Nest architecture in the western harvester ant,Pogonomyrmex occidentalis (Cresson)

Summary The structure and thermal environment produced by the nest cones of the western harvester ant,Pogonomyrmex occidentalis, are investigated. The nest cone is oriented so that the longest slope faces towards the southeast ad the nest entrance faces the southeast. The temperature of the soil was monitored at thirty-six locations within the nest in order to measure the daily temperature change as a function of depth, aspect and radial distance from the center of peak of the cone. The occupancy of the nest cone by workers and by brood was assessed by core samples taken at different times of day in different portions of the cone. The brood are only present during the midmorning sample and are present in greatest numbers on the eastern side of the cone. The adult workers are present in the cone in highest numbers during the midmorning, virtually absent from the cone during mid-afternoon and returning in smaller numbers at dusk, apparently spending the night near the surface on the eastern side of the mound. The eastern and southern portions of the cone are occupied most frequently while the western side of the cone is nearly vacant. The nest cone is an adaptation which magnifies the amplitude of daily temperature fluctation. By moving to appropriate areas of the nest cone, the ants can take advantage of the increased range of temperature.     

Nesting behaviour and foraging characteristics of Andrena cineraria (Hymenoptera: Andrenidae)

The current studies were carried out in the three experimental locations of Kashmir valley during 2013 to 2016. The species Andrena cineraria formed the dense nest aggregations in plan grounds, barren lands and hilly areas near the fruit orchards and other landscapes with clay loam soil type. The species start flying and foraging in the orchards from April till July. The nests were allodalous, 29–36 cm in depth, with cells located obliquely around the main barrow. The nests were dense with a maximum density of 11.09 nests/m² observed in landscapes of Budgam. The barrow diameters were found varying with depth from main entrance. The maximum barrow diameter recorded was 2.05 mm. At certain depth, the female constructs the first cell and the upper nest burrow is vertical and lower is oblique. The nest entrance is generally hidden under the tumulus. In the depth of average 30.48 cm, each cell directly opens to main burrow either alternately or unilaterally. The cell number, diameter, and length varied with depth. Foraging behaviour of A. cineraria on various fruit crops and other shrubs and social forestry trees were determined and the abundance, visitation rate, total visits and time spend per flower were found significant, especially on fruit crops. The significance of the studies is important for the melittologists, as it will help in the conservation of bee fauna. The study is also important in using this species for pollination purpose and would also help to detect and understand the possible pre-adaptation of species in temperate region of Kashmir valley.     

Nest site selection by a neotropical swarm-founding wasp: seasonal alternation of nest orientation

Nest orientation in social insects has been intensively studied in warmer and cooler climates, particularly in the northern hemisphere. Previous studies have consistently shown that species subjected to these climatic conditions prefer to select mostly southern locations where the nests can gain direct sunlight. However, very little is known on nest orientation in tropical and subtropical social insects. We studied nest orientations initiated by swarms throughout a year in a Brazilian swarm-founding wasp, Polybia paulista von Ihering (Hymenoptera: Polistinae). Swarms selected various orientations as nest sites, but there was a particular trend in that swarms in the winter period (May–August) preferred to build northward-facing nests. This preference is opposite from that of social wasps observed in the northern hemisphere. Colonies of this species can potentially last for many years with continuous nesting, but nesting activities of colonies during the winter are severely limited due to cool temperature and a shortened day length. Northward-facing nests are warmer through the gain of direct solar heat during the winter period; consequently, choosing northward-facing sites may be advantageous for swarms in terms of a shortened brood development and shortened time needed to increase metabolic rates during warm-up for flight.     

中华竹鼠的洞穴结构及其生境利用特征

采用徒步不定宽样线法对片口自然保护区中华竹鼠(Rhizomys sinensis)的生境选择和洞穴特征进行了研究.共设置4条样线148个20 m×20 m样方,并对61个有中华竹鼠新鲜土堆的洞穴进行了解剖观察与测量,采用Vanderloeg和Scaiva选择指数对生境选择进行分析.结果表明,其洞系结构由土丘、洞口、取食道、避难所、窝及厕所组成,每个结构都与中华竹鼠的习性及生存活动相适应;中华竹鼠喜欢选择东南坡向、坡度适中(25～45°)、上层乔木郁闭度大于25%的常绿落叶阔叶混交林或落叶阔叶林、竹子密度适中(20～40株/m~2)、竹子较粗(基径大于10 mm)、距水源较近且远离人为活动干扰的箭竹林中筑巢.     

