Blue tits (Cyanistes caeruleus) respond to an experimental change in the aromatic plant odour composition of their nest

Although the use of olfaction by birds is now widely recognised, the olfactory abilities of passerine birds remain poorly explored, for historical reasons. Several studies however suggest that passerines can perceive volatile compounds in several biologically relevant contexts. In Corsica, recent findings suggest that cavity-nesting blue tits may use volatile compounds in the context of nest building and maintenance. Although they build their nests mainly from moss, female blue tits also frequently incorporate fragments of several species of aromatic plants in the nest cup. In field experiments, breeding female blue tits altered their nest maintenance behaviour in response to experimental addition of aromatic plants in their nest. In aviary experiments, captive male blue tits could be trained to detect lavender odour from a distance. Here I report results from a field study aimed to test whether adult blue tits altered their chick-feeding behaviour after an experimental change in nest odour composition. I experimentally added fragments of aromatic plant species that differed from those brought in the nests before the start of the experiment in a set of experimental nests and added moss, the basic nest material, in a set of control nests. Both male and female blue tits hesitated significantly longer entering the nest cavity after addition of new aromatic plant fragments, as compared to moss addition. This response was especially observed during the first visit following the experimental change in nest plant composition. Nest composition treatment had no effect on the time spent in the nest. This study demonstrates that free-ranging blue tits detect changes in nest odour from outside the nest cavity.     

Nest site selection and efficacy of artificial nests for breeding success of Scarlet Macaws Ara macao macao in lowland Peru

Psittacidae (parrots) have the most threatened species of any bird family in the world. Most parrots are obligate secondary cavity nesters, and can be limited in their breeding success by the availability and quality of nest hollows. However, nesting opportunities for parrots can be increased by provision of artificial nest boxes. The Tambopata Macaw Project has been studying the breeding ecology and natural history of the Scarlet Macaw Ara macao macao in the south-eastern Peruvian Amazon for over 20 years by monitoring natural nest hollows and two types of artificial nest (wooden and PVC). We present data for breeding success in natural and artificial nests over 12 consecutive breeding seasons. The aims of this study were to: (a) determine the nesting requirements and reproductive success of breeding macaws; and, (b) compare the efficacy of the two types of artificial nests and natural nest cavities. Our data showed a high rate of reoccupation of successful nests in consecutive years and that nests in artificial and natural nests had very similar reproductive parameters. Our results indicate that artificial nest types can be used by conservation managers seeking to assist A. macao populations where nest hollows are in short supply, and that artificial nests can contribute important data to natural history studies of species where access to natural nests is limited.     

Are Blackcaps (Sylvia atricapilla) defending their nests also calling for help from their neighbours?

One hypothesized function of conspicuous mobbing of intruders by bird nest owners is to attract neighbouring birds (“calling for help” hypothesis) or third-party predators (“attract the mightier” hypothesis). These may help the nest owners by distracting and/or attacking the mobbed intruder. To date, these hypotheses have been studied solely during the mobbing of predators. Here, for the first time, I have studied mobbing attraction in the context of brood parasitism. I experimentally tested the Blackcap (Sylvia atricapilla), a small passerine with a highly aggressive and conspicuous nest defence behaviour. I elicited the aggressive responses of Blackcaps by presenting stuffed dummies of the brood parasitic Common Cuckoo (Cuculus canorus) and controls near their nests. At 32% of the nests (n = 75), the responses of the Blackcaps to dummies attracted up to 15 birds per trial from 21 passerine species. Most of the attracted birds were heterospecifics and rarely participated in mobbing; thus the “calling for help” hypothesis was not supported. No potential predators of the Cuckoo were attracted despite them living in the study area and despite prolonged mobbing by Blackcaps; thus rejecting the “attract the mightier” hypothesis. I argue that this hypothesis is unlikely to apply to typical avian predators during nest predation acts because these only last for several seconds. The number of attracted birds was a positive function of the owner’s intensity of nest defence as measured by the rates of alarm calling but not visual cues (rates of attacks). Suitable and unsuitable Cuckoo hosts did not differ in their behaviour in the vicinity of defended nests. The observed pattern of the positive correlation between the intensity of nest defence and the number of attracted birds is most likely a proximate by-product of the conspicuous nest defence by Blackcaps (but may well be adaptive for recruiting neighbours themselves). Thus, the mobbing behaviour of the Blackcap is directed towards the brood parasite and not towards other audience predators or potential recruits to the mob.     

