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Since in oscine birds song divergence often leads to premating reproductive isolation, we asked which factors drive the evolution of song in a widespread species, the coal tit Parus ater. Based on an almost taxon-complete phylogeny we correlated song divergence with morphometric (ecology), genetic (time), and geographic distances (separation). We found eight well-supported mitochondrial lineages, one of which consists of melanolophus (usually treated as a separate species) and whose relationships remain generally unresolved. Due to intense song variability even sophisticated sonametric analyses failed to separate sub-specific units. We tested for the role of song in reproductive isolation by playing songs from China and the Himalayas to Central European males. They recognize them as conspecific, but react to their playbacks less aggressively than to local songs. While morphological divergence is correlated with neither time nor separation, song divergence coincides more with geographic than genetic distance. This is mainly driven by differences along longitude and is especially prominent in the southern part of the species’ range, where six lineages persisted during the last glaciation while the north was subsequently re-occupied by two lineages.

Climate change has been shown to affect the phenology of many organisms, but interestingly these shifts are often unequal across trophic levels, causing a mismatch between the phenology of organisms and their food.We consider two alternative hypotheses: consumers are constrained to adjust sufficiently to the lower trophic level, or prey species react more strongly than their predators to reduce predation. We discuss both hypotheses with our analyses of changes in phenology across four trophic levels: tree budburst, peak biomass of herbivorous caterpillars, breeding phenology of four insectivorous bird species and an avian predator.In our long-term study, we show that between 1988 and 2005, budburst advanced (not significantly) with 0.17 d yr(-1), while between 1985 and 2005 both caterpillars (0.75 d year(-1)) and the hatching date of the passerine species (range for four species: 0.36-0.50 d year(-1)) have advanced, whereas raptor hatching dates showed no trend.The caterpillar peak date was closely correlated with budburst date, as were the passerine hatching dates with the peak caterpillar biomass date. In all these cases, however, the slopes were significantly less than unity, showing that the response of the consumers is weaker than that of their food. This was also true for the avian predator, for which hatching dates were not correlated with the peak availability of fledgling passerines. As a result, the match between food demand and availability deteriorated over time for both the passerines and the avian predators.These results could equally well be explained by consumers' insufficient responses as a consequence of constraints in adapting to climate change, or by them trying to escape predation from a higher trophic level, or both. Selection on phenology could thus be both from matches of phenology with higher and lower levels, and quantifying these can shed new light on why some organisms do adjust their phenology to climate change, while others do not.

Many animals use hoarding as a long-term strategy to ensure a food supply at times of shortage. Hoarders employ strategies that enhance their ability to relocate caches such as remembering where caches are located. Long-term scatterhoarders, whose caches have potentially high pilferage rates, should also hoard in a way to reduce potential cache pilferers’ ability to find caches. Previous studies have demonstrated that this could be achieved by hyperdispersing caches to reduce the foraging efficiency of pilferers. This study investigates whether coal tits (Parusater) indeed place their caches away from existing ones. In our experiment, birds hoarded food in 3 conditions: when caches from a previous storage session were still present, when caches from a previous storage session were not present anymore because the bird had retrieved them, and when caches from a previous storage session had been removed by the experimenter. We show that coal tits hoard away from existing caches and that they do not use cues from extant caches to do this. This evidence is consistent with the use of memory for the locations of previous caches when deciding where to place new caches. This finding has important implications for our understanding of the selective pressures that have shaped spatial memory in food-hoarding birds. Key words: cache dispersal, coal tits, cognitive ecology, food-hoarding birds, Parus ater. [Behav Ecol]

The benefits of extrapair mating behaviour for females of socially monogamous bird species are unclear despite substantial research effort. The genetic compatibility hypothesis proposes genetic benefits such that females paired to social mates of low genetic compatibility avoid or diminish negative fitness consequences by mating with a more compatible extrapair mate, resulting in offspring of higher genetic quality. Furthermore, within the context of inbreeding depression observed in natural populations, a high degree of overall genetic similarity between social pair mates may be regarded as a special case of genetic incompatibility. We tested the hypothesis that female extrapair matings represent an adaptive behavioural response to avoid negative consequences of being paired to a genetically similar social pair male in the coal tit, Parus ater, a socially monogamous passerine with high rates of extrapair paternity. In contrast to what was predicted, we found no evidence for a positive association between the genetic similarity of social pair mates (measured as band-sharing coefficients from multilocus DNA fingerprints) and the occurrence of extrapair paternity. Furthermore, the genetic similarity of the cuckolding female with its social mate was not higher when compared pairwise to that of its extrapair mate in 63 uniquely composed triplets. Finally, three parameters of reproductive success were not related to the genetic similarity of social pair mates. We conclude that avoiding the potentially negative fitness consequences of being paired to a genetically similar social pair mate did not select for and thus cannot maintain female extrapair mating behaviour in our study population. (c) 2004 The Association for tire Study of Animal Behaviour Published by Elsevier Ltd. All rights reserved.

