Behaviorally mediated spatial and temporal refuges from a cleptoparasite,Argochrysis armilla (Hymenoptera: Chrysididae), attacking a ground-nesting wasp,Ammophila dysmica (Hymenoptera: Sphecidae)

Summary It has been suggested that parasite pressure favors the evolution of sociality within the Hymenoptera. I analyzed the impact of a chrysidid nest parasite, Argochrysis armilla, on its host, the solitary ground-nesting wasp, Ammophila dysmica, to assess the role of parasitism in favoring two steps towards sociality: aggregated nesting and delayed nest provisioning. The foraging strategy of Argochrysis armilla involves discovering host nests during excavation, learning the locations of discovered nest, and returning to oviposit in nests during nest provisioning; I therefore assessed the influence of host behavior on (1) parasite discovery of nests and (2) parasite oviposition in nests. Significantly fewer parasites discovered host nests that were excavated during the early morning and late afternoon, due to partial asynchrony of host and parasite activity. Nests excavated in areas of low nest density were also less likely to be discovered; use of low density nest sites increased during periods of high parasite activity. Due to a rapidly decelerating rate of parasite recruitment to nests under excavation, the duration of nest digging had only a limited influence on nest discovery by parasites. The probability of parasite oviposition in a host nest was determined by the number of parasites discovering the nest during excavation and by the time between nest excavation and provisioning; delaying nest provisioning reduced the risk of parasite oviposition. Delayed provisionings primarily appeared to be a result of the stochastic process of hunting and prey encounter. The number of provisions placed in a nest (one vs two) had no effect on the probability of nest parasitism. Spatial patterns of parasitism were directly density dependent in 1984 and density independent in 1986. In this system parasite pressure acts against the formation of nesting aggregations and in favor of delayed nest provisioning. The dependence of these results on species-specific aspects of the parasite's foraging strategy and the host's defensive strategy suggests, however, that different parasite species may generate qualitatively different selection pressures, potentially contributing to the diversity of nesting behavior in the Hymenoptera.     

Love thy neighbour? Social nesting pattern,host mass and nest size affect ectoparasite intensity in Darwin’s tree finches

Social nesting behaviour is commonly associated with high prevalence and intensity of parasites in intraspecific comparisons. Little is known about the effects of interspecific host breeding density for parasite intensity in generalist host–parasite systems. Darwin’s small tree finch (Camarhynchus parvulus) on Santa Cruz Island, Galápagos Islands, nests in both heterospecific aggregations and at solitary sites. All Darwin finch species on Santa Cruz Island are infested with larvae of the invasive blood-sucking fly Philornis downsi. In this study, we test the prediction that total P. downsi intensity (the number of parasites per nest) is higher for nests in heterospecific aggregations than at solitary nests. We also examine variation in P. downsi intensity in relation to three predictor variables: (1) nest size, (2) nest bottom thickness and (3) host adult body mass, both within and across finch species. The results show that (1) total P. downsi intensity was significantly higher for small tree finch nests with many close neighbours; (2) finches with increased adult body mass built larger nests (inter- and intraspecific comparison); (3) parasite intensity increased significantly with nest size across species and in the small tree finch alone; and (4) nest bottom thickness did not vary with nest size or parasite intensity. These results provide evidence for an interaction between social nesting behaviour, nest characteristics and host mass that influences the distribution and potential impact of mobile ectoparasites in birds.     

Solitary behavior in a high-altitude population of the social sweat bee Halictus rubicundus (Hymenoptera: Halictidae)

In the subalpine region of the Rocky Mountains of Colorado, United States, Halictus rubicundus has a solitary life cycle, but it is social in other parts of its known range. The brood is protandrous, with a nearly equal investment in the sexes. Productivity averages 6.5 offspring per foundress female, similar to the second brood of social nests in New York, but less than the combined productivity of both New York broods. Leucophora sp. (Diptera: Anthomyiidae) is the principal cause of brood mortality in Colorado. Foundress females in about half the nests survive until brood emerge as adults. Retention of these foundresses decreases offspring mortality by 68%. Comparable abilities to express solitary behavior with a single brood may characterize other eusocial halictine lineages that have successfully invaded high altitudes in the Rocky Mountains. The apparent inability to do this may help explain the absence of other eusocial halictine bees and polistine wasps at high altitudes, despite their success at lower elevations in the same mountains. Presence or absence of this ability may help explain latitudinal distributions of these lineages in North America. Holarctic distributions of lineages with eusocial behavior can be explained by migration as solitary populations from Eurasia to North America across Pleistocene Bering land bridges, with re-expression of double-brooded, eusocial behavior when the species then extended their ranges southward in North America. Received: 4 November 1994/Accepted after revision: 23 October 1995     

