Nest-site characteristics of the Red-knobbed Hornbill Aceros cassidix and Sulawesi Dwarf Hornbill Penelopides exarhatus

Nest-site characteristics of two hornbill species, the Red-knobbed Hornbill Aceros cassidix and the Sulawesi Dwarf Hornbill Penelopides exarhatus , are presented and compared at two sites in north Sulawesi, Indonesia. Seventy-four Red-knobbed Hornbill and 12 Sulawesi Dwarf Hornbill nests were located. Sulawesi Dwarf Hornbill nests were at lower densities and more evenly spaced than Red-knobbed Hornbill nests. Although selective, neither species appeared to be nest-site limited, except perhaps for the Red-knobbed Hornbill in hill forest. Principal components analysis indicated that Red-knobbed Hornbills were 'catholic' in their preferences, although nests were generally in tall, mature specimens of large girth, located high and in the upper half of the tree. The Sulawesi Dwarf Hornbill nested exclusively in live trees and nests were on average located half way up in tall canopy trees with large girths. Within certain parameters, both species were flexible with respect to their nest cavity size and shape requirements; Red-knobbed Hornbills choose sites with larger entrances and internal dimensions. Discriminant function analysis produced parsimonious models for each site, with high rates of correct classification, based on structural, floristic and breeding success parameters. Lack of transference of predictive powers of the models between sites demonstrates the apparent variability in hornbill nesting behaviour and indicates the need for caution when extrapolating models to other sites. Possible factors affecting the nesting density and distribution of each hornbill species are discussed.     

Breeding ecology of the Sulawesi Red-Knobbed Hornbill Aceros cassidix

Data are presented for a four-year study of the breeding biology of the Sulawesi Red-knobbed Hornbill Aceros cassidix. The breeding season normally began in mid-June and lasted 27–30 weeks. Initiation of nesting appeared to be stimulated by the cessation of the rains and timed such that chicks emerged during a period of fruit abundance. Nesting period averaged 139 days and incubation was estimated at 35–40 days. Females remain sealed in the nest for an average of 108 days and nestlings fledged, on average, 28 davs after the female emerged. Nesting densities were up to 10.4/km², nesting success was high (up to 80%) and repeated use of nests between years was common. Males delivered a low-protein diet of ripe fruits (89% of total diet) from 12 families and 52 species; invertebrates composed only 1% of food items. Figs ( Ficus spp.) were the primary diet item, accounting for 81% of fruit biomass. Males increased feeding visits throughout the study, but the biomass of fruit delivered declined shortly after the female emerged. Reduced feeding prior to fledging may entice the nestling to emerge. The long developmental period of Sulawesi Red-knobbed Hornbills may result, in part, from the low protein content of the diet. Despite a 16% annual production, numbers in the study area have remained stable over the past 15 years. It is suggested that high post-fledging mortality or dispersal to degraded areas outside the reserve maintains population numbers. Distinguishing between these mechanisms is important for understanding the dynamics of hornbill populations.     

笼养条件下冠斑犀鸟合作繁殖行为

在2003~2005年,每年的2~10月,通过对南宁动物园犀鸟园一窝处于繁殖中的冠斑犀鸟(Anthracoceros albirostris)生殖合作的观察。结果发现,冠斑犀鸟的生殖合作行为属于“巢中帮手”类型。帮手鸟的介入方式是通过食物传递为纽带,从接触雄亲鸟为起点,帮助雄亲鸟运送食物、哺育和护巢。它们之间无亲缘关系,合作是一种互惠合作式的利它行为。帮手的存在主要是性比率失调。     

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.     

Effect of nest and nest site characteristics on the risk of cuckoo Cuculus canorus parasitism in the great reed warbler Acrocephalus arundinaceus

