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1.
The experiment involved two stages: the first one consisted of studying the dynamics of long-distance movements and the characteristics
of moving individuals in a free-living population of bank voles and the second one — of an analysis of paternity of young
individuals born to females representing specific breeding colonies (basing on an analysis of six microsatellite fragments).
The study has shown that both male and female bank voles are capable of covering long distances of up to almost 1 km. Males
moved significantly more frequently than females. The proportion of travelling males was the highest in spring and the lowest
in autumn. Almost all moving males were adult and they were sexually active. Almost all moving females were adult, however,
the majority of them were sexually inactive. This indicates that the character and causes of long-distance movements of females
and males differ. Female movements are supposed to be related to the search for living and breeding grounds by young, already
adult individuals, driven out from their mothers’ territory. Multiple paternity occurred in 25% of all litters analysed. Young
whose fathers were males from outside of their mother’s breeding colonies occurred in litters throughout the whole breeding
season. They made up 59% of all young analysed and in the spring (June) all the young animals were born to fathers originating
outside of the female’s breeding colony. The results obtained may confirm the hypothesis that long-distance movements of male
bank voles constitute a part of their breeding strategy, involving them in searching for breeding partners over an extensive
area. 相似文献
2.
Barbara Wienecke 《Polar Biology》2011,34(2):153-167
In 1902, the first breeding colony of emperor penguins was discovered. Over the following decades, the number of known emperor
penguin colonies increased steadily and new ones are still being discovered. However, rigorous census work has been carried
out at only a few colonies and accurate information on trends in breeding populations is limited to a small number of locations.
Thus, the total number of breeding pairs is still unknown as is the size of the global population (breeders, non-breeders,
juveniles). The International Union for the Conservation of Nature (IUCN) lists the species’ status as ‘least concern’ and
states that although the population trend for emperor penguins has not been quantified, the global population appears to be
stable. This review summarises the currently available information on the populations of emperor penguins at known colonies
in terms of survey methods, count units used and survey frequency. It examines what is known about the state of various colonies
and demonstrates that currently available data are inadequate for a trend assessment of the global population. 相似文献
3.
Almenar David Aihartza Joxerra Goiti Urtzi Salsamendi Egoitz Garin Inazio 《European Journal of Wildlife Research》2011,57(4):929-937
Spatial dynamics of foraging long-fingered bats (Myotis capaccinii) were studied in the Eastern Iberian Peninsula. We analysed the locations of 45 radio-tracked individuals during three discrete
periods through the breeding season and measured the spatial parameters related to their foraging behaviour in order to test
whether variations in spatial use occur. Colony range, measured as the minimum convex polygon through all the radiolocations,
was 345 km2, but the area used during each period was smaller. During pre-breeding, foraging bats gathered at two stretches of different
tributary rivers; during lactation, they scattered throughout the river system; and during weaning, they aggregated at a stretch
of the main river. Individuals on average flew 5.7 km from roosts to foraging areas, with a maximum absolute distance of 22.7 km.
Individual foraging ranges were measured linearly, because the bats foraged mostly along rivers; their values averaged 1.3 km/night
and overlapped extensively between neighbouring bats (>65% on average). The sampling period, rather than the bats’ reproductive
status, age, or sex, explained the observed variability in spatial distribution and size of hunting sites. We did not find
differences in spatial parameters between lactating females and non-lactating bats, nor between juveniles and adults. This
is the first study to split the independent effects of season and population class in order to enable unconfounded interpretations
of the spatial dynamics of foraging reproductive females and juveniles. We speculate that the relationship between colony
size and prey availability ruled the observed changes in foraging area through seasons. The considerable overlap in individual
foraging ranges may be a necessary adaption to large colonies forced by the specific roost requirements of the long-fingered
bat and the narrow foraging niche they appear to occupy. 相似文献
4.
