Potential Nest Sites Research Articles

Slit in a Nest Site Influences the Nest Site Selection in Cavity Nesting Ant Colonies.

For ants, nests provide a refuge against predators and protection from environmental factors. Thus, choosing a good nest site is important for an ant colony, but nest sites are limited resources. Ants of the genus Temnothorax inhabit small cavities in, e.g., acorns, twigs and under rocks. Earlier, it was shown that the ants are able to choose a superior site. In this study, using binary choice tests, we studied the nest site selection by Temnothorax crassispinus ant colonies that typically inhabit empty acorns. For this purpose, we used artificial nest sites without and with an additional slit in the nest wall, mimicking the cracks in potential nest sites under natural conditions. We found that the ant colonies preferred artificial nest sites without these slits. However, no difference in the number of colonies inhabited nest sites with a slit vs. those without a slit was found when the slits were closed using transparent food foil, which prevented the air flow while keeping an inflow of light. What is more, additional light through the hole in the red filter covering the artificial nest sites had no influence on the nest site selection. The results of this study suggest that the air flow through a slit in the nest site wall, rather than additional light, influences the nest site selection. The absence of cracks, e.g., in acorns, could be an indication of the durability of potential nest sites. Thus, choosing a cavity without such damage could be beneficial for the ant colonies.

The strength of sexual signals predicts same-sex pairing in two Coptotermes termites

Abstract Same-sex sexual behavior (SSB) is an enigma in behavioral ecology as it does not result in reproduction. Proximately, the effect of sexual signals on SSB could be distinct between signal receivers and senders. For receivers, the absence of sexual signals leads to smaller phenotypic sex differences, leading to frequent accidental SSB between receivers. Alternatively, for senders, sexual signals could help locate another sender, enhancing intentional SSB. Here, we demonstrate this link between sex pheromone signaling and the frequency of same-sex pairing in two Coptotermes termites that use the same chemical as sex pheromones but in different quantities. In termites, mating pairs engage in tandem runs, where a female emits sex pheromones to guide a male as they move together in searching a potential nest site. So, females are signal senders, and males are signal receivers for sexual communication. We found that female-female tandems were more stable in C. formosanus, whose females produce more pheromones. On the other hand, although both species did not show stable male-male tandems, males of C. gestroi, whose females produce fewer pheromones, spent more time attempting to follow another male. Thus, stronger pheromones lead to sender-sender SSB, while weaker pheromones lead to receiver-receiver SSB. The proximate mechanism of SSB is diverse according to the properties of sexual communications in heterosexual contexts.

Bird flight behavior, collision risk and mitigation options at high-speed railway viaducts

High-speed railway (HSR) networks are rapidly expanding and are predicted to continue to grow over coming decades. However, there is scant knowledge of their environmental impacts. Their possible effects on bird mortality, particularly at viaducts, gives especial cause for concern. This work presents the results of a nine-month monitoring of bird activity in the vicinity of three HSR viaducts in Central Spain. The study focused on the effects of the infrastructure regarding bird frequentation of the site and on bird flight activity in the danger zone for collision with passing trains. The findings show (i) that bird communities may differ markedly between sites and (ii) that bird activity increases near the railway together with changes in relative species abundances. Furthermore, (iii) birds show a significant tendency to avoid flying across the danger zone, but (iv) all kinds of birds are at a real risk of collisions with trains at viaducts. The greatest danger is at viaduct extremes rather than in their central section, particularly during gusts of wind and for small or medium-sized birds. It also appears that relatively low viaducts might pose greater risk. In practical terms, these results (i) emphasise the need for thorough prior prospection of bird species present, and their flight patterns, where new viaducts are to be built, (ii) show that there is a real risk of bird collisions with trains at viaducts, which should be mitigated, with particular attention due to viaduct extremes and areas where their height is not much above the surrounding vegetation and (iii) strongly indicate the need to minimise viaduct features that may attract birds to them, for example as potential nest sites.

