air temperature. Under overcast sky toads remained exposed during the whole day displaying body temperatures at or slightly above ambient levels. Quantitative models to predict the core temperature of toads under the different weather conditions demonstrated that the substrate temperature was the main energy source accounting for 64.6–77.9% of total variance whereas air temperature was of minor importance (1.5–4.4%). The unexplained variance was probably due to evaporative cooling. The volume of urine stored into the urinary bladder of toads varied diurnally; during basking in the morning hours most bladders contained large volumes of urine, whereas during the afternoon the bladders were mostly empty. The bladder contents probably serve as water reserves during basking when evaporative water loss was high. Toads preferred sites that provided shady hiding places as well as sun-exposed bare soil within a radius of 5 m. However, they frequently changed their centers of activity and moved to other sites in 20–70 m distance after periods of 2–5 days. The helio-and thigmothermic behaviour of the Andean toad permits the maintenance of high core temperature during morning which probably increases the digestion rate and accelerate growth. Evaporative cooling and preference of shady sites were employed to regulate body temperature below the morning levels in response to the constraints of water balance. Periodic changes between thigmothermic behaviour and locomotory activity during the night maintains body temperature above air temperature and prolongs the period of food uptake.Dedicated to Prof. Dr. H. Schneider on the occasion of his sixtieth birthday     

Does migration promote or restrict circumpolar breeding ranges of arctic birds?

Aim Migration has been suggested to promote large breeding ranges among birds because of the greater mobility of migratory compared with non‐migratory species, but migration has also been suggested to restrict breeding ranges because of evolutionary constraints imposed by the genetically based migration control programme. We aim to investigate the association between migration and the breeding ranges of both land birds and pelagic birds breeding in the Arctic region. Location The Arctic region. Methods Information on breeding and wintering ranges and migratory status of bird species breeding in the arctic tundra biome was compiled from the literature. The association between breeding range, migration distance and primary winter habitat was tested using multivariate generalized linear models and pair‐wise Mann–Whitney U‐tests. Phylogenetic effects were tested for using Mantel’s permutation tests. Results We found different relationships depending on the species’ major winter habitat. Among birds that are pelagic during winter, long‐distance migrants have the largest breeding ranges, while among terrestrial birds, residents and short‐distance migrants have the largest breeding ranges. Breeding ranges of coastal birds of all migratory distance classes are comparatively restricted. Main conclusions As a new explanation for this pattern we suggest that the possibility of colonizing large winter ranges is a key factor for the subsequent expansion of breeding ranges in arctic bird communities and possibly also in bird communities of other regions of the world. Because of the reversal in the relative extent of continents and oceans between the hemispheres, longitudinally wide winter ranges are more likely for long‐distance than short‐distance migrants among pelagic birds, while the reverse holds true for birds that use terrestrial winter habitats. For coastal birds both continents and oceans form barriers restricting colonization of extensive winter quarters and consequently also of extensive breeding ranges, regardless of the distance to the winter quarters.     

The winter migration of Adelie penguins breeding in the Ross Sea sector of Antarctica

Satellite telemetry was used to monitor the migratory movements of a single Adelie penguin (Pygoscelis adeliae) from Cape Hallett (72.31°S, 170.21°E) following the 1997/1998 breeding season. Locations were obtained using the ARGOS satellite system and compared with the migratory paths taken by two penguins from the Northern Colony at Cape Bird, Ross Island (77.22°S, 166.48°E) following the 1990/1991 breeding season. Although the sample sizes are small, if representative they would indicate that: (1) Adelie penguins breeding in the Ross Sea follow a common migratory path, (2) Adelie penguins breeding in the Ross Sea may travel to a common over-winter feeding ground west and north of the Balleny Islands, and (3) Adelie penguins breeding at 77°S on Ross Island travel nearly twice the distance during their over-winter migration as do those penguins breeding at Cape Hallett and colonies further north. While the Cape Hallett penguin was tracked successfully for 172 days, a record for Adelie penguins, the problem of long-term attachment of transmitters to penguins remains.     

