Nest desertion by Grey Fantails during nest building in response to perceived predation risk

ABSTRACT Grey Fantails (Rhipidura albiscapa), a common Australian flycatcher, commonly desert their nests before egg‐laying. We tested the hypothesis that Grey Fantails desert incomplete nests in response to the attention of predators by placing a mounted Pied Currawong (Strepera graculina), a common nest predator, near fantail nests that were under construction. As a control, we placed a mounted King Parrot (Alisteris scapularis), a nonpredatory bird similar in size to Pied Currawongs, near other fantail nests. Four of six female fantails (67%) deserted incomplete nests in response to the presentation of the Pied Currawong. In contrast, none of the seven females presented with a mounted King Parrot deserted. Female Grey Fantails may use the attention of a predator at the nest during the building stage as a cue to desert. Such desertion may be adaptive for Grey Fantails because currawongs are large predators, making successful nest defense unlikely, and they also present considerable risk to adults. In addition, fantails may raise multiple broods during a breeding season and, therefore, have a high renesting potential.     

Impact of nest sanitation behavior on hosts’ egg rejection: an empirical study and meta-analyses

Egg rejection in birds is a specific adaptation toward avian brood parasitism, whereas nest sanitation is a general behavior for cleaning the nest and avoiding predation. However, both behaviors refer to the action of ejecting objects out of the nest, and nest sanitation has been proposed as a pre-adaptation for egg rejection. Here, we tested the eliciting effect of nest sanitation on egg rejection in the red-whiskered bulbul Pycnonotus jocosus, a potential host species that are sympatric with parasitic cuckoos. We conducted meta-analyses of previous studies on both nest sanitation and egg rejection, in order to evaluate the consistency of our conclusions. Our results showed that nest sanitation did not elicit egg rejection in P. jocosus. The conclusions concerning such an eliciting effect from previous studies were mixed, whereas the methodologies were inconsistent, making the studies unsuitable for comparisons. However, the ejection frequency of nest sanitation was consistently higher than the frequency of egg rejection across different host species or populations. These results suggest that nest sanitation, which is an ancient behavior, is more fundamental than egg rejection, but the effect of the former on the latter is complex and needs further study. Standardized methodologies and the integration of behavior, physiology, and modeling may provide better opportunities to explore the relationship between nest sanitation and egg rejection.     

Nest sanitation behavior does not increase the likelihood of parasitic egg rejection in herring gulls

Birds’ behavioral response to brood parasitism can be influenced not only by evolution but also by context and individual experience. This could include nest sanitation, in which birds remove debris from their nests. Ultimately, nest sanitation behavior might be an evolutionary precursor to the rejection of parasitic eggs. Proximately, the context or experience of performing nest sanitation behavior might increase the detection or prime the removal of parasitic eggs, but evidence to date is limited. We tested incubation-stage nests of herring gulls Larus argentatus to ask whether nest sanitation increased parasitic egg rejection. In an initial set of 160 single-object experiments, small, red, blocky objects were usually rejected (18 of 20 nests), whereas life-sized, 3D-printed herring gull eggs were not rejected whether red (0 of 20) or the olive-tan base color of herring gull eggs (0 of 20). Next, we simultaneously presented a red, 3D-printed gull egg and a small, red block. These nests exhibited frequent nest sanitation (small, red block removed at 40 of 48 nests), but egg rejection remained uncommon (5 of those 40) and not significantly different from control nests (5 of 49) which received the parasitic egg but not the priming object. Thus, performance of nest sanitation did not shape individuals’ responses to parasitism. Interestingly, parents were more likely to reject the parasitic egg when they were present as we approached the nest to add the experimental objects. Depending on the underlying mechanism, this could also be a case of experience creating variation in responses to parasitism.     