Survival and productivity benefits to social nesting in the sweat bee <Emphasis Type="Italic">Megalopta genalis</Emphasis> (Hymenoptera: Halictidae)

Facultatively solitary and eusocial species allow for direct tests of the benefits of group living. We used the facultatively social sweat bee Megalopta genalis to test several benefits of group living. We surveyed natural nests modified for observation in the field weekly for 5 weeks in 2003. First, we demonstrate that social and solitary nesting are alternative behaviors, rather than different points on one developmental trajectory. Next, we show that solitary nests suffered significantly higher rates of nest failure than did social nests. Nest failure apparently resulted from solitary foundress mortality and subsequent brood orphanage. Social nests had significantly higher productivity, measured as new brood cells provisioned during the study, than did solitary nests. After accounting for nest failures, per capita productivity did not change with group size. Our results support key predictions of Assured Fitness Return models, suggesting such indirect fitness benefits favor eusocial nesting in M. genalis. We compared field collections of natural nests to our observation nest data to show that without accounting for nest failures, M. genalis appear to suffer a per capita productivity decrease with increasing group size. Calculating per capita productivity from collected nests without accounting for the differential probabilities of survival across group sizes leads to an overestimate of solitary nest productivity.     

Relationship between body size, provisioning rate, longevity and reproductive success in females of the solitary bee Osmia cornuta

Body size has often been related to reproductive success in bees and wasps. The objective of this 3-year study was to analyze the relationship between nesting female body size, provisioning rate and longevity and their effect on several traits related to parental investment and reproductive success in the solitary bee Osmia cornuta. Body size was not correlated to longevity, and it was only correlated to provisioning rate in the third year (with poor weather conditions during nesting). Variation in fecundity, offspring size and offspring mortality was not well explained by nesting female body size in any of the 3 years. However, in the third year, small females biased their investment toward males, the sex requiring smaller pollen–nectar provisions. Large females were more successful usurpers of other females' nests, but fecundity of usurpers was no higher than fecundity of nonusurpers. Large females were more likely to establish at the release site, probably in relation to size-dependent vigor at emergence. A review of the literature on parental investment in solitary aculeate Hymenoptera showed a stronger relationship between body size and reproductive success in wasps than in bees. In O. cornuta, fecundity was strongly related to longevity and provisioning rate in all 3 years. Offspring size was associated with provisioning rate in 1 year, when females with higher provisioning rates tended to produce larger sons and daughters. Both longevity and provisioning rate appeared to be strongly conditioned by stochastic events.     

Solitary nesting and reproductive success in the paper wasp Polistes aurifer

Female Polistes paper wasps are capable of independent nesting, yet many populations demonstrate a mixture of solitary and cooperative nest foundation. Previous studies of Polistes have found survival and/or productivity advantages of cooperative nest foundation compared to solitary nesting, and reproductive skew models have been designed to predict the dynamics of such flexible cooperation. In this paper, we examine the success of different nesting strategies in a previously unstudied population of Polistes aurifer in southern California. The colony cycle of this population is less synchronous than that of other temperate species, and the frequency of solitary nesting averages 86.2%. Our data suggest that this low rate of cooperative nest founding is adaptive, as demonstrated by the lack of survival or productivity advantages for cooperative foundress associations. Due to foundress turnover and nest foundation later in the season, many nests produce only one set of offspring. This results in a loss of the eusocial nature of some nests in the population. Data from a small sample of multifoundress nests show significant positive reproductive skew, despite concession model predictions that skew should be low in populations with low ecological constraints on independent nesting. This lack of support for the concessions skew model reflects a diminished incentive for cooperation.Communicated by L. Keller     

Parasitic flies (Diptera: Phoridae) influence foraging rhythms and caste division of labor in the leaf-cutter ant,Atta cephalotes (Hymenoptera: Formicidae)