An expert-based landscape permeability model for assessing the impact of agricultural management on amphibian migration

The persistence of pond-breeding amphibian populations is influenced on different spatial scales ranging from the individual breeding pond to surrounding habitat patches to landscape clusters of breeding pond populations. The connectivity among breeding ponds as well as the availability of suitable terrestrial habitats surrounding the ponds plays a major role in long-term viability of amphibian species. Besides road traffic and urban structures agricultural land activity can disrupt landscape connectivity through the use of pesticides, fertilizers and physical activity such as tillage. We developed an expert-based model to assess the impact of agricultural management measures on the migration area and terrestrial habitat availability for seven amphibian species. The model is based on a Habitat Suitability Index to identify suitable terrestrial habitats and includes a landscape permeability approach. Size of migration areas, connectivity of breeding ponds and number of reachable terrestrial habitats were modeled considering species-specific migration ranges and habitat preferences. We consider how pesticides application might lead to fragmentation and isolation of amphibian breeding pond populations. Therefore the potential disrupting impact of pesticides was simulated by inflating landscape resistance to medium and high migration cost. One amphibian species showed a decrease of migration area by 48.3% and a decrease of reachable terrestrial habitats by 41.5% at high migration costs. Three additional species showed a decrease of their migration areas between 31.5 and 35.7%. At increased migration cost, some of the investigated populations were isolated at breeding pond level or restricted to pond clusters. Our model could be used to prioritize conservation efforts for pond-breeding amphibians with adequate consideration of agricultural land use and its impact on amphibian migration.     

A long winter for the Red Queen: rethinking the evolution of seasonal migration

This paper advances an hypothesis that the primary adaptive driver of seasonal migration is maintenance of site fidelity to familiar breeding locations. We argue that seasonal migration is therefore principally an adaptation for geographic persistence when confronted with seasonality – analogous to hibernation, freeze tolerance, or other organismal adaptations to cyclically fluctuating environments. These ideas stand in contrast to traditional views that bird migration evolved as an adaptive dispersal strategy for exploiting new breeding areas and avoiding competitors. Our synthesis is supported by a large body of research on avian breeding biology that demonstrates the reproductive benefits of breeding‐site fidelity. Conceptualizing migration as an adaptation for persistence places new emphasis on understanding the evolutionary trade‐offs between migratory behaviour and other adaptations to fluctuating environments both within and across species. Seasonality‐induced departures from breeding areas, coupled with the reproductive benefits of maintaining breeding‐site fidelity, also provide a mechanism for explaining the evolution of migration that is agnostic to the geographic origin of migratory lineages (i.e. temperate or tropical). Thus, our framework reconciles much of the conflict in previous research on the historical biogeography of migratory species. Although migratory behaviour and geographic range change fluidly and rapidly in many populations, we argue that the loss of plasticity for migration via canalization is an overlooked aspect of the evolutionary dynamics of migration and helps explain the idiosyncratic distributions and migratory routes of long‐distance migrants. Our synthesis, which revolves around the insight that migratory organisms travel long distances simply to stay in the same place, provides a necessary evolutionary context for understanding historical biogeographic patterns in migratory lineages as well as the ecological dynamics of migratory connectivity between breeding and non‐breeding locations.     

Patterns of parasitism in monarch butterflies during the breeding season in eastern North America

1. Migratory behaviour can result in reduced prevalence of pathogens in host populations. Two hypotheses have been proposed to explain this relationship: (i) ‘migratory escape’, where migrants benefit from escaping pathogen accumulation in contaminated environments; and (ii) ‘migratory culling’, where the selective removal of infected individuals occurs during migration. 2. In the host–parasite system between the monarch butterfly (Danaus plexippus Linn.) and its obligate protozoan parasite Ophryocystis elektroscirrha (OE), there is evidence to support both hypotheses, particularly during the monarchs' autumn migration. However, these processes can operate simultaneously and could vary throughout the monarchs' annual migratory cycle. Assessing the relative strength for each hypothesis has not previously been done. 3. To evaluate both hypotheses, parasite infection prevalence was examined in monarchs sampled in eastern North America during April–September, and stable isotopes (δ²H, δ¹³C) were used to estimate natal origin and infer migration distance. There was stronger support for the migratory escape hypothesis, wherein infection prevalence increased over the breeding season and was higher at southern latitudes, where the breeding season tends to be longer compared with northern latitudes. Little support was found for the migratory culling hypothesis, as infection prevalence was similar whether monarchs travelled shorter or longer distances. 4. These results suggest that migration allows individuals to escape parasites not only during the autumn, as shown in previous work, but during the monarchs' spring and summer movements when they recolonise the breeding range. These results imply a potential fitness advantage to monarchs that migrate further north to exploit parasite‐free habitats.     

Interspecific spawning between Common frogs (Rana temporaria) and Common toads (Bufo bufo)

The interaction between Common frogs (Rana temporaria) and Common toads (Bufo bufo) during the breeding season was studied at a small pond on Portland, Dorset. Although the frogs started and finished spawning earlier than the toads there was a period during which interspecific spawning between female toads and male frogs took place. This appears to have resulted from reduced male toad activity caused by the cold breeding season given that spatial, temporal and behavioural species separation did not occur.     