Investigating the effects of age‐related spatial structuring on the transmission of a tick‐borne virus in a colonially breeding host
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Klara M. Wanelik Sarah J. Burthe Mike P. Harris Miles A. Nunn H. Charles J. Godfray Ben C. Sheldon Angela R. McLean Sarah Wanless 《Ecology and evolution》2017,7(24):10930-10940
Higher pathogen and parasite transmission is considered a universal cost of colonial breeding due to the physical proximity of colony members. However, this has rarely been tested in natural colonies, which are structured entities, whose members interact with a subset of individuals and differ in their infection histories. We use a population of common guillemots, Uria aalge, infected by a tick‐borne virus, Great Island virus, to explore how age‐related spatial structuring can influence the infection costs borne by different members of a breeding colony. Previous work has shown that the per‐susceptible risk of infection (force of infection) is different for prebreeding (immature) and breeding (adult) guillemots which occupy different areas of the colony. We developed a mathematical model which showed that this difference in infection risk can only be maintained if mixing between these age groups is low. To estimate mixing between age groups, we recorded the movements of 63 individually recognizable, prebreeding guillemots in four different parts of a major colony in the North Sea during the breeding season. Prebreeding guillemots infrequently entered breeding areas (in only 26% of watches), though with marked differences in frequency of entry among individuals and more entries toward the end of the breeding season. Once entered, the proportion of time spent in breeding areas by prebreeding guillemots also varied between different parts of the colony. Our data and model predictions indicate low levels of age‐group mixing, limiting exposure of breeding guillemots to infection. However, they also suggest that prebreeding guillemots have the potential to play an important role in driving infection dynamics. This highlights the sensitivity of breeding colonies to changes in the behavior of their members—a subject of particular importance in the context of global environmental change. 相似文献
5.
Knowledge of the rate, distance and direction of dispersal within and among breeding areas is required to understand and predict demographic and genetic connectivity and resulting population and evolutionary dynamics. However dispersal rates, and the full distributions of dispersal distances and directions, are rarely comprehensively estimated across all spatial scales relevant to wild populations. We used re‐sightings of European Shags Phalacrocorax aristotelis colour‐ringed as chicks on the Isle of May (IoM), UK, to quantify rates, distances and directions of dispersal from natal to subsequent breeding sites both within IoM (within‐colony dispersal) and across 27 other breeding colonies covering 1045 km of coastline (among‐colony dispersal). Additionally, we used non‐breeding season surveys covering 895 km of coastline to estimate breeding season detection probability and hence potential bias in estimated dispersal parameters. Within IoM, 99.6% of individuals dispersed between their natal and observed breeding nest‐site. The distribution of within‐colony dispersal distances was right‐skewed; mean distance was shorter than expected given random settlement within IoM, yet some individuals dispersed long distances within the colony. The distribution of within‐colony dispersal directions was non‐uniform but did not differ from expectation given the spatial arrangement of nest‐sites. However, 10% of all 460 colour‐ringed adults that were located breeding had dispersed to a different colony. The maximum observed dispersal distance (170 km) was much smaller than the maximum distance surveyed (690 km). The distribution of among‐colony dispersal distances was again right‐skewed. Among‐colony dispersal was directional, and differed from random expectation and from the distribution of within‐colony dispersal directions. Non‐breeding season surveys suggested that the probability of detecting a colour‐ringed adult at its breeding location was high in the northeastern UK (98%). Estimated dispersal rates and distributions were therefore robust to incomplete detection. Overall, these data demonstrate skewed and directionally divergent dispersal distributions across small (within‐colony) and large (among‐colony) scales, indicating that dispersal could create genetic and demographic connectivity within the study area. 相似文献
6.
The ‘benefits of philopatry’ hypothesis states that helpers in cooperatively breeding species derive higher benefits from
remaining home, instead of dispersing and attempting to breed independently. We tested experimentally whether dispersal options
influence dispersal propensity in the cooperatively breeding Lake Tanganyika cichlids Neolamprologus pulcher and N. savoryi. Cooperative groups of these fishes breed in densely packed colonies, surrounded by unoccupied, but apparently suitable breeding
habitat. Breeding inside colonies and living in groups seems to benefit individuals, for example by early detection and deterrence
of predators. We show that despite a slight preference of both species for habitat with a higher stone cover, 40% of the preferred
habitat remained unoccupied. On average, the colonies contained a higher number of (1) predators of adults, juveniles and
eggs, (2) shelter competitors, and (3) other species including potential food competitors, compared to the outside colony
habitat. Apparently, habitat differences cannot explain why these cichlids breed in colonies. Accordingly, dispersal may not
be limited by a lack of suitable breeding shelters, but by the relatively higher risk of establishing an outside- compared
to a within-colony breeding territory. To test whether cichlids prefer within- to outside-colony breeding territories, we
provided breeding shelters inside the colony and at the colony edge and studied helper dispersal. As expected, significantly
more shelters were occupied within the colony compared to the edge. New breeding pairs with several helpers occupied these
shelters. We conclude that although breeding habitat is plentiful outside the colonies, helpers delay dispersal to obtain
a higher quality breeding position within the group or colony eventually, or they disperse in groups. Our results suggest
that (1) group augmentation and Allee effects are generally important for dispersal decisions in cooperatively breeding cichlids,
consistent with the ‘benefits of philopatry hypothesis’, and (2) habitat saturation cannot fully explain delayed dispersal
in these species. 相似文献
7.