Importance of Mesohabitat for Nest-Site Selection in Breeding Eagle Owls (Bubo bubo): A Multi-Scale Model

Apex predators make excellent bioindicators of habitat quality and anthropogenic changes. Eagle owls (Bubo bubo) are such apex and keystone predators, who show preferential nest-site selection, usually away from human activities and habitation. However, Israel is a small country with a burgeoning human population. Hence, in order to understand the habitat requirements of eagle owls in central Israel, we conducted a multi-scale model analysis on their existing nest sites between 2006 and 2010. We identified 203 successful breeding attempts at 73 different sites. Our data suggested that the breeding population of the eagle owls was limited by the availability of quality nest locations, i.e., quarries, and caves. The probability of an eagle pair breeding increased with the presence of both quarries and caves, but was not related to mesohabitat properties. In addition, eagle owl breeding densities were positively related to the number of nest localities and to the planted woodlands. Furthermore, we found that eagle owls successfully raised their young regardless of the surrounding mesohabitat and sought the presence of other potential nest sites in the vicinity of the active nest sites, most likely due to the owls’ opportunistic and generalist hunting behavior, which facilitated the consumption of a wide prey base. Appropriate nest sites (quarries and caves) appeared to increase population numbers and, therefore, should be protected Further studies should determine whether increasing artificial nest sites and reclaiming abandoned quarries could increase eagle owl numbers in a sustainable manner.

Linking wild turkey hen movement data to nesting behavior

AbstractMonitoring of wild turkey (Meleagris gallopavo) females to obtain representative measures of apparent nesting and nest survival rates has long been an important component of wild turkey management. In the interest of improving estimates of apparent nesting and nest survival rates, we assessed the feasibility of inferring reproductive behavior of wild turkeys from remotely acquired movement data. We ascertained detailed nesting stage chronologies using Global Positioning System (GPS) data downloaded from 44 females fitted with transmitters that had both a very high frequency (VHF) beacon and a GPS logger. Then we tracked females using VHF to confirm nest locations and nest fate in north and north‐central Florida. Using twice hourly GPS derived locations, we evaluated 3 predictive machine learning models (Chi‐squared automatic interactive detection [CHAID], exhaustive CHAID, and multivariate adaptive regression splines [MARSpline]) for their ability to accurately classify nesting behaviors (laying and incubating stages) that were confirmed via visual inspection of all potential nest sites. Incubation stage was readily identifiable by the spatial signatures present in each female's GPS‐based movement track across all models (up to 92% true positive and as low as 8% false positives in exhaustive CHAID models), whereas the laying stage was more difficult to identify (up to 65% true positive and as low as 35% false positives in exhaustive CHAID models). Daily averages of movement metrics generally achieved better performance in predictive models than data sets with more frequent sampling (i.e., 30‐minute daytime locations). Our results indicated that exhaustive CHAID models performed best in identifying nesting stages, using movement metrics from GPS data. With continued development, these models may facilitate and improve large‐scale wild turkey monitoring.

Can Reptiles Use Nest Site Choice Behavior to Counter Global Warming Effects on Developing Embryos? Potential Climate Responses in a Turtle

Climate warming is forecasted to cause extinctions, but populations could theoretically avoid extinction in a rapidly changing environmentviaadaptive evolution (i.e., evolutionary rescue), precluding the need for intervention. Although strong links between a changing climate and the physiology of an organism are expected, climate effects can be buffered by behavior. Nest site choice behavior, for example, can reduce environmental variation that would be experienced by embryos placed randomly with respect to environmental temperatures. We tested four provisions of this prediction by quantifying nest sites and “potential” nest sites in the Florida softshell turtle (Apalone ferox). First, turtles chose nest sites with mean canopy openness values (32–47%) that were intermediate between the shadiest (14–17%) and the sunniest potential nest sites (36–57%) available. Second, canopy openness, incident radiation intensity, and nest temperatures were generally, positively related to one another, indicating definitive thermal consequences of nest site choice. Third, our study revealed ample, cooler nest sites available to turtle mothers within close proximity to nest sites utilized; by nesting in the most shaded sites, softshell turtle mothers could depress mean nest temperatures by ∼2°C. Fourth, the growth of vegetative cover throughout incubation had negligible effects on canopy openness, incident radiation intensity, and nest temperatures, supporting the potential for mothers to “predict” developmental temperatures using temperature cues during nest site choice. Finally, our data revealed considerable variation in canopy openness chosen by nesting mothers; such behavior could thus, be subject to natural selectionviaembryonic mortality under future warming. Collectively, our study suggests that Florida softshell turtles, and probably other turtle species nesting in relatively open areas, may be able to counter climate change effects on developing embryos by nesting in more shaded microhabitats, assuming nest site choice behavior is heritable and can evolve at a sufficient rate to keep pace with climate warming. The evolutionary and behavioral mechanisms (e.g., assessing substrate temperatures directly vs. indirect choice of canopy cover) in the repertoire of nesting mother turtles for responding to climate warming remain elusive and are required for a more complete understanding of climate responses.

