Nest Box Design Research Articles

No evidence of adaptive tolerance of parasitism in a cavity-nesting brood parasite host

Abstract Acceptance of avian brood parasitism by hosts is one of the most enigmatic aspects of brood parasite–host coevolution. The most common explanation for acceptance of parasitism by hosts of the brown-headed cowbird (Molothrus ater) is evolutionary lag, which suggests that hosts have not had enough time to evolve defenses against parasitism. Alternatively, acceptance may be the optimal strategy when the costs of rejecting parasitism exceed the benefits. The lack of nest site hypothesis applies to secondary cavity-nesting birds that cannot excavate their own nests and predicts that hosts accept parasitism instead of deserting a parasitized nest when there are no vacant nest sites available in which to renest. I tested this hypothesis using the prothonotary warbler (Pronotaria citrea), a commonly parasitized, cavity-nesting cowbird host. I used a paired nest box design and predicted that if hosts accept parasitism because of a lack of alternative nest sites, they should desert parasitized nests and renest in the vacant nest box on their territory. I recorded 37 cases where a nest was parasitized and warblers only deserted 2 parasitized nest boxes for a vacant nest box. Both desertions were attributable to factors other than parasitism and the rate of desertion did not differ from controls that only had a single nest box. Moreover, 7 of the warblers initiated clutches in nest boxes that already contained cowbird egg despite having vacant nest boxes available on their territories. These results indicate that warblers do not accept parasitism because of tolerance, but likely due to evolutionary lag.

Influence of nest box design on internal microclimate: Comparisons of plastic prototypes

AbstractHollow‐dependent fauna are declining worldwide, due primarily to the widespread clearing of hollow‐bearing trees. Artificial cavities such as timber and plywood boxes are commonly used to increase hollow availability, yet there is increasing evidence that they are poor facsimiles of natural cavities, characterized by lower insulative properties and a shorter field life. We evaluated whether plastic materials could create a nest box with a stable thermal profile that more closely resembles the complex shapes and textures of natural tree hollows while containing fewer mechanical joins that represent potential failure points when installed. We developed three sets of prototype nest boxes comprising various combinations of plastic density (10%, 25% and 50%), insulation (single vs. double wall with or without sawdust between them), nesting chamber (with or without timber inserts) and bedding (with or without decomposed heartwood) and compared their thermal performance in a temperature‐controlled laboratory to compare internal temperature and relative humidity. We found double‐walled plastic nest box with an internal timber‐lined chamber was best able to buffer ambient temperature fluctuations, consistently recording internal temperatures of 6+°C below maximum ambient temperature, maintaining high levels of relative humidity (76%–92%) when furnished with decomposed timber heartwood. This design also performed better during a simulated hot day; internal temperatures exhibiting twice the lag time of single‐walled designs, noting that plastic density had little influence on internal conditions. While the recruitment and protection of hollow‐bearing trees must be a priority, this work shows significant potential in improving the design and functionality of artificial hollows that are critical to the conservation of hollow‐dependent species.

Influence of nest box design and nesting material on ectoparasite load for four woodland passerines

ABSTRACT Capsule Abundance of haematophagous ectoparasites in woodland passerine nests is influenced by complex interactions between nest box design, bird species, amount of nesting material and nest composition. Aims To analyse ectoparasite abundance relative to nest box design (old wooden nest boxes present for over 2 years versus new wooden nest boxes of the same dimensions vs deep wooden nest boxes designed to reduce predation risk) and bird species (Blue Tit Cyanistes caeruleus, Great Tit Parus major, Pied Flycatcher Ficedula hypoleuca and Eurasian Nuthatch Sitta europaea). The potential influence of amount of nesting material and nest composition was also studied. Methods After fledging, nests were collected from nest boxes. Ectoparasites and nest materials were identified and quantified. Generalized linear modelling was used to examine the influence of nest box design, bird species, amount of nest material and nest composition on ectoparasite loads. Akaike’s Information Criterion was used to select optimal models. Results Abundance of Hen Fleas Ceratophyllus gallinae and parasitic Blowfly Protocalliphora was significantly higher for deep nest boxes than nest boxes of standard dimensions. Old nest boxes had significantly higher loads than new nest boxes, despite thorough cleaning between breeding seasons. Hen Flea abundance was highest in Eurasian Nuthatch nests. Blowfly abundance was highest in Pied Flycatcher nests. Abundances of both fleas and blowfly were positively related to nest mass and amount of animal hair in the nest, and, for parasitic Blowfly, were negatively related to the amount of tree bark. Conclusion Ectoparasite load depends not only on bird species but also nest box design and nesting material. We recommend: (1) nest boxes are regularly replaced to reduce parasite load; (2) deep nest boxes are not used as the large nests constructed not only remove anti-predator benefits of eggs/chicks being harder to reach but are also associated with high haematophagous ectoparasite loads.

