Nest location, clutch size and nest success in the Scarlet Ibis Eudocimus ruber

Breeding success and nest-site characteristics were studied during the 1996–1997 breeding season in a colony of Scarlet Ibises Eudocimus ruber in south-eastern Brazil to test the hypothesis that nest-site characteristics and clutch size affect nest success. Two nesting pulses produced young, the earlier being more successful. Predation accounted for most failures during the first pulse, wind destruction during the second. A third pulse with few nests produced no young. Adult Ibises abandoned nests when they lost sight of other incubating birds. Logistic regression analysis indicated that nest success during the first pulse was positively related to clutch size, number of nests in the nest tree and in the nearest tree, and negatively to the distance to the nearest neighbour. During the second pulse there were significant negative associations between success, nest height and distance to the fourth nearest nest, and a positive association between success and nest cover. The results agree with the 'selfish herd' hypothesis, indicating that nest aggregation may increase breeding success, but the nest-site characteristics affecting success can differ over the course of one breeding season.     

Colony structure and sex allocation ratios in the ant <Emphasis Type="Italic">Temnothorax crassispinus</Emphasis>

Summary. We analyzed the impact of ecological parameters, such as nest density and nest site availability, on colony organization and investment patterns in two populations of the ant Temnothorax crassispinus, a parapatric sibling species of the well-studied T. nylanderi (Temnothorax was until recently referred to as Leptothorax (Myrafant); Bolton, 1993). As in T. nylanderi, sex allocation ratios were strongly associated with total sexual reproduction, i. e., nests with large sexual investment produced mainly female sexuals. Furthermore, nest site quality affected sex allocation ratios, with colonies from ephemeral nest sites producing a more male-biased sex allocation ratio than colonies from sturdy nest sites. In contrast to T. nylanderi, workers in colonies of T. crassispinus were mostly fullsisters both in a dense and a sparsely populated area, suggesting that colony fusion and colony usurpation are rare in this species. In addition, the presence of a queen in a local nest unit strongly influenced sex ratio decisions, in that these nests raised a more male biased allocation ratio compared to queenless nests. This also suggests that colony structure is more stable in T. crassispinus than in T. nylanderi. We conclude that sibling species, though often very similar in their morphology and ecological requirements, may nevertheless react very differently to ecological variation.Received 11 December 2003; revised 4 March 2004; accepted 19 April 2004.     

Chemotaxonomy of some Cataglyphis ants from Morocco and Burkina Faso

The taxonomy of Cataglyphis ants has many unsolved problems and chemotaxonomy can provide additional insight for their resolution. We describe here the chemical content of the postpharyngeal and Dufour glands of three Cataglyphis ant species: C. viaticus, C. mauritanicus from Morocco and for the first time a Sub-Saharan Cataglyphis, C. sp. (BF) from Burkina Faso. These three species are very distinct chemically with respect to both the postpharyngeal and Dufour glands. Methyl-alkenes, rare in ants, are characteristic of C. sp. (BF) postpharyngeal glands. A comparison with C. bicolor from Tunisia indicated that C. sp. (BF) can be included into the bicolor group with C. viaticus. We suggest that the content of the Dufour gland is a better phylogenetic indicator than the content of the postpharyngeal gland.     

Nest Defense and Conspecific Enemy Recognition in the Desert Ant Cataglyphis fortis

This study focuses on different factors affecting the level of aggression in the desert ant Cataglyphis fortis. We found that the readiness to fight against conspecific ants was high in ants captured close to the nest entrance (0- and 1-m distances). At a 5-m distance from the nest entrance the level of aggression was significantly lower. As the mean foraging range in desert ants by far exceeds this distance, the present account clearly shows that in C. fortis aggressive behavior is displayed in the context of nest, rather than food-territory defense. In addition, ants were more aggressive against members of a colony with which they had recently exchanged aggressive encounters than against members of a yet unknown colony. This finding is discussed in terms of a learned, enemy-specific label-template recognition process.     

