Potential Nest Sites Research Articles

Current and projected abundance of potential nest sites for cavity‐nesting ducks in hardwoods of the north central United States

AbstractClearing of hardwood forests was widespread in the north central region of the United States at the turn of the 20th century, but largely subsided by the 1920s. Hardwood trees in the region have since regenerated and matured into sizes capable of producing nest cavities suitable for cavity‐nesting ducks. We estimated regional nest‐site abundance for cavity‐nesting ducks during 2008, 2018, and 2028 from cavity density and tree‐abundance estimates obtained at 4 hardwood forest sites in conjunction with Forest Inventory and Analysis data and tree‐growth modeling software from the United States Forest Service (Forest Vegetation Simulator). Land cover data were used to determine area of hardwood forests ≤0.5 km, 0.5–1 km, 1–1.5 km, 1.5–2 km, and >2 km from wetlands and open water available to cavity‐nesting ducks. We estimated 13.2 million, 17.0 million, 19.0 million, and 20.1 million potential duck nest cavities available ≤0.5 km, ≤1 km, ≤1.5 km, and ≤2 km of water, respectively, in the region and predicted nest cavity abundance will increase 41% from 2008 to 2028. Hardwood forests in Indiana, Michigan, Ohio, and Wisconsin currently have the highest abundances of potential nest sites, but cavity‐bearing forests in Minnesota, Michigan, and Wisconsin were more commonly proximate to wetlands and open water. Because current and future estimates indicate sufficient nest sites to support growing cavity‐nesting duck populations in the north central United States, we recommend regional management efforts focus on protecting, restoring, and maintaining quality wetlands in proximity to hardwood forests. © 2011 The Wildlife Society.

Inaccurate and unverified information in decision making: a model for the nest site selection process of Apis florea

We present an agent-based model for the nest site selection process of the open-nesting red dwarf honeybee, Apis florea. Our main aim was to determine how nest site requirements affect the bees’ decision-making process. We either calculated our model parameters from experimental data or chose them so that our model would generate similar numbers of dancing bees and dance followers to those observed in real swarms with access to an abundance of suitable nest sites in all directions. We found that A. florea is less capable of making a collective decision on a new nest site when the area occupied by suitable sites is small compared to when suitable sites are abundant. Increasing the use of information regarding the location of potential nest sites or the accuracy of the information available enhanced the decision-making ability of A. florea when nest sites were scarce. We also found that swarm guidance might be hindered when suitable nest site areas are wide apart. We therefore examined two possible mechanisms for increasing directional agreement among dancers: mimicry of unverified dance information and self-regulation by inhibiting or changing dance behaviour based on observations of other dances. We show that, even at low levels, dance mimicry greatly enhances the ability of an A. florea swarm to make a decision and reduces the time to make a decision. However, in the presence of mimicry errors propagate through the swarm. Self-regulation had little or no effect, probably because of the overall low levels of dance activity present on the swarm at any given time. Our model results suggest that A. florea’s decision-making process allows swarms to locate a new nest site provided nest sites are abundant, even when they are of similar quality.

Relating Microclimate to Epiphyte Availability: Edge Effects on Nesting Habitat Availability for the Marbled Murrelet

Industrial timber harvesting typically creates forest edges with altered microclimate regimes, causing reduced growth and survival of some canopy epiphytes. This process has implications for the marbled murrelet (Brachyramphus marmoratus), a threatened seabird that nests on moss platforms in old-growth forests of the coastal Pacific Northwest in North America. We investigated microclimate and epiphyte availability in old-growth forests of southwestern British Columbia, Canada. We contrasted mean and maximum temperature, mean humidity, mean vapor pressure deficit (VPD) and mean epiphyte cover and platform tree density between forest edge and interior plots at hard edges (recent clearcuts), soft edges (regenerating forest) and natural edges (rivers and avalanche chutes). Differences measured in VPD and epiphyte availability varied due to edge proximity and edge-type. Hard edges had fewer trees with suitable marbled murrelet nest platforms relative to adjacent interiors, and hard-edged patches had the lowest epiphyte cover overall. This suggests that microclimate edge effects and substrate availability can negatively impact epiphyte growth and survival, and may reduce the availability of marbled murrelet nest sites. These negative effects may decrease with time as forests regenerate, as edge effects were lower in magnitude at soft-edged patches. In contrast, natural-edged patches had the greatest levels of epiphyte cover and platform tree density, suggesting that these areas provide an abundant source of potential nest sites. Minimizing the ratio of anthropogenic edge to suitable interior habitat, and maintaining natural edges will limit negative edge effects on moss availability and provide nesting habitat for marbled murrelets.