Testing artificial nestbox designs for in-situ conservation of tamarins

Reconnecting fragmented habitats by planting forest corridors is becoming necessary to support isolated populations of threatened callitrichid primates (marmosets and tamarins) in Brazil. Tamarins frequently use tree holes as sleeping sites, but young forests do not provide these; artificial nestboxes offer a potential solution until trees in the corridors reach maturity. However, how effective such nestboxes are in attracting callitrichids and providing safety from predators is unquantified. We tested three features that might be important in the design of callitrichid nestboxes: internal shelves or entrance tunnels, to prevent predators from reaching tamarins in the boxes, and a second exit point to provide an escape route. Seven groups of zoo-housed pied tamarins (Saguinus bicolor) were given a choice between an unmodified nestbox with a single entrance and a box with one of the three test features. Each group was tested 12–13 times under each choice condition. Tamarins chose to sleep in boxes with tunnels (overall probability of selection = 0.72) and shelves (probability of selection = 0.53) in preference to unmodified boxes, but rarely opted for boxes with two entrance holes (probability = 0.3). A generalised linear mixed model showed that these differences were statistically significant (F = 15.6, df = 2, P < 0.0001). Tamarins spent more time in the hour before retiring in nestboxes with tunnels or shelves than in unmodified boxes, but less time in boxes with two entrances (F = 11.84, df = 2, 53.05, P < 0.0001). They also retired latest and rose earliest if they used boxes with two entrances. To test their susceptibility to predation, boxes of each design were baited and offered to coatis (Nasua nasua), macaques (Macaca nigra), and capuchins (Cebus capucinus and Sapajus xanthosternos). Four trials were conducted for each box type with each species. None managed to obtain bait from boxes with tunnels, but all rapidly retrieved the bait from boxes with two entrances. Pied tamarins therefore preferred nestbox designs (tunnels) offering the most protection from predators.

What makes a house a home? Nest box use by West European hedgehogs (Erinaceus europaeus) is influenced by nest box placement, resource provisioning and site-based factors.

Artificial refuges provided by householders and/or conservation practitioners potentially represent one mechanism for mitigating declines in the availability of natural nest sites used for resting, breeding and hibernating in urban areas. The effectiveness of such refuges for different species is, however, not always known. In this study, we conducted a questionnaire survey of UK householders to identify factors associated with the use of ground-level nest boxes for West European hedgehogs (Erinaceus europaeus), a species of conservation concern. Overall, the percentage of boxes used at least once varied with season and type of use: summer day nesting (35.5–81.3%), breeding (7.2–28.2%), winter day nesting (20.1–66.5%) and hibernation (21.7–58.6%). The length of time the box had been deployed, the availability of artificial food and front garden to back garden access significantly increased the likelihood that a nest box had been used for all four nesting types, whereas other factors related to placement within the garden (e.g., in a sheltered location, on hardstanding such as paving, distance from the house) and resource provisioning (bedding) affected only some nesting behaviours. The factors most strongly associated with nest box use were the provisioning of food and bedding. These data suggest, therefore, that householders can adopt simple practices to increase the likelihood of their nest box being used. However, one significant limitation evident within these data is that, for welfare reasons, householders do not routinely monitor whether their box has been used. Consequently, future studies need to adopt strategies which enable householders to monitor their boxes continuously. Ultimately, such studies should compare the survival rates and reproductive success of hedgehogs within artificial refuges versus more natural nest sites, and whether these are affected by, for example, the impact of nest box design and placement on predation risk and internal microclimate.

