Nest intruders, nest defence and foraging behaviour in the Black-and-white Casqued Hornbill Bycanistes subcylindricus

The female Black-and-white Casqued Hornbill Bycanistes subcylindricus uses mud to seal herself into a nest cavity and remains there until the nesting attempt has ended. The male hornbill is solely responsible for food provisioning and external defence of the nest. Data on hornbill nests in a Ugandan rain forest were used to test Martindale's (1982) model of nest defence and central place foraging. As predicted, nest guarding by the resident male hornbill during intrusions by conspecifics altered foraging patterns; the resident male foraged closer to the nest, made a larger number of shorter visits, and brought smaller food loads. There was a significant change in size composition of fruits brought before, during, and after intrusions. For short intrusions, the volumes of food brought per unit time did not change. However, if intrusions lasted for days or weeks, food delivery rates declined. Nest-sealing by the Black-and-white Casqued Hornbill appears to function primarily to protect the nest from conspecifics rather than from interspecific predators.     

Breeding success and nest site stereotypy in a population of Brewer's Blackbirds (Euphagus cyanocephalus)

Summary Nest site stereotypy and nest-site related breeding success was studied in a population of Brewer's Blackbirds in eastern Washington, USA. Four types of nest sites could be distinguished. Based on individually colour-ringed nestlings, imprinting or genetic fixation of a particular type of nest site can be ruled out since there is no correspondence between the type of nest a bird grew up in and the type it used when breeding. Bush nests make up about two thirds of all nests, and they are relatively more frequent than the other types in the first half of the breeding season, whereas the other types become more frequent in the second half of the nesting season. Differential breeding success was studied and its dependence on colony composition was investigated.The hypothesis that the birds are able to utilize nest site flexibility as an anti-predator strategy within colonies is not supported. Some nest sites are predictably less suitable at a particular time of the season, and the birds have been at least partially able to incorporate this into their nest-site selection behaviour. There is no optimal type of nest site for all conditions. The selective pressures on birds using the different types of nest sites are discussed.     

Eggs in the freezer: energetic consequences of nest site and nest design in Arctic breeding shorebirds

Birds construct nests for several reasons. For species that breed in the Arctic, the insulative properties of nests are very important. Incubation is costly there and due to an increasing surface to volume ratio, more so in smaller species. Small species are therefore more likely to place their nests in thermally favourable microhabitats and/or to invest more in nest insulation than large species. To test this hypothesis, we examined characteristics of nests of six Arctic breeding shorebird species. All species chose thermally favourable nesting sites in a higher proportion than expected on the basis of habitat availability. Site choice did not differ between species. Depth to frozen ground, measured near the nests, decreased in the course of the season at similar non-species-specific speeds, but this depth increased with species size. Nest cup depth and nest scrape depth (nest cup without the lining) were unrelated to body mass (we applied an exponent of 0.73, to account for metabolic activity of the differently sized species). Cup depth divided by diameter(2) was used as a measure of nest cup shape. Small species had narrow and deep nests, while large species had wide shallow nests. The thickness of nest lining varied between 0.1 cm and 7.6 cm, and decreased significantly with body mass. We reconstruct the combined effect of different nest properties on the egg cooling coefficient using previously published quantitative relationships. The predicted effect of nest cup depth and lining depth on heat loss to the frozen ground did not correlate with body mass, but the sheltering effect of nest cup diameter against wind and the effects of lining material on the cooling coefficient increased with body mass. Our results suggest that small arctic shorebirds invest more in the insulation of their nests than large species.     

