The nest structure in four species of solitary wasps of the subfamily Eumeninae (Hymenoptera, Vespidae)

Nests of Syneuodynerus egregius, Euodynerus posticus, Ancistrocerus antilope, and A. nigricornis have a similar structure and consist of a linear row of cells separated by transverse partitions made of soil mastic. The number of cells in the nests is 1–11 (5.6 ± 0.8) in S. egregius, 1–7 (2.6 ± 0.2) in E. posticus, 1–10 (4.0 ± 0.7) in A. antilope, and 1–28 (7.9 ± 1.3) in A. nigricornis. Most nests consist of several cells in S. egregius and A. nigricornis and of one or two cells in E. posticus and A. antilope. The female to male ratio is 1.2: 1.0 in E. egregius, 1.5: 1.0 in E. posticus, 1.9: 1.0 in A. antilope, and 1.0: 1.0 in A. nigricornis. The nests of S. egregius usually contain brood of both sexes; those of A. antilope, that of one sex. The sex ratio is correlated with the diameter of the occupied nest cavities only in A. antilope. The volume of the cells with females exceeds that of the cells with males in all the species studied: by 23, 34, 54, and 98% in S. egregius, E. posticus, A. antilope, and A. nigricornis, respectively. The relative difference between the body masses of male and female prepupae is correlated with the relative difference between the volumes of their cells. The nest cells of S. egregius are separated by double partitions consisting of homologs of cell bottoms and lids. In the nests of E. posticus the partitions are single; each cell has a bottom and a lid, with “false cells” being located between them. In the nests of A. antilope and A. nigricornis, the partitions are single but all of them are homologs of the cell bottoms. The nest cells of S. egregius belong to the equilinear type; their length is relatively constant in the cavities of various diameters. The nest cells of A. antilope are of the equivolumetric type: their length is smaller in broad cavities and greater in narrow ones, the cell volume being relatively constant in the cavities of different diameters. The nest cells of E. posticus and A. nigricornis are of the intermediate type. Statistical models of nests reflecting their mean parameters and composition were built. The evolutionarily primitive and progressive features in the nest structure are discussed.     

The nesting biology of the bee, Osmia dimidiata Morawitz, 1870 (Hymenoptera, Megachilidae) in the Crimea

The structure and composition of Osmia dimidiata nests were studied based on the material of 133 nests obtained from trap-nests in five localities of the Crimea. The nests contained from 1 to 9 cells (on average, 2.2), separated with partitions made of masticated leaves. Most of the cells had a massive hemispherical bottom and a thin flat cover. The final plug had a structure similar to the cell bottom. The cells occurred singly in the nest cavity or were arranged in rows of 2 or 3 cells separated by galleries. The diameter of the occupied cavities was positively correlated with the fraction of the females in the progeny and with the mass of the cocoons, but negatively correlated with the cell length. The cells with females were 1.5 times as long as those with males. The cocoons with females were twice as heavy as those with males. The peculiar characters of the nest structure of O. dimidiata may mean that the typical nesting substrates of this species are abandoned cells of other bee and wasp species. The characteristic mechanism of estimating the mass of the pollen loaf stored in the cells and determining the brood sex ratio has evolved in the O. dimidiata due to its tenantry. This mechanism is based on two constants: the sex-linked cell length and the fixed distance between the pollen loaf and the cell cover. When choosing the nesting cavities, the female prefers broader and longer tubes for cells with females and narrower and shorter ones for cells with males. The overall sex ratio of the progeny was male-biased (1 ♀: 2.5 ♂) and depended on the food supply abundance. The adults of O. dimidiata fly in the Crimea from the last decade of May until the end of July. Hibernation occurs at the adult stage in the cocoons. Females collect pollen from flowers of Asteraceae or, rarely, Fabaceae. The nests may be destroyed by Melittobia acasta, Monodontomerus aereus, M. obscurus, Sapyga quinquepunctata, Stelis phaeoptera, and Trichodes apiarius; 21% of the progeny died from these enemies, and 22%, due to other factors. The previously proposed synonymy of Pseudosmia taurica Radoszkowski, 1874 (nec Osmia taurica Radoszkowski, 1887) and O. dimidiata is rejected.     