Nest relocation in the golden spiny ant, <Emphasis Type="Italic">Polyrhachis ammon:</Emphasis> environmental cues and temporal castes

Summary Despite its apparent costs, nest relocation is a common phenomenon among ants. Polyrhachis ammon, a common ant in open habitats of eastern Australia, exhibits a high rate of colony emigration to new nest sites. We conducted a field survey and shading experiments in different seasons and years to determine which factors affect colony emigration in this species. We also compared morphological features characterising workers involved in adult transport to determine if workers performing different tasks belong-ed to discernible temporal castes. Nests that were abandon-ed after four weeks were smaller, although distance from a food source and low-level disturbance did not alter re-location rates. The effects of shading and nest temperature on nest survival varied between seasons, as did rates of nest relocation. Transporter workers could not be distinguished from foragers, but had greater mandibular wear and smaller dry mass than transportees. Our results suggest that cues promoting nest relocation in P. ammon may be the result of a combination of factors with varying temporal importance.     

Testing the importance of individual nest-site selection for a social and group-living vulture

Nest-site selection by species is expected to be adaptive and lead to improved breeding productivity, but in some settings, there exist mismatches between preferred nesting habitat and breeding productivity. We tested the expectation that nest-site selection is adaptive in a sample of 63 nests of a long-lived social species that breeds and forages in groups: the critically endangered white-backed vulture (Gyps africanus). By studying breeding groups in the same area, we controlled for landscape-level effects on habitat selection and investigated how fine-scale nest-site characteristics affect breeding productivity. We developed models to assess how nine characteristics of nest sites selected by breeding vultures compared with 70 random trees and tested associations between these characteristics and breeding productivity. White-backed vultures selected nest sites in taller trees (>7 m), but neither tree height nor any other nest-site characteristics had a clear effect on breeding productivity. Vultures selected nest trees closer to each other than random trees, and the associations between nest density, nearest neighbour distance and breeding success were all positive. These positive associations and the absence of an observable effect between nest-site characteristics and breeding productivity suggest that for this semi-colonial breeder, the social imperative of proximity to conspecifics (i.e., nesting near other vultures and group foraging) may be more important than individual nest-site selection.     

Relationships between grazing and waterfowl production in the Canadian prairies

The survival of waterfowl nests is positively correlated with the amount of grassland on the landscape, and population growth rates of some waterfowl species (e.g., mallards [Anas platyrhynchos]) are sensitive to nest survival rates. Thus, the effect of actions that alter grassland vegetation physiognomy, such as grazing, on waterfowl production is of interest to waterfowl habitat managers. Additionally, grasslands contribute other ecological goods (e.g., forage for livestock and wildlife) and services (e.g., photosynthesis, carbon sequestration), which can be influenced by grazing practices. We address key uncertainties about the linkages between grazing, vegetation physiognomy, and the survival and density of duck nests at study-site, field, and nest-site spatial scales. Using data from 2,554 duck nests found in 434 grazed or idled fields (median field size = 48.0 ha) in the Canadian Prairie Pothole Region between 2002 and 2009, we found that vegetation physiognomy affected nest survival at both the field and nest-site scales, such that nest survival increased with nest-site vegetation density and late-season field vegetation density. Nest survival also responded to early-season within-field variation in vegetation height in a quadratic manner, such that survival was greatest in fields with moderate variation in vegetation height. Nest survival was negatively related to the intensity of grazing and to the amount of cropland in the surrounding landscape. Both the abundance of wetlands and the average vegetation height in the field had a positive influence on nest density. Fields idled during the breeding season had greater densities of nests than fields grazed either early or late in the breeding season. Leaving lands idled may be the most effective way to increase both waterfowl nest survival and nest density. When management of upland vegetation is required, we recommend grazing at moderate stocking rates (between 2 and 2.5 animal unit months [AUM]/ha) after the waterfowl breeding season is complete and monitoring vegetative characteristics to ensure they remain suitable to attract nesting waterfowl (e.g., leaving vegetation height >28 cm). Where grazing must be carried out during the breeding season, low to moderate stocking rates should be encouraged as these rates appear to have the least negative impact on both waterfowl nest survival and nest density. These stocking rates also will maintain rangeland in good condition to the long-term benefit of producers. © 2013 The Wildlife Society.     

