Microhabitat selection for singing and other behaviour in great tits, Parus major: Some visual and acoustical considerations

Territorial male great tits (Parus major L.) usually forage on the ground, sing from perches with a mean height of 9.3 m, and perform most other activities between 2 and 4 m. Analyses of their habitat's visual and acoustical stratification indicate that great tits sing from high perches to make themselves hard to locate visually rather than to make their songs carry farther. The birds' selection of inconspicuous singing spots is further substantiated by their striking preference for hawthorn trees, which have an extremely dense crown and produce leaves very early in the year.     

Song matching in the great tit Parus major L.

Great tits respond to playback of song from their own repertoire by singing the same song type as that on the tape. This is referred to as song matching. There is a good correlation between the probability of matching and response strength as indicated by latency, approach to the speaker and total number of songs. We propose that matching functions as a graded signal in territorial disputes.     

Heterophil/lymphocyte ratios predict the magnitude of humoral immune response to a novel antigen in great tits (Parus major)

Animals display remarkable individual variation in their capacity to mount immune responses against novel antigens. According to the life-history theory, this variation is caused by the costs of immune responses to the hosts. We studied one of such potential costs, depletion of somatic resources in wintering wild-caught captive passerines, the great tits (Parus major) by immune challenging the birds with a novel antigen, killed Brucella abortus (BA) suspension. We found that despite mild temperature conditions in captivity and ad libitum availability of food, immune challenge depleted somatic resources (as indicated by a body mass loss) and elevated relative proportion of heterophils to lymphocytes (H/L ratio) in the peripheral blood of birds. However, body mass loss did not covary with an increase in H/L ratios between two sampling events, which indicates that these two markers of health state describe different aspects of individual physiological condition. Antibody titres were not associated with the extent of body mass loss during the development of immune response, which shows that the somatic cost of immune response was not proportional to the amount of antibody produced. Birds with high pre-immunisation H/L ratios mounted weaker antibody response, which is indicative of stress-induced suppression of humoral immune response and is consistent with the concept of an antagonistic cross-regulation between different components of the immune system. The latter finding suggests a novel diagnostic value of H/L ratios, which reinforces the utility of this simple haematological index for prediction of the outcomes of complicated immune processes.     

Song matching in the great tit (Parus major): The effect of similarity and familiarity

Great tits were played recordings of one of their own songs, and a song of the same type from a neighbour and one from a stranger (from more than 500 m away). The birds matched their own songs most often and those of strangers least. We had predicted that strangers would be matched most, because previous work had shown an association between matching and a strong response. An analysis using a difference index showed that the birds matched most often when the stimulus song was very similar in detailed structure to their own rendition of the song. This was confirmed in a second experiment in which we played ‘similar’ and ‘different’ renditions recorded from strangers. However, once the effect of similarity was partialled out there was a residual tendency to match strangers more than neighbours, as we had first predicted. We discuss the implications of these results for perception of song categories by the birds, possible use by the birds of their own songs as ‘standards’ and the functional significance of matching.     

The function of the variation in the breast stripe of the great tit (Parus major)

Many winter flocking bird species possess a plumage colour polymorphism. Two hypotheses have been proposed to explain the function of this variability in plumage structure: the signalling of (1) individual identity (IRH), or (2) social status (SSH). These two hypotheses were tested on winter flocking great tits, a species showing intraspecific variation in its breast stripe plumage. The SSH was considered the most probable, because a close correlation between social status and breast stripe width was found. The SSH was further tested by using dummy great tits bearing breast stripes of different widths. Great tits that possessed a breast stripe wider than that of the dummy approached it aggressively, and those with a narrower behaved submissively. We therefore conclude that the function of the variation in width of the breast stripe plumage is to proclaim the social status of the individual.     

