Long-tailed Tit Aegithalos Caudatus Research Articles

Bird ringing in Britain and Ireland in 2010

This is the 74th annual report of the British Trust for Ornithology's Ringing Scheme, covering data received and work carried out in 2010. Analytical work in the year concentrated on considering how we can improve demographic monitoring, an increasing focus for the Scheme. A broad review of the availability of demographic and count data for terrestrial-breeding species was carried out. This work will be further extended in 2011. To inform conservation we need to build population models for species with a range of ecologies and occupying different habitats. Reports of ringed birds make a large contribution to our understanding of two key demographic parameters – survival and dispersal. An analysis of Chiffchaff Phylloscopus collybita recovery data from across Europe suggested they are tending to migrate south later and north earlier over time. There is also a suggestion that the migratory journey is shortening. Analysis of biometrics of birds wintering in Britain showed that they are largely from the breeding populations of the nominate race in Britain and the near Continent. Constant Effort Sites (CES) data showed that, for seven of the 24 species monitored, there was a significant decrease in adult abundance compared to the mean of the previous five years. As six of these species were residents, this may have been a result of the second severe winter in succession, although there was a short-term increase for Long-tailed Tit Aegithalos caudatus, which is usually affected by cold winters. The adult abundance of several long-distance migrants also increased. A long-term decline (1984–2000) is, however, still evident for five migrants and three residents, although for Willow Tit Poecile montana and Linnet Carduelis cannabina the sample sizes are low. The abundance of the short-distance migrants, Blackcap Sylvia atricapilla and Chiffchaff, has increased, possibly as a result of climate change. Productivity was higher than the mean of the previous five years for 12 species with the long-term trend increasing for eight species – four migrants and four residents. The only significant decreases were for Blackbird Turdus merula and Long-tailed Tit, possibly as these species breed early and were affected by the severe winter. Dry summer weather is also likely to have contributed to the low productivity of Blackbirds and increasingly dry summers may be implicated in the long-term declines in productivity for both Blackbird and Song Thrush Turdus philomelos. Long-term trends in survival rates were produced using CES data for the first time in 2010. These suggested that the cold winter weather in 2009–10 reduced the survival rate of resident ground-feeding insectivores such as Dunnock Prunella modularis, Blackbird, Wren Troglodytes troglodytes and Robin Erithacus rubecula. Survival rates of migrants were relatively high, particularly for Garden Warbler Sylvia borin and Sedge Warbler Acrocephalus schoenobaenus, possibly as a result of good conditions on the wintering grounds or passage sites. Data for 129 Retrapping Adults for Survival (RAS) studies covering 39 species were submitted. For the first time we were able to calculate good or moderate annual estimates of survival for 18 species. A list of priority species for RAS was developed and promoted to volunteers. The total number of birds ringed (1,096,533) was the highest ever recorded, as well as being the first time the annual total has surpassed 1 million. It was 28% higher than the mean of the previous five years and 17% higher than in 2009. However, the total number of pulli ringed in 2009 (193,554) was only 12% higher than the preceding five-year mean, while that of fully grown birds (902,979) was 32% higher. The recovery total (17,315) was also the highest ever. This is partly due to changes in the way that records of colour-ringed and other specially marked birds are stored, but also reflects the increasing number of birds being ringed by a growing number of ringers. The number of recoveries of foreign-ringed birds (2,427) was higher than the mean of the preceding five years; this figure was influenced by varying response times of different ringing schemes, but was also partly as a result of multiple sightings. Recovery details for 221 individual birds are given in the final section of the report. They include movements that confirm suspected or known migration patterns, unexpected movements and longevity records.

Brood sex ratio variation in a cooperatively breeding bird

In cooperatively breeding species, the fitness consequences of producing sons or daughters depend upon the fitness impacts of positive (repayment hypothesis) and negative (local competition hypothesis) social interactions among relatives. In this study, we examine brood sex allocation in relation to the predictions of both the repayment and the local competition hypotheses in the cooperatively breeding long-tailed tit Aegithalos caudatus. At the population level, we found that annual brood sex ratio was negatively related to the number of male survivors across years, as predicted by the local competition hypothesis. At an individual level, in contrast to predictions of the repayment hypothesis, there was no evidence for facultative control of brood sex ratio. However, immigrant females produced a greater proportion of sons than resident females, a result consistent with both hypotheses. We conclude that female long-tailed tits make adaptive decisions about brood sex allocation.