Use of terrestrial chemical trails for nest orientation in an open nesting wasp, <Emphasis Type="Italic">Dolichovespula saxonica</Emphasis> F.

Summary The long-cheeked wasp Dolichovespula saxonica typically constructs exposed nests which can be reached by flying. Usually foragers do not walk on substrates in the close vicinity of the nests as cavity breeding wasps do (Steinmetz et al., 2002). Unexpectedly, when forced to walk outside the nest instead of flying in an artificial tunnel system, D. saxonica foragers lay a terrestrial trail and use it for orientation in the nest area in our experiments. 41% of the foragers followed the trail in a direction they were not accustomed to. We suggest that the foragers have employed the same orientation cues normally used for orientation in the close vicinity of the nest when approaching a free-hanging nest by flying, for example nest odour. Nest odour substances may have been transferred to the substrate as a trail as a consequence of foragers walking through the tunnels.Received 23 August 2002; revised 27 January 2003; accepted 30 April 2003.     

Age and breeding success related to nest position in a White stork Ciconia ciconia colony

Coloniality is a breeding system that may produce benefits in terms of breeding success, although these advantages could vary according to factors such as colony size or nest position. We studied breeder's age in relation to nest position (peripheral or central) within the colony. In addition, we studied the relationship between breeding success and nest position, controlling for breeder's age, a highly correlated factor, in a White Stork Ciconia ciconia colony over a 7-year period. Our results show that central nests are mainly occupied by adult birds and had lower failure rates. However, controlling for breeder's age, nest position per se did not explain breeding success. The scarce predation and the lack of human disturbance in the study colony could explain the absence of differences in breeding success between different nest positions within the colony.     

Columbian sharp-tailed grouse nesting ecology: wind energy and habitat

The rapid pace of wind-energy development has increased stakeholder concerns regarding the potential effects on wildlife. Locations targeted for wind-energy development frequently overlap prairie grouse and greater sage-grouse (Centrocercus urophasianus) habitats. Research suggests that anthropogenic developments may have negative effects on these species. There is, however, no information published regarding the effect of wind-energy development on Columbian sharp-tailed grouse (Tympanuchus phasianellus columbianus), a subspecies that has twice been petitioned for Endangered Species Act protection. To address this need, from 2014 to 2015 we studied Columbian sharp-tailed grouse nesting ecology across restored grasslands in eastern Idaho, USA, where a 215-turbine wind-energy complex had been developed. We monitored 147 nests from 135 females captured at leks 0.1–13.8 km from wind turbines. We used an information-theoretic approach to evaluate the influence of wind-energy infrastructure and habitat characteristics on nest-site selection and daily nest survival. We did not detect any influence of wind-energy infrastructure on nest-site selection or nest survival. Nest-site selection and daily nest survival were influenced by vegetation structure and composition measured at 2 spatial scales. Females selected nest sites with more restored grassland containing >30% forb cover within the nesting core-use area (i.e., 60 ha around the nest) and exhibited a functional response to the availability of that land cover type. Daily nest survival was best predicted by visual obstruction at the nest site and the amount of restored grassland containing >30% forb cover within the nesting core-use area. We recommend wildlife managers continue to implement management practices that will provide bunchgrass-dominated grasslands with >30% forb cover in restored grasslands (e.g., Conservation Reserve Program fields) within Columbian sharp-tailed grouse range. © The Wildlife Society, 2019     