The costs and benefits of dominance status have been investigated in the past and it has generally been reported that subdominant birds are at a nutritional disadvantage owing to their low dominance status. The nutritional condition of birds during winter can be important in determining their likelihood of survival. This is particularly so in small passerines that are sensitive to severe weather conditions. Ptilochronology is an accurate method used to produce a long-term estimate of body condition spanning the number of days that it takes to grow a new feather. Ptilochronology was used during this study to estimate the nutritional condition of Coal Tits Pares ater during one winter and how condition was affected by dominance status. Dominant Coal Tits produced poorer quality feathers, which they grew at a slower rate, than did subdominant conspecifics. This study highlights a nutritional cost to high dominance status that could have long-term consequences because the induced tail feathers will not be replaced for at least 5 months.

The probability of perception of prey may depend on the previous experience of the predator, its expectations and its search tactics. In this study we investigated the role of the search area. Based on previous results and on known facts about foraging ecology, we hypothesised that crested tits ( Parus cristatus ) would perform better when searching larger areas for cryptic prey compared with coal tits ( Parus ater ) that have been found to search small areas for cryptic prey more successfully. In our experiments these two tit species were required to search for cryptic prey in large and small dishes. Both species detected cryptic prey less frequently in the larger dishes, however, crested tits performed better initially. Coal tits improved over time. Both species needed more time for detecting prey in large dishes, and crested tits searched longer in small dishes than coal tits. Giving-up times, when no prey was found, also reflected these differences. The results suggest that the tits search with speciesspecifically set search areas and 'time windows'. It also appeared that coal tits are more flexible in adjusting search to a given situation.

Possible biases related to the use of recordings were assessed by comparing captures of Coal Tits Parus ater with mist nets in presence and absence of tape lures. Samples netted with and without tape lures differed in age composition but not in body size. Moreover, tape lured nets caught resident birds less frequently than expected. Group size of flocks captured with the use of recordings was larger than those captured without. Tape lured juveniles had higher levels of subcutaneous fat reserves than Coal Tits captured at random, whereas this difference was not detected in adults. Attraction of dispersing juveniles and habituation to the tape lure by more resident individuals seemed to explain the patterns observed. Caution and knowledge of the biases caused by decoys is recommended before designing bird population studies which rely on the capture of birds by this method.

Current theory predicts small birds should have a reduced body mass when daytime predation risk is high. However, the influence that nighttime predators might have on changes in body mass or daytime foraging behaviour has not been addressed. We therefore studied the effect of changes in perceived nocturnal predation risk on the body mass of captive coal tits. In a soundproof room, eight coal tits were housed in individual cages and an experiment was performed in which the birds were subjected to two treatments. First, morning and evening body mass was monitored following nights that were quiet. Second, these parameters were measured following nights when the call of a tawny owl had been played once per hour. Evening body mass was 3% greater on days following owl-disturbed nights, but morning body masses did not differ between treatments. To ensure this result was a response to the owl calls per se, and not a general response to increased disturbance, a second experiment was necessary. Here the coal tits were exposed hourly to the calls of a nightjar, a non-predatory nocturnal bird, but no increases in body mass were observed compared to quiet nights. We suggest the coal tits increased body mass in response to owl calls to offset increased nighttime energy expenditure in attentive behaviour., The study was funded by project PB95-0102-CO2-01. LMB was supported by a postdoctoral contract from Ministerio de Educación y Ciencia. S.J.L was supported by a Marie Curie Research Training Grant awarded under the Training and Mobility of Researchers Program by the European Commission Directorate General XII for Science, Research and Development.

