A description of nesting behaviors,including factors impacting nest site selection,in black‐and‐white ruffed lemurs (Varecia variegata)

Nest site selection is at once fundamental to reproduction and a poorly understood component of many organisms’ reproductive investment. This study investigates the nesting behaviors of black‐and‐white ruffed lemurs, Varecia variegata, a litter‐bearing primate from the southeastern rainforests of Madagascar. Using a combination of behavioral, geospatial, and demographic data, I test the hypotheses that environmental and social cues influence nest site selection and that these decisions ultimately impact maternal reproductive success. Gestating females built multiple large nests throughout their territories. Of these, females used only a fraction of the originally constructed nests, as well as several parking locations as infants aged. Nest construction was best predicted by environmental cues, including the size of the nesting tree and density of feeding trees within a 75 m radius of the nest, whereas nest use depended largely on the size and average distance to feeding trees within that same area. Microhabitat characteristics were unrelated to whether females built or used nests. Although unrelated to nest site selection, social cues, specifically the average distance to conspecifics’ nest and park sites, were related to maternal reproductive success; mothers whose litters were parked in closer proximity to others’ nests experienced higher infant survival than those whose nests were more isolated. This is likely because nesting proximity facilitated communal crèche use by neighboring females. Together, these results suggest a complex pattern of nesting behaviors that involves females strategically building nests in areas with high potential resource abundance, using nests in areas according to their realized productivity, and communally rearing infants within a network of nests distributed throughout the larger communal territory.     

Nest groups of wild bonobos at Wamba: selection of vegetation and tree species and relationships between nest group size and party size

We examined the location of nest groups, spatial distribution of nests within a nest group, and attributes of individual nests of wild bonobos at Wamba, Democratic Republic of Congo. We also examined the seasonal factors influencing nesting behavior and compared the nest group size with the 1 hr party size during daytime. We defined a nest group to be a cluster of nests that were built in the same evening and found within 30 m from the other nearest nest. Examination of the largest gap within a nest group suggested that 30 m was an acceptable cutoff value. Monthly rainfall or fruit abundance did not significantly influence the monthly mean nest group size. Nests were built in the swamp forest for as many as 13% observation days, suggesting the need for reevaluation of the use of swamp forest by bonobos. The use of swamp forest was influenced not by seasonal rainfall or fruit abundance, but by the fruiting of specific species. Preferred tree species for building nests accounted for 19.8% of standing trees, which suggested that the selection of sleeping sites was not largely restricted by the distribution of specific species. The mean 1 hr party size was almost identical through the day and was similar to the mean nest group size. Parties of bonobos sometimes split into smaller nest groups, especially when feeding on non‐preferred fruits during fruit scarcity. By contrast, when feeding on preferred fruits while ranging in large parties, they often aggregated to form even larger nest groups. When sleeping in small‐ or middle‐sized nest groups, they tended to aggregate the next morning. These tendencies may reflect the gregarious nature of bonobos who prefer to range or sleep together as far as circumstances allow. Am. J. Primatol. 72:575–586, 2010. © 2010 Wiley‐Liss, Inc.     

Nesting Behavior of <Emphasis Type="Italic">Gorilla gorilla diehli</Emphasis> at Kagwene Mountain,Cameroon: Implications for Assessing Group Size and Density

We recorded nesting data at 569 fresh night nest sites, comprising 7032 individual nests, of Cross River gorillas inhabiting the Kagwene Mountain in western Cameroon. The mean night nest group size was 12.4. Overall, 55% of night nests were constructed on the ground and 45% in trees. Significantly more arboreal nests were constructed in the wet season (69%), vs. the dry season (19%). Day nest construction was common at Kagwene (n = 260 nest sites, mean nest group size = 5.98) and we encountered significantly more day nest sites in the wet season. Nest site reuse was also common (35%), though not related to season. Our results of nesting habits concur with those from other western gorilla studies, in which rainfall influences arboreal nesting. However, we encountered wet season arboreal nesting, day nest construction, and overall nest site reuse more frequently than reported for other sites. Our observations have considerable implications when estimating group size and density using traditional nest count data. The gorillas at Kagwene inhabit the highest altitudinal range of all Cross River gorilla subpopulations and rainfall is also high; therefore other subpopulations may demonstrate different nesting characteristics. However, one should consider our findings when attempting to estimate Cross River gorilla density at other localities through nest site data.     