Comparative nest survival of three sympatric loon species breeding in the Arctic

Identifying factors influencing nest survival among sympatric species is important for understanding and managing sources of variation in population dynamics of individual species. Three species of loons nest sympatrically in northern Alaska and differ in body size, life history characteristics, and population trends. We tested the effects of competition, nest site selection, and water level variations on nest survival of Pacific Gavia pacifica, yellow‐billed G. adamsii, and red‐throated loons G. stellata on the Arctic Coastal Plain in Alaska. Although overall nest survival rates did not differ between species, the factors influencing nest survival varied. Nest site selection influenced nest survival for Pacific and yellow‐billed loons, with both species having high nest survival when nesting on islands and peninsulas, likely due to a reduction in access by terrestrial predators. However, on mainland shorelines, Pacific loons had lower nest survival than yellow‐billed loons, and used a higher proportion of vegetation mats for nest sites suggesting that their smaller body size makes them less adept at nest defense. Nest site selection did not influence nest survival of red‐throated loons corresponding to our result of no nest site preferences by this species. Initiation date had a strong influence on nest survival for Pacific and yellow‐billed loons with nests laid earlier having higher survival. Pacific and yellow‐billed loon nests were susceptible to flooding due to precipitation, which contrasted with red‐throated loons that nest on smaller lakes with lower water level variations. Competition did not affect nest survival for any of the species likely due to most territorial encounters occurring prior to incubation. The only influence we found on red‐throated loon nest survival was differences among years. Our results indicate that loons chose nest sites based on predation risk and that factors influencing breeding success of closely related species may differ under similar breeding conditions.     

Nest-site selection and its impact on breeding success of the Lesser Kestrel,Falco naumanni,in the North of Iran (Aves: Falconiformes)

The Lesser Kestrel (Falco naumanni) is a small migratory falcon which nests coloni- ally on inland cliffs and ruined buildings. Bandar Turkman city holds one of the most important breeding colonies in Iran. It nests in holes in roofs, walls or on ledges of buildings throughout of the city. We tried to find out whether there is a relationship between nest-site selection and breeding success. Although height from the ground is the most important factor in nest-site selection by F. naumanni, height from the floor and distance to the nearest neighbour are other main factors which affect breeding success. This could be the result of accessibility by human and natural predators such as domestic cats which threaten nests. The number of possible nest-sites in the study area is limited as many old, ruined buildings are being replaced by new construc- tions; this colonially breeding bird species therefore suffers from a lack of highly suitable nest-sites and this directly affect breeding success.     

Nest survival in year‐round breeding tropical red‐capped larks Calandrella cinerea increases with higher nest abundance but decreases with higher invertebrate availability and rainfall

Nest survival is critical to breeding in birds and plays an important role in life‐history evolution and population dynamics. Studies evaluating the proximate factors involved in explaining nest survival and the resulting temporal patterns are biased in favor of temperate regions. Yet, such studies are especially pertinent to the tropics, where nest predation rates are typically high and environmental conditions often allow for year‐round breeding. To tease apart the effects of calendar month and year, population‐level breeding activity and environmental conditions, we studied nest survival over a 64‐month period in equatorial, year‐round breeding red‐capped larks Calandrella cinerea in Kenya. We show that daily nest survival rates varied with time, but not in a predictable seasonal fashion among months or consistently among years. We found negative influences of flying invertebrate biomass and rain on nest survival and higher survival of nests when nests were more abundant, which suggests that nest predation resulted from incidental predation. Although an increase in nest predation is often attributed to an increase in nest predators, we suggest that in our study, it may be caused by altered predator activity resulting from increased activity of the primary prey, invertebrates, rather than activity of the red‐capped larks. Our results emphasize the need to conduct more studies in Afro‐tropical regions because proximate mechanisms explaining nest predation can be different in the unpredictable and highly variable environments of the tropics compared with the relatively predictable seasonal changes found in temperate regions. Such studies will aid in better understanding of the environmental influences on life‐history variation and population dynamics in birds.     

Effects of prescribed burning on avian nest survival in the southern Great Plains

Shrubs, such as mesquite (Prosopis spp.) and cholla (Opuntia spp.), now dominate fire-suppressed grasslands in southwestern North America. Responses of birds to prescribed burning of the shortgrass prairie in this region are poorly understood. We examined daily survival rates of mourning dove (Zenaida macroura) and lark sparrow (Chondestes grammacus) nests in an experimental landscape (4,811 ha) of spatially replicated, inter-annual fire frequencies (burning every 2 yr, 4 yr, or 10 yr) near Amarillo, Texas. Herbaceous habitat structure was most developed in infrequently burned plots, but shrub densities were less variable among the burn treatments. We modeled daily nest survival (DSR) against burn frequency, shrub density at nest sites, and nest stage (incubation or nestling). Daily survival of mourning dove nests was not well-related to any measured covariate, but lark sparrow DSR was negatively related to the duration of inter-annual burn frequency. In semiarid grasslands heavily inundated with shrubs, prescribed burning may positively influence the nest success of some bird species. © 2011 The Wildlife Society.     