Nesting and biology of Jucancistrocerus caspicus (hymenoptera,vespidae, eumeninae)

Females of Jucancistrocerus caspicus nest in dense clay ground on the vertical surface of cliffs. The nests contain 1–9 cells (on average 2.8) and have a linear-branched construction. Females surmount the entrance of the burrow with a curved chimney which has a laced structure. The cells are positioned vertically in the main burrow and obliquely or horizontally in the lateral tunnels; the cells in a row are separated with double partitions. The size of the cells is 7–9 × 4–4.5 mm, the diameter of the nest burrow is 4 mm. The egg is laid before provisioning and is attached to the cell ceiling with a filament. Females hunt for weevil larvae and store 23–33 larvae (on average 27.8) in each cell. The species is univoltine, with prepupae hibernating in their cocoons. The nests are parasitized by the cuckoo wasps Chrysis rutilans which cause 11.5% of brood mortality. Adult wasps are killed by the spiders Pholcus sp. living near the nests.     

Nest site selection and efficacy of artificial nests for breeding success of Scarlet Macaws Ara macao macao in lowland Peru

Psittacidae (parrots) have the most threatened species of any bird family in the world. Most parrots are obligate secondary cavity nesters, and can be limited in their breeding success by the availability and quality of nest hollows. However, nesting opportunities for parrots can be increased by provision of artificial nest boxes. The Tambopata Macaw Project has been studying the breeding ecology and natural history of the Scarlet Macaw Ara macao macao in the south-eastern Peruvian Amazon for over 20 years by monitoring natural nest hollows and two types of artificial nest (wooden and PVC). We present data for breeding success in natural and artificial nests over 12 consecutive breeding seasons. The aims of this study were to: (a) determine the nesting requirements and reproductive success of breeding macaws; and, (b) compare the efficacy of the two types of artificial nests and natural nest cavities. Our data showed a high rate of reoccupation of successful nests in consecutive years and that nests in artificial and natural nests had very similar reproductive parameters. Our results indicate that artificial nest types can be used by conservation managers seeking to assist A. macao populations where nest hollows are in short supply, and that artificial nests can contribute important data to natural history studies of species where access to natural nests is limited.     

Experiments with artificial nests provide evidence for ant community stratification and nest site limitation in a tropical forest

Ants are dominant in tropical forests and many species nest in hollow cavities. The manner in which species are vertically stratified in these complex habitats is not known, with lack of nest sites being proposed to limit ant populations. Here, we assess ant community stratification and nest site limitation in a lowland rainforest in New Guinea using experimental addition of artificial bamboo nests of two cavity sizes (small: ~12 mm large: ~32 mm diameter) placed at ground level, in the understorey, and in the canopy. We also conducted a pilot experiment to test the utility of nest translocation. Nests were checked for occupancy after 10 weeks and half of the occupied nests were then translocated between forest plots, while keeping same vertical position. Occupancy of small nests was much higher in the understorey and canopy than at ground level (~75% vs. ~25%). Translocation was successful, as a majority of nests was inhabited by the same species before and after translocation and there was no impact of translocation to a different plot compared to the control, except for a reduction in colony size at ground level. Our experiment demonstrates a vertical stratification in community composition of ants nesting in hollow dead cavities and shows that these ants are more nest site limited in the higher strata than at ground level. Use of small artificial cavities has great potential for future experimental studies, especially for those focused on arboreal ants, as occupancy is high and translocation does not negatively affect their colony size. Abstract in Tok Pisin is available with online material.     

First Data on the Bionomics of the Solitary Wasp <Emphasis Type="Italic">Leptochilus membranaceus</Emphasis> (Morawitz) (Hymenoptera,Vespidae: Eumeninae)

The bionomics of Leptochilus membranaceus (Morawitz) was studied in Crimea. The species is confined to herbaceous xerophytic habitats with sparse vegetation and has two generations per year. Adult feeding was recorded on flowers of 8 plant species of 6 families. A single nest was found in an old acridid egg pod in clayey soil. The inner cavity of the empty egg pod was 12 mm long and 3 mm wide. The nest contained one cell with a prepupa in the cocoon. The cell was sealed with a final plug 2 mm thick, made of gravel and mud. The cocoon consisted of three equal thin layers, the outer layer being firmly attached to the cell walls. Females of L. membranaceus do not visit water sources. The origin of the agent bonding the building material (soil) used by L. membranaceus and other congeneric species is discussed. In addition, nests of Ancistrocerus scoticus (Curtis) are also discussed; these nests occur in old acridid egg pods which were earlier misinterpreted as bottle-shaped cells built by the wasps themselves.     