Evan C. Fricke Katherine M. Blizzard Damon P. Gannon Robert A. Mauck 《Journal of Field Ornithology》2015,86(4):326-336
Patterns of nest site selection exhibited at the scale of a population should result from initial preferences of individuals occupying nest sites as well as preferences exhibited by individuals moving between nest sites. We tested whether nest‐site preferences measured at the population scale were predictive of patterns of burrow switching by Leach's Storm‐Petrels (Oceanodroma leucorhoa), a long‐lived seabird that nests in underground burrows. Breeding pairs generally choose from the pool of available existing burrows rather than constructing new burrows, and a portion of the burrows in a colony remains unused in any breeding season. We quantified burrow preference at a colony on Kent Island, New Brunswick, over four breeding seasons. We used a classification and regression tree analysis to build a predictive model of nest‐site selection. Preferentially occupied burrows were drier, longer, had larger nest chambers, and were in areas of higher burrow density. To measure preferences during burrow switching, we tracked individuals that switched burrows, comparing characteristics of the burrows in which these birds were originally found to those they inhabited at the end of the study period. Characteristics preferred by switching individuals were a subset of those observed at the scale of the population; individuals moved to burrows that were drier, longer, and had larger nest chambers. Our results show how preferences of individuals that move between nest sites contribute to nest site preferences exhibited at the population scales commonly tested. 相似文献
8.
Influence of density‐dependent competition on foraging and migratory behavior of a subtropical colonial seabird
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Density‐dependent competition for food resources influences both foraging ecology and reproduction in a variety of animals. The relationship between colony size, local prey depletion, and reproductive output in colonial central‐place foragers has been extensively studied in seabirds; however, most studies have focused on effects of intraspecific competition during the breeding season, while little is known about whether density‐dependent resource depletion influences individual migratory behavior outside the breeding season. Using breeding colony size as a surrogate for intraspecific resource competition, we tested for effects of colony size on breeding home range, nestling health, and migratory patterns of a nearshore colonial seabird, the brown pelican (Pelecanus occidentalis), originating from seven breeding colonies of varying sizes in the subtropical northern Gulf of Mexico. We found evidence for density‐dependent effects on foraging behavior during the breeding season, as individual foraging areas increased linearly with the number of breeding pairs per colony. Contrary to our predictions, however, nestlings from more numerous colonies with larger foraging ranges did not experience either decreased condition or increased stress. During nonbreeding, individuals from larger colonies were more likely to migrate, and traveled longer distances, than individuals from smaller colonies, indicating that the influence of density‐dependent effects on distribution persists into the nonbreeding period. We also found significant effects of individual physical condition, particularly body size, on migratory behavior, which in combination with colony size suggesting that dominant individuals remain closer to breeding sites during winter. We conclude that density‐dependent competition may be an important driver of both the extent of foraging ranges and the degree of migration exhibited by brown pelicans. However, the effects of density‐dependent competition on breeding success and population regulation remain uncertain in this system. 相似文献
9.
Seasonal forcing on the dynamics ofClethrionomys rufocanus: Modeling geographic gradients in population dynamics 总被引:7,自引:7,他引:0
We interpret gradients in population dynamics of the gray-sided vole from the southwestern part of the island of Hokkaido
to its northeastern part within the framework of a phenomenological model involving the relative length of summer and winter.
In Hokkaido, as in other northern regions, both spring and fall is considered as short transition periods between the two
main seasons — summer (the primary breeding season) and winter (the non-reproductive or secondary breeding season). We show
that the geographic transition in dynamics may be understood as the combined consequence of different patterns of density-dependence
during summer and winter, and geographically varying season lengths. Differences are shown to exist between summer and winter
with respect to strength of density-dependence. Direct density-dependence, in particular, is stronger during winter than during
summer. A model is presented to show how relative lengths of seasons can induce both stable and periodically fluctuating population
dynamics. The results are compared and contrasted with what is otherwise known about the gradient in rodent dynamics in Fennoscandia. 相似文献
10.