Summary Three lines of evidence, including interspecific comparisons, temporal division of foraging between size castes, and experimental manipulations, suggest that the diurnal parasitoid Neodohrniphora curvinervis (Diptera: Phoridae) influences both the caste sizes and numbers of leaf-cutter ants (Atta cephalotes) that leave their underground nests to collect leaves. At Parque Nacional Corcovado in Costa Rica, A. cephalotes was attacked by Neodohrniphora during the daytime, and foraged less during the day than at night; a closely related ant at the same site, A. colombica, had no phorid parasites and foraged exclusively during the day. Most daytime foragers of A. cephalotes were smaller than the lower size threshold for attack by Neodohrniphora, while nocturnal foragers, active when parasitoids were absent, were both larger than this threshold and within the energetically optimal size range for foraging. When I supplied artificial lighting to allow phorids to hunt at A. cephalotes colonies past dusk, ants foraged less than when light was provided but flies were removed. The influence of Neodohrniphora on the foraging activity of A. cephalotes may explain why investigations focusing on abiotic factors have largely failed to discover what drives this ant's daily foraging cycles, and suggests that forager sizes are influenced not only by energetic efficiency, but also by the threat of parasitism.     

Opportunistic discrimination of alien eggs by social wasps (Polistes biglumis, Hymenoptera Vespidae): a defense against social parasitism?

Foundresses of the social wasp Polistes biglumis were tested to see whether they were able to recognize alien eggs experimentally introduced into their own nests. Foundresses removed alien conspecific reproductive-destined eggs while they accepted worker-destined eggs. The results indicate that social wasps discriminate among eggs and that they discriminate against alien eggs destined to produce unrelated reproductives. P. biglumis is a strictly solitary founding species, with no reproductive competition within colonies; thus, brood discrimination abilities could have evolved as a counteradaptation against intra- and inter-specific brood parasitism. Received: 12 May 2000 / Revised: 15 July 2000 / Accepted 20 July 2000     

Parasitism in a social wasp: effect of gregarines on foraging behavior, colony productivity, and adult mortality

Behavior in eusocial insects likely reflects a long history of selection imposed by parasites and pathogens because the conditions of group living often favor the transmission of infection among nestmates. Yet, relatively few studies have quantified the effects of parasites on both the level of individual colony members and of colony success, making it difficult to assess the relative importance of different parasites to the behavioral ecology of their social insect hosts. Colonies of Polybia occidentalis, a Neotropical social wasp, are commonly infected by gregarines (Phylum Apicomplexa; Order Eugregarinida) during the wet season in Guanacaste, Costa Rica. To determine the effect of gregarine infection on individual workers in P. occidentalis, we measured foraging rates of marked wasps from colonies comprising both infected and uninfected individuals. To assess the effect of gregarines on colony success, we measured productivity and adult mortality rates in colonies with different levels of infection prevalence (proportion of adults infected). Foraging rates in marked individuals were negatively correlated with the intensity of gregarine infection. Infected colonies with high gregarine prevalence constructed nests with fewer brood cells per capita, produced less brood biomass per capita, and, surprisingly, experienced lower adult mortality rates than did uninfected or lightly infected colonies. These data strongly suggest that gregarine infection lowers foraging rates, thus reducing risk to foragers and, consequently, reducing adult mortality rates, while at the same time lowering per-capita input of materials and colony productivity. In infected colonies, queen populations were infected with a lower prevalence than were workers. Intra-colony infection prevalence decreased dramatically in the P. occidentalis population during the wet season.An erratum to this article can be found at     

Nesting success of rufous-naped wrens (Campylorhynchus rufinucha) is greater near wasp nests

Summary Rufous-naped wrens (Campylorhynchus rufinucha) in northwestern Costa Rica build breeding nests most frequently in ant-acacia trees (Acacia collinsii) and occasionally near wasp nests in ant-acacia trees. By moving occupied wasp nests (Polybia rejecta) to randomly chosen ant-acacia trees with wren nests, I tested the hypothesis that wrens nesting near wasp nests were more likely to fledge young than wrens not nesting near wasp nests. Wrens whose nests were near experimentally relocated wasp nests were significantly more likely to fledge young (37.5% of 16 attempts in 1987 and 75% of 12 attempts in 1988) than were wrens whose nests had no wasp nests placed near them (0% of 16 attempts in 1987 and 20% of 15 attempts in 1988). In 15 cases, repeated nesting attempts occurred in the same trees both with and without experimentally-placed wasp nests. Analysis of these data allowed a comparison of the effect of wasp nests on fledging success while differences among trees were controlled. Within the same tree, nesting attempts associated with wasp nests were significantly more likely to fledge young than nesting attempts without wasp nests. Predation was the primary cause of nest failure, and within forest, white-faced monkeys (Cebus capucinus) were the most important predators. The difference in success of wren nests with and without wasps and observations of predators indicate that enhancement of fledging success was due to deterrence of predatory vertebrates by wasps.     