Factors influencing overnight loss of body mass in the communal roosts of a social bird

1. Communal roosting behaviour in birds is hypothesized to reduce the risk of starvation by lowering the energetic expenditure required to survive the night. However, the metabolic benefit gained is likely to depend on various factors, including an individual's position within the roost. 2. The long-tailed tit Aegithalos caudatus L. is a social species that lives in flocks during the non-breeding season, forming linear roosting huddles in which individuals compete to avoid occupying the peripheral positions at either end of the roost. Using observations of 18 temporarily captive flocks of long-tailed tits, we examine the effects of position and other factors on the mass lost during roosting. 3. We found that, on average, long-tailed tits lost about 9% of their body mass overnight, and that individuals occupying the peripheral positions in a roost lost significantly more mass than those occupying inner positions. 4. Overnight mass loss was related to minimum temperature, being greatest at 4 degrees C and decreasing at higher and lower temperatures. This result suggests that long-tailed tits may use facultative nocturnal hypothermia to reduce energetic costs at low ambient temperature. Mass loss also tended to increase with group size, perhaps because of the greater competition for inner positions in larger flocks, although we have no direct evidence for this. Mass loss was also positively correlated with mass when going to roost, and males lost marginally more mass than females. 5. There was no evidence that individuals strategically adjusted their daily mass when going to roost in relation to their likely roosting position even though outer positions are consistently and therefore predictably occupied by the same individuals on successive nights. 6. We conclude that long-tailed tits mitigate the costs of surviving the night by roosting communally, but the benefits gained vary in relation to position within the roost, explaining previous observations of competitive interactions during roost formation. 7. The benefit derived from communal behaviour is likely to vary among individuals and the degree of conflict over these benefits is likely to depend on both intrinsic and extrinsic factors.

２００５年の東大秩父演習林におけるウグイスおよびその他の鳥類の生息状況について

In 2005, we surveyed the birds inhabiting the Tokyo University Forest in Chichibu, in western Saitama Prefecture, Japan. Special attention was given to the Bush Warbler Cettia diphone, which appeared at the study site after 22nd March. We captured seven male Bush Warblers and banded them with individually unique combinations of color rings. Six males of them maintained the same home ranges (territory) throughout the study period, and no other males were observed. The population density of the males was 19.2 individuals per km2. Although we were unable to locate an active nest to study the breeding and rearing process, juveniles were captured in August. The tarsus length of juveniles reached the size of adults earlier than the natural wing length. Thus, in the juveniles, sexual size dimorphism was evident in the tarsus length to the same extent as seen in adults. We found nests of the Japanese White-eye Zosterops japonicus, Long-tailed Tit Aegithalos caudatus, Short-tailed Bush Warbler Urosphena squameiceps, Blue-and-white Flycatcher Cyanoptila cyanomelana and Red-billed Leiothrix Leiothrix lutea. The clutch of the Short-tailed Bush Warbler was believed to have been parasitized by the Oriental Cuckoo Cuculus saturatus. We confirmed that 40 species of birds occurred in the study area during the study period.

Diversity and plasticity in branch-side use by birds in mixed-species flocks: niche differentiation or competitive hierarchy

ABSTRACT Two models of mechanisms have been proposed to account for resource partitioning between species with overlapping niches, i.e., niche differentiation and competitive hierarchy. I examined branch-side uses by color-marked individuals of eight canopy-foraging species (Long-tailed Tit Aegithalos caudatus, Marsh Tit Parus palustris, Great Tit P. major, Eurasian Nuthatch Sitta europaea, Japanese Pygmy Woodpecker Dendrocopos kizuki, Great-spotted Woodpecker D. major, White-backed Woodpecker D. leucotos and Grey-headed Woodpecker Picus canus) in mixed-species flocks on artificial feeding trees for three years. The three tit species and the Nuthatch used the upper sides of branches most frequently whereas the four woodpecker species used the lateral sides of the branches most frequently, as expected from the niche differentiation model. Among the three tit species and among the four woodpecker species, small-subordinate species foraged on a wider range of branches than large-dominant species, as expected...