The importance of odor in nest site selection by a lodger bee, Centris Bicornuta Mocsáry (Hymenoptera: Apidae) in the dry forest of Costa Rica.

The more common lodger bee occurring in the dry forest of Costa Rica, Centris bicornuta Muscáry), has been observed nesting in new nest cavities drilled into wooden blocks placed next to cavities used by another female within 2-3 days. In contrast, new nest cavities placed in similar areas with no nesting Centris nearby were not used for weeks. These observations suggest that the presence of nesting bees may play a role in nest site selection. To confirm our observations, new nest cavities were placed in areas with or without nesting. We found nest initiation in newly placed nest cavities only in areas where bees were actively nesting. To examine the possibility that nesting locations are not unique, we placed new nest cavities in new locations either with (a) a number of completed nest cavities or (b) placed alone. Within three days we only found bees nesting in the newly placed nest cavities in situation "a". The results suggested that odor might be involved. We next compared nesting in new cavities placed alone with cavities contaminated with either (a) nest entrance plug material, (b) nest nectar, (c) nest pollen or (d) a combination of pollen and nectar. Nesting was significantly low in cavities placed next to cavities with nest entrance plug material (a), and high in cavities placed next to cavities "b, c, or d". The results suggest that pollen and /or nectar odor play a role in the location of potential nest sites.

The function of polydomy: the ant Crematogaster torosa preferentially forms new nests near food sources and fortifies outstations

Many ant species are polydomous, forming multiple spatially segregated nests that exchange workers and brood. However, why polydomy occurs is still uncertain. We investigated whether colonies of Crematogaster torosa form new polydomous nests to better exploit temporally stable food resources. Specifically, we tested the effect of food presence or absence and distance on the likelihood that colonies would form a new nest. Because this species also forms little-known structures that house only workers without brood (outstations), we also compared the function of this structure with true nests. Laboratory-reared colonies were connected to a new foraging arena containing potential nest sites with or without food for 4 months. When food was present, most colonies formed polydomous nests nearby and the remainder formed outstations. When food was absent, the behavior of colonies differed significantly, frequently forming outstations but never polydomous nests. Distance had no effect on the type of structure formed, but when food was present, a larger proportion of the workforce moved shorter distances. Workers often fortified the entrances to both structures and used them for storage of dried insect tissue (“jerky”). In an investigation of spatial fidelity, we found that workers on the between-nest trail were associated with the original nest, whereas workers collecting food were more likely to be associated with the new nest or outstation. C. torosa appears to have a flexible colony structure, forming both outstations and polydomous nests. Polydomous nests in this species were associated with foraging and were only formed near food resources.

Embryonic mortality as a cost of communal nesting in the delicate skink

Lizards are appropriate organisms to investigate causes and correlates of communal egg laying because their general lack of parental care focuses attention on nest site choice. We field-tested hypotheses associated with nest site choice and communal egg laying in the delicate skink Lampropholis delicata, in south-eastern Australia. Specifically, we predicted that lizards would nest at sites with lower openness and solar radiation than random sites, but within crevices with higher humidity than random crevices. However, we predicted that these environmental factors would not differ between communal and solitary nest sites (based on previous research), but that egg mortality in communal nests would be higher than that in solitary nests due to conspecific interference. Despite being ground dwellers, skinks in this population nested above the ground level in narrow horizontal crevices within vertical faces of sandstone outcrops. At the broadest scale, skinks nested at sites with significantly lower canopy openness and incident (solar) radiation than random sites, while at the smallest scale, skinks nested in crevices with significantly higher relative humidity than potential nest crevices. Humidity averaged 94% in nest sites, and nesting females did not trade-off humidity for temperature, despite an inverse relationship between the two at potential nest sites. Of 60 nests, about half to two-thirds were communal. Communal nest sites did not differ from solitary nest sites with respect to temperature, humidity, rock size, aspect, height of crevice above ground, or crevice dimensions. Eggs from communal nests were three times more likely to desiccate and perish than eggs from solitary nests, a clear cost of communal nesting. Desiccation was caused by eggs being displaced from their original positions within the crevices, possibly by conspecific gravid females.