Edible bird’s nest protects histomorphology of rat’s uterus against cadmium (Cd) toxicity through a reduction of Cd deposition and enhanced antioxidant activity

Cadmium (Cd) is often associated with reproductive disorders of mammals. Edible bird’s nest (EBN) is a natural food product made of swiftlet''s salivary secretion used to make their nests and it has been consumed as a tonic food for decades. This research aimed to study the protective effects of EBN against Cd-induced uterine toxicity in Sprague Dawley rats. Thirty (30) female Sprague Dawley rats were assigned into five groups as follows: group 1- negative control (NC) received distilled water; group 2 - positive control (PC) administered with CdCl₂, 5 mg/kg BW; while groups EBN-1, EBN-2, and EBN-3 received CdCl₂ (5 mg/kg BW) plus graded concentrations of 60, 90 and 120 mg/kg BW of EBN, respectively. After four weeks of daily oral treatment, rats were euthanized to collect the uterus for evluations of histopathological changes, Cd concentrations and Metallothionein (MT) expressions using H&E stain, inductive coupled plasma mass spectrometry (ICP-MS) and immunohistochemistry, respectively. Blood samples were collected for superoxide dismutase (SOD) analysis using SOD assay kit. Results revealed that the CdCl₂ without EBN supplement (PC) group had elevated levels of Cd in the uterus along with increased MT expressions and decreased SOD enzyme activity as compared to the NC group. Moreover, uterine histopathological changes, including glandular cysts and loss of normal structure of luminal epithelium (LE) and glandular epithelium (GE) were found in the PC group. Interestingly, groups treated with CdCl₂ along with EBN (EBN1, EBN2, EBN3) showed lower levels of uterine tissue Cd deposition and MT expression, lower degenerative changes with normal histomorphology of glands, and increased SOD activity as compared to the PC group. Overall, the findings revealed that oral exposure to Cd at a dose of 5 mg/kg BW resulted in significant alterations in the rat''s uterus. However, the toxicity effect was averted by EBN treatment in a dose dependant manner; highest protection achieved with EBN 120 mg/kg BW, through a possible detoxification mechanism and prevention of Cd deposition.     

Sociometry and sociogenesis of colonies of the harvester ant, Pogonomyrmex badius: distribution of workers, brood and seeds within the nest in relation to colony size and season

1. The vertical distribution in the nest of chambers, workers, callow workers, brood and seeds was studied in the harvester ant, Pogonomyrmex badius, in northern Florida. On each of four sample dates (May, July, October, January), six to seven colonies, chosen to represent the full range of sizes, were excavated. All chamber contents were collected and counted. Chambers were mapped and measured. In a preliminary study, two nests were excavated after preventing vertical migration by driving barriers into the wall of a pit next to the nest, severing the vertical tunnels. The vertical distribution of these barrier-nests differed little from unrestrained nests, indicating that unrestrained excavation produced a reasonable picture of vertical distributions. 2. Nest depth, chamber number and total area increased with colony size. Chamber area declined sharply with depth, as did chamber number, such that more than half of the total area was found in the upper quarter of the nest. 3. The proportion of dark-coloured (older) workers also declined strongly with depth, but this decline was weaker in the spring, and depended to a modest degree on colony size. Conversely, in the distribution of callow (young) workers, the proportion increased towards the bottom of the nest. Mean worker age was inversely related to the depth at which workers were found. The proportion of the brood also increased towards the bottom of the nest, with worker brood, sexual brood, pupae and larvae all being distributed similarly. 4. By contrast, seeds were stored at a preferred absolute depth between 40 and 100 cm. Colonies shallower than 100 cm stored seeds in their deepest chambers. Larger colonies stored most seeds in the upper third of the nest, but patterns were somewhat erratic because chambers were either filled completely with seeds or were empty. 5. Because chamber area decreased sharply with depth, the densities (individuals cm^–2) of all colony members, including dark workers, were lowest near the surface and highest in the deepest parts of the nest. Here, worker densities ranged from 2 to 8 cm^–2, and brood from 2 to 25 cm^–2. 6. The regularity of the patterns of distribution suggests that harvester ant colonies have considerable spatial and temporal structure, which serves or is the outcome of important colony processes. A simple mechanism that could generate several of these patterns is discussed. New workers produced deep in the nest move upwards as they age. As they leave the brood zone they change from brood care to general nest duties, including increased nest excavation, leading to the top-heavy pattern of nest area. As they appear at the surface, they change to guarding and foraging. Thus, age polyethism may be partly the result of this upward migration of workers.     