Ranges of males of the Great Hornbill Buceros bicornis, Brown Hornbill Ptilolaemus tickelli and Wreathed Hornbill Rhyticeros undulatus in Khao Yai National Park, Thailand

Ranges of individual males of three hornbill species were determined by radio telemetry during the breeding and non-breeding seasons in Khao Yai National Park, Thailand. Two Great Hornbills Buceros bicornis and two Brown Hornbills Ptilolaemus tickelli were studied in both 1988 and 1989, and two Wreathed Hornbills Rhyticeros undulatus were studied in 1989, 1990 and 1991.
In the breeding season, the home range of the Great Hornbill was 3.7 km², similar to that of the Brown Hornbill (4.3 km²), while the Wreathed Hornbill occupied the largest home range (10.0 km²). In the non-breeding season, the range size of the Wreathed Hornbill (28.0 km²) was greater than that of the Great Hornbill (14.7 km²). Differences in range sizes of different species may be related to differences in diet and breeding strategy. Ranges overlapped within and between the species, and this has implications for the estimation of the minimum area required for the conservation of hornbills within the Khao Yai National Park.     

Plant selection for nest building by western lowland gorillas in Cameroon

We examined 834 nests built by western lowland gorillas in Cameroon between July 2008 and July 2011 to identify the plant species used in their construction. Preference for each plant species for nesting was assessed using a ‘preference index’ calculated by combining information on the occurrence of each species in the forest and in the nests. Forty-six plant species representing about 15 % of the total number of species in the forest and 26 % of species used for nest building were frequently used by gorillas. Preference levels significantly varied among these species. Nests were mostly built with herbs of the families Marantaceae and Zingiberaceae and woody species such as Manniophyton fulvum (liana) and Alchornea floribunda (shrub). As observed in other gorilla populations, suitability for nest building and availability of gorilla food in stems were the likely determinants of plant selection. The total number of species used per nest ranged from 1 to 11, with an average of 4.9. This is high compared to other sites, emphasizing variability in the availability of nest building materials and habitat differences across the range of the western gorilla. Seasonal changes in the use of different habitat types for nesting did not appear to influence plant use for nest building as there was little variation in plant selection across seasons or the composition of nests. Our findings suggest that gorillas non-randomly select plant species to build nests, and use a particular set of species combined at varying proportions, with no clear seasonal or spatial patterns.     

Spatial patterns of granivorous ant nest abundance and nest site selection in agricultural landscapes of Central Spain

Summary Patterns of abundance and site selection of granivorous ant nests were investigated in extensive cereal croplands of Central Spain. Nest densities and distributions were measured in two consecutive summers (1988 and 1989), together with habitat physiognomy and seed availability. Nest site selection patterns were analysed at two spatial scales (landscape and microhabitat) with respect to habitat physiognomy. Results indicate a very constant and predictable pattern of both nest abundance and nest site selection. Granivorous ant nests were most abundant in shrublands, and shrubby microsites were selected for nest placement. Croplands, and microsites with high covers of bare ground and litter, were avoided. These patterns were consistent between years despite a 1.7-fold increase in shrubland nest densities, that was attributed to the exceptionally dry winter between nest censuses. I suggest that winter survivorship of ant nests in the unploughed landscape units, and periodic ploughing in croplands, may be the main factors constraining granivorous ant densities in the landscape studied.     

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.     

Breeding group size, nest position and breeding success in the chinstrap penguin

We studied the effect of breeding group size and nest position on breeding success in the chinstrap penguin (Pygoscelis antarctica). Large subcolonies sited at Vapour Col, Deception Island, had higher breeding success than small subcolonies, which suffered a higher chick mortality than large subcolonies. Hatching date was earlier in large colonies. Relationships were not found between mean hatching date per subcolony and mean chick survival. Chick mortality related to nest position showed no difference between central and peripheral nests in large subcolonies. Central nests hatched earlier than peripheral nests. Nests in large subcolonies, whatever their position, were more successful compared with nests in small subcolonies. Received: 16 April 1997 / Accepted: 12 July 1997     