Effects of Edge Habitat and Nest Characteristics on Depredation of Artificial Nests in Fragmented Australian Tropical Rainforest

Variation in nest predation levels associated with rainforest fragmentation (edge effects) was assessed in Australia's Wet Tropics bioregion. Artificial nests were placed in the forest understorey at seven edge sites where continuous forest adjoined pasture, seven interiors (about 1 km from the edge), and six linear riparian forest remnants (50–100 m wide) that were connected to continuous forest. Four nest types were also compared, representing different combinations of two factors; height (ground, shrub) and shape (open, domed). At each site, four nests of each type, containing one quail egg and two model plasticine eggs, were interspersed about 15 m apart within a 160 m transect during September–October 2001. Predators were identified from marks on the plasticine eggs. The overall depredation rate was 66.5% of 320 nests' contents damaged over a three-day period. Large rodents, especially the rat Uromys caudimaculatus, and birds, especially the spotted catbird Ailuroedus melanotis, were the main predators. Mammals comprised 56.5% and birds 31.0% of predators, with 12.5% of unknown identity. The depredation rate did not vary among site-types, or between open and domed nests, and there were no statistically significant interactions. Nest height strongly affected depredation rates by particular types of predator; depredation rates by mammals were highest at ground nests, whereas attacks by birds were most frequent at shrub nests. These effects counterbalanced so that overall there was little net effect of nest height. Mammals accounted for 78.4% of depredated ground nests and birds for at least 47.4% of shrub nests (and possibly up to 70.1%). The main predators were species characteristic of rainforest, rather than habitat generalists, open-country or edge specialists. For birds that nest in the tropical rainforest understorey of the study region, it is unlikely that edges and linear remnants presently function as ecological population sinks due to mortality associated with increased nest predation.     

Nest Defence Behaviour of the Eurasian Kestrel (Falco tinnunculus) Against Human Predators

Man has become the main predator of many animal species. Because the characteristics of humans are quite distinct with respect to other terrestrial predators, the cost and benefits of defence behaviour may also differ. In this paper, we study the factors affecting nest defence behaviour of the Eurasian Kestrel ( Falco tinnunculus canariensis ) against a potential human predator throughout the reproductive cycle, as well as the balance of cost and benefits of this behaviour. The study population inhabits the island of Tenerife, and the nests are located on cliffs. The intensity of the defensive behaviour was unrelated to the frequency of human visits, prey abundance (Orthoptera, Coleoptera, lizards, birds and rodents), laying date, or number of offspring in the nest. Both males and females increased their defensive behaviour as the nesting period advanced, particularly when the chicks were older than 15 days. Moreover, the intensity of the defensive behaviour, especially of males, decreased when nests were more inaccessible. Although nest defence behaviour against humans appeared to be similar to those against other predators, the benefits are not clear because the probability of nest robbing was greater for these more aggressive pairs.     

Ectoparasites,nest site choice and breeding success in the pied flycatcher

It has recently been suggested that nest box studies might bias the measurement of behavioural and life-history traits, because the removal of old nests may reduce the load of ectoparasites. This experimental artefact may have notable effects on nest site choice and breeding success in cavity-breeding birds. We tested (i) if pied flycatchers Ficedula hypoleuca prefer clean nest boxes and (ii) if old nest material affects the number of parasites and the breeding success of pied flycatchers. In the first experiment we offered birds one cleaned nest box and one nest box with old nest material from the previous year. The two nest boxes were placed in very similar sites near each other. In this experiment all pied flycatchers clearly preferred dirty nest boxes. In the second part of the study we distributed clean nest boxes and dirty ones on the same study area. After breeding was over we counted the number of fleas Ceratophyllus gallinae in the nest material. This flea species was the most abundant and probably the most hazardous parasite in the nests. Surprisingly, we found that there were significantly more fleas in the nest boxes with nests of the current year only than in the boxes with nests of both current and previous year. This might explain the preference for the dirty boxes. However, our results do not indicate that the number of fleas affects breeding success in the pied flycatcher.     

