Male-built nest volume varies with colony and the timing of the breeding season but not with the nesting-substrate quality and egg production in whiskered terns

Nest building can represent an energetically-costly activity for a variety of animal taxa. Besides, the determinants of within-species variation in the design of nests, notably with respect to natural and sexual selection, are still poorly known although the situation has been partly remedied recently. Based on an observational study, we examined the influence of nesting conditions (nesting-substrate quality, colony, laying date, and year) on the volume of male-built nests and its potential role as a post-mating sexually-selected display in the whiskered tern Chlidonias hybrida, a monogamous species with obligate bi-parental care breeding on unstable aquatic vegetation beds. No relationship was found between the nest volume and the nesting-substrate quality (i.e. nest stability) indicating that the density of white waterlily leaves was large enough when whiskered terns breed. In contrast, building a large nest likely constitutes a selective advantage since nests were larger in less densely populated colonies and for early breeders whatever the year. Since being influenced by nesting conditions, the volume of male-built nests was unlikely to be a sexually selected trait in whiskered terns. The reproductive effort by females (the probability of laying one, two or three eggs, and variation in mean egg volume per clutch) was indeed not correlated with the volume of male-built nests. The fitness consequences of building a large nest are yet to be studied and additional investigations are recommended to better depict the participation of males early during breeding (including notably courtship feeding) and later to chick provisioning.

Record of Anthophora (Clisodon) terminalis in a wooden trap-nesting block and comparison to available nesting information (Hymenoptera: Apidae)

Bee nesting substrate choice can influence habitat use, conservation effort efficacy, and population or landscape-use modeling, but information on nesting sites are often scattered in the literature. Here we bring together the available information on nests of a widespread bee, Anthophora (Clisodon) terminalis Cresson, and describe an unusual new nesting substrate use for this species.

Nesting Ecology of Polistes Species (hymenoptera, Vespidae) in Urban Areas of South-western Iberian Peninsula

Urbanization is increasing across the globe and it is recognized as a major factor affectingspecies, populations and assemblages. Although urbanization is recognized as a major threat to biodiversity, there is increasing evidence that urban habitats may play a role in conservation. The objective of this work was to verify the occurrence of Polistes species (Vespidae) and the substrates used for nesting in urban areas in south-western Iberian Peninsula. The study was carried out from March to August of 2018 in three small towns in the Llanos de Olivenza region (SW Spain). Active searching was conducted for colonies of social wasps along and for each colony that was found we identified the species, type of substrate used for nesting, height of the colony in relation to the ground level and orientation. 753 colonies of social wasps were found belonging to two species: Polistes dominula and P. gallicus. The most used nesting substrate was clay roof tile followed by metals. The height of the nests was related to the height of the buildings on which they were built. In all the tree towns nests exposure were oriented to the SE with mean angle values oscillating between 127.42° and 140.68°. In addition, our results confirm the prediction that wasps are more abundant in less or non-urbanized areas even if they are small urban areas such as those studied in our case.

Unique nesting biology of Osmia ( Melanosmia) uncinata, a Palaearctic osmiine bee specialized on thick-barked conifers (Hymenoptera, Megachilidae)

Osmia (Melanosmia) uncinata Gerstäcker is a Palaearctic megachilid bee distributed from temperate and northern Europe eastwards to the Russian Far East. The discovery of over 80 nests in Switzerland, southern Germany and Scotland enabled for the first time a closer investigation of its nesting biology and prompted the assessment of the species’ phenology, distribution and habitat. O. uncinata nested in self-excavated burrows inside the bark of both living trunks and dead stumps of Pinus sylvestris. The nests were excavated at a height of 10–220 cm above ground either on the underside of prominences of longitudinal bark ribs or inside beetle borings and extended more or less vertically upwards. They consisted of a single straight to slightly curved burrow with rarely one to three side burrows, had a total length of 1.2–12.0 cm and contained 1–6 brood cells. The brood cells, which faced downwards with the larval provisions being located in the upper cell half, were separated from each other by one-layered walls of chewed leaves (“leaf pulp”). The nests were sealed with a plug of 2–4 closely adjacent walls of leaf pulp. DNA metabarcoding of cell and plug walls revealed that Potentilla and Fragaria (Rosaceae) served as leaf pulp sources. Pre-imaginal mortality amounted to 77%, partly caused by brood parasites such as Sapyga similis (Sapygidae) and Cacoxenus indagator (Drosophilidae) or predators such as snakeflies (Raphidioptera). At low elevations, O. uncinata needs one year for its development and overwinters as imago inside the nest, whereas in the subalpine zone of the Alps it has a two-year cycle passing the first winter as prepupa and the second winter as imago. O. uncinata starts to emerge between the end of March at low elevations and the end of May at higher elevations qualifying as an early flying bee like the other European O. (Melanosmia) species. The distribution of O. uncinata in Central Europe and Scotland largely coincides with the occurrence of P. sylvestris. As in the pine, it extends over a wide altitudinal range from below 100 m up to 1900 m a.s.l. and encompasses dry and wet as well as warm and cold habitats including open pine forests, inner and outer forest edges dominated by pine and isolated pine groups. At a few locations in the subalpine zone of the Alps, O. uncinata occurs in the absence of P. sylvestris; here, the thick bark of Larix decidua serves as a substitute nesting substrate.