Understanding hippocampal neural plasticity in captivity: Unique contributions of spatial specialists.

Neural plasticity in the hippocampus has been studied in a wide variety of model systems, including in avian species where the hippocampus underlies specialized spatial behaviours. Examples of such behaviours include navigating to a home roost over long distances by homing pigeons or returning to a potential nest site for egg deposit by brood parasites. The best studied example, however, is food storing in parids and the interaction between this behaviour and changes in hippocampus volume and neurogenesis. However, understanding the interaction between brain and behaviour necessitates research that includes studies with at least some form of captivity, which may itself affect hippocampal plasticity. Captivity might particularly affect spatial specialists where free-ranging movement on a large scale is especially important in daily, and seasonal, behaviours. This review examines how captivity might affect hippocampal plasticity in avian spatial specialists and specifically food-storing parids, and also considers how the effects of captivity may be mitigated by researchers studying hippocampal plasticity when the goal is understanding the relationship between behaviour and hippocampal change.

The Power of Population Effect in Temnothorax Ant House-Hunting: A Computational Modeling Approach.

The decentralized cognition of animal groups is both a challenging biological problem and a potential basis for bioinspired design. In this study, we investigated the house-hunting algorithm used by emigrating colonies of Temnothorax ants to reach consensus on a new nest. We developed a tractable model that encodes accurate individual behavior rules, and estimated our parameter values by matching simulated behaviors with observed ones on both the individual and group levels. We then used our model to explore a potential, but yet untested, component of the ants' decision algorithm. Specifically, we examined the hypothesis that incorporating site population (the number of adult ants at each potential nest site) into individual perceptions of nest quality can improve emigration performance. Our results showed that attending to site population accelerates emigration and reduces the incidence of split decisions. This result suggests the value of testing empirically whether nest site scouts use site population in this way, in addition to the well-demonstrated quorum rule. We also used our model to make other predictions with varying degrees of empirical support, including the high cognitive capacity of colonies and their rational time investment during decision-making. In addition, we provide a versatile and easy-to-use Python simulator that can be used to explore other hypotheses or make testable predictions. It is our hope that the insights and the modeling tools can inspire further research from both the biology and computer science community.

Characteristics and selection of nest sites of the flexible cavity-nester, the European robin Erithacus rubecula, in the temperate primeval forest (Białowieża National Park, Poland)

Despite its broad range and high abundance, nest sites of the European robin Erithacus rubecula, a small forest passerine, are rarely characterised, and most studies refer to human-transformed habitats. In this paper, we describe the species’ nest sites in the natural conditions of a primeval forest. We also investigate robin preferences to address nest site selection which can only be assessed if the availability of potential nest sites is known. We studied robins’ nest sites in Białowieża National Park, eastern Poland, on three study plots (~30 ha each) in 2016–2019. Among all nests found (n = 165), the majority (118, ~72%) were found in tree holes, followed by ground nests (25, ~15%) and root-soil plates (22, ~13%). When the availability of cavities and root-soil plates is accounted for, it appears that robins preferred tree holes over plates. Robins appeared to be weakly selective in respect to tree species, preferring hornbeam Carpinus betulus, small-leaved lime Tilia cordata and Norway spruce Picea abies over other trees. Since both cavities and root-soil plates are superabundant in the Białowieża Forest, but scarce or absent in the heavily transformed robin breeding habitats of Western Europe (parks, orchards, hedgerows or managed forests), ground-nesting may predominate there simply due to these choice limits. In summary, our results provide a basis for understanding how original nest-site choices that evolved in natural, unmodified habitats can change when a species adapts to human-transformed habitats.

