Nest quality limits the number of hole-nesting passerines in their natural cavity-rich habitat

We experimentally tested whether the lack of high-quality nest holes may limit the number of secondary cavity-nesters in cavity-rich habitats. We mapped and measured natural tree-holes in 10 mature aspen forests in Estonia. In five experimental plots, we provided nest-boxes on trees having suitable cavities for hole-nesting passerines. This improved the quality of available cavities but retained their total number (due to territoriality, sites in the same tree could not be occupied simultaneously) and location on the landscape. In the next breeding season, the density of hole-nesting passerines increased in experimental plots but remained at the same level in control plots. The increase was due to the species that used boxes: Parus major that preferred these over natural cavities, and Ficedula hypoleuca that used both nest types more opportunistically. We concluded that the quality of cavities can influence the numbers of hole-nesting birds in old cavity-rich forests, also; probably, adaptive habitat selection is the proximate mechanism in this case.     

Providing nest boxes for hole-nesting birds – Does habitat matter?

Nest boxes are a popular management tool to increase nest site availability for hole-nesting birds, but biological consequences of this technique in different habitats are poorly studied. In our study area in southwestern Estonia, nest boxes for small passerines were set up in deciduous and coniferous woods. Great tits Parus major preferred the food-rich deciduous habitat for breeding, as judged by higher nest-box occupation, earlier egg-laying and larger clutches and eggs. However, in coniferous habitat more and heavier young fledged per nest, and the return rate of both fledglings and adults was higher. We propose two mutually non-exclusive explanations, both related to the maladaptive outcome of the provision of nest boxes: (i) in the preferred habitat, nest boxes caused a supra-optimal breeding density leading to an ecological trap; (ii) boxes drastically improved the non-preferred habitat, but birds were unable to exploit the breeding habitat fully. One should be careful in providing large numbers of artificial nest sites in preferred habitats. Sometimes it would be more preferable to improve less favourable habitats by removing critical constraints.     

Population genetic structure of the tree-hole tick Ixodes arboricola (Acari: Ixodidae) at different spatial scales

The endophilic tick Ixodes arboricola infests cavity-nesting birds, and its dispersal strongly depends on the movements of its host. Population genetic structure of I. arboricola was studied with seven polymorphic microsatellite markers. We collected 268 ticks from 76 nest boxes in four woodlots near Antwerp, Belgium. These nest boxes are mainly used by the principal hosts of I. arboricola, the great tit Parus major and the blue tit Cyanistes caeruleus. As these birds typically return to the same cavity for roosting or breeding, ticks within nest boxes were expected to be highly related, and tick populations were expected to be spatially structured among woodlots and among nest boxes within woodlots. In line with the expectations, genetic population structure was found among woodlots and among nest boxes within woodlots. Surprisingly, there was considerable genetic variation among ticks within nest boxes. This could be explained by continuous gene flow from ticks from nearby tree holes, yet this remains to be tested. A pairwise relatedness analysis conducted for all pairs of ticks within nest boxes showed that relatedness among larvae was much higher than among later instars, which suggests that larvae are the most important instar for tick dispersal. Overall, tick populations at the studied spatial scale are not as differentiated as predicted, which may influence the scale at which host–parasite evolution occurs.     

潜在洞巢资源差异对次级洞巢鸟及繁殖鸟类群落的影响

为了解次生林中潜在洞巢资源(包括各种啄木鸟的啄洞和人工巢箱)的多寡对次级洞巢鸟集团及繁殖鸟类群落结构的影响, 2007年11月至2008年7月, 我们在吉林省吉林市大岗林场选择洞巢密度不同的样地, 对其次级洞巢鸟及鸟类群落结构进行了比较研究。根据洞巢资源密度我们将9块样地分为3组, 即巢箱区(啄洞密度最低, 悬挂人工巢箱使其潜在洞巢资源总密度大幅提高)、低密度区(啄洞密度较低, 无巢箱)和高密度区(啄洞密度较高, 无巢箱), 调查了3组样地内鸟类的组成和密度、潜在洞巢资源的利用情况等。3组样地中均调查到4种初级洞巢鸟, 其种类组成略有不同; 4种次级洞巢鸟在3组样地广泛分布, 分别为白眉姬鹟(Ficedula zanthopygia)、大山雀(Parus major)、沼泽山雀(P. palustris)和普通鳾(Sitta europaea)。巢箱区和高密度区的次级洞巢鸟总密度显著高于低密度区。巢箱区同高密度区一样, 大山雀和白眉姬鹟的密度显著高于低密度区, 这是由于大山雀和白眉姬鹟是人工巢箱的主要利用鸟种, 而沼泽山雀和普通鳾的密度在三组样地间差异不显著。初级洞巢鸟总密度与啄洞密度、次级洞巢鸟总密度与潜在洞巢资源总密度都呈显著正相关关系。潜在洞巢资源丰富的样地中鸟类群落多样性指数显著高于潜在洞巢资源贫乏样地中的鸟类群落多样性指数, 人为增加洞巢资源可以改变鸟类群落组成并显著提高群落的多样性指数。三组样地中鸟类群落的均匀性、丰富度指数和种间相遇率没有显著差异, 群落相似性指数也相近。高密度区和低密度区鸟类群落集团结构相似。次级洞巢鸟密度的增加短时期内未对群落内其他主要鸟种的密度产生显著影响。研究结果显示, 初级洞巢鸟的密度决定了啄洞的丰富程度, 而洞巢资源的差异会对次级洞巢鸟集团的分布模式产生影响, 进而影响整个繁殖鸟类群落的结构。     