New species of Augochlora (Oxystoglossella) Eickwort (Hymenoptera; Apoidea) from Northeastern Brazil with an identification key for the region

Within Augochlorini, Augochlora Smith is one of the most speciose genera, with 118 species, and widely distributed groups, occurring from Argentina to Canada. The genus has a remarkable range of social behaviors and nesting substrate preferences. There are two recognized extant subgenera: Augochlora s.s., whose species nest in decaying wood cavities and Oxystoglossella, whose species nest in soil. To date, a single species revision is available for Central Argentina and Uruguay. In the present study we provide a revision of Oxystoglossella species occurring in Northeastern Brazil including the description of three new species: Augochlora bipunctata sp. nov., Augochlora modica sp. nov. and Augochlora tenax sp. nov. Herein Halictus eucnemis Vachal is resurrected from synonymy with Augochlora thalia Smith, and the lectotype of Halictus hemitomes Vachal is presently designated. Augochlora aurinasis is cited for Brazil for the first time. A key to the six species of Oxystoglossella occurring at Northeastern region in Brazil is provided. The three new species are apparently restricted to this region, being one of them probably linked to the Caatinga biome.

Reproductive success of the threatened San Clemente Bell’s Sparrow (Artemisiospiza belli clementeae) in recovering habitats is similar to success in historical habitat

The San Clemente Bell’s Sparrow (Artemisiospiza belli clementeae) is a federally threatened subspecies endemic to San Clemente Island, California. Previous research suggested dependence on boxthorn (Lycium californicum) as breeding habitat and nesting substrate; however, this conclusion was based on data collected when introduced feral ungulates had severely degraded the soil and vegetation cover. Since removal of the ungulates, native vegetation has gradually increased and the San Clemente Bell’s Sparrows have expanded into areas where habitat had been unsuitable. To explore how Bell’s Sparrows use these areas, we examined reproductive metrics associated with habitat covariates gathered at 214 nest sites used by Bell’s Sparrows from 2014 to 2016. We found that nest success in boxthorn habitat, previously considered an essential habitat for Bell’s Sparrow nesting, was similar to success in alternative habitat types. Our findings contradict previous conclusions that Bell’s Sparrows were boxthorn-dependent. We believe this previously documented relationship was likely due to the lack of available alternative nesting habitat following years of feral ungulate degradation, and Bell’s Sparrows now reproduce in multiple habitat types and throughout most of San Clemente Island. Furthermore, our findings illustrate the importance of long-term monitoring and corresponding adaptive management when monitoring species in changing and recovering landscapes.

Occurrence and nesting behavior of social wasps in an anthropized environment

Some effort had been made concerning the social biodiversity of wasps in Brazil; however, few approaches have been made relating to how this taxa have adapted their nesting behavior to anthropic mixed environments. Thus, the present work aimed to survey the occurrence of social wasps in an anthropic area and their relationship with different types of nesting substrates. Increasing the knowledge of social wasps in anthropic areas would allow us to develop strategies for their conservation and management. Twenty long-term surveys were made at the Universidade de São Paulo, Ribeirão Preto campus, São Paulo State. During the searches, we collected information about wasp species and nesting substrate. A total of 20 species of 8 genera were identified, and a total of 431 active colonies were registered. Epiponini was the richest in terms of species richness. On the other hand, Mischocyttarini was represented by more active colonies. Mischocyttarus cerberus had a remarkably greater number of colonies, which agreed with the idea of preference of anthropic environments by independent founding wasps. Nesting behavior was associated with eight substrate categories. We observed that some species might express certain plasticity regarding their nesting substrate usage, whereas some expressed certain specificity. Facing the increase in the actual urbanization process and, consequently, habitat loss, this type of study might contribute towards better understanding how these insects are affected by altered environment.

Changes in nesting sites abundance and their use by woodpeckers along an urban gradient: a ten-year comparison

Woodpeckers nesting substrate abundance may be reduced by urban expansion, negatively affecting their reproduction. Long-term studies in the tropics are rare but valuable to estimate how urban development has affected ecological communities. We present a ten-year comparison on nesting substrate abundance and their use by Melanerpes rubricapillus and M. chrysauchen woodpeckers along an urban gradient in Golfito, Costa Rica; which include three habitats and three substrates (snags, palms, and posts). Conditions remained unchanged in non-urban areas. In semi-urban areas, snag, posts, and nests on them, have decreased. In urban areas, despite snags and posts remaining constant, their use also decreased. In semi-urban and urban areas, palms and palm nests increased. This long term comparison indicates that woodpeckers took advantage of the increased presence of ornamental palms in gardens.