Nesting Behaviour of Abert Squirrels (Sciurus aberti)

Nesting behaviour of Abert squirrels (Sciurus aberti), including site selection and use, was studied in the foothills of the Rocky Mountains in Boulder County, Colorado. Only females were observed building nests, although both males and females maintained nests once they were built. Communal nesting by Abert squirrels was rare, but the majority of observed nest sharings involved unrelated male and female pairs. A total of 14 variables were used to evaluate the nests (n = 49) inhabited by Abert squirrels from May 1988 to Jun. 1991. All nests were located in Ponderosa pine (Pinus ponderosa) trees. The majority of nests were constructed of twigs and located in the upper one-third of the canopy, near the trunk, on the south-east side of the tree. Trees with nests were predominantly located in closed stands. Nest trees, when compared with unused control trees that were equally accessible to squirrels, were significantly different from control trees in five of nine variables. Nest tree crowns intertwined with a larger number of adjacent tree crowns than did control tree crowns. Nest trees were also significantly taller than control trees, but subdominant to adjacent trees within a stand. Seasonal and diurnal patterns of nest use indicate that Abert squirrels do not choose nest locations on the south-east sides of trees to facilitate behavioural thermoregulation. Rather, Abert squirrels select nest site locations to (1) maximize accessibility and (2) maximize structural stability which may provide protection from wind and rain.     

Female contributions to the peaceful nature of bonobo society

Although chimpanzees (Pan troglodytes) and bonobos (Pan paniscus) are closely related, females of the two species show surprisingly large differences in many behavioral aspects. While female chimpanzees tend to range alone or in small parties during non-estrous periods, female bonobos aggregate even more often than do males. Female chimpanzees do not have frequent social interactions with other females, whereas female bonobos maintain close social associations with one another. Although the ranging patterns of chimpanzee parties are generally led by males, female bonobos often take the initiative in ranging behavior. While female chimpanzees usually do not exhibit estrus during postpartum amenorrhea or pregnancy, female bonobos exhibit a prolonged pseudo-estrus during such non-conceptive periods. Studies of these two species have also shown great differences in agonistic behaviors performed by males. Male chimpanzees frequently fight with other males to compete for estrous females, but male bonobos seldom do so. While there are many records of infanticide by male chimpanzees, there is no confirmed record of such an event among bonobos. Several cases of within-group killing among adult male chimpanzees have been reported, but there is no such record for bonobos. While intergroup conflicts among chimpanzees sometimes involve killing members of the other group, intergroup conflicts among bonobos are considerably more moderate. In some cases, bonobos from two different groups may even range together for several days while engaging in various peaceful interactions. I will address two important questions that arise from these comparisons, exploring why females of such closely related species show such clear differences in behavior and whether or not the behavioral characteristics of female bonobos contribute to the peaceful nature of bonobo society.     

Old nests are cues for suitable breeding sites in the Eurasian penduline tit Remiz pendulinus

Nest-sites often have a major influence on avian reproductive success. The use of reliable cues that assist nest-site selection should thus be favoured by natural selection. The old nests have been known to serve as a cue in nest-site selection in several species. To find out whether the old nests act as cue in nest-site selection in the Eurasian penduline tit Remiz pendulinus , we carried out two experiments in southern Hungary, where the penduline tits breed around fishponds and build sophisticated pendulous nests on tree branches that often hang over water. In April 2006, we choose 20 groups of two nearby trees, and hung an old nest on one of the trees in each group. The male penduline tits choose 12 of these groups to build a new nest, and every of the twelve nests were built on trees with an old nest. This suggests that the old nests serve as a cue in the selection of breeding sites for males when they enter a habitat. To find out whether the old nests are cues of plentiful nest building material, or to signal high quality breeding areas, we carried out a second experiment in 2007 by selecting 13 groups of three nearby trees. A "worn-out" old nest was hung on one of the trees, a "re-utilize" type of old nest on another tree, whereas the third tree was left without an old nest in each group. The rationale was that while the worn-out material of the old nests is of no use in building the new nests, material of the "re-utilize" nests is good enough to be used for building new nests. Males built a new nest in 10 of the 13 groups, and eight of the new nests were built on trees with an old nest. Of the eight new nests, five were built on trees with a "worn-out" old nest and three on trees with a "re-utilize" type of old nest. It appears that for the penduline tit males it is the presence of an existing old nest and not the quality of the old nest material that serves as cue during the selection of the suitable breeding sites.     