Nestmate recognition in three species of stenogastrine wasps (Hymenoptera,Vespidae)

The capacity to recognise a conspecific intruder was investigated in Parischnogaster jacobsoni, Liostenogaster flavolineata and L. vechti, three species of primitively social wasps of the subfamily Stenogastrinae. Results of behavioural experiments carried out in the field showed that females of all three species react pacifically if presented with female nestmates, but aggressively reject an intruder from a conspecific colony. As L. flavolineata and L. vechti both build large clusters of nests, often very close to each other, the recognition capacity among females from different nests, but in the same conspecific cluster, was also investigated. Females of both species were more aggressive towards females from a different colony in the same cluster than towards their female nestmates. Additional experiments on L. flavolineata showed that there was no difference in reaction towards females from colonies nearer or further from the tested colony but within the same cluster, nor towards females from a different cluster. The capacity to recognise an alien conspecific nest containing immature brood was investigated in P. jacobsoni. Adult females of this species, invited to land on an alien nest which had experimentally been exchanged for their own, accepted the new nest and partially destroyed the immature brood. The behaviour of the females when they land on an alien nest, however, suggests that they do recognise the nest as foreign. Acceptance of foreign nests coupled with low immature brood destruction is probably due to the high energetic costs of egg-deposition and larval rearing in stenogastrine wasps. These results suggest that nestmate recognition in these wasps is very efficient, even though they belong to the most primitive subfamily of social wasps. Received: 16 April 1996/Accepted after revision: 9 August 1996     

Is big the best? Queen size,usurpation and nest closure in a primitively eusocial sweat bee (<Emphasis Type="Italic">Lasioglossum malachurum</Emphasis>)

For primitively eusocial insects in which a single foundress establishes a nest at the start of the colony cycle, the solitary provisioning phase before first worker emergence represents a risky period when other, nestless foundresses may attempt to usurp the nest. In the primitively eusocial sweat bee Lasioglossum malachurum (Hymenoptera, Halictidae), spring foundresses compete for nests which are dug into hard soil. Nest-searching foundresses (‘floaters’) frequently inspected nests during this solitary phase and thereby exerted a usurpation pressure on resident queens. Usurpation has been hypothesised to increase across the solitary provisioning phase and favour closure of nests at an aggregation, marking the termination of the solitary provisioning phase by foundresses, before worker emergence. However, our experimental and observational data suggest that usurpation pressure may remain constant or even decrease across the solitary provisioning phase and therefore cannot explain nest closure before first worker emergence. Levels of aggression during encounters between residents and floaters were surprisingly low (9% of encounters across 2 years), and the outcome of confrontations was in favour of residents (resident maintains residency in 94% of encounters across 2 years). Residents were significantly larger than floaters. However, the relationship between queen size and offspring production, though positive, was not statistically significant. Size therefore seems to confer a considerable advantage to a queen during the solitary provisioning phase in terms of nest residency, but its importance in terms of worker production appears marginal. Factors other than intraspecific usurpation need to be invoked to explain the break in provisioning activity of a foundress before first worker emergence.     

Reduced disease in offspring: A benefit of coloniality in sunfish

Summary Increased disease and parasitism are a well-documented cost of group living for colonial birds and mammals, but we now show that disease in offspring of fish may be reduced by nesting in colonies. The aquatic fungusSaprolegnia sp., which is a common cause of egg mortality among freshwater fishes, is more prevalent in the nests of solitary than colonial male bluegill sunfish (Lepomis macrochirus). Moreover, fungal infection decreases with nest density in colonies. This may be due in part to a behavioural advantage since colonial males can devote less time to defending eggs and more time to fanning them, which reduces fungal infection. In addition, we demonstrate experimentally that solitary nests become infected at higher rates than colonial nests, even in the absence of parental males. This suggests that colonies are encountered by spores at a lower rate and/or that the large number of nests in colonies dilutes the number of fungal spores per nest. Through one or all of these mechanisms, egg mortality in colonial nests is lowered significantly. Therefore, in some cases, disease may select for group living.     