Dominance and anti-predator behaviour in blue tits (Parus caeruleus)

Evidence from captive flocks of blue tits (Parus caeruleus) suggests that following the appearance of a predator, socially dominant individuals are likely to wait until subordinate members of their flock resume feeding before doing so themselves. After a model sparrowhawk (Accipiter nisus) was flown over captive flocks of blue tits at a feeder, there was a significant negative correlation between sequence of return to the feeder and status within a linear dominance hierarchy. During this period, birds increased the proportion of their time budgets devoted to scanning for predators. These results suggest that during periods of danger, high-ranking individuals are able to be more cautious than are low-ranking individuals, possibly because their ability to control food resources reduces the energetic costs of their extra caution.     

北京西山地区大山雀与其它鸟类种群种间联结分析

引入2*2列联表联结指数法,用固定样带法月连续全天定位调查数据,以森林鸟类广布种山雀科大山雀(Parus major)为目标种,研究了北京西山地区该种与留鸟、夏候鸟、冬候鸟、旅鸟的种间联结关系,结合前人关于营巢行为、取食行为、生态位等方面成果分析了产生联结的原因,首次确立了鸟类群落种间联结的研究方法。结果表明： （1）用固定样带法月连续全天定位调查,引入2*2列联表以日尺度的定性数据检验与测定联结度,与月尺度的联结频率结合起来,分析鸟类群落的种间联结是可行的;鸟类群落的种间联结具有时间与空间尺度的双重属性,鸟类群落的种间联结度不仅是鸟类群落时空结构与格局的表征,同时,反映了鸟类群落的动态性,而且,鸟类群落的种间联结对栖息的植物群落具有依赖性与关联性。 （2）日尺度上,选择χ2统计量、PCC与PC指数相结合进行种间联结检验、测度,能充分反映鸟类群落的种间联结特征,但由于鸟类的居留、繁殖、迁移等季节动态性特征,种间联结度存有不确定性。 （3）月尺度上,鸟类总体种间联结8月份为显著负联结,其余各月为显著正联结;根据PCC联结度的月联结频率,可将鸟类划分为正联结组、正负联结均较弱组、负联结组;大山雀与留鸟、夏候鸟、冬候鸟、旅鸟等不同居留型的联结关系,随着种数的减少,显著联结种对、联结度、联结复杂程度呈递减趋势。大山雀与留鸟的联结：与鸦科鸟类呈明显正联结,与同科鸟类呈正负均等的弱联结并趋于负联结,与体型较大的雉、啄木鸟、乌鸦等鸟类呈负联结。大山雀与夏候鸟的联结：与杜鹃科四声杜鹃呈正联结,与同科的黄腹山雀、鹟科的白眉姬正负联结均较弱,与莺科的黄腰柳莺、鸫科的北红尾鸲等呈负联结。大山雀与冬候鸟的联结：与岩鹨科棕眉山岩鹨的正负联结均较弱,与鸫科的斑鸫、鹀科多种鸟类呈明显的负联结。大山雀与旅鸟的联结：与莺科鸟类由正负联结均较弱到明显的负联结。     

Deferred independence and prolonged infantile behaviour in young varied tits, Parus varius, of an island population

In identical conditions under captivity, island fledglings of the varied tit, Parus varius, showed begging behaviour for about three times as long as did mainland fledglings. Moreover, the begging posture and call were exaggerated in island fledglings. The exaggerated begging behaviour and its long maintenance in island fledglings are considered to contribute to the extended duration of postfledging parental care which has been observed in the field. The prolongation of begging behaviour and parental care in island varied tits seems to have been evolved as a result of the low food availability which is expected from the smaller seasonal flush of food and the high population density of the birds.     

Body mass of female great tits (Parus major) at egg laying

Based on automated weighing of nest-boxes, we found that female great tits (Parus major) usually maintained their body mass during the egg-laying period. A drop in temperature (3°C or more) during laying was followed by a drop in body mass, and female body mass also depended slightly but significantly on mean temperature on the other days. Day to day change in body mass depended negatively on the actual body mass. Moreover, the repeatability of the morning body mass was high (r _I =0.90, n=24). Thus, female body mass seems to be regulated around a female specific, but temperature-dependent, level during laying. The lack of strong correlation between female average body mass and clutch size makes it improbable that body mass at laying plays a leading, proximate role in the control of clutch-size of great tits.     