Evidence of Entrance Sharing and Subterranean Connections in Andrena agilissima (Hymenoptera; Andrenidae)

Andrena agilissima is a bee that nests on sloped or vertical earth walls. Data from 3 years of fieldwork presented here show that this species is communal and uses the same nesting site for many years. On an earth wall on Isola d'Elba (Tuscany, Italy), covered with many bee nest entrances, we studied an aggregation of Andrena agilissima to determine if bees share entrances, if the sharing provides evidence for subterranean connections, and if bees involved in sharing show a division of labor. We marked several females coming out of the same entrance, as well as recapturing the same females using different entrances. No division of labor was observed in our observations.     

Effect of habitat saturation on the number and turnover of queens in the polygynous ant,Myrmica sulcinodis

In polygynous social insects more than one queen reproduces in a colony. In such populations ecological factors affecting survival and reproduction of queens are likely to be of prime importance for social organization. In particular, habitat saturation leading to severe limitations in the availability of nest sites has been suggested to promote high queen number. In this study we examine the social and genetic structure of colonies in the polygynous ant Myrmica sulcinodis. We investigated a single breeding population in two adjacent habitats which differed markedly in the availability of nest sites. In the main habitat M. sulcinodis occupied almost all suitable nest sites, whereas in the other (marginal) habitat most sites were unoccupied by ants, due to a recent fire. In support of the habitat saturation hypothesis, the number of queens per colony which could explain the estimated relatedness among workers was almost five times higher for the main habitat than for the marginal habitat. This is the first demonstration that the kin structure of a social insect population is plastic and responds adaptively to short-term changes in ecological constraints such as nest site availability. Based on combined genetic and demographic data we discuss queen reproductive strategies and suggest that a special class of queen ‘floaters’ only stays ephemerally in the colonies, thus causing a substantial turnover of reproducing queens across years.     

Benefits of communal breeding in burying beetles: a field experiment

1. The ultimate causes of communal breeding and joint parental care in various species of Nicrophorus burying beetles have not been resolved satisfactorily. One hypothesis suggests that females remain on the carcass for extended periods of time because joint defence affords them improved probabilities of retaining the carcass successfully in the face of intense competition from intra‐generic competitors. 2. In a field experiment designed to test this hypothesis in N. defodiens (Mannerheim), breeding associations of two females and a male were no more successful at retaining their carcass than were monogamous pairs, lending no support to the hypothesis. 3. Intra‐generic intruders that usurped already‐buried carcasses were typically much larger than the original residents. 4. The body size of original residents affected both the burial depth and the probability of a takeover. Larger beetles buried the carcass deeper and were more likely to retain possession of the carcass. Group composition also did not affect the depth at which carcasses were buried. 5. Severe and even fatal injuries incurred by some residents indicated the occurrence of violent and damaging fights between competitors over carcasses in the field.     

布氏田鼠越冬集群贮草面积的两种估算方法比较

布氏田鼠 (Ｍｉｃｒｏｔｕｓｂｒａｎｄｔｉ)为内蒙古典型草原区的主要害鼠 ,具贮草越冬习性[2 ,5～ 7] 。因此 ,研究其越冬集群的贮草面积 ,对于分析该鼠的越冬生态特征以及定量衡量其危害程度 ,具有重要的意义。本文提出两种估算布氏田鼠越冬集群贮草面积的方法 ,即黄蒿根计数法和跑道测量法 ,并对两种估算方法进行了比较。1　材料与方法本项研究是于 1 995年度在内蒙古赤峰市克什克腾旗阿其乌拉苏木 ( 1 1 6°2 5′Ｎ ,37°5 1′Ｅ)以及中国科学院内蒙古草原生态系统定位研究站 ( 43°37′Ｎ ,1 1 6°4 1′Ｅ)进行的。1 0月中旬 ,在阿其…