The risk of cuckoo Cuculus canorus parasitism for great reed warbler Acrocephalus arundinaceus nests was evaluated in respect to nest and nest site structure in the reedbeds along canals in central Hungary, In total 90 nests were analysed, from which 31 remained unparasitised. 37 were single parasitised and 22 multiple parasitised. Multiple discriminant analysis, based on eight structural variables, separated well the unparasitised clutches from the cases of single and multiple parasitism, but the latter two categories also showed a weaker separation. Nests close to cuckoo vantage points are most vulnerable to parasitism. The variable "distance from nest to closest available cuckoo perch site" (tree or electric wire) played the most important role in the risk of parasitism. It showed highly significant differences among the groups: lowest distances were found in the case of multiple parasitism, and the highest distances were measured when nests remained unparasitised. Additionally, "nest visibility" also showed significant differences among the three groups: a more visible nest is more likely to be parasitised. Risk of parasitism affects on the host on two levels: 1) female cuckoos search for nest-building hosts from a perch site, but 2) when they are in the act of parasitism, they can find more visible nests in the reed. Besides the robust effects of the variables "distance to cuckoo perch site" and "nest visibility", the variable "distance from nest to open water" may reduce, but "nest volume" increases the risk of multiple parasitism. Differences between cases of single and multiple parasitism are weak, mainly affected by chance. We explain it by the high abundance of the cuckoo, the parasitism rate was 65.6% (59/90), Cuckoos parasitised almost all of the available nests in the close vicinity of potential perch sites. There was no evidence that great reed warblers nested closer to each other when risk of parasitism was high.     

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.     

Polygyny and nest site selection in the pied flycatcher

Nest site choice, and its influence on mating and breeding success were studied in a population of individually marked pied flycatchers (Ficedula hypoleuca) for 7 years. Some nest boxes were used more frequently than expected from random choice of nest site. Flycatchers bred more successfully in such attractive boxes, irrespective of whether the brood was attended by the male or not. Arriving males and females settled at boxes in descending order of attractiveness. Boxes accepted by females were more attractive than alternative boxes advertised simultaneously by males. Secondary nest boxes of polygynous males tended to be more attractive than boxes at which monogamous males displayed, without success, for secondary mates. Returning males with local breeding experience started to sing at nest boxes earlier in spring than first season males, settled at more attractive boxes, and mated polygynously more often. The results indicate that male mating success should be closely dependent on the male's ability to monopolize attractive nest sites.     

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.     

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.     

喀斯特森林石壁营巢冠斑犀鸟繁殖行为初报

2019和2020年,在广西崇左恩城观察了喀斯特森林一对冠斑犀鸟(Anthracoceros albirostris)的繁殖行为.此对冠斑犀鸟每年4～7月在石壁上的洞穴里营巢,其孵卵期约为35 d,育雏期约为55 d.每年均有2只幼鸟成功离巢.幼鸟及雌鸟食物以植物性食物为主,雄鸟喂食时缺少明显的高峰.结果表明,冠斑犀鸟...     

Individual variation in nest size and nest site features of the Bornean orangutans (Pongo pygmaeus)

Nest construction is a daily habit of independent orangutans for sleeping or resting. Data on their nests have been used in various ecological studies (e.g., density estimation, ranging behavior, evolution of material culture) because they are the most observable field signs. We investigated nest size and nest site features of Bornean orangutans in the wild during 10 months' fieldwork at three sites in East Kalimantan, Indonesia: Kutai National Park, Birawa, and Meratus. To examine individual variation, we followed 31 individual orangutans and recorded the 92 nests they made for nest size (diameter) and nest site features (height of nest above ground, tree species used for the nest site, the diameter and height of the tree, whether the nest was new or reused, and nest location within the tree). Analyses taking age–sex classes of the focal individuals into consideration showed significant age–sex differences in nest size and location, but not in nest height or nest tree features (diameter, height of tree, and height of lowest branch). Mature orangutans (adult females, unflanged and flanged males) made larger nests than immatures (juveniles and adolescents). Flanged male orangutans with larger nests used stable locations for nesting sites and reused old nests more frequently than immatures. The overall proportion of nests in open (exposed) locations was higher than in closed (sheltered) locations. Flanged males and immatures frequently made open nests, whereas adult females with an infant preferred closed locations. The good correspondence between nest size and age–sex classes indicates that nest size variation may reflect body size and therefore age–sex variation in the population. Am. J. Primatol. 71:393–399, 2009. © 2009 Wiley‐Liss, Inc.     