利用多旋翼微型飞行器监测天山地区高山兀鹫繁殖简报

高山兀鹫(Gyps himalayensis)喜在山崖绝壁上营巢,海拔2 400~4 800 m的野外高空作业攀爬危险,观察难度较大。2014年4~9月,笔者在新疆天山中段尝试用国产遥控多旋翼微型飞行器寻找和拍摄高山兀鹫巢穴,结合路线搜索法和行为扫描法,进行栖息地调查、巢数统计、巢材分析,以及窝卵(雏)数、雏鸟生长与发育、繁殖周期、食性及食物分析。在7个地点的14个巢区的调查统计表明,高山兀鹫喜欢在朝南的崖壁上集群营巢(78.6%朝南,n=112),最长的一个繁殖地绵延7.3 km,距另外一个较近的巢区约47 km。巢材以禾草为主,如早熟禾(Poa spp.)、针茅(Stipa spp.)、老芒麦(Elymus sibiricus)等,缺乏粗大枝条。高山兀鹫1~2月产卵,窝卵数为1枚(n=21),整个繁殖周期长达8~9个月(1~10月份)。     

Nest temperature fluctuations in a cavity nester,the southern ground-hornbill

Southern ground-hornbills Bucorvus leadbeateri inhabit savanna and bushveld regions of South Africa. They nest in the austral summer, which coincides with the wet season and hottest daytime temperatures in the region. They are secondary cavity nesters and typically nest in large cavities in trees, cliffs and earth banks, but readily use artificial nest boxes. Southern ground-hornbills are listed as Endangered in South Africa, with reintroductions into suitable areas highlighted as a viable conservation intervention for the species. Nest microclimate, and the possible implications this may have for the breeding biology of southern ground-hornbills, have never been investigated. We used temperature dataloggers to record nest cavity temperature and ambient temperature for one artificial and 11 natural southern ground-hornbill tree cavity nests combined, spanning two breeding seasons. Mean hourly nest temperature, as well as mean minimum and mean maximum nest temperature, differed significantly between southern ground-hornbill nests in both breeding seasons. Mean nest temperature also differed significantly from mean ambient temperature for both seasons. Natural nest cavities provided a buffer against the ambient temperature fluctuations. The artificial nest provided little insulation against temperature extremes, being warmer and cooler than the maximum and minimum local ambient temperatures, respectively. Nest cavity temperature was not found to have an influence on the breeding success of the southern ground-hornbill groups investigated in this study. These results have potentially important implications for southern ground-hornbill conservation and artificial nest design, as they suggest that the birds can tolerate greater nest cavity temperature extremes than previously thought.     

Colony development and social structure in a subtropical paper wasp,Ropalidia fasciata (F.) (Hymenoptera: Vespidae)

More than 50% of nests of Ropalidia fasciata were founded by association of foundresses (multifemale nests). The multifemale nests were generally initiated earlier and grew faster than the single-female nests. The survival rate of the multifemale nests was significantly higher than that of single-female nests, and the productivity as measured by the number of cells produced per foundress had a peak at a foundress-group size from 6 to 10. The number of marked foundresses which were seen on their original nest decreased as the colony cycle proceeded, but some of them continued to coexist on the original nests after emergency of many female progeny. Except in the case where a large number of foundresses attended a young nest so that some foundresses could not sit on the nest, the dominance interactions among cofoundresses were mild. More than twothirds (71.4%) of nests (including those at the post-emergence stage) had multiple egg-layers. The foundress association in this species is considered to be beneficial for every foundress because it raises ability to avoid predation or to reconstruct their nests when the nests are destroyed by typhoons.     