To eject or to abandon? Life history traits of hosts and parasites interact to influence the fitness payoffs of alternative anti‐parasite strategies

Hosts either tolerate avian brood parasitism or reject it by ejecting parasitic eggs, as seen in most rejecter hosts of common cuckoos, Cuculus canorus, or by abandoning parasitized clutches, as seen in most rejecter hosts of brown‐headed cowbirds, Molothrus ater. What explains consistent variation between alternative rejection behaviours of hosts within the same species and across species when exposed to different types of parasites? Life history theory predicts that when parasites decrease the fitness of host offspring, but not the future reproductive success of host adults, optimal clutch size should decrease. Consistent with this prediction, evolutionarily old cowbird hosts, but not cuckoo hosts, have lower clutch sizes than related rarely‐ or newly parasitized species. We constructed a mathematical model to calculate the fitness payoffs of egg ejector vs. nest abandoner hosts to determine if various aspects of host life history traits and brood parasites’ virulence on adult and young host fitness differentially influence the payoffs of alternative host defences. These calculations showed that in general egg ejection was a superior anti‐parasite strategy to nest abandonment. Yet, increasing parasitism rates and increasing fitness values of hosts’ eggs in both currently parasitized and future replacement nests led to switch points in fitness payoffs in favour of nest abandonment. Nonetheless, nest abandonment became selectively more favourable only at lower clutch sizes and only when hosts faced parasitism by a cowbird‐ rather than a cuckoo‐type brood parasite. We suggest that, in addition to evolutionary lag and gape‐size limitation, our estimated fitness differences based on life history trait variation provide new insights for the consistent differences observed in the anti‐parasite rejection strategies between many cuckoo‐ and cowbird‐hosts.     

Invertebrate infestation on eggs and hatchlings of the loggerhead turtle, Caretta caretta, in Dalaman, Turkey

The damage caused by some invertebrates to the eggs and hatchlings of loggerhead turtles, Caretta caretta, was investigated during the summer of 2002 on Dalaman beach, Turkey. The specimens, identified to family or genus levels, from nine families representing seven orders were recorded as infesting nests of loggerhead turtles. The heaviest impacts on loggerhead turtle nests was made by Pimelia sp. (Tenebrionidae, Coleoptera). Twenty-four (36.3%) out of 66 intact loggerhead hatched nests were affected by these larvae. Larval damage by Pimelia sp. was recorded in 188 (10.6%) out of 1773 eggs, but only in two (0.28%) hatchlings. The results show that fewer insects were in the nest the further from vegetation and therefore the relocation of nests from the water's edge to further inland close to vegetation may increase the infestation rate of the eggs.     

Breeding ecology and nest site selection in allopatric mainland Citril Finches Carduelis[citrinella] citrinella and insular Corsican Finches Carduelis[citrinella] corsicanus

The breeding ecology and nest site selection of mainland Citril Finches and insular Corsican Finches have been studied throughout their limited range. For many years both endemic forms were considered to be two sub-species; however, based on evidence from more recent molecular studies they have been split into two species. This study provides data on the variations in breeding ecology and nest site selection in the different sub-populations of these little studied species. A secondary aim was to search out evidence of ecological differentiation between mainland Citril Finches and insular Corsican Finches. We found that the studied sub-populations of both species largely overlapped in breeding ecology. Our data confirms the close similarity of Citril Finches and Corsican Finches, both which are, similar to mountain birds, well adapted to the local habitat conditions of their different mountain systems. Several differences were identified within the studied sub-populations of the two (sub-) species with respect to nest site selection, probably caused by environmental conditions and local predators. One of the main differences between the two species is that Citril Finches breed mainly in half-open conifer forests (especially pine forests), while Corsican Finches breed in the more open scrubby mountains of the Mediterranean islands dominated mainly by the Tree Heath as an adaptation to the different landscapes on the islands. In contrast to Citril Finches, this preference of the Corsican Finches for Tree Heath as nesting plants – even if suitable pines are available – is typical of the species. These behavioural changes result in a niche expansion into open habitats at lower altitudes. We suggest that the observed niche expansion and behavioural variations are not suitable criteria for taxonomic status, a proposal in contrast to that of Sangster [Ibis 142:487–490 (2000)]. We further suggest that the few ecological differences found in this study between the two (sub-)species are the result of the so-called insular syndrome, which includes changes in life history traits such as morphology, demography and behaviour.     