The ability of conditioned Microplitis croceipes (Hymenoptera: Braconidae) to distinguish between odors of aflatoxigenic and non-aflatoxigenic fungal strains

Summary. The parasitic wasp Microplitis croceipes (Cresson) (Hymenoptera: Braconidae) learns to associate odors with food resources and subsequently exhibits a characteristic food-seeking behavior when encountering the learned odor. Wasps so conditioned, learned and subsequently demonstrated an ability to distinguish among aflatoxigenic and non-aflatoxigenic Aspergillus flavus and A. parasiticus strains. The effects of fungal species, strain, age (5, 10-12, 20, and 30 d) and growth media (potato dextrose agar, peanut agar and corn agar) on the learning and recognition responses of the conditioned wasps were examined. The level of differentiation between fungal strains by conditioned wasps was lowest when working with 5-d-old fungal cultures but increased with age and generally peaked with 20-d-old fungi. Wasps responded generally stronger to the fungal strain conditioned to independent of growth media. This ability of parasitic wasps to learn and distinguish fungal odors can open new avenues in insect learning.     

Clutch size adjustment, information use and the evolution of gregarious development in parasitoid wasps

As larvae, solitary species of parasitoid wasps eliminate rivals, including sibs, through contest competition. In gregarious species, larvae tolerate each other and several individuals can develop from a single host. We report experiments on two congeneric braconid species aimed at understanding how gregarious development evolved in one genus, and the consequences of larval interactions for parental behavior. In the transition from solitary to gregarious development, one possible intermediate stage is if solitary species frequently lay more than one egg per host. If the risk of conspecific superparasitism (another female of the same species oviposits into a single host) is high, optimal clutch size theory predicts the laying of multiple-egg clutches, because a female will increase the probability of the surviving larva being her own. Under the same conditions, theory predicts that gregarious species should reduce their clutch size. In our experiments, the solitary Aphaereta genevensis increased their clutch size under the risk of intraspecific competition for hosts whilst the gregarious A. pallipes reduced their clutch size, as predicted. In A. genevensis, the response to the risk of competition was dependent upon body size, being greatest amongst small females. In A. pallipes, the response did not depend on female body size, but clutch size increased with body size in all treatments, unlike in A. genevensis. Under the risk of competition from the other species, the response differed relative to the intraspecific treatments and differed between species. Thus, our data suggest that: (1) competition for hosts may have contributed to the evolution of gregarious development in this genus; (2) female wasps can combine information from both external and internal cues in complex ways during clutch size adjustment; and (3) the social environment may alter the adaptive response to both external and internal cues in adult females.Communicated by M. Elgar     

Location of suitable nests by great spotted cuckoos: an empirical and experimental study

Brood parasites depend entirely on their host species to raise their nestlings until independence. Thus, brood-parasite females must discover and select nests that are at a suitable stage for parasitism, and thus, the location of each parasitic egg is crucial in determining the brood-parasite female’s fitness. In relation to host behaviour, one of the main hypotheses proposed to explain how brood-parasite females find and select a suitable nest posits that the most active hosts during nest building should undergo a higher risk of being parasitised (the “host-activity hypothesis”). Here, using the great spotted cuckoo, Clamator glandarius–magpie, Pica pica system, we found that not only cuckoo females parasitise magpie nests regardless of the location and characteristics of nests, but also that the parasite’s observation of host activity near the nest determines a cuckoo female’s decision of laying in a nest. Only one experimental nest (without host activity) was parasitised before the magpie started laying, while 34.14?% of natural active nests were parasitised before the magpie started laying. These observations support the host-activity hypothesis for nest location in great spotted cuckoos.     

Support for maternal manipulation of developmental nutrition in a facultatively eusocial bee, <Emphasis Type="Italic">Megalopta genalis</Emphasis> (Halictidae)

Developmental maternal effects are a potentially important source of phenotypic variation, but they can be difficult to distinguish from other environmental factors. This is an important distinction within the context of social evolution, because if variation in offspring helping behavior is due to maternal manipulation, social selection may act on maternal phenotypes, as well as those of offspring. Factors correlated with social castes have been linked to variation in developmental nutrition, which might provide opportunity for females to manipulate the social behavior of their offspring. Megalopta genalis is a mass-provisioning facultatively eusocial sweat bee for which production of males and females in social and solitary nests is concurrent and asynchronous. Female offspring may become either gynes (reproductive dispersers) or workers (non-reproductive helpers). We predicted that if maternal manipulation plays a role in M. genalis caste determination, investment in daughters should vary more than for sons. The mass and protein content of pollen stores provided to female offspring varied significantly more than those of males, but volume and sugar content did not. Sugar content varied more among female eggs in social nests than in solitary nests. Provisions were larger, with higher nutrient content, for female eggs and in social nests. Adult females and males show different patterns of allometry, and their investment ratio ranged from 1.23 to 1.69. Adult body weight varied more for females than males, possibly reflecting increased variation in maternal investment in female offspring. These differences are consistent with a role for maternal manipulation in the social plasticity observed in M. genalis.     