Time constraint on food choice in provisioning blue tits, Parus caeruleus: the relationship between feeding rate and prey size

Previous work on food-provisioning behaviour in blue tits suggested that the parents could gather larger prey items only by making longer foraging excursions, for example, by being more selective or by reaching more distant (and less exploited) feeding sites. Here, I show that within-nest, within-day variation in size of prey delivered by the parent could be explained by the time since its last visit. In unmanipulated conditions, size of larvae tended to increase with the time spent away from the nest. A significant positive relationship was more likely at high provisioning rates, suggesting that periods of intense feeding limited the size of prey delivered to the brood. To assess the effect of less intense feeding on prey size, I experimentally increased food availability to the tits. The parents could decide whether to eat the extra food or feed it to the nestlings. In both cases, food supplementation could result in longer time lags between natural feedings. Food-supplemented parents consumed the extra food and fed it to their nestlings, made longer foraging trips and delivered larger natural larvae than controls. In this group, size of larvae was more constant during the observation period and was independent of the time since the parent's last visit. This suggests that, below some value of visit rate, prey size is no longer limited by the duration of the foraging trip. The results support the view that tits continually vary visit rate and prey size. There is some evidence that these adjustments are made by changing food selectivity in response to changes in the state of the brood and of the parents.Copyright 2002 The Association for the Study of Animal Behaviour. Published by Elsevier Science Ltd. All rights reserved .     

Breeding patterns of great tits ( Parus major ) in pine forests along the Portuguese west coast

The breeding biology of great tits (Parus major) was studied in two forests of maritime pine (Pinus pinaster) on the west coast of Portugal, 200 km apart: Leiria (north) and Aposti?a (south). These two forests are located in a transition zone between Atlantic climate in the north, and Mediterranean climate in the south. Breeding onset was, on average, in the second and third week of March, which are the earliest records of breeding for this species. The southern population started to breed earlier than the northern one and produced a larger first clutch, 8.3 and 7.4 eggs, respectively. Corresponding to larger clutch sizes, we also found a higher first brood fledgling production in Aposti?a compared to Leiria, 6.1 and 5.4 fledglings, respectively. However, the total number of fledglings produced per pair was higher in Leiria (8.3) than in Aposti?a (7.7), due to higher productivity of second clutches (4.7 and 2.7 fledglings, respectively). Accordingly, the allocation of eggs between successive breeding attempts was more equal in Leiria. Results are discussed in accordance to the different climatic patterns in the two areas. It is suggested that the timing of breeding and different allocation of reproductive investment between successive breeding attempts play an important role in optimizing breeding tactics in this facultative multiple-brooded passerine in different climatic areas.     

Social stability and daily body mass gain in great tits

This paper presents the results of an experiment on the influenceof changes in flock composition and social rank on the patternof daily mass gain in captive wintering great tits. We createdflocks of three male great tits and scored dominance when rankshad stabilized after a few days. We then moved the dominantbird from each flock into a neighboring flock, thus creatinga certain amount of social instability and unpredictable resourceaccess. Both before and after moving the dominants, we collectedindividual body mass data three times a day. When the hierarchieshad stabilized in the second flocks, individual ranks were scored.After the dominant birds were moved, the rate of daily massgain increased for the average individual. There was also adecrease in average morning body mass, so the birds startedthe day at a lower mass and ended at a slightly higher massthan previously. Dominants were on average heavier than subordinates,but we found no statistically significant effect of rank changeon body mass. The pattern of daily mass gain was linear overtime both before and after treatment. We conclude that an impressionof unpredictable resource access can be created by disturbingthe social structure in a flock, with similar effect as fromrestricting individual access to feeders. Within a flock, instabilityof the social hierarchy thus seems to have an influence on bodymass management in addition to that of environmental stochasticity.