Between a rock and a large place: the importance of multi-scale geomorphological features to seabird nest site selection.

The importance of habitats to animal, and, in particular, bird conservation, has long been recognized (Martin et al. 2007, Yorio 2009, Oppel et al. 2018). From the study of habitat has emerged the importance of geodiversity (Hjort et al. 2015, Hunter et al. 2017, Malcolm and Hunter 2017). The relationship between geodiversity and biodiversity is a fundamental, yet often-overlooked aspect of ecology; for example, we recently demonstrated that several seabird species show preferences for particular small natural features of potential nest sites (Eveillard-Buchoux et al. 2019 and Fig. 1).

Acorn Ants May Create and Use Two Entrances to the Nest Cavity.

Simple SummaryLarge nests of ants, or ant hills, which are inhabited by numerous workers, are universally known. However, many ant species live in small colonies and do not construct nests, but instead dwell in ready-for-use cavities. In Central Europe, acorn ants are among the most widely distributed and common species but are also frequently overlooked as the workers are small and colonies of the species typically range from only a few dozen to about two hundred individuals. Often, a whole colony lives in just one empty acorn or a cavity inside a small twig. Such a cavity, such as an empty acorn, typically has one hole resulting from the activity of wood-boring beetles, and that hole is used by the ant colony as the entrance to the nest. Acorn ants have been the subject of numerous experiments, including those focused on the choice of nest sites. For example, it was previously found that ants prefer sites with a narrow vs. a wider entrance. However, cavities with good-sized hole are rare; thus, the possibility to modify a potential nest site, including a reduction in the size of the hole, should be a favorable matter for the ants. The results of this study showed that the ant colonies could inhabit imperfect cavities that need a modification, e.g., a reduction of the available holes, and that such small colonies may even create two entrances to the nest cavity. However, the effect of the presence of more than one entrance to the nest on the behavior of the ants is unknown.Many ant species construct large nests that are inhabited by numerous workers, but other species dwell in ready-for-use cavities and live in small colonies. Ants of the genus Temnothorax inhabit small cavities, e.g., in acorns, twigs, and under rocks. Although a preference for nest sites with a narrower entrance is known, recent studies have shown that they also use cavities with wider entrances and may modify the size of such entrances. As good cavities for nest sites are a limited resource, the possibility to modify a potential nest site, including a reduction in the size of the hole, should be a favorable matter for the ants. Through field and laboratory experiments, I studied the acorn ant Temnothorax crassispinus. Observations showed that they readily inhabited imperfect cavities and, if necessary, modified the holes to such cavities. If they had to repair a nest site, they sometimes created a second entrance; there was no difference in the sizes of the entrances. In the field, for entrance modification or blocking an unnecessary hole, the acorn ants used soil, grains of sand, and parts of plants. In the laboratory, the ant colonies showed no preference for nest sites with one entrance vs. a nest cavity with two entrances. The results of this study showed that even such small ant colonies could use nest sites with multiple entrances; however, the effect of the presence of more than one entrance on the behavior of the ants is unknown.

Red mason bee (Osmia bicornis) thermal preferences for nest sites and their effects on offspring survival

Ectotherms usually require a narrow range of thermal conditions for development; thus, parental selection of oviposition sites is crucial. In a field experiment, we investigated female solitary red mason bee (Osmia bicornis) preferences for potential nest site temperatures and their effects on offspring development. The results showed that bees detected and avoided nest sites with high temperatures (28°C) and often chose cooler (24°C) or ambient temperatures (average 18–20°C). This is a protective behaviour because offspring survival decreases with increasing nest temperature, mostly due to mortality at the egg stage. Elevated temperatures also led to weight loss in adult bees. However, hot nest temperatures appeared to deter adults or kill parasite larvae, as the highest numbers of parasites were observed in unheated nests. We concluded that choosing the proper temperature for nests is an important element in bee life strategies, especially in warming environments.