Variable effects of the Hen Flea Ceratophyllus gallinae on the breeding success of the Great Tit Parus major in relation to weather conditions

We investigated the effect of an ectoparasite, the Hen Flea Ceratophyllus gallinae (Siphonaptera), on the reproductive success of the Great Tit Parus major, a hole-nesting passerine bird. Parasite levels of cleaned nesting boxes were experimentally manipulated during the egg-laying period of the birds either by spraying nests with pyrethrin or by introducing c. 100 adult fleas, while other nests were left as controls. Only in 2 out of 5 years did hen fleas significantly affect reproductive success. Nestlings from parasitized nests showed reduced body-mass, tarsus-length and condition, whereas wing-length did not differ between nestlings reared with or without fleas. The impact of the fleas on the growth performance of host nestlings was more noticeable in years with lower temperatures and higher precipitation.     

Anthropogenic noise reduces avian feeding efficiency and increases vigilance along an urban–rural gradient regardless of species’ tolerances to urbanisation

Anthropogenic noise can adversely impact urban bird populations by interfering with vocal communication. Less research has addressed if anthropogenic noise masks the adventitious sounds that birds use to aid predator detection, which may lead to increased vigilance and reduced feeding efficiency. We test this hypothesis using a controlled playback experiment along an urban–rural gradient in Sheffield (UK). We also test the related predictions that anthropogenic noise has the greatest impacts on vigilance and feeding efficiency in rural populations, and on species that are more sensitive to urbanisation. We focus on six passerines, in order from most to least urbanised (based on how urbanisation influences population densities): blue tit Cyanistes caeruleus, robin Erithacus rubeculla, great tit Parus major, chaffinch Fringilla coelebs, coal tit Periparus ater and nuthatch Sitta europaea. We used play-back of anthropogenic urban noise and a control treatment at 46 feeding stations located along the urban–rural gradient. We assess impacts on willingness to visit feeders, feeding and vigilance rates. Exposure to anthropogenic noise reduced visit rates to supplementary feeding stations, reduced feeding rates and increased vigilance. Birds at more urban sites exhibit less marked treatment induced reductions in feeding rates, suggesting that urban populations may be partially habituated or adapted to noisy environments. There was no evidence, however, that more urbanised species were less sensitive to the impacts of noise on any response variable. Our results support the adventitious sound masking hypothesis. Urban noise may thus interfere with the ability of birds to detect predators, reducing their willingness to use food rich environments and increase vigilance rates resulting in reduced feeding rates. These adverse impacts may compromise the quality of otherwise suitable foraging habitats in noisy urban areas. They are likely to be widespread as they arise in a range of species including common urban birds.     

Bird predation by tawny owls (Strix aluco L.) and its effect on the reproductive performance of tits

The density of great tit Parus major L. and blue tit Parus caeruleus L. was artificially increased by placing nest-box colonies for these species in the vicinity of the nests of breeding tawny owls during 1993–1997. Bird prey composition in the owl nests, the proportion of parents disappearing from the breeding tit populations and the reproductive performance of the widowed parents were analysed. The frequency of predation on tits by tawny owls was greater in areas where tit density had been artificially increased. Owls preyed more on tits during the feeding period of owlets than during the incubation period and more in years when snow covered the ground during the incubation period than when it did not. Mortality due to predation was male biased and more females lost their mates in populations breeding near tawny owl nests. Reproductive performance of the widowed parents was lower and their body weights were lighter at the end of the nestling period than those found in birds rearing youngs with their mates. Predation by owls increased the between-year turnover in the breeding tit population: widowed parents did not return to the nesting site for the next breeding season.     