Experimental tests of nest site competition in two Peromyscus species

The importance of interspecific competition for nest sites between the white-footed mouse (Peromyscus leucopus noveboracensis) and the cloudland deermouse (P. maniculatus nubiterrae) were investigated in the montane forests of southwestern Virginia over 3 years. Trials were conducted for both species using large, outdoor enclosures in order to examine: (i) nest site preference in isolation and (ii) nest site selection made in the presence of potential competitors. Both species demonstrated a strong preference for arboreal nest sites when tested without competitors present. After the introduction of a heterospecific intruder, P. leucopus often shifted to a non-arboreal nest while P. maniculatus continued to use arboreal nests. Intruding P. maniculatus displaced resident P. leucopus from P. leucopus' preferred nest sites in all 3 years while intruding P. leucopus never displaced P. maniculatus. Neither species was routinely displaced in conspecific trials. Resident P. maniculatus also excluded P. leucopus from access to preferred nesting sites in all three years while P. leucopus were only able to exclude P. maniculatus in the 3rd year. Both species exhibite relatively low frequencies of exclusion in conspecific trials with the exception of P. maniculatus which excluded high proportions of conspecific intruders in the second year. We suggest that the asymmetrical advantage enjoyed by P. maniculatus in nest site selection may result from both site-specific effects and a species-specific influence on P. leucopus. Nonetheless, the intensity of such influence varied between years, perhaps as a function of population density, and did not appear to drastically influence continued coexistence of these congeners.     

Breeding site characteristics regulating life history traits of the brown tree frog, Litoria ewingii

Past research has determined the habitat requirements of amphibian species predominantly from presence/absence studies. This study tested the hypothesis that relationships between breeding site habitat components, life history traits and fitness may provide a higher resolution of biological data relating to the habitat requirements of amphibian species. We tested this novel approach by using Litoria ewingii as our model species. We correlated larval and metamorph life history traits with habitat variables at 28 small to medium sized ponds within a commercially logged forest in southern Tasmania, Australia. To avoid larval mortality due to pond desiccation, L. ewingii laid eggs and metamorphosed earlier in smaller ponds. Snout vent length at metamorphosis increased with elevation and metamorphosis was earlier in less shaded ponds. Breeding ponds that maximised the fitness of L. ewingii were higher elevation ponds with reduced shading, steeper bank slopes and reduced pond isolation. The findings of the study equip land managers with a greater ecological understanding of ecosystem function in relation to specific species. The methodological approach has broad application to conservation biology where an awareness of the specific habitat requirements of amphibians is critical to successful ecosystem management.     

State-dependent decisions in nest site selection by a web-building spider

Foraging decisions may reflect a trade-off between food intake and safety and can also be influenced by the animal's internal state. Foraging in the web-building spider Stegodyphus lineatus depends on a capture web associated with a retreat (the nest). The relocation of nests, including the take-over of conspecific nests, may be viewed as a foraing decision, which depends on risk of exposure, cost of silk production and hunger state. We investigated a possible state-dependent trade-off in nest site choice of S. lineatus spiderlings. The philopatric nature ofS. lineatus implies a high risk of encounters with potentially cannibalistic conspecifics and a potential loss of inclusive fitness because encountered conspecifics are likely to be kin. To test for state dependence of foraging decisions, we compared preferences of well-fed and hungry spiders for their own nests and those of siblings and nonsiblings. We expected satiated spiders to prefer their own to conspecific nests and hungry spiders to choose the risky option of a conspecific nest. SinceS. lineatus is less aggressive towards kin, we tested the ability of spiders to discriminate kin by silk-bound cues. Because of this reduced aggression, preference for kin nests should be safer than preference for nonkin nests. A strong preference for self-nests demonstrated self-recognition in well-fed spiders. However, neither well-fed nor hungry spiders discriminated between nests of siblings and nonsiblings. Well-fed spiders preferred self-nests to empty chambers, but showed no discrimination between nonself-nests and empty chambers. Hungry spiders showed a reduced preference for self-nests, suggesting that hunger elicits a more risky foraging strategy. A tendency of hungry spiders to adopt the nests of conspecific spiders may reflect a silk-saving strategy. We conclude that S. lineatus spiders show state-dependent decision making in nest site selection. Copyright 2002 The Association for the Study of Animal Behaviour. Published by Elsevier Science Ltd. All rights reserved.     