No effect of lack of wood for acorn ant colonies development

Acorn ants mostly inhabit cavities in fallen twigs and hollow acorns. Such places, e.g., dead wood, provide an attractive living resource for many groups of microorganisms, like fungi and bacteria, which can be important for ants. However, during experiments in laboratories, acorn ant colonies are typically kept without dead wood. During laboratory experiments, the preferences of the ant Temnothorax crassispinus for nest sites with pieces of dead wood were checked, and whether the presence of such wood influenced productivity. In binary choice tests, colonies had to choose a nest site when presented with two potential nest sites, one empty, or two cavities with different contents. The ant colonies preferred nest cavities with pieces of dead wood versus empty nest cavities. When cavities were filled with pieces of wood or with pieces of wood previously sterilized (72 hours, 70°C), colonies preferred the unsterilized zones. During a three-month laboratory experiment, colonies were kept in the Petri dishes containing pieces of dead wood, containing “sterilised” pieces of dead wood, or without access to wood. In the experiment, no influence was discovered on the availability of dead wood in either colony growth or colony per capita productivity. Thus, the ants prefer cavities with pieces of wood, but the lack of availability of dead wood during a multi-month experiment has no influence on life history parameters.

Nest-site selection in a fish species with paternal care

Fish that perform paternal care may increase their fitness by choosing nest sites that enhance survival and development of embryos. We studied nest-site choice with respect to dissolved oxygen concentration and water temperature in males of the three-spined stickleback (Gasterosteus aculeatus), a small fish species with exclusive male parental care that usually breeds in the littoral zone of freshwaters of the Northern hemisphere. Fathers oxygenate the embryos by fanning movements of their pectoral fins. We expected choice for conditions at potential nest sites that would benefit offspring development, i.e., higher temperature and higher dissolved oxygen concentration. In the laboratory, we offered males a choice between two potential nest sites that differed in dissolved oxygen concentration or water temperature. Males preferred to build a nest at sites with a higher dissolved oxygen level or higher temperature and thus chose sites that would promote embryo development.

Clear Plastic Bags of Bark Mulch Trap and Kill Female Megachile (Hymenoptera: Megachilidae) Searching for Nesting Sites

In 2017, we found 17 dead females of Megachile frigida Smith in clear plastic bags of composted bark mulch in a residential yard in Bozeman, Montana, USA. Females apparently entered bags via small ventilation holes, then became trapped and died. To investigate whether this is a common source of mortality, we deployed unmodified bags of mulch and those fitted with cardboard tubes (as potential nest sites) at three nearby sites in 2018. We found two dead M. frigida females and five completed leaf cells in one of these bags of mulch fitted with cardboard tubes; two male M. frigida emerged from these leaf cells. In 2018, we also discovered three dead female M. frigida and three dead females of a second leafcutter bee species, Megachile gemula Cresson, in clear bags of another type of bark mulch. Both mulches emitted nearly identical blends of volatile organic compounds, suggesting their odors could attract females searching for nesting sites. These findings suggest that more research is needed to determine how common and widespread this is for Megachile species that nest in rotting wood and if there are simple solutions to this problem.

Computational intelligence within a resource budget: The case of the honey bee (Apis mellifera) swarm

AbstractThis study investigated the resource budget available to a typical honey bee swarm as it gathered information and decided which was the best of some 13–34 potential nest sites to move into and become its new home. After a brief description of the decision‐making mechanisms involved, the utilization of the swarm's finite energy, memory and carrier resources is described. It was found that each individual scout decision maker only carried enough energy reserves to provide for 2.6 days of visits to evaluate distant sites and, effectively, only enough memory space to remember the location and quality of approximately one site. Scouts, who only formed 4.4% of the swarm bees, consumed 22.8% of the swarm's energy budget, showing that their best‐of‐N computations were energetically very expensive. A typical swarm of 12,000 bees only contained enough energy reserves to last for 13.5 days after which foraging had to restart.

The interrelationship between torpor expression and nest site use of western and eastern pygmy-possums (Cercartetus spp.)