Interference from long-tailed finches constrains reproduction in the endangered Gouldian finch

1. Interspecific interference competition for nest-sites among cavity-nesting birds can have important effects on reproductive fitness and the distribution of competing species. 2. We observed interference at nest-sites in free-living populations of the endangered Gouldian finch (Erythrura gouldiae) and sympatric long-tailed finch (Poephila acuticauda), and also experimentally tested the relative strength and effect of interference at nest-sites in captive populations. 3. Levels of competitive interference at nest-sites in the wild were high for Gouldian, but not long-tailed finches, and interference frequency was inversely related to Gouldian finch reproductive success. High levels of interference conferred reduced fledging success but did not affect offspring condition. 4. Captive experiments corroborated the field data, also demonstrating fitness costs of interspecific competition, and that long-tailed finches dominated resources under standardized conditions. 5. Such asymmetrical competition dynamics are likely to constrain reproduction in Gouldian finch populations, potentially affecting recruitment and hindering the recovery of remaining populations of this endangered species.

Nest‐Site Defense by Competing Honey Bee Swarms During House‐Hunting

AbstractCavity‐nesting animals must often defend their homes against intruders, especially when the availability of suitable cavities is limited. Competition for nest sites is particularly strong when multiple groups of the same species migrate synchronously to found a new home. This may be the case for honey bees during the reproductive season, because neighboring colonies often cast swarms simultaneously, leading to potential competition for high‐quality nesting cavities. To test the idea that honey bee swarms may compete for and defend potential nest sites as they search for a new home, we observed pairs of artificial swarms that were house‐hunting concurrently. Workers from one swarm in each pair carried a gene influencing body color, so that the bees from the two swarms were easily distinguished. We set up a high‐quality nest box and waited for nest‐site scouts from each swarm to explore and recruit swarm mates to it. We recorded all the interactions between competing scouts at the nest box and found that when scouts from both swarms explored the box simultaneously they behaved agonistically toward bees from the other swarm. The level of aggression depended on the number of scouts from each swarm present at the nest box. When only one to three scouts from each swarm were at the box, they rarely fought. But when the scouts from one swarm outnumbered those from the other swarm (4–20 vs. one to three bees), those in the majority advertised their presence with a buzzing behavior at the entrance opening, and started mobbing and killing those in the minority. When one swarm gained clear control of the nest box (20+ vs. zero to one bees), some of its scouts guarded the box’s entrance, preventing entry by foreign scouts. Our study exemplifies how cavity‐nesting animals may compete for and defend suitable nesting sites.

Nest-Site Selection by Abbott's BabblersMalacocincla abbottiin Northeastern Thailand

Identifying nesting microhabitat variables associated with nest site choice is important for understanding bird-habitat relationships. We studied nest-site selection at two spatial scales along with structural vegetation variables associated with nesting success of the Abbott's Babbler in north-eastern Thailand. Seventy-nine nests were found during the study. Ninety percent of the nests were placed in rattans (Daemonorops sp. or Calamus sp.). The vegetation and vegetation structure around nest sites (0.01 ha circular plots) were compared with those in areas surrounding the nestsite (4 × 0.01 ha circles), defined as a nest patch, and with randomly selected non-use sites. Nest sites had a significantly higher percentage of foliage cover and a greater cover and abundance of rattans, suggesting that Abbott's Babbler sites its nests in areas with a large number of potential nest sites. There were no clear vegetational differences associated with successful versus failed nests, probably reflecting the diversity of local predators and their search patterns.

Nest‐site choice and fidelity in tuatara on Stephens Island, New Zealand

Nest-site microhabitat influences hatching success, hatchling phenotype and offspring sex in reptiles with temperature-dependent sex determination (TSD). How females assess environmental features at potential nest sites, and then use such features in predicting the future incubation regime of the site, is integral to understanding how nest-site choice affects offspring fitness and ultimately female reproductive success. Tuatara Sphenodon punctatus are colonially nesting reptiles with TSD. We examined nest-site fidelity and nest-site choice in tuatara over 5 years on Stephens Island, New Zealand. Female tuatara nested every 2–4 years and showed high fidelity to nesting rookeries. Over 93% of females nested in the same rookery at least twice in 5 years. Approximately 25% of nests contained conspecific cues from previous nesting seasons, indicating that some females choose nest sites based on locations already selected by conspecifics. In experimental plots, female tuatara selected nest sites with loose soil and minimal vegetation, but they showed no preference for shaded compared with unshaded sites. This study provides insight into the development of colonial nesting structures in reptiles in that females are both attracted to nesting areas used by conspecifics, and show strong site fidelity to areas they have used in the past.

