Delayed timing of breeding attempts, but not time lost to nest construction, reduces the annual reproductive output of the Eastern Phoebe (Sayornis phoebe)

For many birds, nest construction is a costly aspect of parental care, trading finite energetic resources between parental care and self-maintenance. For multi-brooded organisms with short breeding seasons, such as migratory passerines, repeated nest construction could be especially costly if the activity delays the onset of breeding attempts. Earlier studies on passerines that reuse nests between breeding seasons suggested that time lost to initial nest construction reduces seasonal reproductive output. However, costs associated with building new nests between breeding attempts, within the same breeding season, have largely been ignored. Here, we experimentally removed first nests, after fledging or failing, of Eastern Phoebes ( Sayornis phoebe), to evaluate how the annual onset of breeding and nest construction between breeding attempts affected parental investment into second attempts. We found that first egg laying date negatively predicted the probability of second breeding attempts, but experimental treatment (first nest removal vs. control) did not. Neither first egg laying date nor treatment statistically influenced any of the reproductive traits in second breeding attempts (clutch size, nestling body condition, and nestling growth rate). We conclude that in this species, second breeding attempts are limited by the initial onset of seasonal reproduction, and not by time lost to nest construction between breeding attempts.

Failure to account for behavioral variability overestimates bonobo populations and compromises accuracy in population monitoring

Wildlife population monitoring depends on accurate counts of individual animals or artefacts of behavior (e.g., nests or dung), but also must account for potential biases in the likelihood to encounter these animals or artefacts. In indirect surveying, which depends largely upon artefacts of behavior, likelihood to encounter indirect signs of a species is derived from both artefact production and decay. Although environmental context as well as behavior contribute to artefact abundance, variability in behaviors relevant to artefact abundance is rarely considered in population estimation. Here we demonstrate how ignoring behavioral variability contributes to overestimation of population size of a highly endangered great ape endemic only to the Democratic Republic of the Congo, the bonobo (Pan paniscus). Variability in decay of signs of bonobo presence (i.e., nests) is well documented and linked to environmental determinants. Conversely, a single metric of sign production (i.e., nest construction) is commonly used to estimate bonobo density, assumed to be representative of bonobo nest behavior across all contexts. We estimated nest construction rates from three bonobo groups within the Kokolopori Bonobo Reserve and found that nest construction rates in bonobos to be highly variable across populations as well as seasonal within populations. Failure to account for behavioral variability in nest construction leads to potentially severe degradation in accuracy of bonobo population estimates of abundance, accounting for a likely overestimation of bonobo numbers by 34%, and in the worst cases as high as 80% overestimation. Using bonobo nesting as an example, we demonstrate that failure to account for inter- and intra-population behavioral variation compromises our ability to monitor population change or reliably compare contributors to population decline or persistence. We argue that variation in sign production is but one of several potential ways that behavioral variability can affect conservation monitoring, should be measured across contexts whenever possible, and must be considered in population estimation confidence intervals. With increasing attention to behavioral variability as a potential tool for conservation, conservationists must also account for the impact that behavioral variability across time, space, individuals, and populations can play upon precision and accuracy of wildlife population estimation.

Nesting behavior of the Elegant Euphonia (Euphonia elegantissima, Aves: Fringillidae) in urban and suburban sites of east Mexico

Between 2005, 2014–2017, we studied six Elegant Euphonia (Euphonia elegantissima) nests from two sites (urban and suburban) in the city of Xalapa, Veracruz. They were located in a macadamia tree crown, under epiphytic bromeliads, and under hanging fern and Euphorbia pots. The two nests we extracted and measured (7.2 x 7.5 x 5.6 cm; 10.1 x 8.6 x 11 cm), were closed and globular, with a lateral entry and mainly made of plant fibers, leaves, and cobwebs. Our observations included nest construction, egg incubation and chick care (nestling phase). Nest construction took at least 10–11 days, while egg incubation took 14–18 days. Incubation was done by the female in all but one observation, and the male escorted the female to the nest on every occasion. Time of incubation sessions ranged from 36–88 min (mean = 62 min) with shorter out nest sessions (3–18 min, mean = 9 min). There were three eggs in two of the nests, and in one only two eggs hatched; four chicks were observed in another nest. The nestling phase lasted 20 days in two nests, with the male spending more time (35–300 s, mean = 109 s) than the female taking care of the chicks (25–99 s, mean = 53 s). Reciprocal escorting was observed during the nestling phase, with the male always arriving first. Breeding occurred in January, April, May (two nests), June, and July. Observing the male of the Elegant Euphonia escorting the female during the incubation period, corroborates previous observations of this behavior in genera Euphonia and Chlorophonia. Incubation and nestling time periods were similar to other species of these genera.

