Personality and Nest Defence in the Great Tit (Parus major)

A growing number of studies have shown that individuals differ consistently in a suite of correlated behavioural traits across various contexts and situations. Yet, most work on animal personalities has been performed under laboratory conditions and still little is known about the ecological significance of differences in personality in the wild, and the behavioural mechanisms underlying possible fitness consequences. In this study, we investigated individual differences in personality in relation to nest defence behaviour in wild great tits. Nest defence is an important aspect of parental care and involves a trade‐off between two fitness components (i.e. survival and reproduction). As a measure of personality we used exploratory behaviour in a novel environment as this has been shown to be correlated with several other behavioural traits including risk‐taking and aggression, two important behavioural components of nest defence. We found that the intensity of alarm calling towards a human intruder was positively associated with exploratory behaviour, while there was a negative association between exploration score and number of movements during nest defence. Thus, fast explorers are shown to respond more boldly towards predators in the field. More generally we show that individuals with different personalities vary in their anti‐predator and reproductive investment strategies.     

Competition and egg-weight in the Great Tit Parus major

The mean weight of eggs in clutches of the Great Tit Parus major varies markedly between clutches. Eggs are lighter in years of high density of breeding pairs than in years of low density, but egg weight is also inversely correlated with the density of breeding Blue Tits Parus caeruleus .     

Characterizing the mammalian hair present in Great Tit (Parus major) nests

Capsule Many birds are known to incorporate mammal hair into their nest lining, but the frequency with which they use hair from different mammals is unknown. We performed one of the first detailed examinations of mammalian hair from 54 Great Tit nests. We identified 5317 hairs belonging to 21 mammal species. Almost all of the examined nests contained hair from Roe Deer (Capreolus capreolus), but hair from Wild Boars (Sus scrofa), European Hares (Lepus europaeus) and Red Foxes (Vulpes vulpes) was also common.     

Evidence for cuckoldry in the Great Tit Parus major

We estimated the frequency of cuckoldry (the proportion of offspring resulting from extra-pair copulations) in Great Tits Parus major using heritability estimates based on the resemblance of offspring tarsus-length to that of their parents. Our results suggest that cuckoldry occurs and may be relatively common in certain years.     

Clutch Defence in Great Tit (Parus major) Pairs and the Concorde Fallacy

We conducted an experiment to test whether great tits (Parus major) base their decisions of clutch defence on past investment or future benefits. Results were obtained by manipulation of future benefits. Great tit pairs of an experimental group with reduced clutch-size and thus diminished benefits defended their offspring against a live raptor significantly less than a comparable, non-manipulated control group with the same amount of past investment (clutch-size, incubation stage, time of year). While in the females the difference between the two groups was obvious from the beginning of a trial, the difference in the males developed only during the course of a trial, suggesting that the male bases its response on the female's response deficit. A more onerous explanation of the female signaling the male the egg loss by using a language-like symbol is not supported by the data. The experiment thereby permits the conclusion that at least the great tit female avoids committing the Concorde fallacy in the strict sense.     

Factors affecting divorce in the Great Tit Parus major

In a population of the Great Tit Parus major in Sagamihara, the divorce rate was 17.8% over 10 years from 1984/85 to 1993/94. Most of the divorces occurred in the year following pair formation. There were no differences in breeding success between faithful and divorced pairs. The birds were divided into three groups in relation to their home ranges: residents, emigrants and migrants. The residents established their home ranges within their flock ranges and remained there for life. Non-residents (of which two sorts were identified) left their flock ranges to breed, but returned to their original flock ranges after breeding. Therefore, their home ranges were separated into breeding and previous flock ranges. Most of the faithful pairs consisted of residents whose home ranges overlapped extensively. The divorce rate was higher in the pairs consisting of residents and non-residents and in those of non-residents. Since the non-breeding home ranges of emigrants and migrants did not overlap with their mates' non-breeding home ranges, an important factor affecting divorce seems to be the non-overlap of non-breeding home ranges between both mates of pairs after breeding.     

Parasites as mediators of heterozygosity-fitness correlations in the Great Tit (Parus major)

Positive correlations between heterozygosity and fitness traits are frequently observed, and it has been hypothesized, but rarely tested experimentally, that parasites play a key role in mediating the heterozygosity-fitness association. We evaluated this hypothesis in a wild great tit (Parus major) population by testing the prediction that the heterozygosity-fitness association would appear in broods experimentally infested with a common ectoparasite, but not in parasite-free broods. We simultaneously assessed the effects of parental and offspring heterozygosity on nestling growth and found that body mass of nestlings close to independence, which is a strong predictor of post-fledging survival, increased significantly with nestling levels of heterozygosity in experimentally infested nests, but not in parasite-free nests. Heterozygosity level of the fathers also showed a significant positive correlation with offspring body mass under an experimental parasite load, whereas there was no correlation with the mothers' level of heterozygosity. Thus, our results indicate a key role for parasites as mediators of the heterozygosity-fitness correlations.     