Physiology and behaviour are closely linked, making knowledge of the interaction between species’ energetics and activities important when attempting to understand how animals function in the wild. I examined torpor use by western pygmy-possums (Cercartetus concinnus) and eastern pygmy-possums (C. nanus) in relation to nest site characteristics and movement patterns. In coastal mallee heath in winter, C. concinnus nested beneath leaf litter at the base of dead Banksia ornata, where they employed torpor on 69% of observed days. In warm temperate sclerophyll forest, C. nanus nested in tree hollows of Eucalyptus spp. and used torpor on 64% of days in winter and 10% in summer. Torpor was used in nest sites that were buffered from outside temperature extremes. Both species frequently reused nest sites and while C. nanus was more likely to employ torpor in a previously used site, site familiarity did not influence torpor use for C. concinnus. Additionally, C. nanus was more likely to use torpor in hollows with a higher relative thickness in both seasons. No relationship was found between range size and the number of tracking days or capture body mass, though sample sizes were small. I suggest that the thermal attributes of nest sites influence torpor use for both species and this is likely vital for maintaining a positive energy balance, stressing the importance of preserving habitat with ample potential nest sites for conservation management.

Mackenzie River Peregrine Falcon Surveys 1966–2018

Abstract The author with assistants monitored the breeding distribution of Peregrine Falcons (Falco peregrinus) along the length of the Mackenzie River, Northwest Territories, Canada from 1966 to 2018. This river traverses a thousand miles (1600 km) of the western Canadian Arctic from Great Slave Lake to the Beaufort Sea and roughly parallels the eastern slope of the Mackenzie Mountain cordillera between latitudes 61 degrees N and 68 degrees N. All potential nest sites have been checked on each survey and counts of nest sites occupied (at least one bird seen) decreased from the count of 12 sites in 1966 to the lowest count of 7 in 1972. In 1990 the count was 37 and up to 2018 the highest count was 75 in 2010. A count of nest sites successfully producing young was variable with a low of 5 in 1972 to a high of 58 in 2011. Production of young averaged 2.43/successful site from 1990 until 2018 (excluding 2012). Production of young averaged 1.4/occupied site over this period. Recent increases in availability of passerine prey because of widespread fires in the last decades are felt to be the latest phenomena affecting these birds (pers.obs.) Prey utilized by Peregrines was studied over a period of four years and passerines composed 20% of their diet. Two species Lesser Scaup (Athya affinis) and Lesser Yellowlegs (Tringa flavipes) formed 25% of their diet.

Different bees, different needs: how nest-site requirements have shaped the decision-making processes in homeless honeybees (Apis spp.).

During reproductive swarming, a honeybee swarm needs to decide on a new nest site and then move to the chosen site collectively. Most studies of swarming and nest-site selection are based on one species, Apis mellifera Natural colonies of A. mellifera live in tree cavities. The quality of the cavity is critical to the survival of a swarm. Other honeybee species nest in the open, and have less strict nest-site requirements, such as the open-nesting dwarf honeybee Apis floreaApis florea builds a nest comprised of a single comb suspended from a twig. For a cavity-nesting species, there is only a limited number of potential nest sites that can be located by a swarm, because suitable sites are scarce. By contrast, for an open-nesting species, there is an abundance of equally suitable twigs. While the decision-making process of cavity-nesting bees is geared towards selecting the best site possible, open-nesting species need to coordinate collective movement towards areas with potential nest sites. Here, we argue that the nest-site selection processes of A. florea and A. mellifera have been shaped by each species' specific nest-site requirements. Both species use the same behavioural algorithm, tuned to allow each species to solve their species-specific problem.This article is part of the theme issue 'Collective movement ecology'.

Psychophysical Laws and the Superorganism

Through theoretical analysis, we show how a superorganism may react to stimulus variations according to psychophysical laws observed in humans and other animals. We investigate an empirically-motivated honeybee house-hunting model, which describes a value-sensitive decision process over potential nest-sites, at the level of the colony. In this study, we show how colony decision time increases with the number of available nests, in agreement with the Hick-Hyman law of psychophysics, and decreases with mean nest quality, in agreement with Piéron’s law. We also show that colony error rate depends on mean nest quality, and difference in quality, in agreement with Weber’s law. Psychophysical laws, particularly Weber’s law, have been found in diverse species, including unicellular organisms. Our theoretical results predict that superorganisms may also exhibit such behaviour, suggesting that these laws arise from fundamental mechanisms of information processing and decision-making. Finally, we propose a combined psychophysical law which unifies Hick-Hyman’s law and Piéron’s law, traditionally studied independently; this unified law makes predictions that can be empirically tested.