Influence of nest-floor slope on the nest choice of laying hens

Group nests in alternative housing systems for laying hens primarily fulfil the hen's needs for seclusion and protection. Commercial nests used in Switzerland are built according to the provisions of the Swiss Animal Welfare Legislation. However, nest types can differ in aspects, such as floor slope, that could have an impact on egg-laying behaviour. Floor slope has to be designed so that eggs roll away without breaking and so that hens feel comfortable laying their eggs. In commercial nests, the slope is usually between 12% and 18%. The aim of this study was to investigate the effect of floor slope on the hen's nest preference and laying behaviour. We predicted that hens would prefer nests with a lower sloped floor for evolutionary reasons and for reasons related to comfort.Eight pens, each with 17-18 white laying hens (LSL), were equipped with two roll-away nests (0.54 m²) having different floor slopes (12% and 18%). Eggs were collected each day (from approximately 20 weeks of age until 28 weeks of age); the number of eggs in each nest and on the floor of the pens was recorded. Behaviour inside the nest was filmed for two consecutive days during the main egg-laying time from the second hour to the fifth hour (4 h) after lights came on in week 27/28. The following data were recorded: number of hens in each nest, the nest visits/egg number ratio, the number of sitting events, the body alignment of hens sitting in the nest and the number and duration of nest visits. Data were analysed with a repeated-measures ANOVA. There was no difference between the numbers of eggs in the two nests, but more hens were counted in nests with a 12% slope (p = 0.027). The ratio between the number of nest visits and number of eggs did not differ significantly between the nests. However, we counted more sitting events in the nest with 12% slope (p = 0.007). The percentage of body alignment towards the back (p = 0.044) and towards the front (p = 0.028) of the nest differed between the nests. Furthermore, for nest visits lasting between 10 and 90 min, we found significant differences in the total number of nest visits (p = 0.039). For visits in this range of duration, we also found significant differences for nest visits with sitting (p = 0.025) and for the number of nest visits with egg laying (p = 0.049). All of these differences favoured the 12% nest.Both nests were generally accepted by the hens. However, because of the higher number of hens counted in the 12% nest and the higher amounts of nest visits and sitting events found in these nests, we recommend to use nests with a floor slope of 12% rather than 18%.     

Life cycle of Anthracophora rusticola (Coleoptera: Cetoniidae) from the commensal nests of Chinese Sparrowhawks (Accipiter soloensis)

Commensal breeding habits of the Anthracophora rusticola (Coleoptera: Cetoniidae) in stick nests of carnivorous, piscivorous, and omnivorous birds were recently reported, but the detailed life history of the scarab beetle has not been thoroughly elucidated. To understand the breeding cycle of the declining A. rusticola related to that of nesting Chinese sparrowhawks (Accipiter soloensis) in Korea, we examined six sparrowhawk nests from 2005 to 2008 and reared larvae and cocoons in a cage in 2008. Each sparrowhawk nest hosted 11.3 ± 3.0 larvae and cocoons, implying that sparrowhawk nests might be the most important nesting resource of the beetles in Korea. The beetles may lay their eggs between late May and early July after nest building by sparrowhawks. Larvae were observed from July to August in the sparrowhawk nests, and adult beetles emerged in September after a mean pupal period of 25.5 days. Our results on the coinciding breeding of two commensal taxa over three months from May to September may provide key information regarding the life history of the commensal scarabid beetle and potential causes of the concurrent decline of both taxa in Korea.     

Predation of Lapwing Vanellus vanellus nests on lowland wet grassland in England and Wales: effects of nest density, habitat and predator abundance

There is concern that predation of Lapwing Vanellus vanellus nests may create additional pressure on declining populations of this species in Europe. At seven sites in England and Wales, daily nest predation rates on 1,390 nests were related to variables using Generalised Linear Mixed Models. The strongest predictor was Lapwing nest density (number of nests within 100 m): predation rates declined as nest density increased. Since nocturnal species, probably mammals, have been identified as the major predators of Lapwing nests at these sites, these results suggest that Lapwings are able to deter mammalian predators or may settle to nest at high densities in areas with low predation pressure. At the site level, there was no relationship between Lapwing nesting density and fox density, and a positive relationship with Carrion Crow Corvus corone nesting density. There was a weaker effect of distance to field boundary: nests closer to boundaries were more likely to be predated. Weak interactive effects between crow density and both nest visibility and distance to vantage point were identified in models using a reduced subset of nests. These were counter-intuitive, did not persist in the larger data set, and do not have obvious explanations. If Lapwings nesting at high density are able to deter predators, there are implications for land management. Smaller areas could be managed within potential breeding habitat to encourage Lapwings to nest in dense colonies. Selection of larger fields for such management, where nests could be located far from the field boundary should improve the value of such measures.     