Do Fleas,and/or Old Nest Material,Influence Nest-site preference in Hole-nesting Passerines?

This study examined nest-site choice in a migratory population of pied flycatchers (Ficedula hypoleuca) and sympatric populations of three resident tit species (Parus major, P. caeruleus and P. palustris) in central Sweden. All four species are secondary-cavity nesters which naturally breed in pre-formed tree cavities but readily use artificial nest boxes. We asked whether flycatchers and tits discriminate between nest boxes that: 1. Are ‘empty’; 2. Contain old nests without ectoparasites (fleas Ceratophyllus sp.); or 3. Contain old nests with ectoparasites. We found that pied flycatchers preferred nest boxes containing old nests, regardless of whether these nests held parasites. In contrast, tits did not discriminate between the three types of boxes. Tits may pay a cost for their lack of choosiness: after the breeding season, tit nests contained more fleas than flycatcher nests. Nevertheless, parasites did not affect the choice of a nest site in any of the species studied. We suggest that the migratory flycatchers are in a hurry to start breeding upon arrival and use the presence of an old nest as a shortcut cue to assess nest-site quality. Also, they may save valuable time by copying the choice of previous breeders. Non-migratory tits may have more time to inspect nest sites, but do not seem to use the same cues in nest-site selection as the pied flycatcher.     

Ant Colonies Prefer Infected over Uninfected Nest Sites

During colony relocation, the selection of a new nest involves exploration and assessment of potential sites followed by colony movement on the basis of a collective decision making process. Hygiene and pathogen load of the potential nest sites are factors worker scouts might evaluate, given the high risk of epidemics in group-living animals. Choosing nest sites free of pathogens is hypothesized to be highly efficient in invasive ants as each of their introduced populations is often an open network of nests exchanging individuals (unicolonial) with frequent relocation into new nest sites and low genetic diversity, likely making these species particularly vulnerable to parasites and diseases. We investigated the nest site preference of the invasive pharaoh ant, Monomorium pharaonis, through binary choice tests between three nest types: nests containing dead nestmates overgrown with sporulating mycelium of the entomopathogenic fungus Metarhizium brunneum (infected nests), nests containing nestmates killed by freezing (uninfected nests), and empty nests. In contrast to the expectation pharaoh ant colonies preferentially (84%) moved into the infected nest when presented with the choice of an infected and an uninfected nest. The ants had an intermediate preference for empty nests. Pharaoh ants display an overall preference for infected nests during colony relocation. While we cannot rule out that the ants are actually manipulated by the pathogen, we propose that this preference might be an adaptive strategy by the host to “immunize” the colony against future exposure to the same pathogenic fungus.     

Nistplatzwahl, Neststandort und Nestbau beim Wasserpieper (Anthus spinoletta)

We investigated specific adaptations in nest-site selection and nest building behaviour of female Water Pipits, which are thought to be key mechanisms explaining the high reproductive success of this species in the alpine tundra. Water Pipits were studied from 1983 to 1989 in Obergurgl (1935–2400 m), Ötztal, Austria. Female Water Pipits spent 3–4 weeks for thorough scanning of potential nest cavities within territories. Nests were situated at sites which gave shelter from drifting snow or rain, from prevailing winds and from extreme radiation. All nests were deeply sunken into the ground and more resembled nest cavities, than simple ground-troughs. Additional adaptations were found in the technique of nest building.

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Ellen Thaler zum 60. Geburtstag gewidmet     

Lifespan Analyses of Forest Raptor Nests: Patterns of Creation,Persistence and Reuse