The influence of nest availability on the abundance and diversity of twig-dwelling ants in a Papua New Guinea forest

Tropical ant communities are frequently diverse, but highly patchy in nature. The availability of suitable nest sites may be a regulating force in structuring litter ant communities. Our aim was to examine ant resource utilization in naturally occurring twigs, and to modify the availability of these resources in order to quantify the influence of nest availability on ant communities in a Papua New Guinean forest. First, we compared ant communities that assemble in artificial twigs (drilled, wooden dowels), naturally occurring twigs, and the leaf litter. A total of 55 ant species were captured: 33 from the leaf litter, 29 from naturally occurring twigs, and only 12 from artificial nests. Significantly different communities formed in each of the three nest types. Second, we examined how the density of natural or artificial nest material influenced the ant abundance and species richness. Plots had between 5 and 96 potential nest sites. An average of only 11.2% of these twigs was colonized. Both species richness and the total abundance of adult ants were significantly positively correlated with increasing naturally occurring twig density. Conversely, increasing the availability of artificial nests from 5 to 20 per plot had no significant effect on the proportion of artificial nests colonized, species richness, or the colony size. We observed that ant species richness and abundance increased with natural twig density, at least for naturally occurring communities. But why so many twigs remain vacant and available for ant colonization remains unknown. Other biotic and abiotic factors likely influence the use of nesting habitat in these ant communities.

Endangered Seabird Habitat Management as a Partially Observable Markov Decision Process

The marbled murrelet (Brachyramphus marmoratus) is an endangered seabird that nests in coastal forests from Alaska to California. The value of these forests for human use, coupled with the difficulty of determining whether a forest stand is occupied by nesting marbled murrelets, poses a dilemma for land managers. Should they implement a costly survey to gather information on whether a potential nest site is occupied, or should they allow human use, effectively assuming the site is unoccupied? This article demonstrates the application of the partially observable Markov decision process (POMDP) as a framework for addressing this question. The analysis yields a policy in which the optimal action is a function of the decision-maker’s subjective probability that a potential nest site is occupied by marbled murrelets. By incorporating stochastic state dynamics and the choice of whether to invest in learning, the POMDP provides a formal representation of adaptive management when active learning is possible.

Nesting in a thermally challenging environment: nest-site selection in a rock-dwelling gecko, Oedura lesueurii (Reptilia: Gekkonidae)

In egg-laying species, maternal oviposition choice can influence egg survival and offspring phenotypes. According to the maternal-preference offspring-performance hypothesis, females should choose oviposition sites that are optimal for offspring fitness. However, in thermally challenging environments, maternal oviposition behaviour may be constrained by the limited availability of suitable oviposition sites. We investigated nest-site selection in a nocturnal lizard [velvet gecko Oedura lesueurii (Dumeril and Bibron)] that inhabits a thermally challenging environment in south-eastern Australia. The viability of these gecko populations is critical for the persistence of an endangered snake species (Hoplocephalus bungaroides Wagler) that feeds heavily on velvet geckos. Female geckos chose nest sites nonrandomly, with 87% of nests (N = 30) being laid in deep crevices. By contrast, only 13% of clutches were laid under rocks, which were the most readily available potential nest sites. Nest success in crevices was high (100%), but no eggs hatched from nests under rocks. Temperatures in nest crevices remained relatively low and constant throughout the incubation period (mean = 22.7 degrees C, range 21.0-24.5 degrees C), whereas thermal regimes under rocks showed large diurnal fluctuations. Geckos selected crevices that were deeper, had less canopy cover, and were warmer than most available crevices; in 85% of cases, such crevices were used simultaneously by more than one female. The thermally distinctive attributes of nest sites, and their frequent communal use, suggest that nest sites are a scarce resource for female velvet geckos, and that the shading of rock outcrops through vegetation encroachment may influence nest success in this species.