Sand Pile Formation in <Emphasis Type="Italic">Dorymyrmex</Emphasis> Ants

We studied circular sand pile formation by two colonies of Brazilian Dorymyrmex ants, in which workers dumped sand excavated from their underground nest around the nest entrance hole. In most cases a worker dumped its load just beyond the ridge of the pile. Each dumped piece either stayed where it was deposited (81.9% in colony A and 73.0% in colony B) or rolled down the outer slope of the sand pile away from the entrance (17.9% in colony A and 27.0% in colony B). Ants almost never dumped in a way that resulted in the load rolling back to the entrance. When one side of the sand pile was experimentally removed, ants preferentially dumped soil on the now flat side, thereby restoring the original circular shape.     

Effects of Large-Scale Predator Reduction on Nest Success of Upland Nesting Ducks

ABSTRACT Population growth for mallards (Anas platyrhynchos), and presumably other upland nesting ducks, in the Prairie Pothole Region of the United States and Canada is most sensitive to nest success, and nest success is most strongly influenced by predation. We evaluated the efficacy of reducing predator populations to improve nest success of upland nesting ducks on township-sized (93.2 km²) management units in eastern North Dakota, USA, during 2005–2007. We monitored 7,489 nests on 7 trapped and 5 nontrapped sites. Trappers annually removed an average of 245 predators per trapped site, and we found nest success to be 1.4–1.9 times greater on trapped sites than nontrapped sites, depending on year. Nest success was greater on both trapped and nontrapped sites when compared with a study conducted in the same areas in the mid-1990s, likely because of changes in red fox (Vulpes vulpes) and coyote (Canis latrans) population dynamics. Nests initiated midseason had higher daily survival rates (DSR) than those initiated earlier or later in the season. Daily survival rates for nests in the middle of the nesting cycle were higher than for nests that were early in laying or late in incubation. Nests near the periphery of trapped sites had slightly higher DSRs than nests in the center of trapped sites. Predator reduction at the township scale provides managers with an effective tool to improve nest success at large spatial scales.     

东北地区北红尾鸲巢址选择及繁殖成效

北红尾鸲(Phoenicurus auroreus)是一种分布广泛的小型雀形目鸟类,主要分布于南亚东北部,东南亚北部、东亚及俄罗斯等地区,我国东北、华北、华中至西南等地也均有分布,是重要的食虫益鸟。为探究北红尾鸲巢址选择的影响因素,找到影响北红尾鸲繁殖成功率的主要巢址因子,于2017年4—7月,在辽宁仙人洞国家级自然保护区开展系统研究。共发现北红尾鸲自然巢44个,其中29巢繁殖成功,15巢繁殖失败。北红尾鸲主要筑巢于石墙缝、空心砖墙缝及废旧电表箱中。巢址参数的主成分分析结果表明:巢口因子(27.738%)、巢位因子(14.195%)、光照因子(12.145%)、人为干扰因子(10.440%)、安全因子(9.266%)和隐蔽因子(7.187%)是影响北红尾鸲巢址选择的重要因子。采用二元逻辑斯蒂回归分析繁殖成功巢与失败巢参数发现,成功巢的巢口最大高度显著小于失败巢(P=0.047),且其距顶的距离更近(P=0.043)。多元线性回归分析表明,巢上方盖度对繁殖成功率有极显著影响(t=2.883,P=0.009)。总的来说,北红尾鸲虽偏爱筑巢于人为干扰较大的村庄房屋附近,但较小的巢口能有效避免巢捕食者的捕食,更近的距顶距离和更大的巢上方盖度能有效降低巢上方的可视程度和降水等不利因素的影响,从而提高繁殖成功率。     