Utilizing material from old nests - a way to time-saving in a short breeding species? The case of the Long-tailed Tit Aegithalos caudatus

The Long-tailed Tit (Aegithalos caudatus) is a species characterized by high levels of nest depredation and a short breedingseason. In the face of such high levels of nesting failures, behavioural adaptations to reduce failures should be expected.Here I report on two cases where Long-tailed Tits appeared to reduce their re-nesting interval by utilizing material fromdestroyed nests to build new ones. I suggest that using a previous nest to build a subsequent nest is an adaptation in Longtailed Tits aimed at increasing the speed with which a pair can begin to re-nest and hence increasing their breeding success in a given year.

Helpers increase long-term but not short-term productivity in cooperatively breeding long-tailed tits

Helpers at the nest in the cooperative breeding system of long-tailed tits Aegithalos caudatus exhibit kin preference in their helping behavior. The aim of this study was to use multivariate analyses to investigate whether helpers accrue indirect fitness benefits through their cooperation by increasing the productivity of relatives. All birds started each season breeding independently in pairs, but birds that failed in their own breeding attempt often redirected their care to help another pair provision their offspring. About half of all broods had one or more helpers, 86% of which were male. Provisioning rates increased and there was a corresponding increase in the mass of nestlings within broods as the number of helpers increased. Helpers had no significant short-term effect on productivity because nest predation, nestling survival, and brood size were unaffected by the presence of helpers. However, in the long term helpers had a highly significant effect on the recruitment of fledglings, the positive effect of helpers being linear within the range of helper numbers that we observed. We found no evidence to suggest that these results were confounded by the effects of individual or habitat quality. We conclude that long-tailed tits accrue indirect fitness benefits by helping kin. Nevertheless, the inclusive fitness benefit from helping is substantially lower than that of independent breeding, showing that helpers are making the best of a bad job.

Temporal Variation in Fitness Payoffs Promotes Cooperative Breeding in Long‐Tailed Tits Aegithalos caudatus

Cooperative breeding is paradoxical because some individuals forego independent reproduction and instead help others to reproduce. The ecological constraints model states that such behavior arises because of constraints on independent reproduction. Spatial variation in constraints has been shown to co-vary with the incidence of cooperative breeding in correlational and experimental studies. Here, we examine whether temporally variable ecological constraints can act in a similar way to promote cooperative breeding in the atypical system of long-tailed tits Aegithalos caudatus. In this species, individuals may switch reproductive tactics from breeding to helping within the same breeding season. Using 7 yr of field data, we show that reproductive success declined seasonally because of declines in brood size, nestling weight, and juvenile survival. The survival to breeding age of chicks from nests with helpers was higher than for chicks from nests without helpers, and since helpers usually helped at the nest of a close relative, they accrued inclusive fitness benefits. We used these data to model the expected fitness payoffs of breeding and helping at different times during the season. The model shows that late in the breeding season, the fitness payoff from a kin-directed helping tactic becomes greater than that from independent breeding. The behavioral switch predicted by the model is consistent with the observed switch from breeding to helping, which shows that cooperative breeding may evolve as a way of making the best of a bad job at the end of a temporally constrained breeding season.

Kin discrimination in cooperatively breeding long-tailed tits.

Long-tailed tits Aegithalos caudatus are cooperative breeders in which helpers exhibit a kin preference in their cooperative behaviour. We investigated the mechanism through which this preference is achieved by first conducting an experiment for testing whether breeders could recognize the calls of their relatives while controlling for spatial effects. We found that there were significant differences in the responses of breeders to the vocalizations of kin and non-kin, suggesting that vocal cues may be used for kin recognition. We conducted a second experiment in order to investigate whether recognition is achieved on the basis of relatedness per se or through association. Nestlings were cross-fostered between unrelated broods in order to create broods composed of true and foster siblings. In subsequent years, survivors from experimental broods did not discriminate between true and fostered siblings when making helping decisions, indicating that recognition is learned and not genetically determined. We discuss the effectiveness of learning through association as an indirect cue to kinship.

Divorce in cooperatively breeding long-tailed tits: a consequence of inbreeding avoidance?