人工巢箱条件下两种山雀鸟类的同域共存机制

种间竞争会导致鸟类对自身的生存策略进行多方面调整,将多种因素结合起来分析不同鸟类的同域共存机制具有十分重要的意义.2009-2011年的3-7月,在辽宁省东部山区以悬挂人工巢箱的方法招引杂色山雀(Parus varius)和大山雀(Parus major),通过比较这两种鸟类在繁殖时间、繁殖参数和巢址选择上的差异,分析其繁殖期的栖息地选择及繁殖对策,探讨这两种鸟类同域共存的机制.结果表明,生态位的部分分离是大山雀和杂色山雀能够长期共存的基础.两者都是在繁殖期到来立即开始繁殖,均出现两次繁殖高峰,采用消减窝卵数的对策来适应环境质量的下降.对繁殖参数的分析表明,两种鸟类的繁殖对策都为k-选择,但大山雀略偏向r端,大山雀倾向高窝卵数、低繁殖成功率的繁殖策略;杂色山雀倾向低窝卵数、高繁殖成功率的繁殖策略.两种鸟类都选择在林龄较长的森林中筑巢,但是大山雀较注重巢址的安全性能,巢距地面较高,周围乔木密集;杂色山雀较为注重植被类型的选择,巢址多选择在植被多样、灌木生长茂盛的针阔混交林中,推测可能与杂色山雀的食物构成有关.     

SONGS OF BLUE TITS PARUS CAERULEUS PALMENSIS FROM LA PALMA (CANARY ISLANDS)—A TEST OF HYPOTHESES

ABSTRACT

Parus major and Parus caeruleus palmensis have some song types in common. They consist of whistled element-types in different frequency ranges. Both species show territorial reactions to playback of the song-types belonging to the other species. P.c. palmensis does not share any songtypes with Central European Parus caeruleus. This is confirmed by playback experiments with the different song types, which do not elicit any territorial behaviour. The songs of P.c. palmensis also differ from those of blue tits from any other Canary Island. They may be derived from contact calls of the Lanzarote population. They have been developed by young birds that had not yet learnt their songs when they colonized La Palma from Lanzarote without reaching any of the other Canary Islands. It is suggested that the uniform song repertoire was developed by adapting the already learned contact calls to each other. The similarities to song types of P. major are due to convergence rather than character displacement. All other Canary Island tit populations share the main features of their songs, which are characterized by quick frequency changes. It seems most likely that these islands have been colonized by birds which had already learnt their songs. Differences in song repertoires are mainly caused by drift events which happen to occur because of population bottlenecks during the colonization process.     

Density dependent effects between three competitive bird species

Summary Density and breeding success of the great tit Parus major, blue tit Parus caeruleus and collared flycatcher Ficedula albicollis were studied in nest box colony in oak forest over a period of 19 years.Intraspecific density dependent clutch size reduction was found with blue tit and great tit. In interspecific relation the high density of blue tits reduced the clutch size of great tits.In the hatching period neither intraspecific nor interspecific density dependence were showed between the tits when the third competitive species, collared flycatcher was present. The collared flycatcher significantly reduced the hatching success of both tit species and the number of fledglings of great tit.The effects of the great tits and combined density of the great and blue tits on the hatching failure and number of fledglings of collared flycatcher were found when the density of the tits was high. There were not significant relationships to the single density of blue tits.The temporal variability of the competition of the three bird species is discussed.     

Snake-like calls in breeding tits

Hole-nesting tits belonging to the family Paridae produce a hissing display that resembles the exhalatory hiss of a snake. When a predatory animal enters the nest hole of a tit, tits often hiss vigorously, while lunging their head forward and shaking their wings and tail, until the intruder retreats. We assessed the acoustic similarity between such hiss calls from 6 species of tits, snake hisses, and tit syllables used in alarm vocalizations, as well as white noise as a control. Tit hiss calls showed a high degree of similarity with snake hisses from 3 different snake families. Tit hisses had lower similarity to syllable alarm calls, suggesting convergence of tit hisses in their spectral structure. Hiss calls would only be effective in protecting nest boxes if nest predators responded to these calls. In order to test this hypothesis, we trained individual Swinhoe’s striped squirrels, Tamiops swinhoei hainanus, a common predator of egg and nestling tits, to feed at feeders in proximity to nest boxes. We compared the aversive response of squirrels to tit’s hiss calls and white noise, presented in random order. Squirrels showed a higher degree of avoidance of feeders when hiss calls were played back than when white noise was presented. In conclusion, our study suggests that hole-nesting birds have evolved convergent snake-like hiss calls, and that predators avoid to prey on the contents of nest boxes from which snake-like hisses emerge.     