Structural elements for breeding such as nests are key resources for the conservation of bird populations. This is especially true when structural elements require a specific and restricted habitat, or if the construction of nests is costly in time and energy. The availability of nesting-platforms is influenced by nest creation and persistence. In a Mediterranean forest in southeastern Spain, nesting-platforms are the only structural element for three forest-dwelling raptor species: booted eagle Aquila pennata, common buzzard Buteo buteo and northern goshawk Accipiter gentilis. From 1998 to 2013, we tracked the fate of 157 nesting-platforms built and reused by these species with the aim of determining the rates of creation and destruction of nesting-platforms, estimating nest persistence by applying two survival analyses, describing the pattern of nest reuse and testing the effects of nest use on breeding success. Nest creation and destruction rates were low (0.14 and 0.05, respectively). Using Kaplan Meier survival estimates and Cox proportional-hazards regression models we found that median nest longevity was 12 years and that this was not significantly affected by nest characteristics, nest-tree dimensions, nest-builder species, or frequency of use of the platform. We also estimated a transition matrix, considering the different stages of nest occupation (vacant or occupied by one of the focal species), to obtain the fundamental matrix and the average life expectancies of nests, which varied from 17.9 to 19.7 years. Eighty six percent of nests were used in at least one breeding attempt, 67.5% were reused and 17.8% were successively occupied by at least two of the study species. The frequency of nest use had no significant effects on the breeding success of any species. We conclude that nesting-platforms constitute an important resource for forest raptors and that their longevity is sufficiently high to allow their reuse in multiple breeding attempts.     

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.     

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.     

Birds adopting weaver nests for breeding in Africa

Weavers build domed, long-lasting nests that may also be adopted by other species for breeding, probably reducing the energetic costs of nest building to varying degrees. In an extensive literature search, 57 species were found to have at least one record of adopting a weaver nest. There is one known obligate nest user, the Pygmy Falcon Polihierax semitorquatus. Four species were classed as near obligate nest adopters. Four species were listed as common, 10 as occasional, and 38 species as rare nest adopters. Other than the falcon and lovebirds Agapornis species, these nest adopters are passerines. Of the 57 species of nest adopters, 35 species had confirmed eggs and/or chicks found in the weaver nests. Most nest adopter species were in the Estrildidae family (20 species), with three estrildids classed as near obligates. This was followed by the Muscicapidae family, species that build cup nests. By building their cup nests inside weaver nests, there is likely protection from adverse weather and predators. Overall, there appeared to be a large diversity of nest adopter species for the traditional savanna living weavers (Ploceus, Bubalornis, Anaplectes, Plocepasser and Philetairus).     

Vertical nest stratification of four heron species in southern Brazil

Herons generally breed in mixed flocks and their nests are made in shrub wetlands and on islands. Waterbirds can select different tree species in the heronries which can influence the vertical stratification of the heron nests. The aim of the present study was to determine the vertical nest stratification among four Ardeidae species in heronries in southern Brazil. The study was carried out during four breeding seasons between 2004 and 2009. No significant species-specific difference in mean nest height was observed between the three heronries. However, there was some variation in nest heights per species in the four years of the study and among the heron species. Nest height was correlated with the body size of the heron species. The smaller species, Bubulcus ibis, Egretta thula, and Nycticorax nycticorax, occupied mainly the lower stratum and the largest, Ardea alba, the higher stratum. The colonist species B. ibis did not show a clear preference, occupying both Mimosa bimucronata and Cephalanthus glabratus for nest building, while the other three herons selected mainly M. bimucronata if the two tree species were available.     

Big is better: the importance of size for reproductive success in male Pomatoschistus minutus (Pallas) (Pisces, Gobiidae)

The sand goby, Pomatoschistus minutus , was used in aquarium experiments to study the importance of body size for the ability of males to gain access to nest sites and mates. When several male and female P. minutus were allowed to reproduce together, on average, half of the males built nests, and half of those males obtained eggs in their nests. Males with nests were significantly larger than males without nests, and nests with eggs belonged to males larger than the males with empty nests. In another experiment, when two males were competing for one nest, the largest male occupied the nest when both fish were put into the aquarium simultaneously. However, when the smaller male had been allowed to establish a nest before the larger male was introduced, the small male could usually retain the nest. Males with a body length < 50 mm did not build nests at all in the early part of the breeding season. In female choice experiments, no preference for larger males was found. Thus, male-male competition for nest sites and behavioural differences between different sized males seem to be the main factors influencing the non-random mating success in male P. minutus.     

The thermal properties of some nests of the Eurasian Tree Sparrow Passer montanus

Using an electronic apparatus simulating a bird roosting in a nest at night, we examined the insulating qualities of Eurasian Tree Sparrow (Passer montanus) nests built in nest boxes under winter conditions. Nests of different construction were compared with an empty box, and with roosting in open air. Energy savings in an empty box accounted for 18%, in boxes with incomplete nests for 23% and in boxes with complete nests up to 36%. The insulating value of nests mostly depended on their completeness and the proportion of feathers in the lining.     