On the evolution of clutch size and nest size in passerine birds

Summary I examined the hypothesis that the clutch size of some altricial birds may be limited by over-crowding of the nestlings in the nest, by comparing data on different species of European passerines. Large-sized birds build, relative to the body, larger nests than small-sized birds, both as regards the inner and the outer nest widths and as regards edge breadth; only inner nestcup depth did not change relatively to body size. Nest size also varied in relation to nesting place. Birds with open nests built off the ground had a rather narrow nestcup, whereas those with a domed nest, or which nest in a cavity, had a wide nestcup. When only open-nesters were compared, birds nesting on, or close to, the ground tended to have a wider nestcup than birds nesting above the ground. Inner nestcup width was correlated with the amount of mosses and lichens used in building the nest; the more of such materials the narrower the nestcup. The three variables: standardised body size, nesting place, and type of nesting material used accounted for 92% of the overall variation observed in inner nestcup width. When controlling for adult body size, clutch size was positively correlated with the size of the nestcup. A multiple regression analysis showed that relative nestcup depth, nest site, and type of nesting materials used, accounted for 64% of the overall variation in clutch size.     

Habitat deterioration and efficiency of antipredator strategy in a meadow-breeding wader,Temminck's stint (Calidris temminckii)

Many populations of waders breeding on open shores and shores with short vegetation especially on the Baltic coasts have recently become endangered. The declines have taken place simultaneously with human-induced loss and deterioration of habitats due to eutrophication and overgrowth. To investigate mechanisms by which habitat changes could affect breeding success and ultimately population dynamics, we studied an endangered coastal population of Temminck's stint. We hypothesized that the rate of nest predation has become higher because the nest defence strategy (early detection of predator and early departure from the nest), which originally evolved in open habitats, is less effective on shores with reduced visibility. As predicted, nests survived better on wide than on narrow shores. Predation made a major contribution to this trend, although successful and predated nests did not differ in concealment at a microhabitat scale. The better the visibility from the nest, the longer was the flushing distance, but only in response to alarm calls or behaviour of other species, not when they were absent. Temminck's stints seem to obtain information about an approaching predator visually from sentinels. Therefore, it is essential that there is at least moderate visibility around the nest. We conclude that habitat characteristics – visibility from the nest and sentinel birds – affect the effectiveness of the nest defence strategy of Temminck's stint. These should be taken into account when seeking causes and mechanisms for declines of Temminck's stint and other waders of open and shortly vegetated shores. Received: 5 January 1998 / Accepted: 20 April 1998     

Adjustment of incubation according to the threat posed: a further signal of enemy recognition in the Blackcap Sylvia atricapilla?

Nest predation and brood parasitism are costly for nest owners, and natural selection should therefore favour the evolution of parental counterdefences. We addressed the question of whether Blackcaps Sylvia atricapilla change their incubation behaviour in response to various nest intruders and whether this adjustment matches the intensity of mobbing exhibited towards these intruders. Near focal nests, we successively exposed a dummy of a brood parasite, nest predator and an innocuous species. After the parents had responded, we removed the dummy and filmed their incubation. The most aggressive response towards the Common Cuckoo Cuculus canorus and high nest attendance after its disappearance indicated recognition of the brood parasite. Low-intensity response to the Jay Garrulus glandarius, together with reduced subsequent parental care, suggested that Blackcaps perceived it either as less deleterious at the egg stage than the Cuckoo or as a danger to themselves. Almost no aggression towards the Turtle Dove Streptopelia turtur, along with the resumption of incubation after its removal, implied that Blackcaps recognised it as harmless. In addition, we found that the level of aggression positively correlated with nest attendance, suggesting a link between the intensity of mobbing and subsequent parental care. Altogether, our results demonstrate that the issue of enemy recognition may be viewed as a complex of both aggressive and post-presentation behaviours.     

Nest predation is little affected by parental behaviour and nest site in two African Sylvia warblers

Parental behaviour and nest site are supposed to affect nest predation in birds. Few nest visits and high nest attentiveness are assumed to lead to low predation rates. Poorly concealed nests are thought to be more likely to be preyed upon than well concealed nests. Studies on the relationship between parental behaviour, nest site, and nest predation are rare and none have, so far, been conducted in the Afrotropics. We studied the effect of nest site, nest visitation rate, and nest attentiveness on the nest predation rate of the two tropical warblers Sylvia boehmi and Sylvia lugens in Kenya. Parental behaviour and predation on nests of 13 breeding pairs of both species were observed daily in two consecutive breeding seasons. In both species, parental activity at the nest was low [0.9 trips to the nest in 30 min during incubation, maximum 4.6 (S. boehmi) and 5.8 (S. lugens) trips to the nest in the nestling stage]. Predation rates in both species were high (Mayfield nest success 19.4 and 33.2%). Our analysis revealed only weak evidence for an effect of nest site, nest visitation rate, and nest attentiveness on the predation rate. It is suggested that smaller clutches of tropical in comparison to northern temperate birds result from lower feeding rates in tropical ecosystems with high predation rates (Skutchs hypothesis). The underlying mechanism could not be proven in this study.     