Seven males and thirteen female Diplotriaena henryi Blanc 1919 were collected from body cavities (heart, sternum, and chest) of tits (one Parus major and three Parus ater) in plain woodland of Noor, in Northern Iran.

Abstract. Two playback experiments were carried out to test the prediction on coal tits that singing rate could be used to assess the vigour of rival males, and that song length might be used in the same way, during singing interactions. Playbacks of songs with increasing rate inhibited the songs of responding birds, but induced more calls in response. The results suggested that a bout of singing with increasing rate is reacted to as a more serious threat than one with decreasing song output. The playback of long songs induced a greater number of calls in response, while fewer were produced during playback of shorter songs. The results suggest that a bout of long songs is responded to as a more serious threat than one of short songs.

The performances of the coal tit (a food storer) and the great tit (a non-storer) were compared in two experiments in which the bird was rewarded in phase 2 of a trial for returning to sites where it had seen food in phase 1 (‘window-shopping’). In both experiments the differences in performance between the species were small. In the first experiment the storing species was better than the non-storer at returning to the site where it had seen a seed, and in the second experiment the storing species was better at discriminating in phase 2 between sites visited in phase 1 that contained a seed and sites visited in phase 1 that were empty. A third experiment demonstrated that the motivational variables of reward size and deprivation were unlikely to account for the difference between the species. The results might indicate that there are differences in the spatial memory of the storing and non-storing species, but a difference in perceptual discrimination cannot be excluded.

An important step to a better understanding of the adaptive significance of extrapair mating behavior in socially monogamous species is to uncover the identity of extrapair sires (EPS). Here, we used a combination of multilocus DNA fingerprinting and microsatellite analysis to identify EPS in the socially monogamous coal tit (Periparus ater), a passerine bird with high rates of extrapair paternity. We then analyzed how fertilization success was related to male age in 2 consecutive first brood periods based on knowledge of the exact age of the majority of territorial males. EPS were significantly older compared with the males they cuckolded. Furthermore, extrapair and, as a consequence, also total fertilization success were positively related to male age, while within-pair success was not. Interestingly, fertilization success did not increase linearly with male age but leveled off for older age classes and was most parsimoniously described by the inverse term of male age. Results were consistent over the 2 years, while the demography of the study population differed with respect to the age distribution of territorial males. Furthermore, we also show that individual males increased their extrapair fertilization (EPF) success with age indicating that cross-sectional analyses were not confounded by cohort effects. Together with the results from other species, these findings suggest that male age (or a strong correlate thereof) is a major determinant of EPF success in several socially monogamous bird species. Copyright 2007, Oxford University Press.

In the majority of socially monogamous bird species, extra-pair paternity (EPP) has been shown to be common, while its frequency varies considerably among as well as within species. Our knowledge of factors affecting this variation, however, still remains comparatively poor. A thorough analysis of EPP patterns on an individual level may lead to a better understanding of the general diversity in EPP. Here, we analyse intra- and inter-annual as well as individual variation in the occurrence of EPP in first and second broods of coal tits (Parus ater) in three successive years. Based on a sample of 483 broods with 3559 offspring genotyped, we show that EPP was extraordinarily frequent in the study population, surpassing the values observed in other species of the genus Parus by far. On the population level, the rates of EPP were found to be remarkably similar between years, while there was pronounced intra-annual variation such that EPP rates increased significantly from first to second broods. Considering consecutive broods of individual females and males, the general occurrence of EPP was 'inconsistent' (i.e. EPP often affected only one of two broods), but the proportion of extra-pair young (EPY) per brood showed significant repeatability for both sexes in case of mate retention. When mate change occurred, repeatability collapsed, indicating that pair identity was more important in determining the repeatability of EPP than female or male identity alone. This was further supported by the fact that, besides female and male age, also their interaction (reflecting pair age combination) significantly predicted the proportion of EPY, though not in all breeding periods surveyed. Hence, the identity of the breeding pair (reflecting possible interactions of male and female characteristics) should be explicitly considered and accounted for in future studies investigating patterns of EPP on an individual level. Finally, we show that, depending on the boundary conditions, in principle, all coal tits experience EPP: When analysing three or more broods of the same individual, there were no completely 'faithful' females and also nearly no males, which were not cuckolded at least once.