Studies on the characteristics of Michelia odora po- pulation and its community in south-central Jiangxi

采用样地调查法,对赣中南观光木种群及群落特征进行了研究.结果表明:观光木种群分布格局呈集群分布,径级结构为衰退型.观光木所在群落有维管植物60科94属112种,植物生活型以高位芽植物为主,占总种数的69.64%.植物区系起源古老,成分复杂,具有明显的热带性质.群落除Pielou指数较高外,其它各种多样性指数偏低,各样地间多样性指数有一定的差异;测度观光木所在群落物种多样性时,4种多样性指数未表现出相同的趋势,Simpson指数和Pielou指数在群落不同层次的变化规律为:灌木层＞草本层＞乔木层,Shannon-wiener指数和物种丰富度指数在群落不同层次的变化规律为:灌木层＞乔木层＞草本层.观光木本身的生物学特性和人类掠夺式的破坏是导致观光木种群濒危的主要原因.     

Breeding site specificity in the domestic species of Drosophila

Summary The emergences of domestic Drosophila species from fruits and vegetables in a market are analysed by partitioning the species diversity. Confidence limits are determined for the components of diversity.Despite some coexistence of different species within the same breeding site, ecological differences between them are revealed. Partitioning of the breeding sites is more important than partitioning of the season. D. melanogaster, D. simulans, and D. subobscura are specialised on fruits and D. busckii on vegetables. D. immigrans and D. hydei are less specialised. The coexistence is explained by reference to ecological theory.     

Breeding pattern and nest guarding in Sicyopterus lagocephalus, a widespread amphidromous Gobiidae

Amphidromous gobies are usually nest spawners. Females lay a large number of small eggs under stones or onto plant stems, leaves or roots while males take care of the clutch until hatching. This study investigates the breeding pattern and paternal investment of Sicyopterus lagocephalus in a stream on Reunion Island. In February 2007 and January 2010, a total of 170 nests were found and the presence of a goby was recorded at 61 of them. The number of eggs in the nests ranged from 5,424 to 112,000 with an average number of 28,629. We showed that males accepted a single female spawning in the nest and cared for the eggs until hatching. The probability for a nest to be guarded increased with the number of eggs within it, suggesting that paternal investment depends on a trade-off between the reproductive value of the current reproduction and future nesting events. We showed that large nest stones were occupied by large males (TL >80 mm), whereas smaller males (TL <50 mm) were found under smaller cobbles, probably because of male–male competition for available nests. Our results suggest that the male’s choice relies upon a similarity to the female size, while the female’s choice was based on both body and nest stone sizes.     

Trade-offs in nest site selection in coastal populations of Lapwings Vanellus vanellus

In coastal populations of Lapwings Vanellus vanellus in southwestern Sweden, arable fields predominated as foraging habitat before laying. Females caught more large prey items on arable fields and shores than on pastures. Close to egg laying, females foraged mainly near their future nest sites. Arable land and pastures were used to a similar extent for nesting. We found no difference in nest predation between habitats. Egg volume varied among females and was correlated with wing-length, body mass and condition. Mean egg volume also was positively correlated with feeding time on arable land before laying. Pairs nesting on arable fields therefore generally produced larger eggs than those on pastures. The distances between nests and chick foraging areas, however, were significantly longer for birds nesting on arable land than for those on pastures. Moreover, in 2 of 3 years, the proportion of hatched chicks that survived until fledging was negatively correlated with this distance. There was no difference in chick survival between broods hatched on arable fields and pastures. We suggest that nest site selection and offspring production involve a trade-off between the benefits of nesting close to rich feeding grounds for adults and the costs of moving long distances between nest sites and chick-rearing areas.     

Two grouse clutches in the same nest: evidence for nest site adoption in capercaillie ( Tetrao urogallus)

We describe the case of an unusually large capercaillie Tetrao urogallus clutch consisting of 12 eggs, of which four chicks hatched. Eight eggs died in an early stage of development. Genetic analyses revealed that the putative mother of the chicks was different from the one laying the unhatched eggs. We compare our results with reports from clutches elsewhere and conclude that nest site adoption is a likely explanation for joint clutches in grouse.This revised version was published online in December 2004. The german abstract has been included.