Interspecific territoriality in the chaffinch and great tit on islands and the mainland of Scotland: Playback and removal experiments

Territories of the chaffinch (Fringilla coelebs) and great tit (Parus major) overlap on the mainland of Scotland but are mutually exclusive on adjacent islands. Birds on the mainland responded only to playbacks of conspecific song. On the island both species responded to conspecific song and non-conspecific song, but not to the song of the willow warbler. On the island, great tits responded significantly more strongly to songs than did the chaffinches. When chaffinches were removed from part of the island woodland, great tits rapidly expanded into the vacated areas. It is suggested that on the island there is a limit to the co-existence of these two species because they forage in a similar manner and that this has resulted in interspecific territoriality, not seen on the richer mainland environment.     

Density fluctuations represent a key process maintaining personality variation in a wild passerine bird

Heritable personality variation is subject to fluctuating selection in many animal taxa; a major unresolved question is why this is the case. A parsimonious explanation must involve a general ecological process: a likely candidate is the omnipresent spatiotemporal variation in conspecific density. We tested whether spatiotemporal variation in density within and among nest box plots of great tits (Parus major) predicted variation in selection acting on exploratory behaviour (n = 48 episodes of selection). We found viability selection favouring faster explorers under lower densities but slower explorers under higher densities. Temporal variation in local density represented the primary factor explaining personality‐related variation in viability selection. Importantly, birds did not anticipate changes in selection by means of adaptive density‐dependent plasticity. This study thereby provides an unprecedented example of the key importance of the interplay between fluctuating selection and lack of adaptive behavioural plasticity in maintaining animal personality variation in the wild.     

Differential Begging and Locomotory Behaviour by Early and Late Hatched Nestlings Affecting the Distribution of Food in Asynchronously Hatched Broods of Altricial Birds

Distribution of food to early and late hatched nestlings was studied in asynchronously hatched broods of the great tit Parus major, the blackbird Turdus merula, and the fieldfare T. pilaris. Food distribution is related to the locomotory and begging behaviour and positions in the nest of these nestlings. Late hatched (small) nestlings were found to beg more often per feed than bigger nestlings and move more towards favoured positions in the nest to counteract selective feeding of bigger young. The functional significance of these differences in the behaviour of early and late hatched nestlings are discussed. It is argued that they are adaptive by 1) ensuring that each nestling survives when food supplies are ample, and 2) by mediating an optimal brood reduction when food is insufficient to raise the entire brood. The roles of asynchronous hatching, and selective feeding which follows from differential behaviour of early and late hatched young are discussed in relation to food conditions during the breeding season.     

Island shape,size, and isolation affect nest‐site selection by Little Terns

ABSTRACT Populations of many seabirds and other species that nest along coasts are declining due to habitat degradation and loss. An improved understanding of the species‐specific factors that determine nest density across a landscape is therefore critical for conservation efforts. We examined factors that affected the density (number per hectare) and abundance (number at a sampling site) of nests of Little Terns (Sternula albifrons) on the Sinai Peninsula, Egypt. Terns preferred to nest on islands rather than the mainland, with islands constituting 64% of the area surveyed, but containing 99% of the 439 tern nests we found. Nest densities were highest on islands that were small, located at moderate distances from the mainland, and irregularly shaped or elongated. Most nests (69%) were on islands with areas < 3 ha, although these islands represented < 5% of total island area, and islands with the highest nest densities were 80–300 m from the mainland. Terrestrial predators were more likely to occur on larger islands, visiting three of the largest four islands. Most tern nests were within 1 m of shorelines, causing island perimeter to be a strong influence on nest density. Island shape was the only factor that significantly affected nest abundance, with more nests on islands with relatively long perimeters for their size. Our results suggest that protection or creation of relatively small, slender islands at moderate distances from shore may be an effective means of increasing the number of breeding sites for Little Terns. Although not generally considered a potential determinant of nest site preferences for seabirds, island shape is likely to be important for species that prefer sites adjacent to water, including species that nest on beaches and seaside cliffs.     

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.     