Spatial heterogeneity in predator activity, nest survivorship, and nest-site selection in two forest thrushes

The ability of prey to find and use predator-free space has far-reaching consequences for their persistence and interactions with their predators. We tested whether nest survivorship of the ground-nesting veery (Catharus fuscescens) and shrub-nesting wood thrush (Hylocichla mustelina) was related to the local absence of a major nest predator, the white-footed mouse (Peromyscus leucopus). Mouse-free space was defined by trap stations that failed to trap a mouse during the avian breeding season (~May through July). In addition, mouse activity was quantified at individual trap stations based on the number of captures during the same period (six 2.25-ha trapping grids, each containing 121 trap stations trapped repeatedly throughout the summer between 1998 and 2002.) Annual mouse-free space was correlated with other measures of mouse activity based on trapping data. Both mouse-free space and activity metrics were significantly related to annual rates of nest predation (i.e., nest daily mortality rate) in veery but not wood thrush. Likewise, mouse-free space and mouse activity within the nest neighborhood (~30×30 m² surrounding each nest) was significantly related to nest survivorship in veery but not wood thrush. More trap stations had consistently greater (hotspots) and lesser (coldspots) mouse activity than expected by chance, and veeries were significantly more likely to nest near stations that had below the grid-average trapping success. Our study thus documented significant spatial variability in predator activity and its relationship to nest predation and nest-site selection in a ground-nesting songbird.     

Can cat predation help competitors coexist in seabird communities?

On oceanic islands, nest site availability can be an important factor regulating seabird population dynamics. The potential for birds to secure a nest to reproduce can be an important component of their life histories. The dates at which different seabird species arrive at colonies to breed will have important consequences for their relative chances of success. Early arrival on the island allows birds to obtain nests more easily and have higher reproductive success. However, the presence of an introduced predator may reverse this situation. For instance, in the sub-Antarctic Kerguelen archipelago, early arriving birds suffer heavy predation from introduced cats. Cats progressively switch from seabirds to rabbits, since the local rabbit population starts to peak after early arriving seabird species have already returned to the colony. When late-arriving birds arrive, cat predation pressure on seabirds is thus weaker. In this paper, we investigate the assumption that the advantage of early nest mnopolization conferred to early arriving birds may be counterbalanced by the cost resulting from predation. We develop a mathematical model representing a simplified situation in which two insular seabird species differ only in their arrival date at the colony site and compete for nesting sites. We conclude that predation may ensure the coexistence of the two bird species or favor the late-arriving species, but only when seasonal variations in predation pressure are large. Interestingly, we conclude that arriving early is only favorable until a given level where high reproductive success no longer compensates for the long exposure to strong predation pressure. Our work suggests that predation can help to maintain the balance between species of different phenologies.     

欧夜鹰的繁殖生态与移巢行为

2008年6至8月及2018年6月和7月,采用实地观察、测量和红外相机监测方法对新疆乌鲁木齐郊外头屯河流域欧夜鹰（Caprimulgus europaeus）的栖息环境、巢间距、窝卵数、孵卵、育雏、幼鸟生长及移巢行为进行了调查和分析。利用红外相机监测3个巢,监测时间分别为 15 d、23 d和11 d,共拍摄照片8 462 张,视频4 152个片段,约40 h,经过筛选得到有效照片6 807张。结果表明,欧夜鹰的巢均置于河道中央的河心岛及乱石滩沙地上,周围植被稀疏。两巢间距最近为69 m,巢密度3 ~ 7个/km2。每窝产卵2枚（n = 7）,卵长径为（30.53 ± 0.88）mm,卵短径为（21.39 ± 0.85）mm,卵体积为（7.13 ± 0.50）cm3,卵重为（7.27 ± 0.38）g（n = 5）。孵卵期为15或16 d,孵卵期成鸟离巢觅食呈双峰型,分别在天黑后的20:00 ~ 21:00时和黎明前的03:00 ~ 04:00时。育雏期为16 ~ 18 d,育雏期和孵卵期成鸟活动强度存在明显的差异,成鸟喂食幼鸟亦呈双峰型,分别在夜里的20:30 ~ 22:30时和黎明前的02:30 ~ 04:30时。成鸟的行为谱可分为9类46种,幼鸟的行为谱可分为6类32种。雏鸟的体重、体长、翅长生长发育遵循Logistic方程规律,呈曲线变化,尾长、跗跖长和嘴峰长则遵循线性生长规律。欧夜鹰的移巢行为十分独特：一是为了躲避日晒,以避免幼鸟被阳光灼伤;二是避开干扰（天敌、牧群、洪水及人类活动等）。