Nest-Site Selection and Nesting Success of Cavity-Nesting Birds in High Elevation Forest Drainages

ABssAcr.-We identified habitat features that characterized successful and unsuccessful nest sites, nest sites vs. random sites, and differences among coexisting species of cavitynesting birds for 356 nests in central Arizona. Live and, more commonly, dead quaking aspens (Populus tremuloides) were used for 88% of all nest sites, but aspens constituted only 12% of all trees in random plots (n = 152). Nest patches (11.3-m-radius circle centered on the nest tree) of most bird species contained significantly more aspens and conifers, which provided foraging substrates for cavity-nesting species, than random plots, but the patches had fewer deciduous trees (except aspens). Thus, more potential nest sites and foraging substrates existed in chosen nest patches than in random plots. Failed nests generally were more concealed by foliage and were closer to conifers. Nest success was lower for species with lower nest height. Reduced nest success at lower and more concealed nests may occur because predators are more successful. Nonexcavator species had lower nesting success than excavator species possibly because they nested lower, had greater nest concealment, used older cavities, and tended to have smaller body mass. Received 21 May 1990, accepted 26 November 1990.

Black-Chinned Hummingbird Nest-Site Selection and Nest Survival in Response to Fuel Reduction in a Southwestern Riparian Forest

Despite widespread efforts to avert wildfire by reducing the density of flammable vegetation, little is known about the effects of this practice on the reproductive biology of forest birds. We examined nest-site selection and nest survival of the Black-chinned Hummingbird (Archilochus alexandri) in New Mexico riparian forests treated or not for fuel reduction. In untreated plots the hummingbirds frequently nested in exotic trees such as saltcedar (Tamarix spp.) and Russian olive (Eleagnus angustifolia). Following fuel reduction, they increased use of cottonwood (Populus deltoides ssp. wislizenii) as a nest substrate and nested at greater heights. Though fuel reduction influenced habitat and nest-site selection, it did not immediately affect nest survival. A logistic exposure model containing effects of year and interaction of nest height and substrate explained nest survival better than did other models. Estimates of daily nest-survival rates from this model varied by year from 0.970 (95% CI: 0.949– 0.982) to 0.992 (95% CI: 0.983–0.996), corresponding with period survival rates of 31% (95% CI: 13.7%–50.1%) to 73% (95% CI: 52.1%–85.9%). In addition, in all substrates except saltcedar, nest survival decreased with nest height. Our relatively high nest-survival estimates suggest that the riparian forest along the Middle Rio Grande provides high-quality nesting habitat for this species. Fuel reduction, however, reduces nest-site availability and can lower nest survival by removing potential nest sites in the forest understory, forcing hummingbirds to nest at greater heights where predation risk is higher.

Nest-Site Selection by Wood Turtles (Glyptemys insculpta) in a Thermally Limited Environment

Abstract In oviparous species that lack parental care, fitness of the mother depends on the selection of a high-quality nest site, as mothers do not compensate for poor incubation environment post-hatching. Near the northern range limit of Glyptemys insculpta (Wood Turtle), short summers and cool temperatures may be factors that limit population persistence because potential nest sites may not provide adequate conditions for successful egg incubation in some years. We quantified nest-site selection by examining soil temperature and substrate composition of real Wood Turtle nests (n = 5) and constructed false nests. False nests comprised two treatments: negative-test false nests (n = 5) constructed on beaches not used by females, and positive-test false nests (n = 5) constructed on beaches used by females but in microsites not chosen by females. Temperature was measured as total thermal units and mean temperature during the diel cycle. Soil composition was quantified using moisture content, organic content...

Strategies for Nest‐Site Selection by King Eiders

ABSTRACT Nest site selection is a critical component of reproduction and has presumably evolved in relation to predation, local resources, and microclimate. We investigated nest‐site choice by king eiders (Somateria spectabilis) on the coastal plain of northern Alaska, USA, 2003–2005. We hypothesized that nest‐site selection is driven by predator avoidance and that a variety of strategies including concealment, seclusion, and conspecific or inter‐specific nest defense might lead to improved nesting success. We systematically searched wetland basins for king eider nests and measured habitat and social variables at nests (n = 212) and random locations (n = 493). King eiders made use of both secluded and concealed breeding strategies; logistic regression models revealed that females selected nests close to water, on islands, and in areas with high willow (Salix spp.) cover but did not select sites near conspecific or glaucous gull (Larus hyperboreus) nests. The most effective nest‐placement strategy may vary depending on density and types of nest predators; seclusion is likely a mammalian‐predator avoidance tactic whereas concealment may provide protection from avian predators. We recommend that managers in northern Alaska attempt to maintain wetland basins with islands and complex shorelines to provide potential nest sites in the vicinity of water.