The decision of whether to divorce a breeding partner between reproductive attempts can significantly affect individual fitness. In this paper, we report that 63% of surviving pairs of long-tailed tits Aegithalos caudatus divorced between years. We examine three likely explanations for the high divorce rate in this cooperative breeder. The 'better option' hypothesis predicts that divorce and re-pairing increases an individual's reproductive success. However, divorcees did not secure better partners or more helpers and there was no improvement in their reproductive success following divorce. The 'inbreeding avoidance' hypothesis predicts that females should disperse from their family group to avoid breeding with philopatric sons. The observed pattern of divorce was consistent with this hypothesis because, in contrast to the usual avian pattern, divorce was typical for successful pairs (81%) and less frequent in unsuccessful pairs (36-43%). The 'forced divorce' hypothesis predicts that divorce increases as the number of competitors increases. The pattern of divorce among failed breeders was consistent with this hypothesis, but it fails to explain the overall occurrence of divorce because divorcees rarely re-paired with their partners' closest competitors. We discuss long-tailed tits' unique association between divorce and reproductive success in the context of dispersal strategies for inbreeding avoidance.

Incubation Behavior of Long-Tailed Tits: Why Do Males Provision Incubating Females?

The incubation period of Long-tailed Tits Aegithalos caudatus is highly variable, ranging from 14 to 21 days. Females alone incubate the eggs, but males provide females with some food during the incubation period, although females must also forage for themselves. Our aim was to investigate whether male provisioning of incubating females influenced fe male incubation behavior and the length of the incu bation period. Provisioning rates varied betwee males, and female nest attentiveness was negatively related to short-term variation in the rate at which their partner fed them. However, the provisioning rate of individual males also varied significantly through time, and there was no significant effect of male care on female incubation across the whole incubation period. There was no evidence that variation in the behavior of either males or females influenced the length of the incubation period.

Investment Strategies of Breeders in Avian Cooperative Breeding Systems.

An individual's optimal investment in young depends partly on the number of individuals caring for the same brood. In cooperative breeders, the investment strategy of parents with helpers is variable. When parents maintain the same effort regardless of helper number, helper care is additive. When parents fully compensate for the care of helpers by decreasing their own effort, total care does not increase. A study of long-tailed tits Aegithalos caudatus showed that both parental strategies may occur within a species, depending on the number of helpers. A comparative analysis of 27 cooperative breeders was conducted to test the predictions of a graphical model that care is additive when nestling starvation is frequent and parents exhibit compensatory reductions in care when starvation is rare. Both predictions were supported. In this interspecific comparison, a species' mean group size was not associated with compensatory responses by parents. There was some evidence that males and females had different investment rules. Males tended to show compensatory reductions in care when adult survival rate was low. In contrast, while both sexes showed compensation when nestling starvation was infrequent, this association was significant only for females.

Provisioning rules in cooperatively breeding long-tailed tits Aegithalos caudatus : an experimental study

In a population of long-tailed tits Aegithalos caudatus all birds attempted to breed monogamously, but some helped to provision the nestlings of another pair if their own breeding attempt failed. An individual’s investment rules will determine the fitness consequences of helping for breeders and helpers, and the aim of this study was to examine how individual investment varied with the number of carers. Provisioning behaviour was investigated in two ways. First, observations of natural variation showed that males and females reduced their provisioning effort when aided by one helper, but showed no further reduction with additional helpers. By contrast, helpers did not adjust their provisioning effort in relation to the number of helpers at a nest. Secondly, the reaction of parents to the presence of helpers was tested experimentally by the temporary removal of helpers. Both parents significantly increased their provisioning rate when helpers were absent, and the total provisioning rate was unaffected by the manipulation. The reactions of breeders and helpers to the number of carers, and the fitness benefits for breeders and helpers are discussed.

Influences of population size and woodland area on bird species distributions in small woods.

Distributions of individual bird species in 151 small woods (size range 0.02-30 ha) were investigated in 3 consecutive years during which the abundance of certain species varied markedly. Relationships between the probabilities of certain bird species breeding and woodland area were described using incidence functions derived from logistic regression analysis. In general, for species which were largely dependent on woodland and seldom occurred in other habitats (such as hedgerows and gardens), the probability of breeding approached 100% only for woods of 10 ha and more, whereas species with less stringent habitat requirements occurred in the majority of woods, including those of 1 ha and less. The sensitivity of incidence functions to changes in regional abundance and the size distribution of the study woods was examined. For some species, distribution patterns could not be distinguished from those expected if pairs had been distributed in proportion to woodland area (random placement), but the majority did not conform to random placement in at least 1 of the 3 years. This nonconformity was consistent across all 3 years for some species, such as wren (Troglodytes troglodytes), despite substantial fluctuations in population sizes between years, while for others, such as robin (Erithacus rubecula), distribution patterns changed with changes in regional abundance. The results suggested that some species, such as wren and blackbird (Turdus merula), preferred small woods, while other species, such as chiffchaff (Phylloscopus collybita), preferred large woods. For several other species, including robin, great tit (Parus major), long-tailed tit (Aegithalos caudatus) and marsh tit (P. palustris), small woods appeared to be sub-optimal under at least some conditions.