Tobias Dittmann 《Animal behaviour》2003,65(5):981-986
Several studies have shown that seabird colonies consist to a large extent of young nonbreeders (prospectors). These individuals appear at the colony later in the season than established breeders. The reasons for this late arrival have remained unclear in most cases, mainly because of technical difficulties in collecting sufficient data from nonbreeding individuals. We used a novel transponder system to identify remotely the members of a common tern colony, including nonbreeders, during eight breeding seasons and we combined the system with automatic balances. Ninety-two per cent of prospectors returned for the first time when 2 years old and 88.9% of recruits to the breeding population had spent at least one previous season at the colony as prospectors. In both sexes, most individuals prospected for one season, but more males than females prospected for more than one season, although a higher proportion of females started breeding without a previous prospecting phase. Terns arrived earlier in the season the older they were and the more experience of the colony they had, but experience proved to be more important than age. Prospectors gained about 3 weeks with a previous prospecting season whereas an additional year of age allowed birds to arrive only about 6 days earlier. Prospectors returning later in the season arrived with lower body masses. Males on average arrived earlier at the colony than females. Copyright 2003 Published by Elsevier Science Ltd on behalf of The Association for the Study of Animal Behaviour. 相似文献
11.
JULIA KARAGICHEVA ELDAR RAKHIMBERDIEV DMITRY DOBRYNIN ANATOLY SAVELIEV SOFIA ROZENFELD OLGA POKROVSKAYA JULIA STAHL JOUKE PROP KONSTANTIN LITVIN 《Ibis》2011,153(3):622-626
Avian breeding colonies are generally in a continuous state of flux, some parts growing whilst others shrink as individuals move within the colony on the search for better nest‐sites. We examined the role of experience in breeding patch choice by individually marked Barnacle Geese Branta leucopsis in a recently established colony in sub‐arctic Russia. Individuals failing to reproduce successfully tended to shift nest location further the following season than did successful pairs, and they did so towards the most dense nest aggregations within the colony, where reproductive success was higher. We suggest that individual decisions on nest‐site choice shape the spatial dynamics of this colony. 相似文献
12.
Here, we study how scaling up to the metapopulation level affects predictions of a population dynamics model motivated by an aphidophagous predator–aphid system. The model incorporates optimization of egg distribution in predatory females, cannibalism among their offspring, and self-regulation of the prey population. These factors determine the within-year dynamics of the system and translate the numbers of prey and predator individuals at the beginning of the season into their numbers at the end of the season at the level of one patch—one suitable host plant or a group of these. At the end of each season, all populations of prey and all populations of predators are mixed (this simulates aphid host-alternation and ladybird migration to hibernation sites), and then redistributed at the beginning of the next season. Prey individuals are distributed at random among the patches as a “prey rain”, while adult predators that survived from the previous season optimize the distribution of their offspring, in that they prefer patches with sufficient amount of prey and absence of other predators. This redistribution followed by within-season dynamics is then iterated over many seasons. We look at whether small-scale trends in population dynamics predicted by this model are consistent with large-scale outcomes. Specifically, we show that even on the metapopulation scale, the impact of predators on prey metapopulation is relatively low. We further show how the dates of predator arrival to and departure from the system affect the qualitative behaviour of the model predictions. 相似文献
13.
The population dynamics of the Tatra vole Microtus tatricus (Kratochvíl, 1952) (Arvicolinae, Rodentia) was monitored as part of a long-term study (1996–2008) of demography of small
mammals conducted in Western Tatra Mountains—Roháče, Slovakia. We observed low abundance and population densities and a balanced
sex ratio but slightly more frequent captures of females. Reproductively active Tatra voles were significantly larger and
heavier than reproductively inactive voles. Reproduction in both sexes tended to begin in early spring, and females moved
less than males. Individuals start to reproduce after overwintering. Spatial characteristics differed between sexes, with
home range size, distance travelled, and observed range length being non-significantly greater in males than in females, suggesting
greater male mobility. Females remained longer on the site than did males. Mature individuals of both sexes exhibited territoriality
during the peak of breeding season in spring. Home range overlap occurred more often within females, and mainly in summer
and autumn. 相似文献
14.