Nest composition and worker relatedness in three slave-making ants of the genus Rossomyrmex Arnoldi and their Proformica Ruzsky hosts (Hymenoptera,Formicidae)

Abstract In this paper, we analyze and compare nest composition and architecture as well as worker relatedness in three related species of slave-making ants: Rossomyrmex anatolicus, R. minuchae, and R. quandratinodum. Colony structure within nests is an important trait in ants, especially in the case of mixed societies, when host and parasite coexist in the same nest. Data for their respective free-living hosts, Proformica korbi, P. longiseta and P. sp., are also provided. For our study, we integrated a meticulous excavation procedure with a genetic method. We conclude that the average number of parasites, as well as of slaves, is species-specific, whereas nest depth depends on the nest architecture of the host. The genus Rossomyrmex seems to be monogynous and monandrous, whereas Proformica shows differences in the number of queens and mating frequency. R. quandratinodum shows different traits in nest composition (host/parasite ratio: P/R) and architecture. The difference in traits may account for some differences in parasitism: raid process or avoidance of parasitism.     

Colony structure in a plant-ant: behavioural,chemical and genetic study of polydomy in<Emphasis Type="Italic"> Cataulacus mckeyi</Emphasis> (Myrmicinae)

Social organisation of colonies of obligate plant-ants can affect their interaction with myrmecophyte hosts and with other ants competing for the resources they offer. An important parameter of social organisation is whether nest sites of a colony include one or several host individuals. We determined colony boundaries in a plant-ant associated with the rainforest understorey tree Leonardoxa africana subsp. africana, found in coastal forests of Cameroon (Central Africa). This myrmecophyte is strictly associated with two ants, Petalomyrmex phylax and Cataulacus mckeyi. Plants provide food and nesting sites for P. phylax, which protects young leaves against insect herbivores. This mutualism is often parasitised by C. mckeyi, which uses but does not protect the host. The presence of C. mckeyi on a tree excludes the mutualistic ant. Because Petalomyrmex -occupied trees are better protected, their growth and survival are superior to those of Cataulacus -occupied trees, giving P. phylax an advantage in occupation of nest sites. C. mckeyi often colonises trees that have lost their initial associate P. phylax, as a result of injury to the tree caused by disturbance. Polydomy may allow C. mckeyi to occupy small clumps of trees, without the necessity of claustral colony foundation in each tree. Investigating both the proximate (behavioural repertoire, colony odour) and the ultimate factors (genetic structure) that may influence colony closure, we precisely defined colony boundaries. We show that colonies of C. mckeyi are monogynous and facultatively polydomous, i.e. a colony occupies one to several Leonardoxa trees. Workers do not produce males. Thus, the hypothesis that polydomy allows workers in queenless nests to evade queen control for their reproduction is not supported in this instance. This particular colony structure may confer on C. mckeyi an advantage in short-distance dispersal, and this could help explain its persistence within the dynamic Leonardoxa system.     

Estimating nest locations of bumblebee <Emphasis Type="Italic">Bombus ardens</Emphasis> from flower quality and distribution

The central-place forager in a social-insect colony, e.g., the bumblebee, has been expected to maximize its net rate of energy gain to increase the success of its colony. In addition to foraging behavior, the nest location is an important factor for the success of the colony. The bumblebee’s nest location would be affected by the spatial distribution of flowers and their food quality. In this study, we constructed a model to estimate bumblebee nest sites, using the net energy intake rate at available food sites for workers foraging from the nest site. We hypothesized that the probability of colony establishment at a site in coordinates (x, y) was high as the sum of the net energy intake rate I(x, y) increased. To obtain I(x, y), nectar standing crop, sugar concentration, and foraging time were measured for ten plant species in the study site covering 6.25 km². As available flowers changed seasonally, I(x, y) was calculated for three periods: the end of April, the beginning of May, and the middle of May. To verify our hypothesis, we compared the estimations in our model with the actual nest sites of Bombus ardens found in the beginning of May and June by means of tracking bumblebees. From the results, we considered that the net energy intake rate at mid-May might represent the probability of colony establishment, because it could affect colony persistence and reproductive success.