Effects of habitat fragmentation on provisioning rates, diet and breeding success in two species of tit (great tit and blue tit)

The aim of this study was to examine the effects of forest fragmentation on the ability of parent birds to provide their young with an adequate food supply. To examine whether prey population densities of the great tit (Parus major L.) and the blue tit (P. caeruleus L.) vary between study areas in different forest size classes we compared provisioning rates and chick diet and related these parameters to breeding success. We filmed 217 nests over two breeding seasons and collected data on frass fall as a general estimate of caterpillar availability. Nests which were attended by none or one parent only during filming (n = 46) were excluded from the analyses. In both years and for both species feeding rates were highest in the smallest fragments and lowest in the large forest. There was also a suggestion that differences in feeding rates between areas vary between years. We found no consistent tendency for prey size to change with forest size, although both species brought slightly smaller prey items to the nest in the smallest forest fragments and feeding rates correlated negatively with prey size. Caterpillars were the main item fed to nestlings, in both species. We found no evidence to suggest that either frass fall or the proportion of caterpillars in the diet varied with forest size. There was also no correlation between mean frass fall and the total number of caterpillars brought to the nests, in either species. Breeding success, as measured by clutch size, brood size, fledging weight and fledging success, did not differ between the small fragments and the large forest, in either species. There was also no relationship between provisioning rate (as concerns volume of prey fed to nestlings and the quality of chick diet) and breeding success parameters. In conclusion, this study does not suggest suboptimal foraging or breeding conditions in small fragments compared to a nearby large forest, for either species. Received: 23 June 1997 / Accepted: 29 December 1997     

Nest site preference depends on the relative density of conspecifics and heterospecifics in wild birds

Background

Social learning allows animals to eavesdrop on ecologically relevant knowledge of competitors in their environment. This is especially important when selecting a habitat if individuals have relatively little personal information on habitat quality. It is known that birds can use both conspecific and heterospecific information for social learning, but little is known about the relative importance of each information type. If provided with the choice between them, we expected that animals should copy the behaviour of conspecifics, as these confer the best information for that species. We tested this hypothesis in the field for Pied Flycatchers Ficedula hypoleuca arriving at their breeding grounds to select a nest box for breeding. We assigned arbitrary symbols to nest boxes of breeding pied flycatchers (conspecifics) and blue and great tits, Cyanistes caeruleus and Parus major (heterospecifics), in 2014 and 2016 in two areas with different densities of tits and flycatchers. After ca 50% of flycatchers had returned and a flycatcher symbol was assigned to their nest box, we gave the later arriving flycatchers the choice between empty nest boxes with either a conspecific (flycatcher) or a heterospecific (tit) symbol.

Results

As expected, Pied Flycatchers copied the perceived nest box choice of conspecifics, but only in areas that were dominated by flycatchers. Against our initial expectation, flycatchers copied the perceived choice of heterospecifics in the area heavily dominated by tits, even though conspecific minority information was present.

Conclusions

Our results confirm that the relative density of conspecifics and heterospecifics modulates the propensity to copy or reject novel behavioural traits. By contrasting conspecific and heterospecific ecology in the same study design we were able to draw more general conclusions about the role of fluctuating densities on social information use.

     

A new method for catching cavity‐nesting birds during egg laying and incubation

ABSTRACT The physiological condition of female birds during the egg‐laying and incubation periods is of considerable interest and yet is relatively understudied in wild birds, primarily due to the difficulty of catching birds during this period without causing nest desertion. We therefore developed a box‐net to capture cavity‐nesting birds using sections of a mist‐net placed around a metal cubic frame. We captured female Great Tits (Parus major) as they left nest boxes during the egg‐laying and incubation periods and measured desertion rates. Using box‐nets, we captured 108 of 119 (90%) females during egg laying and 10 of 12 (83%) during incubation. Our recapture rate over two consecutive days during incubation was 50% (5 of 10). Females not captured left nest boxes before we attempted to capture them, escaped through a hole in the mist‐net, or remained in nest boxes for more than 2 h, after which we ended capture attempts. Overall, 22% of egg‐laying females deserted, with desertion rates highest early in the egg‐laying period. Desertion rates of females captured using box‐nets did not differ from those of undisturbed females. One of 10 females captured in a box‐net deserted during the incubation period. Box‐nets are portable, can be set up and taken down quickly and easily, and could potentially be used with nest boxes or natural cavities at any height. Box‐nets are easy to construct and adaptable for use with an array of cavity‐nesting birds, and can be an important tool for studying female physiology during egg laying and incubation.