Male short-tailed field voles (Microtus agrestis) build better insulated nests than females

Nest construction is an extremely widespread behaviour. In small endotherms the nest serves primarily to provide insulation, and thereby retard heat loss of the constructor, or its offspring. In arctic and temperate regions many small mammals build nests to protect themselves from low ambient temperatures. We measured the physical properties of nests built by short-tailed field voles Microtus agrestis that were kept in captivity under cold conditions. The most important factor influencing nest insulation was nest wall thickness; however, nests with thick walls also contained more nesting material. Insulative capacity of the nest did not reach an asymptote up to nests containing 20 g of material. Nest insulation was not correlated with resting metabolic rate, body mass or body composition of the vole that constructed the nest. However, nests built by males had greater insulation than those made by females; males also had significantly lower food intake rates when compared to females with nests. No significant difference was observed in either fat mass or whole animal thermal conductance between males and females. Thermal conductance did increase significantly with increasing body mass, although not with resting metabolic rate. Voles with nests for prolonged periods had lower food intakes than voles without nests. The absolute saving averaged 1.9 g and was independent of body mass. This was a 28% saving on intake for a 22-g vole but only an 18% saving for a 40-g individual. When voles had nests for short periods they used the energy they saved to reduce food intake and increase body mass. Accepted: 2 September 1999     

Anti-social and social behaviour of adolescent yellow-rumped caciques (Icterinae: Cacicus cela)

In an individually marked population in southeastern Peru, males and females of the polygynous, colonial yellow-rumped cacique delayed successful breeding until they were 3 years old. Adolescent (2-year-old) females competed for nest sites, built nests, laid fertile eggs, incubated, and sometimes fed nestlings, but always abandoned nests before they fledged young. Females that completed nests during their adolescent years were also more successful in establishing nest sites the following year. Adolescent females that failed to establish nest sites and those that lost nests to predators tended to leave the study area altogether. By attempting to nest early, adolescent females may facilitate future nesting attempts by forming coalitions with other females and assessing nest site quality in an area. Adolescent males, on the other hand, avoided aggressive interactions with other males, but were very aggressive towards adult females and fledglings. Adolescent males attacked females in nests, chased females to and from the colony, pecked and mounted recent fledglings, and, rarely, pulled nestlings out of nests. This harassment resulted in the death of nestlings and fledglings and was energetically costly to females, which often fought adolescent males while defending their young. Adolescent males preferentially harassed nestling-feeding females, avoided egg-laying females and were never observed attempting to mate with females. Adult males rarely interfered during any of these interactions. Such anti-social behaviour may function as a way of practising adult behaviour, as a means of eliminating future competitors, or may be an epiphenomenon of rising hormone levels and therefore of no adaptive significance.     

Elaborate Nests in a Weaverbird: A Role for Female Choice?

Studies on sexual selection have focused on behaviour and morphology, but several groups of animals build elaborate structures associated with acquiring a mate. I investigated female choice for nests built by male baya weavers (Ploceus philippinus). Nest choice by females should be strong, as nests are obvious direct benefits provided by males. I used a field experiment supplemented with correlational information to ask whether females appear to base mate choice decisions on male behaviour, nest architecture, and nest location. When the nests of highly visited males were exchanged with those of poorly visited males, female visits remained highest at the original male and location. I found no relationship between female choice and male display or other behaviour. Correlational analyses show that nest location was a better predictor of female choice than was nest architecture. These data suggest that current female choice is driven more by access to safe nesting sites rather than to well‐built nests, possibly because all males are able to build nests of adequate quality. However, nest architecture is unlikely to be irrelevant to females, and its role deserves further investigation.     