Photoperiodically regulated cycle of locomotory activity and fat reserves during migration seasons in the irruptive bird species,the long‐tailed tit Aegithalos c. caudatus

In northern Europe the long‐tailed tit Aegithalos c. caudatus shows irregular outbreaks of migrating individuals in autumn. Therefore, this species is generally believed to be irruptive, moving in response to external environmental stimuli such as food limitation or overpopulation in the breeding area. We studied the locomotory activity of 24 young captive long‐tailed tits from August up to early May of the following year. All hand raised birds from the local population of Lake Ladoga region (NW Russia) exhibited a distinct seasonal pattern in their locomotory activity similar to birds trapped on migration. They showed a rise in activity both in autumn and spring period. Fat reserves did not peak in autumn but increased along with spring activity. The timing of increase in the locomotory activity and fat reserves, as well as daily pattern and maximum level of activity in autumn depended on photoperiod. Long‐tailed tits kept on the photoperiod, simulating late hatching, started to migrate at an earlier age and showed a significantly higher level of activity in autumn compared to their siblings kept on the photoperiod simulating early hatching. The present findings suggested that in the studied species there is an annual cycle of migratory restlessness that is exhibited in captivity and is influenced by photoperiod.     

Migration and wintering strategies in vulnerable Mediterranean Osprey populations

A broad range of migration strategies exist in avian species, and different strategies can occur in different populations of the same species. For the breeding Osprey Pandion haliaetus populations of the Mediterranean, sporadic observations of ringed birds collected in the past suggested variations in migratory and wintering behaviour. We used GPS tracking data from 41 individuals from Corsica, the Balearic Islands and continental Italy to perform the first detailed analysis of the migratory and wintering strategies of these Osprey populations. Ospreys showed heterogeneous migratory behaviour, with 73% of the individuals migrating and the remaining 27% staying all year round at breeding sites. For migratory individuals, an extremely short duration of migration (5.2 ± 2.6 days) was recorded. Mediterranean Ospreys were able to perform long non‐stop flights over the open sea, sometimes overnight. They also performed pre‐ and post‐migratory trips to secondary sites, before or after crossing the sea during both autumn and spring migration. Ospreys spent the winter at temperate latitudes and showed high plasticity in habitat selection, using marine bays, coastal lagoons/marshland and inland freshwater sites along the coasts of different countries of the Mediterranean basin. Movements and home‐range areas were restricted during the wintering season. The short duration of trips and high levels of variability in migratory routes and wintering grounds revealed high behavioural plasticity among individuals, probably promoted by the relatively low seasonal variability in ecological conditions throughout the year in the Mediterranean region, and weak competition for non‐breeding sites. We stress the importance of considering the diversity in migration strategies and the particular ecology of these vulnerable populations, especially in relation to proactive management measures for the species at the scale of the Mediterranean region.     

Autumn migration and wintering areas of Peregrine Falcons Falco peregrinus nesting on the Kola Peninsula, northern Russia

Four female Peregrine Falcons Falco peregrinus breeding on the Kola Peninsula, Russia, were fitted with satellite-received transmitters in 1994. Their breeding home ranges averaged 1175 (sd = ±714) km², and overlapped considerably. All left their breeding grounds in September and migrated generally south-west along the Baltic Sea. The mean travel rate for three falcons was 190 km/day. Two Falcons wintered on the coasts of France and in southern Spain, which were, respectively, 2909 and 4262 km from their breeding sites. Data on migration routes suggested that Falcons took a near-direct route to the wintering areas. No prolonged stopovers were apparent. The 90% minimum convex polygon winter range of a bird that migrated to Spain encompassed 213 km² ( n  = 54). The area of the 50% minimum convex polygon was 21.5 km² ( n  = 29). Data from this study agree with others from North America that show that Falcons breeding in a single area do not necessarily follow the same migratory path southward and do not necessarily use the same wintering grounds.     

Migratory diversity predicts population declines in birds

Declines in migratory species are a pressing concern worldwide, but the mechanisms underpinning these declines are not fully understood. We hypothesised that species with greater within‐population variability in migratory movements and destinations, here termed ‘migratory diversity’, might be more resilient to environmental change. To test this, we related map‐based metrics of migratory diversity to recent population trends for 340 European breeding birds. Species that occupy larger non‐breeding ranges relative to breeding, a characteristic we term ‘migratory dispersion’, were less likely to be declining than those with more restricted non‐breeding ranges. Species with partial migration strategies (i.e. overlapping breeding and non‐breeding ranges) were also less likely to be declining than full migrants or full residents, an effect that was independent of migration distance. Recent rates of advancement in Europe‐wide spring arrival date were greater for partial migrants than full migrants, suggesting that migratory diversity may also help facilitate species responses to climate change.