Animal culture research should include avian nest construction

Material culture—that is, group-shared and socially learned object-related behaviour(s)—is a widespread and diverse phenomenon in humans. For decades, researchers have sought to confirm the existence of material culture in non-human animals; however, the main study systems of interest—namely, tool making and/or using non-human primates and corvids—cannot provide such confirmatory evidence: because long-standing ethical and logistical constraints handicap the collection of necessary experimental data. Synthesizing evidence across decades and disciplines, here, I present a novel framework for (mechanistic, developmental, behavioural, and comparative) study on animal material culture: avian nest construction.

Social consequences of energetically costly nest construction in a facultatively social bee

Social groups form when the costs of breeding independently exceed fitness costs imposed by group living. The costs of independent breeding can often be energetic, especially for animals performing expensive behaviours, such as nest construction. To test the hypothesis that nesting costs can drive sociality by disincentivizing independent nest founding, we measured the energetics of nest construction and inheritance in a facultatively social carpenter bee ( Xylocopa sonorina Smith), which bores tunnel nests in wood. We measured metabolic rates of bees excavating wood and used computerized tomography images of nesting logs to measure excavation volumes. From these data, we demonstrate costly energetic investments in nest excavation of a minimum 4.3 kJ per offspring provisioned, an expense equivalent to nearly 7 h of flight. This high, potentially prohibitive cost of nest founding may explain why females compete for existing nests rather than constructing new ones, often leading to the formation of social groups. Further, we found that nest inheritors varied considerably in their investment in nest renovation, with costs ranging more than 12-fold (from 7.08 to 89.1 kJ energy), probably reflecting differences in inherited nest quality. On average, renovation costs were lower than estimated new nest construction costs, with some nests providing major savings. These results suggest that females may join social groups to avoid steep energetic costs, but that the benefits of this strategy are not experienced equally.

Observation of Megachile saulcyi (Guérin-Méneville, 1844) (Hymenoptera: Megachilidae) using plastic for nest construction in Chile

Megachile saulcyi (Guérin-Méneville, 1844) is reported for first time cutting pieces from a plastic bag that are used for the construction of its nest, this being the first record of a bee performing this activity in Chile. The growing problem of solitary bees that use plastic for the construction of cells for their nest is analyzed as well as the consequences that they can originate in the survival of their populations.

Two new Nearctic genera in the tribe Odynerini s. str. revealed on the bionomics and morphology, with a comment on the cocoons of the eumenine wasps (Hymenoptera: Vespidae: Eumeninae)

Two new genera are described for three species in the “red” group of the North American eumenine wasps from the genus Odynerus Latreille, 1802: Bohartodynerus Fateryga, gen. n. for O. margaretellus Rohwer, 1915 (type species) and O. cinnabarinus Bohart, 1939, and Parkerodynerus Fateryga, gen. n. (type species O. erythrogaster Bohart, 1939). Bohartodynerus cinnabarinus comb. n. is newly recorded from Nevada and New Mexico and B. margaretellus comb. n. from California, New Mexico, Utah, and Wyoming. Bionomics of the species included to these genera are summarized. Nectar robbing is reported for wasps in the genus Bohartodynerus at flowers of Astragalus spp. (Fabaceae), Penstemon sp. (Plantaginaceae), and Calylophus sp. (Onagraceae). It is speculated that nectar is used by them to bond the gravel during the construction of the closing plug of the nest. Parkerodynerus erythrogaster comb. n. apparently does not use liquid for the nest construction. Bionomics of other genera in the Odynerus group of the tribe Odynerini s. str. are discussed. Neither Bohartodynerus nor Parkerodynerus can be treated as members of the genus Odynerus according to their ethology, and the differences between these two newly described taxa are also enough to recognize them as separate genera. A cocoon of P. erythrogaster is described in detail; it has a sandwich-like structure with two layers of silk strands and a layer of sand in-between. Similar structure is found in the cocoons of other genera in the Odynerus group but only at the free part of the cocoon instead over its whole surface; that was overlooked during the previous studies of those genera.

Avian mud nest architecture by self-secreted saliva

Mud nests built by swallows (Hirundinidae) and phoebes (Sayornis) are stable granular piles attached to cliffs, walls, or ceilings. Although these birds have been observed to mix saliva with incohesive mud granules, how such biopolymer solutions provide the nest with sufficient strength to support the weight of the residents as well as its own remains elusive. Here, we elucidate the mechanism of strong granular cohesion by the viscoelastic paste of bird saliva through a combination of theoretical analysis and experimental measurements in both natural and artificial nests. Our mathematical model considering the mechanics of mud nest construction allows us to explain the biological observation that all mud-nesting bird species should be lightweight.