An evaluation of thermal imaging as a tool for assessing occupancy of enclosed nests

ABSTRACT Thermal cameras are being used increasingly in the bird-ringing community and preliminary reports suggest they have a wide range of relevant applications. However, there has been little quantitative assessment of these methods. In this study we tested the use of a thermal imager to assess the occupancy of enclosed nests, using nest-box populations of small passerines. Based on a thermal image of each nest box, observers were able to predict nest-box occupancy with a combined success rate of 85.9%. The observers were able to identify when nest boxes contained a heat source relating to an active nest but unable to differentiate between warm clutches and live broods. The age of the brood significantly influenced the predictions, reflecting the limited ability of young broods to maintain their body temperatures independently. There were no significant effects from potential confounding variables relating to solar exposure, nest-box design or ambient temperature, although these may have accounted for a small number of incorrect predictions. Overall, it was found that thermal imagers provide an effective, non-invasive and efficient method for monitoring nest-box occupancy, with inferences about suitability for other types of enclosed nest.

Helping wildlife beat the heat: Testing strategies to improve the thermal performance of nest boxes

ABSTRACT Nest boxes are often deployed in an attempt to offset the loss of natural tree hollows following landscape disturbance (e.g., land clearing, logging and wildfire). However, nest boxes can experience more variable and extreme microclimates than natural hollows, which could harm animals that use them. In this study, we tested the thermal performance of candidate nest box designs prior to their deployment for greater gliders (Petauroides volans) in forests impacted by the 2019–2020 bushfires. The tests were conducted under controlled laboratory conditions to investigate the thermal response of different designs to radiant heat and changes in ambient temperature. We examined how paint type (i.e., no paint, white exterior paint, and reflective white paint), insulation thickness (0 mm, 20 mm, and 40 mm Foilboard), and insulation amount (i.e., number of sides insulated) influenced the internal temperature profiles of these nest boxes. We found that nest boxes with the reflective white paint had the lowest temperatures on the inside wall closest to the radiant heat source, but internal nest box air temperature did not differ among paint treatments. Similarly, the internal wall closest to the radiant heat source was cooler in nest boxes with thicker compared to thinner insulation, but there was no difference in internal air temperature between the two thicknesses. Both 20 mm and 40 mm Foilboard insulation resulted in significantly cooler air temperatures and internal wood panel temperatures compared to nest boxes without insulation. Fully insulated nest boxes and those with three of the four sides insulated exhibited less temperature variability and remained cooler than the less-insulated nest boxes. Temperatures inside nest boxes with more than one side insulated took longer to increase and decrease in a convective heat chamber, but importantly, never reached the heat extremes (&amp;gt; 40°C) of less insulated nest boxes. Fully insulated nest boxes also maintained heat longer than any other nest box type in a cold room. Understanding how different construction materials influence nest box temperature profiles and identifying designs that minimise thermoregulatory costs for animals is important for the safe implementation of nest box programs.

Effects of nest-box environment on fledgling success rate and pathogen load.

Nest boxes have been used for many decades as tools for conservation and to study avian population dynamics. Plastic is increasingly used as a material for nest boxes, but no studies have investigated effects of this different material. Two consecutive studies were conducted to investigate effects of nest-box environment on nidicolous parasites, bacteria and fungi, as well as nest success, in blue tits Cyanistes caeruleus and great tits Parus major. The first compared microclimate and parasite and pathogen load in plastic and wooden nest boxes. The second tested the nest protection hypothesis – that birds naturally incorporate aromatic herbs into nests to decrease nest parasites and pathogens – by comparing parasite and pathogen load in plastic nest boxes to which aromatic or non-aromatic plant material was added. No significant difference in nest-box temperature or relative humidity was found between plastic and wooden boxes. Wooden boxes, however, contained 30-fold higher numbers of fleas and a higher total bacterial load on chicks. Fledging success for blue tit broods was significantly higher in wooden boxes. Parasites and bacteria did not decrease by the inclusion of aromatic herbs. The results increase the evidence base for nest-box design in support of plastic, which can provide an appropriate alternative nest-box material to wood, with apparently no difference in microclimate and no increase in the load of measured parasites and pathogens.