Re-use of courtship nests for quick remating in the polygynous Fan-tailed Warbler Cisticola juncidis

In a population of Fan-tailed Warblers Cisticola juncidis near Osaka, Japan, the males were polygynous, building a succession of elaborate courtship nests within their territories, and advertising them to females. Nest desertion by females frequently occurred early in the breeding cycle. Deserted nests were generally left untouched, but 17 out of 88 territorial males cleaned and re-used 20 of 79 nests deserted by females for their next courtship. The frequency of nest re-use increased with season. Of the re-used nests six (300%) were re-occupied by secondary females. Newly built nests were preferred to the 'second-hand' nests, probably because new nests were likely to last longer. Breeding success did not differ between the two categories of nests. In males, nest re-use seems to save time and energy expenditure for additional mating.     

北京小龙门林场黄眉姬鹟的巢与巢址特征

2003—2006年,在北京小龙门林场共发现黄眉姬鹟(Ficedula narcissina elisae)巢43个。其中34巢筑于天然巢址:开放巢占29.4%,位于树枝间(10巢);洞巢占70.6%,位于树桩顶端凹坑中(10巢)和树洞中(14巢)。开放巢距地高度高于洞巢。黄眉姬鹟的主要营巢树种是棘皮桦(Betula dahurica)。在研究区内共悬挂了100个大洞口巢箱和130个小洞口巢箱,结果发现黄眉姬只利用大洞口巢箱(9巢),不利用小洞口巢箱。以巢为中心,取半径6m的样方测量巢址的植被特征。对海拔、坡向、林冠郁闭度、乔木数量、乔木高、乔木胸径、枯树数量、树桩数量和林下郁闭度等变量进行主成分分析。结果表明,黄眉姬鹟的巢址具有乔木高大、林冠郁闭度高、多枯树和树桩等特征。黄眉姬鹟的繁殖成功率为51.2%,天敌破坏是造成繁殖失败的主要原因。     

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.     

An alternative strategy for maintenance of eusociality after nest destruction: new nest construction in a primitively eusocial wasp

Although nests are central to colonial life in social insects, nests are sometimes damaged by predators or natural disasters. After nest destruction, individuals usually construct new nests. In this case, a sophisticated mechanism like the scent trail pheromone used in large insect colonies that recruit individuals to new nest sites would be important for the maintenance of eusociality. In independent-founding Polistes wasps, it is well known that queens enforce workers physiologically on the natal nests even if evidence of trail pheromone use has not been exhibited. We investigated the effect of the queen on an alternative strategy for the maintenance of eusociality by first females after nest destruction in the primitively eusocial wasp Polistes chinensis. We predicted that the first females in queen-absent colonies have various behavioral options after nest destruction. Even if the females construct new nests cooperatively with other individuals, the new nest construction should be conducted more smoothly in queen-present colonies because the queens regulate the behavior of wasps. We made wasps construct new nests by removing the entire brood from existing nests. The presence of the queen did not cause variation in the alternative strategy of the first females, as the first females (workers) usually constructed new nests cooperatively irrespective of the queen-presence. Thus, the workers in the queenpresent colonies affiliated to the new nest construction more smoothly and constructed new nests more efficiently than workers in the queen-absent colonies. Our results suggest that the presence of the queen is important for maintaining eusociality in primitively eusocial wasps after nest destruction. Received 8 February 2005; revised 5 October 2005; accepted 17 October 2005.     

Social behaviour ofRopalidia fasciata (Hymenoptera: Vespidae) females on satellite nests and on a nest with multiple combs

The social behaviour ofRopalidia fasciata females on 3 satellite nests and on a nest with multiple, independent combs was observed. Many females often visited satellite nests, and even dominant foundresses, who usually spent more of their time on the nest, became active when satellite nests were being constructed. Three foundresses laid eggs on a satellite nest and eggs laid by 2 of these (who performed foraging) survived. On another satellite nest, only the dominant foundress laid an egg which survived. On a nest consisting of 2 independent combs, females frequently shifted between the 2 combs even after the emergence of many adults. Constructions of satellite nests and of multiple independent combs are considered to be adaptive for this species living in Okinawa, where most of nests are destroyed by frequent typhoons or abandoned after predation by ants.     