Habitat structure mediates predation risk for sedentary prey: experimental tests of alternative hypotheses

1. Predation is an important and ubiquitous selective force that can shape habitat preferences of prey species, but tests of alternative mechanistic hypotheses of habitat influences on predation risk are lacking. 2. We studied predation risk at nest sites of a passerine bird and tested two hypotheses based on theories of predator foraging behaviour. The total-foliage hypothesis predicts that predation will decline in areas of greater overall vegetation density by impeding cues for detection by predators. The potential-prey-site hypothesis predicts that predation decreases where predators must search more unoccupied potential nest sites. 3. Both observational data and results from a habitat manipulation provided clear support for the potential-prey-site hypothesis and rejection of the total-foliage hypothesis. Birds chose nest patches containing both greater total foliage and potential nest site density (which were correlated in their abundance) than at random sites, yet only potential nest site density significantly influenced nest predation risk. 4. Our results therefore provided a clear and rare example of adaptive nest site selection that would have been missed had structural complexity or total vegetation density been considered alone. 5. Our results also demonstrated that interactions between predator foraging success and habitat structure can be more complex than simple impedance or occlusion by vegetation.

Speed versus accuracy in decision-making ants: expediting politics and policy implementation

Compromises between speed and accuracy are seemingly inevitable in decision-making when accuracy depends on time-consuming information gathering. In collective decision-making, such compromises are especially likely because information is shared to determine corporate policy. This political process will also take time. Speed-accuracy trade-offs occur among house-hunting rock ants, Temnothorax albipennis. A key aspect of their decision-making is quorum sensing in a potential new nest. Finding a sufficient number of nest-mates, i.e. a quorum threshold (QT), in a potential nest site indicates that many ants find it suitable. Quorum sensing collates information. However, the QT is also used as a switch, from recruitment of nest-mates to their new home by slow tandem running, to recruitment by carrying, which is three times faster. Although tandem running is slow, it effectively enables one successful ant to lead and teach another the route between the nests. Tandem running creates positive feedback; more and more ants are shown the way, as tandem followers become, in turn, tandem leaders. The resulting corps of trained ants can then quickly carry their nest-mates; but carried ants do not learn the route. Therefore, the QT seems to set both the amount of information gathered and the speed of the emigration. Low QTs might cause more errors and a slower emigration--the worst possible outcome. This possible paradox of quick decisions leading to slow implementation might be resolved if the ants could deploy another positive-feedback recruitment process when they have used a low QT. Reverse tandem runs occur after carrying has begun and lead ants back from the new nest to the old one. Here we show experimentally that reverse tandem runs can bring lost scouts into an active role in emigrations and can help to maintain high-speed emigrations. Thus, in rock ants, although quick decision-making and rapid implementation of choices are initially in opposition, a third recruitment method can restore rapid implementation after a snap decision. This work reveals a principle of widespread importance: the dynamics of collective decision-making (i.e. the politics) and the dynamics of policy implementation are sometimes intertwined, and only by analysing the mechanisms of both can we understand certain forms of adaptive organization.

Sensory coding of nest-site value in honeybee swarms

This study investigates the first stage of the decision-making process of a honeybee swarm as it chooses a nest site: how a scout bee codes the value of a potential nest site in the waggle dances she produces to represent this site. We presented honeybee swarms with a two-alternative choice between a high-value site and a medium-value site and recorded the behavior of individually identifiable scout bees as they reported on these two alternatives. We found that bees performed equally lengthy inspections at the two sites, but that, on the swarm cluster, they performed more dance circuits per bee for the high-value site. We also found that there was much individual-level noise in the coding of site value, but that there were clear population-level differences in total dance circuits produced for the two sites. The first bee to find a site had a high probability of reporting the site with a waggle dance, regardless of its value. This discoverer-should-dance phenomenon may help ensure that a swarm gives attention to all discovered sites. There was rapid decay in the dance response; the number of dance circuits produced by a bee after visiting a site decreased linearly over sequential visits, and eventually each bee ceased visiting her site. This decay, or ;leakage', in the accumulation of bees at a site improves a swarm's decision-making ability by helping a swarm avoid making fast-decision errors.