Lo?c Lesobre Frédéric Lacroix Alain Caizergues Yves Hingrat Toni Chalah Michel Saint Jalme 《Conservation Genetics》2010,11(4):1489-1497
The major decline of Houbara Bustards—sensu lato—throughout their range has led to their classification as ‘vulnerable’ on
the IUCN Red List. Within this context, a captive breeding program was established in Morocco to restock North African wild
populations of Houbara Bustard (Chlamydotis undulata undulata). At present, founders originate from locations that are currently being reinforced through the addition of captive bred
individuals. However, it is planned to restock others areas of the species’ range. Before this could be considered, an accurate
knowledge of the genetic structure of the wild recipient population is essential to delineate potential conservation units.
We therefore sampled populations throughout most of the remaining range, and used several methods to evaluate their genetic
differentiation by means of both mtDNA and microsatellite markers. Very little genetic differentiation was found for both
genetic markers (Φst ranged from −0.181 to 0.118 and F
st ranged from −0.004 to 0.019). This suggests that C. u.
undulata populations could be managed as a single Conservation Unit. 相似文献
15.
It is very difficult to find natural colonies of bumble bees in the field. In this study, the yearly dynamics of floral resources and foraging bumble bee workers were investigated. The optimal colony locations were estimated from the data using moving average on the assumption that bumble bee queens and workers were omniscient. Fortunately, a colony of Bombus ardens was found, and the true location of the colony was evaluated with the estimated optimal locations. The true location was optimal at the latter half of the breeding season.An erratum to this article can be found at 相似文献
16.
Food availability and nest predation influence life history traits in Audouin's gull, Larus audouinii 总被引:2,自引:0,他引:2
The effects of food availability and nest predation on several life history traits such as adult survival, dispersal, and
reproductive performance were assessed in an Audouin's gull (Larus audouinii) colony during the period 1992–1997. The amounts of fish discarded from trawlers were used as a measure of food availability,
and a trawling moratorium which partially overlapped with the breeding season of the gulls was taken into account. The effects
of nest predation were assessed in 1994, when a terrestrial predator entered the colony and remained for the whole breeding
season preying on both eggs and chicks. Using the moratorium and the predatory event as natural experiments, several hypotheses
were tested: (a) food supply would affect breeding performance but not adult survival (independently of age and sex), since
gulls are long-lived and adult survival is the most sensitive demographic parameter in their population dynamics; (b) the
predator would trigger breeding dispersal (although gulls are mostly philopatric, they are known to abandon their natal colony
after breeding failure instigated by events such as this). If breeding dispersal occurs, the rate is expected to be higher
in females than in males, and higher in new breeders than in more experienced breeding birds, as is usually recorded in colonial
seabirds. Probabilities of resighting and survival were estimated separately, using capture-recapture models. As expected,
changes in food availability did not affect adult survival, whereas they influenced egg volume, clutch size, and breeding
success. Local adult survival was estimated to be 0.908 (SD = 0.007) for males and females, and it did not change significantly
with the age of individuals (range 3–8 years). The predator significantly decreased breeding success, and caused the dispersal
of a number of adults probably to breed in another colony; this rate was estimated at an average of 0.10 (SD = 0.02). As expected,
inexperienced breeders dispersed significantly more (14%) than more experienced breeders (8%) after the predator event, but
dispersal was not sex biased. Recapture probabilities after the predator event suggest that birds that left the colony still
had not returned. Results confirm that population dynamics of ground-nesting seabirds are sensitive to terrestrial predation,
even when predation caused only a partial breeding failure.
Received: 16 July 1998 / Accepted: 16 November 1998 相似文献
17.