Sequential settlement by nesting male and female Baya weaverbirds Ploceus philippinus: the role of monsoon winds

Theory predicts that females should track resources while making decisions about where to reproduce, and males should track females. However, when males create the resource that females require, female settlement follows that of males. In this situation, how do individuals make settling decisions and what are the fitness consequences of these decisions? Here, I test the hypothesis that environmental factors (wind direction and velocity) affect optimal nest placement and orientation, and thus male and female settlement, in Baya weaver Ploceus philippinus colonies. Nests experimentally placed in windward locations with entrance tubes oriented toward the wind were more likely to lose clutches of artificial eggs than were nests placed in other combinations of placement and orientation. Correspondingly, males built their nests strongly clustered on the leeward side of colony trees, with entrance tubes oriented away from the wind. However, females did not discriminate amongst natural nests on the basis of nest placement or orientation. This may be because the effect of wind on the success of natural nests was small and was overwhelmed by other causes of nest loss. I suggest that, in some situations, female preference may remain undetected because the options available to females are constrained by preceding settlement decisions by males. In these cases, it is necessary to manipulate male distribution outside the range of natural variation to gain a better understanding of selective pressures imposed by female preferences.     

Mate availability affects female choice in a fish with paternal care: female counterstrategies against male filial cannibalism

Theory predicts that individuals should adopt counterstrategies against intersexual conflict with their mating partners if the counterstrategies are effective and cost-efficient. In fishes, males with parental care often cannibalize their own offspring, which reduces the female’s fitness and creates intersexual conflicts. Males of the goby Rhinogobius flumineus cannibalize more eggs in the nest when they have access to additional females prior to spawning. Thus, it is predicted that females will strategically avoid spawning with males that have high mate availability. In the present study, we experimentally tested this prediction. When sexual pairs were placed in tanks, most females (control females; 21/22) successfully spawned inside the nest. In contrast, when a gravid female (stimulus female) that was housed in a small transparent cage was shown to the experiment pairs prior to spawning, only about half of the females (experiment females; 16/29) spawned inside the nest; the remaining females released unfertilized eggs outside of the nest. Moreover, experiment females infrequently accepted and followed males into nests, and delayed spawning more often than control females. R. flumineus females prefer males that court frequently. Indeed, experiment females that infrequently received courtship tended to spawn outside of the nest. However, infrequent courtship alone could not explain outside-nest spawning, delay in spawning, or the shorter stay of females in nests. These results imply that the presence of a stimulus female dampens female spawning with males. We suggest that R. flumineus females may strategically reject or hesitate to spawn with males that have high mate availability, and that this spawning avoidance may be a counterstrategy against male filial cannibalism.     

Raptors breeding on weaver nests in trees and on man-made structures

Several raptor species nest on top of large weaver nests. These weaver nests are usually sited in trees, but 11.7% of Red-billed Buffalo-Weaver Bubalornis niger and 25.7% of Sociable Weaver Philetairus socius nests occur on man-made structures. In an extensive literature search, a total of 16 raptor species were recorded as nesting on top of weaver nests. At least 10 raptor species used weaver nests built in trees. Seven raptor species used weaver nests on man-made sites and four raptor species only used weaver nests built on man-made sites. No owls have been recorded as using weaver nests on man-made sites. There are historical records of raptors nesting on top of weaver nests in trees, while nesting on top of weaver nests sited on man-made structures appears to be a more recent adaptation. Costs and benefits of nesting on man-made sites are briefly listed. Nesting on man-made sites may increase (by both weavers and raptors) and raptor researchers are encouraged to document cases of raptors nesting on weaver nests where these are placed in trees or artificial sites, so that there is a record of changes in frequency of nest site usage by raptors.     