The Tradeoff Between Territorial Defense and Foraging in the Great Tit (Parus major)

We analyze territorial behavior in terms of decisions abouttime allocation.Such decisions must be made whenever time investedin territorial defense cannot be devoted to feeding, and viceversa. We describe the ecology and territorial behavior of thegreat tit (Parus major) to show that a tradeoff exists, andthen outline a series of laboratory and field experiments inwhich the value of feeding or defense was experimentally manipulated.Territorialmale great tits began to invest more heavily in territorialvigilance after encountering intruders, but the increase invigilance depended on the rate at which they could feed, aswell as their hunger level. We outline a dynamic analysis thattakes account of the fact that the optimal tradeoff will changeas hunger is reduced. The results of an experimental test ofthis dynamic model are also presented. We briefly review othertechniques whereby territorial tradeoffs have been investigated.     

Feather ornaments are dynamic traits in the Great Tit Parus major

In behavioural studies it has been common to quantify plumage colours or ornaments over a range of dates and link them to fitness characteristics without accounting for seasonal changes in these traits. Such changes are likely to be widespread among birds, yet we lack assessments of this variability within individuals. We studied both within‐ and between‐individual temporal changes in Great Tit Parus major ornaments, specifically the melanin‐based black breast stripe and the pigment‐free white cheek patch. During the non‐breeding season both ornaments varied. In juveniles and adult females, the area of the breast stripe first rose and then, from near the end of December, decreased. In adult males there was a linear decrease. In the cheek patch, the irregularity of the cheek borders showed either a linear (adults) or a non‐linear (juveniles) increase as the season progressed. In individuals repeatedly sampled during the same winter, the decrease in the size of the breast stripe was larger for males than females and there was an overall decrease in the regularity of the cheek borders. There was no relationship between the size of the breast stripe and the white cheek patch irregularities or the cheek patch area. These results imply that more attention should be paid to quantification, within individuals, of the components of expression of phenotypic traits. In addition, we suggest that further research should focus on explaining the causes and functions of ornament change.     

Handling Stress as a Measurement of Personality in Great Tit Nestlings (Parus major)

Interest in personality is growing in a wide range of disciplines, but only in a few systems it is possible to assess the survival value of personality. Field studies looking at the relationship between personality and survival value early in life are greatly hampered by the fact that personality can at present only be assessed after individuals become independent from their parents. In passerines, for example, this is often after a period of intensive selection for the survival on fledglings. The main aim of this study is therefore to develop a method to measure personality before this period of selection. For this purpose, we developed the handling stress (HS) test. We measured HS in 14-d-old great tit nestlings by counting the number of breast movements (breath rate) in four subsequent 15-s bouts for 1 min; before and after they were socially isolated from their siblings for 15 min. To calculate the repeatability of HS, we repeated the test 6 mo later. To assess the relationship between HS and exploratory behaviour, we correlated the outcome of both tests. We ran tests both on birds of lines selected for extreme personality and on wild birds from a natural population. We found that birds selected for fast exploration reacted more to HS compared with birds selected for slow exploration and that HS was repeatable in different life phases. We confirmed this by finding an increase in the HS with increasing exploratory scores in wild birds. These results show that we can use the HS test as a measurement of personality, making it a potential tool for studying the relationship between personality and survival value early in life.     

Isolation and characterization of 16 microsatellite loci in the Great Tit Parus major

Six dinucleotide, three trinucleotide and seven tetranucleotide microsatellite loci developed for the great tit Parus major are presented. Thirty individual birds were screened at each locus. Loci were polymorphic (four to 19 alleles per locus). These markers provide a system to study paternity, genetic diversity in natural populations, gene flow, dispersal and inbreeding.     

Intraspecific Variation and Interspecific Differences in the Bacterial and Fungal Assemblages of Blue Tit (Cyanistes caeruleus) and Great Tit (Parus major) Nests

Although interest in the relationship between birds and microorganisms is increasing, few studies have compared nest microbial assemblages in wild passerines to determine variation within and between species. Culturing microorganisms from blue tit (Cyanistes caeruleus) and great tit (Parus major) nests from the same study site demonstrated diverse microbial communities with 32 bacterial and 13 fungal species being isolated. Dominant bacteria were Pseudomonas fluorescens, Pseudomonas putida, and Staphylococcus hyicus. Also common in the nests were the keratinolytic bacteria Pseudomonas stutzeri and Bacillus subtilis. Dominant fungi were Cladosporium herbarum and Epicoccum purpurascens. Aspergillus flavous, Microsporum gallinae, and Candida albicans (causative agents of avian aspergillosis, favus, and candidiasis, respectively) were present in 30%, 25%, and 10% of nests, respectively. Although there were no differences in nest mass or materials, bacterial (but not fungal) loads were significantly higher in blue tit nests. Microbial species also differed interspecifically. As regards potential pathogens, the prevalence of Enterobacter cloacae was higher in blue tit nests, while Pseudomonas aeruginosa—present in 30% of blue tit nests—was absent from great tit nests. The allergenic fungus Cladosporium cladosporioides was both more prevalent and abundant in great tit nests. Using discriminant function analysis (DFA), nests were classified to avian species with 100% accuracy using the complete microbial community. Partial DFA models were created using a reduced number of variables and compared using Akaike’s information criterion on the basis of model fit and parsimony. The best models classified unknown nests with 72.5–95% accuracy using a small subset of microbes (n = 1–8), which always included Pseudomonas agarici. This suggests that despite substantial intraspecific variation in nest microflora, there are significant interspecific differences—both in terms of individual microbes and the overall microbial community—even when host species are closely related, ecologically similar, sympatric, and construct very similar nests.     