In a dominance-structured flock, social status may determine priority of access to food. Birds of low social status may perceive present and future access to food as less predictable, and so have a higher risk of starvation, than birds of high social rank. Theoretical models predict that subordinate birds should carry larger fat reserves and incur higher mass-dependent costs than dominants. However, empirical tests of the assumptions of these models are still scarce and controversial. We investigated the effect of dominance rank on daily mass gain under conditions of fluctuating food availability in a laboratory experiment using four flocks of four coal tits (Parus ater) each. The same amount of food was delivered in two treatments, but in one treatment the food was offered at a constant rate between days (fixed treatment), while in the other treatment the daily food supply varied in an unpredictable sequence between days (variable treatment). All birds showed greater variance in body mass in the variable treatment than in the fixed treatment. Body mass within birds showed the same variability at dawn than at dusk in the fixed treatment, but less variability at dawn than at dusk in the variable treatment. This may be a mechanism to reduce the immediate risk of starvation at the beginning of the day, when fat reserves are at their lowest and the aggression between flock members when feeding highest. Subordinate birds were excluded from the feeders by dominants more often in the early morning than in the rest of the day, and they showed more variability in daily mass gain and body mass at dawn than dominant birds. These results support the hypothesis that subordinate birds have a reduced probability of surviving when food availability changes unexpectedly compared to dominants., This study was funded by DGCYT project PB95-0102-CO2-01 of Ministerio de Educación y Cultura (MEC, Spain)

Current theory of risk-sensitive foraging predicts that foragers should choose feeding sites on the basis of variation in as well as mean reward rate when there is a shortfall in their food supply or a decrease in their energy budget. For a given mean reward delay, they should choose high variance feeding sites if they are running below energy requirement, but low variance sites if they are running above. It has been suggested that the smaller the animal size, the stronger the preference reversion between high and low variable feeding sites. Previous tests of the energy budget rule when there was time variability have used bird species heavier than 80 g. Hence we tested energy budget rule predictions with coal tits Parus ater, a bird of 9 g of body mass, foraging at two feeding sites with high or low variability in food delivering delay. We manipulated energy budgets by controlling air temperature in the laboratory. In one treatment (positive budget), individuals were allowed to eat at the level of their own ad-libitum daily consumption and the air temperature was set to 24°C, while for the other treatment (negative budget), temperature was set to 14°C, and food availability was limited to the maximum daily intake observed in the positive budget treatment. When air temperature was low, daily intake increased but body mass decreased. Birds were also less active in the low temperature treatment, hopping less times every day. Latency to peck decreased as well, pecking for food when it was available sooner than in the high temperature treatment. These results show that coal tits were living in a negative energy budget when air temperature was set to 14°C. Preference for the variable feeding site was greatest in the negative energy budget, as it was predicted by the energy budget rule. Contrary to the energy budget rule, coal tits consistently preferred the variable option also in the positive energy budget. Possible explanations for these results are explored, including alternative foraging models to the energy budget rule.

Several mechanisms can explain individual differences in foraging behaviour, such as variation in predation risk between patches, variation in the ability of individuals to detect or escape from predators, variation between individuals in their requirement for food, the quality and abundance of food in different patches, phenotypic variation giving rise to differences in resource use (exploitation hypothesis) and interference competition such as the exclusion of subordinate individuals by dominants. Subordinates can develop compensation mechanisms. One of these mechanisms is morphological differentiation. However not every change in morphology can account for the same variation in behaviour, since some morphologies can be ecologically more plastic than others (i.e. some morphs can exploit a broader niche than other morphs). Under controlled conditions in the Coal Tit Parus ater, we tested whether (1) differences in resource use were explained by either the exploitation hypothesis or by the interference hypothesis, and (2) the presumed costs of subordination can be reduced through different ecological plasticities associated with different morphologies. Our results support the interference hypothesis as there are no differences in hanging behaviour between dominants and subordinates when foraging solitarily; while in the presence of other individuals, we observed differences in foraging behaviour that varied with social status. Our results also show that body mass influenced foraging behaviour; lighter birds can exploit patches where hanging postures are needed more easily than heavier birds. Moreover, this relationship varied among individuals, as predicted by the ecological plasticity hypothesis. Lighter subordinate individuals used hanging postures more frequently than heavier ones, differentially reducing the costs of subordination. We propose that differences in the breadth of ecological niche due to differences in morphology can reduce the costs of subordination., This study was carried out with the logistic support of El Ventorrillo Field Station, and was funded by DGES project PB95-0103 to E.M. A.B. was supported by a CSIC-CAMMNCN postdoctoral grant. M.B. was supported by a PhD grant from El Ventorrillo. J.J. Sanz kindly provided us with the discriminant function for sexual dimorphism. A. Gosler, N. Metcalfe and an anonymous referee greatly improved an early draft of the manuscript.