Habitat and Landscape Factors Influencing the Presence of Individual Breeding Bird Species in Woodland Fragments

Bird species distributions in 151 woods (0.02-30 ha) in a lowland arable landscape in eastern England were investigated using logistic regression analysis. Of 31 species included in the study, only Marsh Tit Parus palustris, Nightingale Luscinia megarhynchos and Chiffchaff Phylloscopus collybita failed to breed in woods of <0.5 ha. For many woodland species, the probability of breeding was positively related to woodland area and other variables decribing the woods themselves. For other species, including Blackbird Turdus merula and Sparrowhawk Accipiter nisus, woodland perimeter, rather than area, was significant. Variables describing the landscape surrounding the woods were important for both woodland species and those more typical of open country. The length of hedgerow in the surrounding landscape was positively related to the breeding presence in particular woods of Long-tailed Tit Aegithalos caudatus, Robin Erithacus rubecula, Bullfinch Pyrrhula pyrrhula, Garden Warbler Sylvia borin and Blackcap Sylvia atricapilla, and the area of surrounding woodland was important for Long-tailed Tit, Great-spotted Woodpecker Dendrocopos major and Chaffinch Fringilla coelebs. The presence of Treecreeper Certhia familiaris was negatively related to the distance to the nearest wood, whereas that of Tree Sparrow Passer montanus was negatively related to the amount of woodland in the surrounding landscape. Thus species breeding distributions were influenced by factors associated with the wider landscape, on a scale larger than that of their immediate habitats.

Helping is costly to young birds in cooperatively breeding white-winged choughs

Cooperative breeding among birds is at its most extreme in white-winged choughs ( Corcorax melanorhamphos ). Choughs have never been observed to breed successfully without helpers, and reproductive success increases linearly across all group sizes (maximum = 16). Further, helpers contribute to every aspect of reproduction, including nest building and incubation. Here we show that the contribution of young helpers (one year old and less) to incubation depends on the group in which they live. In small groups (3-5 birds), young helpers contribute as much to incubation as older birds, but in large groups they contribute little. In large groups, help increases sharply with age. Old birds contribute equally, regardless of group size. Although choughs generally do not lose body mass over incubation, young helpers lose mass in proportion to the amount of incubation they perform, independent of any effect of group size. This provides evidence that helpers in cooperatively breeding birds suffer costs from providing help additional to the costs incurred from remaining philopatric. It also demonstrates that the needs of the group influence whether young birds provide help.

Disintegration and Reorganization of the Flock of Long-Tailed Tits Aegithalos caudatus in an Urban District in Kyoto, Japan a

Long-tailed tits are seen all the year round in an urban district in Kyoto City, Japan. We studied dynamic aspects of social organization of this species in this district.1) The study area included a grove, university campuses and residential area neighboring them. Outside the grove trees and shrubs are sparsely planted almost all over the area. Two different groups of long-tailed tits wintered and bred outside the grove and one within the grove.2) Winter flocks of this species were stable in composition and spaced out from one another. Disintegration of the flock occurred in early spring. Although dispersed, they nested within the range of winter flocks. Helpers were recorded in more than half of the nests. After young fledged, families deriving from the same winter flock joined together. The period of substantial separation of the flock members was limited to a few months at the midst of the breeding season. The long-tailed tit is likely to be a group-living species which has a short period of disintegration of members during the breeding season.3) Along with the invariability in composition of the group, movements of birds between different groups during the breeding season were also suggested. In one of the groups some of the helpers were probably immigrants. Nest helping might give birds chances of joining the group they helped other than their own.4) Fledging success was much higher than that recorded in populations of woodland which is the presumed native habitat of this species. One of the reasons for the higher survival rate in the urban district would be the absence of jays which are major predators of woodland populations. The higher breeding success by itself may not be able to retain the population outside the grove because resource condition outside the grove may be poor from summer to autumn.