Effects of habitat edges and nest‐site characteristics on Painted Bunting nest success

Declines in populations of Painted Buntings (Passerina ciris) over the past several decades have led to their recent classification as a species of conservation concern. To better assess their status, we investigated factors associated with productivity and abundance of a population in south‐central Louisiana during 2010–2011. We monitored 41 Painted Bunting nests, 14 with video cameras, to identify predators, parasitism events, and improve nest success estimates. Vegetation measurements were also collected at nest sites and non‐nest sites to quantify habitat characteristics. We used an information‐theoretic approach to evaluate support for multiple models evaluating nest success. Highly supported models indicated large negative effects of Brown‐headed Cowbird (Molothrus ater) parasitism, and positive effects of increased canopy cover and distance to habitat edge on daily survival rates. Our estimate of daily survival rate was 0.94 ± 0.03 and the probability of survival was 0.25 ± 0.02. Point‐count data revealed that densities of Painted Buntings were greater in treeline habitats than in open scrub‐shrub and mature forest edge habitats. Furthermore, treelines had higher densities of large trees (>23 cm dbh) and percent canopy cover, variables positively associated with nest success, than open scrub‐shrub and forest edge habitats. In general, survival rates and causes of nest failure in southern Louisiana were similar to those determined for breeding populations of Painted Buntings at other sites. Our results suggest that treelines, despite having a high edge‐to‐area ratio, might be preferred nesting habitat for Painted Buntings in our study area.     

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.     

Long-billed curlew nest site selection and success in the Intermountain West

Grassland birds have experienced steeper population declines between 1966 and 2015 than any other bird group on the North American continent, and migratory grassland birds may face threats in all stages of their annual cycle. The grassland-associated long-billed curlew (Numenius americanus) is experiencing population declines in regional and local portions of their North American breeding range. The nesting period is an important portion of the annual cycle when curlews may face demographic rate limitations from a suite of threats including predators and anthropogenic disturbance. We compared nest sites to random sites within breeding territories to examine nest site selection, and modeled correlates of nesting success for 128 curlew nests at 5 Intermountain West sites. Nest sites were 6 times more likely than random sites to be situated adjacent to existing cowpies. Additionally, curlews selected nest sites with shorter vegetation, and less bare ground, grass, and shrub cover than at random sites within their territories. Nest success varied widely among sites and ranged from 12% to 40% in a season with a mean of 27% for all nests during the 2015 and 2016 seasons. Higher nest success probability was associated with higher curlew densities in the area, greater percent cover of conspicuous objects (cowpies, rocks) near the nest, and higher densities of black-billed magpies (Pica hudsonia) and American crows (Corvus brachyrhynchos) at the site. We also found increased probability of nesting success with increased distance from a nest to the nearest potential perch in that territory. Given the central role of working lands to curlews in much of the Intermountain West, understanding limitations to nesting success in these diverse landscapes is necessary to guide adaptive management strategies in increasingly human-modified habitats. We suggest some grazing and irrigation practices already provide suitable nesting conditions for curlews, and others may require only minor temporal shifts to improve compatibility. © 2019 The Wildlife Society.     

Artificial nest predation rates in tropical and temperate forests: a review of the effects of edge and nest site

Nest predation rates are believed to be higher in tropical than in temperate forests. This notion is central in explaining different life history traits of tropical and temperate birds, but it is not known whether this assertion is true for all nest sites, such as ground and shrub nests, and at different distances from forest edge. I reviewed 22 studies using artificial nest experiments which concurrently contrasted predation rates of ground and shrub nests in temperate and tropical forests and found, contrary to the current dogma, no overall difference in predation rates between regions. However, there was a significant interaction between region and nest site. Ground nest predation rates were significantly higher in the tropical region, while predation rates on shrub nests were similar between regions. Within the tropical region, ground nests had significantly higher predation rates than shrub nests. Elevated nest predation rates at forest edges were found in both temperate and tropical forests. The results may have great implications for expected patterns of avian life histories and for the effects of forest fragmentation in temperate and tropical regions. First, if nest predation affects avian life histories, my results predict ground-nesting species in tropical forests to have shorter nestling periods, more broods and smaller clutch sizes than shrub-nesting species. Second, vulnerability of ground- and shrub-nesting guilds is suggested to differ between regions due to differences in forest vegetation structure, and the composition of predator faunas and their specific responses to forest fragmentation. Data to test these hypotheses are limited, but agree with the results of this review.     

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.