Theoretical models predict that birds should decrease their body mass in response to increased predation risk because lighter birds take off faster and are more manoeuvrable. We studied the effect of predation risk by chasing coal tits in large outdoor aviaries thus simulating an attempt to capture them. With this increase in predation risk, both perceived and actual, coal tits lost significantly more weight than in a control situation when they were not pursued. This pattern was attributable to a smaller gain in weight only during the day; nocturnal weight did not change in relation to diurnal predation risk. The lower daily weight gain was not consistent with predictions from models of interrupted foraging, but was consistent with predictions from risk adjustment models. Moreover, there was no difference in weight gain over 2-h periods that included a 1-h fast and those in which feeding was ad libitum, suggesting that coal tits could easily regain their body mass after a predator had interrupted their feeding. Our results therefore suggest that pursuit by predators leads to a decrease in the body mass of small birds. Copyright 1999 The Association for the Study of Animal Behaviour.

We compared the ability of coal tits, Parus ater (a food-storing species), great tits, P. major, and blue tits, P. caeruleus (two nonstoring species) to remember spatial locations in a spatial delayed-matching-to-sample task. Presentation of a single sample image on a touch screen was followed by a choice phase containing two, three or four images, in which the bird had to choose the original image. Storers made more correct choices than did nonstorers. Performance was affected by the proximity of the distractors: both groups performed less well when distractors were close to the sample although storers were less affected by proximity of distractors than were nonstorers. Both groups made correct decisions sooner than errors. We conclude that the accuracy of spatial memory in food-storing birds is greater than that of nonstorers. Copyright 1999 The Association for the Study of Animal Behaviour.

A female Pied Flycatcher (Ficedula hypoleuca) built over a Coal Tits' (Parus ater) nest containing five chicks. Nevertheless, the nestlings survived on account of their parents' feedings, and because they were probably lifted up in the nest-box sitting on top of the material brought into the box by the flycatcher-♀. After nest-completion the Pied Flycatcher-♀ layed four eggs, but refused breeding. Instead, and probably due to the intense begging of the five Coal Tit chicks, the Flycatcher-pair immediatly started to rear “its” young. Based on the good care the chicks were given by their parents and foster-parents they came along nicely and fledged some days later.

Gosler, A. G. & King, J. R. 1989. Asexually dimorphic plumage character in the Coal Tit Parus ater with notes on the Marsh Tit Parus palustris. Ring. & Migr. 10: 53–57. Although Coal Tits may be sexed during the breeding season on the presence or absence of a brood patch or cloacal protruberance, no plumage differences have been noted previously, so that sexing has not been possible outside this period. We present observations of Coal Tits trapped at two sites in southern England which indicate that the bib of this species is strongly dimorphic in shape, extent and colour intensity.

The aim of this study was to reveal the causes and consequences of individual differences in foraging behaviour of coal tits, Parus ater, on the island of Gotland in the Baltic. On Gotland the willow tit, P. montanus, and the crested tit, P. cristatus, are absent, while these larger species are abundant competitors on the mainland. The Gotland population of coal tits exploited parts of the foraging niches of their absent competitors. Gotland coal tits are bigger than those on the mainland; they have thus evolved towards the size of the missing competitors. Individual differences in niche use were related to their morphology. Large birds more often used the inner parts of trees whereas small individuals foraged more on needles in the outer parts of the trees. Also, individuals with wing shapes more suitable for hovering and slow flight foraged more on needles. It is argued that morphology affects the profitability of different foraging sites. However, for foraging site selection, age was more important than morphology. Older, and probably more dominant, individuals occupied the most profitable foraging sites.

A banded pair of the Coal Tit,Parus ater, nested during 6 years in the same two sawdust-boxes. 65 eggs were laid, 59 young fledged. The female was at least 7 years old; in the first year of observation, paired with another male, it had two clutches.