Nest preference and ecology of cavity-nesting bees (Hymenoptera: Apoidea) in Punjab,Pakistan

Among bees, 85 % are solitary species, most of them are ground-nester and some are cavity-nesting and construct their nests in pre-existing cavities. This work was conducted to evaluate the substrate preference and nest architecture (acceptance, occupation percentage, seasonality and parasitism) of cavity-nesting bees in different substrates. Trap nests offered comprised five different materials (drilled cavities in wood, bamboo, cardboard tubes, plastic soda straws, and mud blocks). These were installed in four districts for two years. The nesting cavities of five different diameters (6, 8, 10, 12 and 14 mm) were provided in each nesting material with an average length of 180 ± 9.92 mm. In all the materials, 5400 nesting cavities were offered, out of which 628 were colonized by bees from two families (Megachilidae and Apidae) and six species (Megachile cephalotes, M. lanata, M. bicolor, Xylocopa basalis, X. fenestrata and Ceratina smaragdula), including one parasitic bee (Euaspis carbonaria). The bee species differed significantly in occupying five nesting materials. The most preferred diameters were 8 mm and 10 mm, with 52.20% and 29.45% of colonization, respectively. Nesting was done throughout the year except in winter. This study will serve as a baseline for future studies and conservation programs of cavity-nesting bees in Pakistan.     

The relationship between introduced European Starlings and the reproductive activities of Mountain Bluebirds and Tree Swallows in British Columbia,Canada

The European Starling Sturnus vulgaris is an introduced species in North America and is an aggressive competitor for tree cavity nest‐sites. Starlings are commonly considered to influence nest‐site selection and reproductive success of native cavity‐nesting species negatively. We examined the relationship between Starling nest density and the fecundity of two native secondary cavity‐using passerines, Mountain Bluebird Sialia currucoides and Tree Swallow Tachycineta bicolor. We monitored a total of 622 nests (approximately equal numbers for each of the three species) in woodpecker‐excavated and naturally occurring cavities in 29 small forest groves in central British Columbia, Canada, between 2000 and 2009. The dimensions of cavities used and the timing of nest initiation overlapped for all species, although Starlings initiated clutches earliest. Mixed‐effects models were used to assess whether nest abundance, clutch size or nest success were affected directly by Starling nest abundance, or indirectly via a shift in cavity selection or timing of breeding. Starlings and Mountain Bluebirds showed inverse trends in nest abundance. Mountain Bluebird clutch sizes were smaller if they were initiated later in the breeding season. There was weak evidence that Tree Swallow clutch size decreased with cavity depth when Starling nests were abundant, and increased with cavity depth where there were few Starling nests. We conclude that despite the aggressive nature of this exotic cavity‐nester, the influence of Starlings on native secondary cavity‐nesting passerines is modest where cavities are abundant.     

The Significance of the Vestibular Cell in Trap Nesting Wasps (Hymenoptera: Crabronidae): Does its Presence Reduce Mortality?

In a study carried out with the trap-nesting solitary wasp Trypoxylon attenuatum (Hymenoptera: Crabronidae) in 2000, we analysed the significance of different nest characteristics, like the vestibular cell and empty intercalary cells, and its role in the reduction of mortality. Analysis of the presence of the vestibular cell suggested that it represents a nest completion structure, whose presence reduces mortality in the initial stages (M1) but does not affect that due to chrysidid parasitoids (MP). The length of such vestibular cell was found to depend mainly on the space between the last provisioned cell and the exterior, pointing to a possible role in the reduction of the remaining space that could be used by other females to establish a nest exterior to the completed one. The empty intercalary cells were smaller than the vestibular cells, did not affect M1 or MP mortality rates in the nest, and exhibited an “aggregated” pattern of occurrence. This suggests that they could be the result of “abnormal” behaviour by the female owning the nest. The total mortality rate decreased with the increase in the number of cells in the nests, also being greater in nests established at low heights above the ground. M1 was lower in the innermost cells, while MP increased towards the interior and in the nests with more cells. The distribution in the nests of cells parasitized by Trichrysis cyanea (the main natural enemy found in the wasp population studied) reflects an “aggregated” pattern, suggesting repeated attacks against certain nests.