凉水自然保护区松鼠巢址选择的特征

2006 年6 月11 日至9 月27 日和2007 年8 月14 日至9 月21 日采用样线法,并结合定位观察的方法在凉水国家级自然保护区对松鼠的巢址选择进行了定量研究,共获取107 个巢样方和230 个对照样方。对每个样方分别测定了12 个巢树参数和7 个环境参数。统计分析结果表明,松鼠仅在针叶树上营巢,59.8 ± 4. 7% 的巢建于红松上,但对枝叶比红松更为浓密的云杉和臭冷杉有显著的选择性,而且显著倾向于在以云杉、臭冷杉为优势树种的生境中营巢。松鼠选择比较高大(树高21.5 ± 0.4 m)、活动通道比较多(3.6 ±0.1)的树营巢,巢树周围的树木密度(169 ± 4 株/ hm² )和多样性(辛普森指数0.51 ± 0.01)显著高于对照样方。巢址生境多位于南向的中、下坡位。巢址高12.4 ± 0.4 m,紧贴树干,多朝南。红松树上的巢多建于树冠的中下部,云杉和臭冷杉树上的巢多建于树冠的上部。松鼠巢对包括道路在内的林隙没有显著的回避。     

Influence of Natal Experience on Nest-Site Selection by Urban-Nesting Cooper's Hawks

Abstract: Exposure to environmental features early in life potentially can influence the kinds of places animals select to live later in life. We examined whether there is evidence that Cooper's hawks (Accipiter cooperii) hatched in an urban environment choose sites with features similar to their natal areas when they nest for the first time. The features we examined were the nest tree species and the level of development surrounding the nest tree. We banded nestling and fledgling Cooper's hawks in Tucson, Arizona, USA, from 1994 to 2004. We then monitored nests in Tucson to identify hawks that had been hatched in the city and eventually secured a breeding site. Percent cover of buildings around first breeding nests was not related to percent cover of buildings around natal nests for either sex. There was some evidence that being hatched in a particular tree species influenced choice of tree species at first breeding sites for males, but the influence was weak. In contrast, tree species in which first-time breeders built their nests, and the sites where the trees were located relative to development, were proportional to what was available in the Tucson metropolitan area. Our data suggest that natal experience played a limited role in nest-site selection by Cooper's hawks in Tucson for the features we examined. If learning occurred, it could have been for the general structure of natal sites. Thus, any small grove of large trees planted in Tucson could be used as a nest site by Cooper's hawks regardless of the level of development surrounding the nest.     

Nest site selection and patterns of nest re-use in the Hooded Crow Corvus cornix

Capsule: Hooded Crows Corvus cornix selected nesting trees based on species, height, grouping and distance from an occupied house. Nest re-use was common and pairs that re-used old nests produced more fledglings than those that built a new nest.

Aims: To determine the features of trees that influenced whether they were used by Hooded Crows as nest sites, to establish what factors influenced nest re-use between years and to explore potential costs or benefits of nest re-use.

Methods: In a large area of Orkney, Scotland, the features of trees that contained a Hooded Crow nest were compared to those of trees where nests were absent. Patterns of nest re-use between years were examined in relation to the availability of alternative sites, previous nesting success and the number of equivalent options to the tree used previously within 200?m of this site.

Results: Hooded Crows favoured spruce and pine trees as nest sites, above the most locally abundant tree species, elder and willow. Preference for trees increased with tree height, local tree density and distance from occupied houses. Over half of the crows studied re-used an old nest when one was available and crows that re-used an old nest fledged more offspring than those that built a new nest. The likelihood of a new nest being built increased as the number of potential locations to build increased. Territories where a nest survived the winter were more likely to be reoccupied the following year than those where nests fell, while territories with fewer trees around the old site were most likely to be abandoned, suggesting that those were territories of lower quality.

Conclusions: Hooded Crows displayed strong preferences for nest sites that might favour nesting success by offering concealment, shelter and protection from ground-based predators. Nest re-use was common, especially when alternative sites were scarce, and appeared to facilitate greater reproductive output.