Cd~(2+)处理后麻雀脑组织中糖皮质激素受体和盐皮质激素受体表达变化

目的检测在Cd~(2+)处理后糖皮质激素受体(GR)和盐皮质激素受体(MR)在麻雀Passer montanus脑组织中的表达变化。方法 6只麻雀随机分成2组,每组3只。处理组饮水中添加500μg·L~(-1)Cd~(2+),对照组不添加。用Clustal W2将麻雀的GR和MR氨基酸序列与其他物种氨基酸序列进行相似性比对分析。采用Real-time PCR检测基础水平下麻雀各组织中GR和MR基因的表达水平。Cd~(2+)处理后,测定GR和MR基因在脑组织中的表达变化。结果麻雀与斑胸草雀Taeniopygia guttata和原鸡Gallus gallus的GR和MR氨基酸序列的相似性大于90%;GR和MR基因在麻雀肝脏、肠、心脏、眼球、脑、肺、肌肉、肾脏和性腺9个组织中均有表达;Cd~(2+)处理后,处理组脑组织中GR和MR mRNA表达水平均上调,且显著高于对照组(P0.05)。结论 GR和MR在麻雀各组织中广泛表达;推测GR和MR基因在Cd~(2+)的应激反应中具有重要作用,具体作用还有待于进一步论证,同时该研究为野外工作提供了一定的实验依据。     

Seasonal changes in carotenoid- and melanin-based plumage coloration in the Great Tit Parus major

Plumage coloration plays an important role as a signal of individual quality. We studied plumage coloration in two Great Tit Parus major populations to test the hypothesis that coloration changes during the year without moult. As expected, the coloration of 'yellow' and 'dark green' areas in the breast and back changed with time but not the colour characteristics of the 'black' crown. This suggests that colours based on carotenoids could be more exposed to abrasion or fading than melanin-derived colours, although other factors could affect the patterns of change found. Our results show that effects of colour alteration could be important to the understanding of the potential for reliable signalling of different colours. Seasonal changes in plumage colour should be considered in future analysis of intraspecific variation in coloration.     

Seasonal variation of circulating plasma carotenoids in Mediterranean Great Tit males Parus major

Capsule Mediterranean Great Tits showed a marked increase in levels of circulating carotenoids during moult and autumn.

Aims To study seasonal variation in plasma carotenoid content during a whole annual cycle for Great Tits Parus major inhabiting a Mediterranean woodland.

Methods We used a sample of 71 adult male Great Tits captured in NE Spain during a whole year. Data were organized into four seasons (winter, breeding, moult and autumn). We sampled blood to extract plasma. Carotenoid plasma concentrations were analysed by High-performance liquid chromatography (HPLC).

Results Lutein and zeaxanthin content varied seasonally, with a marked increase in levels during moult and autumn. Within the moulting period, levels increased gradually as the season progressed. This pattern differed significantly from that previously described in northern European populations, where high values appear mainly in the breeding season. Carotenoid concentrations (lutein: 1.2?±?0.25, zeaxanthin: 0.07?±?0.03?µg mL^?1) were also lower than in northern Europe.

Conclusion Mediterranean Great Tits show a very different pattern of circulating carotenoids and lower levels than northern European populations. The increasing pattern of carotenoid availability found within the moulting period raises the need to control for the effect of sampling date when analysing data on carotenoid concentrations at different times of year.     

Differences in reproductive success and parental qualities between habitats in the Great Tit Parus major

Reproductive success and parental attributes of Great Tits Parus major nesting in good and poor habitats were compared to investigate whether they differed and, if so, whether parental or environmental variation contributed most to the differences.
Monitored over 3 years, clutches in mature woodland were started earlier, were larger and produced larger broods of heavier chicks than those in marginal habitats such as gardens and hedgerows. Fledging success was significantly higher in woodland in 2 of the 3 years although egg weights were lower. Parents nesting in different habitats were very similar in body-size although those in woodland were in better condition. The prey delivered to nestlings in woodland was of significantly higher quality than that delivered in marginal habitats. Furthermore, the heritability of body-size (tarsus-length) was higher in woodland, suggesting that the environment limits nestling growth in poorer habitats. Reproductive success was considerably lower in poor habitats and appears to be constrained primarily by environmental quality, although this may operate partly through its affect on parental body condition.