Bird Survey of Mt. Kisokoma, Central Honshu

Mt. Kisokoma (2, 956m above sea level) is the highest peak of the Chuo Alps, Central Honshu.Bird censuses were made throughout a year from February 1977 to February 1978 in the mid-mountain zone at 900-1, 650m altitude. Line transect method along the road is used in the census work. The total number of birds recorded was 1, 525 individuals belonging to 43 species (Table 1). The number of species and that of birds showed similar seasonal changes, i.e., maximum in the breeding season and minimum in winter. The dominant species were Pale-legged Willow Warbler Phylloscopus tenellipes, Siberian Meadow Bunting Emberiza cioides, Bush Warbler Cettia diphone, and Blue-and white Flycatcher Cyanoptila cyanomelana in breeding season and Long-tailed Tit Aegithalos caudatus, Willow Tit Parus montanus, Coal Tit Parus ater, Great Tit Parus major, and Nuthatch Sitta europaea in non-breeding season. A marked expansion of range in vertical distribution was noted for Siberian Blue Robin Erithacus cyane, Bush Warbler Cettia diphone and Blue-and-White Flycatcher Cyanoptila cyanomelana. Mixed flocks of tits were encountered in every censuses except for the three breedingmonths, and all five species of tits formed mixed flocks.

Analysis of mixed flocks of tits in the Botanical Garden of Tohoku University, Sendai

1. In October 1962-January 1963 and October 1963-January 1964, foraging behavior of tits and other species forming mixed flocks were observed at Botanical Barden of Tohoku University in Sendai, for the purpose of analysis of interspecific relations.2. During winter season, the foraging differed by species in the following manners: the Longtailed Tit Aegithalos caudatus took food mainly from bark and foliage; the Great Tit Parus major from bark, foliage and ground; the Coal Tit P. ater from foliage, bark and cones; and the Goldcrest Regulus regulus from leaves of conifers (by hovering), foliage and bark.3. Statistically, the percentage frequencies of foraging patterns differed by species significantly, with confidence intervals in 60% reliability (Kato 1955), showing that each species in mixed flocks takes food by its own specific foraging method.4. The same statistical comparison, by confidence intervals in 60% reliability, was applied to the analysis of foraging patterns of each species in mono-specific (Sf) and mixed flocks, with (Mf+) or without (Mf-) Long-tailed Tit.As the result, the Long-tailed and Great Tits showed no change in their specific foraging patterns in either kind of mixed flocks (Sf, Mf+ or Mf-). But, significant change occurred in the foraging patterns of Coal and Willow Tits, as well as Goldcrest, when they belonged to diffrent kind of mixed flock. These three species should therefore be affected by the presence of other species, especially through the interspecific attacks.5. Judging from the number of interspecific supplanting attacks and of approach-avoidance, the Great Tit is most aggressive among these flock forming species, the Coal Tit being the second, and Long-tailed Tit, Willow Tit, and Goldcrest are in lower ranks as for aggressiveness, but the order of aggressiveness among these three species are not clear.6. It is suggested that the order of aggressiveness of each species forming mixed flocks is different from the leading order of foraging movements of mixed flocks.

Analysis of mixed flocks of tits in the Botanical Garden of Tohoku University, Sendai

1. Based on data of 56 censuses in July 1961-January 1962 and 124 censuses in April 1962-April 1963, and of other observations during 1960-'65, the annual number fluctuations of Long-tailed Tit Aegithalos caudatus in the Botanical Garden of Tohoku University, Sendai, are analysed.2. As compared with territorial annual life cycle of Great Tit, the annual cycle of Long-tailed Tit is based on flock life with separate pair life in the breeding season, which is started in late December 11/2 month earlier than in the Great Tit.3. The number of breeding Long-tailed Tit was same as the number in previous winter flock. One male bird banded among 16 birds in 1962, nested near its birth place in 1963 and '64. It was found in the same summer and autumn-winter flocks of 1962, '63 and '64.4. Each bird in autumn-winter flock of Long-tailed Tit remains in the next spring in its winter flock (or feeding) range, the number of breeding birds in spring being about the same as that of winter flock. Thus, the home range and size of winter flocks are important in determining the breeding area and density in the next spring.