Gerald Kastberger Ronald Thenius Anton Stabentheiner Randall Hepburn 《Journal of Insect Behavior》2009,22(1):65-85
Colony defence in Apis mellifera involves a variety of traits ranging from ‘aggressive’ (e.g. entrance guarding, recruitment
of flying guards) to ‘docile’ (e.g. retreating into the nest) expression. We tested 11 colonies of three subspecies (capensis, scutellata, carnica) regarding their defensiveness. Each colony was selected as reportedly ‘aggressive’, ‘intermediate’ or ‘docile’ and consisted
of about 10,000 bees. We applied three stimulation regimes (mechanical disturbance, exposure to alarm pheromones, and the
combination of both) and measured their behaviours by tracking the rates of outflying bees at the entrance sites of the test
hives. We provided evidence that for mechanical disturbances the test colonies resolved into two response types, if the ‘immediate’
defence response, assessed in the first minute of stimulation, was taken as a function of foraging: ‘releaser’ colonies allocated flying guards, ‘retreater’ colonies reduced the outside-hive activities. This division was observed irrespective
of the subspecies membership and maintained in even roughly changing environmental conditions. However, if pheromone and mechanical
stimulation were combined, the variety of colony defensiveness restricted to two further types irrespective of the subspecies
membership: six of nine colonies degraded their rate of flying defenders with increasing foraging level, three of the colonies
extended their ‘aggressiveness’ by increasing the defender rate with the foraging level. Such ‘super-aggressive’ colonies
obviously are able to allocate two separate recruitment pools for foragers and flying defenders. 相似文献
18.
A. G. Degtyarev 《Contemporary Problems of Ecology》2010,3(1):90-99
In 1982—1995 and 2007 the Bewick’s swan was monitored. The air record routes were 48 000 km long. An increase in population,
widening of the range in the north and west directions are recorded. The data on dynamics of population, territorial location,
social structure, and breeding parameters are given. The ecological problems related to the increase in the swan population
are discussed. 相似文献
19.
Dispersal and recruitment during population growth in a colonial bird, the great cormorant Phalacrocorax carbo sinensis 总被引:1,自引:0,他引:1
While the factors influencing reproduction and survival in colonial populations are relatively well studied, factors involved in dispersal and settlement decisions are not well understood. The present study investigated exchanges of great cormorants Phalacrocorax carbo sinensis among six breeding colonies over a 13‐year period when the breeding population in Denmark increased from 2800 to 36 400 nests. We used a multistate capture‐recapture model that combined multisite resightings and recoveries to examine simultaneously recruitment, natal dispersal, breeding dispersal and annual survival of first‐year, immature and breeding great cormorants. Mean survival of first‐year birds (0.50±0.09, range=0.42–0.66 among colonies) was lower than survival of breeders (0.90±0.06, range=0.81–0.97). Mean survival of immature birds over the study period was 0.87±0.08. Dispersal from a colony increased with decreasing mean brood size in the colony in both first‐time and experienced breeders. The choice of the settlement colony in first‐time breeders was affected by conditions in the natal colony and in the colonies prospected during the pre‐breeding years. In particular, first‐time breeders recruited to colonies where they could expect better breeding success. Experienced breeders relied mainly on cues present early in the season and on their own breeding experience to choose a new breeding colony. Newly established colonies resulted mainly from the immigration of first‐time breeders originating from denser colonies. Dispersal was distance‐dependent and first‐time breeders dispersed longer distances than breeders. We suggest that the prospecting behaviour allows first‐time breeders to recruit in nearby as well as more distant potential breeding colonies. Dispersing breeders preferred to settle in neighbouring colonies likely to benefit from their experience with foraging areas. We discuss the importance of these movements for growth and expansion of the breeding population. 相似文献
20.
We examined how large seasonal influxes of migratory prey influenced population dynamics of arctic foxes and how this varied
with fluctuations in small mammal (lemming and vole) abundance—the main prey of arctic foxes throughout most of their range.
Specifically, we compared how arctic fox abundance, breeding density and litter size varied inside and outside a large goose
colony and in relation to annual variation in small mammal abundance. Information-theoretic model selection showed that (1)
breeding density and fox abundance were 2–3 times higher inside the colony than they were outside the colony and (2) litter
size, breeding density and annual variation in fox abundance in the colony tracked fluctuations in lemming abundance. The
influence of lemming abundance on reproduction and abundance of arctic foxes outside the colony was inconclusive, largely
because fox densities outside the colony were low, which made it difficult to detect such relationships. Lemming abundance
was, thus, the main factor governing reproduction and abundance of arctic foxes in the colony, whereas seasonal influxes of
geese and their eggs provided foxes with external subsidies that elevated breeding density and fox abundance above that which
lemmings could support. This study highlights (1) the relative importance of migratory prey and other foods on the abundance
and reproduction by local consumers and (2) how migratory animals function as vectors of nutrient transfer between distant
ecosystems such as Arctic environments and wintering areas by geese thousands of kilometres to the south. 相似文献