Nest recognition in neighboring colonies: a comparison of two European species of Polistes wasps (P. dominulus and P. nimphus, Hymenoptera: Vespidae)

The ability of two species of Polistes wasps to distinguish their own from nearby nests was tested, following the procedure used by Espelie et al. Our experiments demonstrated that, in the laboratory, females of Polistes dominulus and Polistes nimphus preferentially selected their own nests rather than nearby nests. We also evaluated the role of odor cues in nest recognition by washing nests in hexane to remove the apolar solvent-soluble components of nest odor. Although P. nimphus females continued to discriminate nests even after washing, P. dominulus individuals failed to discriminate between their own and a foreign neighboring nest. In both species, wasps were able to recognize their own nests when nest extracts were subsequently reapplied to the nest surface. These results indicate that P. dominulus wasps recognize their nests through perception of nest odor. The ability of P. nimphus wasps to distinguish their own nests even after presumed removal of the nest odor is discussed. Received: January 27, 2000 / Accepted: May 22, 2000     

Termitarium volume as a determinant of invasion by obligatory termitophiles and inquilines in the nests of Constrictotermes cyphergaster (Termitidae, Nasutitermitinae)

A range of organisms can be found inside termite nests where the degree of association can vary from facultative to obligatory dependence. Studies of the dynamics of nest invasion are still unresolved, so how and when cohabitants enter termite nests remain open questions. This study analyzed one specific aspect of the dynamics of termite nest invasion by obligatory termitophiles and inquilines, i.e., whether cohabitants were more likely to invade a nest when it reached a critical nest size. We collected 36 Constrictotermes cyphergaster nests of different sizes and sampled their cohabitant fauna. Our results indicated that the invasion of C. cyphergaster nests by obligatory termitophiles and inquilines was dependent on nest size. There appeared to be a critical nest size above which nests were more prone to invasion. Above this size, there was a significantly higher likelihood of finding obligatory cohabitants. Termitophile species were observed in nests ≥2.2?L, whereas inquiline species were only occur in nests ≥13.6?L. This may indicate that the obligatory cohabitants studied here did not occupy C. cyphergaster nests at random and that they were dependent on features that made these nests suitable for cohabitation, which are linked to colony development.     

Forest fragmentation and rhinocryptid nest predation in central Chile

Fragmentation of forest landscapes can raise the intensity of nest predation by increasing the abundance and richness of generalist or introduced predators. Understory foraging birds, such as rhinocryptids, can be highly vulnerable to nest predation in fragmented landscapes because they often place their nests on the ground. Temperate deciduous forests in Chile have been intensively fragmented in the last centuries, causing changes in nest predator densities. We tested if predation of artificial nests, mimicking those of rhinocryptids, placed on and above ground was higher in the remnant fragments of central Chile due to an increase in predator abundance. The rate of nest predation in forest remnants was larger than in native continuous forest. Small mammals were the main nest predators. Despite high predation rates, the abundance of rhinocryptids is higher in forest remnants, suggesting that fragments might constitute ecological traps.     

Happy is the man that findeth wisdom

The hypothesis is suggested that resource depression is one important factor behind the observed regular nest spacing of many birds of prey. It predicts that the proportion of evasive prey in the predator's diet should be reflected in the degree of regularity in its nest spacing. The idea is tested on data from 24 raptorial bird populations of 19 species. The proportion of supposed evasive prey (birds and large mammals) in the diet was positively correlated with the degree of regularity in spacing of the nests, considering all populations or species. No such significant correlation was found for the six highly territorial species, whereas the correlation was highly significant for the other 13 species. Thus, the hypothesis seems most applicable to species with widely overlapping home ranges. However, resource depression could be one reason for territoriality.