Intraspecific brood parasitism in the moorhen: parentage and parasite-host relationships determined by DNA fingerprinting

Parasitic female moorhens (Gallinula chloropus) lay from one to six eggs in the nests of conspecific neighbours. DNA fingerprinting was used to show that parasitic eggs could be correctly identified when they appeared in addition to or outside the host’s laying sequence. Moorhen hosts accept all parasitic eggs laid after the 2nd day of their laying period. To understand why moorhen hosts tolerate parasitic eggs, we tested two hypotheses. (1) The quasi-parasitism hypothesis: females lay their eggs in the evening when the host males are normally in attendance at the nest, so host males may allow parasitic females to lay in their nests in exchange for fertilizing their eggs. However, DNA fingerprinting showed that all the parasitic eggs were sired by the parasites’ mates. Parasitic moorhens frequently continue laying a clutch in their own nest, without a break in the laying sequence after a parasitic laying bout. The eggs laid by brood parasites in their own nests were also sired by their own mates. Therefore this hypothesis was rejected. (2) The kin selection hypothesis: if one or both members of the host pair are close relatives of the parasite, the costs of rearing parasitic chicks will be to some degree offset by inclusive fitness benefits. We examined the genetic relationships between parasites and their hosts using DNA fingerprinting and genealogical data. Natal philopatry by both sexes was relatively common in this population, and the probability that a neighbour of either sex was a first-order relative (parent-offspring) was calculated as 0.18. Although first-order relatives were not preferentially chosen as hosts over individuals that were not first-order relatives, even through random host selection there is almost a one-in-five chance that brood parasites in this population are closely related to their hosts. This may facilitate host tolerance of parasitic eggs. Other hypotheses are also discussed. Received: 3 February 1995/Accepted after revision: 27 August 1995     

Infanticidal and anti-infanticidal strategies in the swallow Hirundo rustica

Summary Five definite and nine suspected cases of infanticide were documented in the swallow Hirundo rustica. Unmated males visited neighbouring nests and removed entire broods during the first days of the nestling period, preferentially from nests owned by young late-breeding individuals. Infanticide followed the disappearance of the male nest owner in 11 of the 14 cases. The unmated infanticidal male later mated with the female victim although renesting during the same season only took place in 12 of the 14 cases. The fraction of unmated males increased with colony size, and infanticide was relatively more common if unmated males were abundant. Females did not engage in extra-pair copulations in order to avoid infanticide. Intense guarding of the nest and its contents prevented infanticide. Nest guarding intensity was higher in colonial compared with solitarily breeding swallows, and guarding intensity increased with colony size. Experimental removal of male swallows during the early nestling period reduced the nest guarding intensity and increased frequency of visits from unmated males in colonies, but not among solitarily breeding swallows. Colonial nests from which the male was removed suffered from infanticide more often than solitary nests, and nests where infanticide was recorded were guarded significantly less intensely than other nests before the infanticidal incidents.     

Temporal changes in demand for and supply of nests in red bishops (Euplectes orix): dynamics of a biological market

The red bishop (Euplectes orix) is a highly polygynous and colonial weaverbird. Males construct several nests within their territories to which they try to attract females, and females are solely responsible for incubation and raising offspring. In this paper, we describe the characteristics of the red bishop’s mating system as a biological market and investigate the role of nests built by males as a traded commodity in a mating market. As timing of breeding in red bishops in arid and semi-arid zones depends on rainfall patterns which are often unpredictable, there are temporal changes in demand for and supply of nests within a breeding season, with breeding activities of males and females being highly synchronised. We found that males increased their nest-building speed with increased female breeding activity independently of rainfall, indicating that supply follows demand in this mating market. The supply of nests was always larger than the demand for nests. Construction costs for nests increased with demand for nests as indicated by shorter nest-building duration and shorter building delays between two consecutively built nests at times of high breeding activity. Males as a trading class are chosen according to the age of their nests offered, with young nests having a higher probability of being accepted by females. Furthermore, female choosiness with regard to nest age decreased when their own market value decreased, as predicted by biological market theory. The temporal changes of breeding activity together with the female preference for young and fresh nests require that males quickly adjust nest-building activity to varying female demand for new nests. However, males with a better adjustment of building speed to female breeding activity did not gain higher mating success.