Current nest box designs may not be optimal for the larger forest dormice: Pre-hibernation increase in body mass might lead to sampling bias in ecological data.

Biologists commonly use nest boxes to study small arboreal mammals, including the forest dormouse (Dryomys nitedula). Hibernating dormouse species often experience pronounced seasonal variations in body mass, which might lead to sampling biases if it is not taken into account when designing nest boxes. In my study of the forest dormouse, I noticed that the entrance hole of nest boxes had been gnawed. I hypothesized that this behavior was exhibited by the individual dormice of higher body mass, who were unable to pass through the entrance holes.To test my hypothesis, I categorized the individual dormice present inside nest boxes based on their body mass and then compared the seasonal body mass dynamics with the timing of the gnawing behavior. I also compared nest box occupancy by the forest dormouse before and after the gnawing behavior.Interestingly, I found that the gnawing behavior was displayed exclusively when part of the dormouse population increased considerably in body mass, which supports my hypothesis. Additionally, nest box occupancy decreased significantly from 20% before to 4.6% after the gnawing behavior.I suggest that researchers include nest boxes with entrance holes larger than 4 cm in future studies of the forest dormouse to prevent the possible exclusion of the conspecifics that have higher body mass before hibernation. This type of sampling bias might also concern studies of other species, such as the fat dormouse, that similarly show pronounced seasonal variations in body mass. I recommend that biologists consider the seasonal body mass dynamics of the target species when designing nest boxes to minimize bias in ecological data and improve management actions.

Spout hollow nest boxes provide a drier and less stable microclimate than natural hollows

AbstractArtificial tree hollows (e.g., nest‐boxes) are commonly deployed to mitigate the loss of mature trees within human‐disturbed landscapes. Their effectiveness as a habitat resource, and thus conservation management tool, is strongly influenced by the suitability of internal microclimate conditions. In south‐eastern Australia, spout hollows are a nesting resource used by a diverse community of vertebrate species. We tested the suitability of a novel nest box design (spout boxes) that mimicked the physical characteristics of spout hollows. We monitored the occupancy (n = 193) and internal microclimate (n = 131) of natural hollows and spout boxes within a woodland where natural tree hollows were once abundant. Both natural hollows and spout boxes were occupied and used for breeding by birds and mammals. Natural hollows had consistently higher humidity, and thermal maxima and minima were buffered, when compared with spout boxes. These differences were largely explained by wall thickness. Spout boxes displayed even more extreme temperature variation and lower humidity when not shaded. While more extreme microclimate conditions did not prevent usage, tolerable thresholds for hollow‐dependent species may soon be exceeded under current climate change projections. Managers need to carefully consider nest box design and positioning to ensure the suitability of these supplementary resources for conservation purposes.

Multi‐year nest box occupancy and short‐term resilience to wildfire disturbance by barn owls in a vineyard agroecosystem

AbstractLandscape composition can strongly affect the delivery of ecosystem services in agroecosystems. Conserving uncultivated habitats can support ecosystem services, but in Mediterranean biomes, these lands can also increase the area susceptible to wildfires. In the world‐renowned wine‐producing region of Napa Valley, California, wine grape growers install nest boxes to attract American barn owls (Tyto furcata), which may reduce rodent crop damage. Annual monitoring of 273 nest boxes began in 2015, and devastating wildfires burned approximately 60,000 ha in the region in 2017, including homes and businesses, as well as some vineyards and uncultivated land. The goal of this study was to determine whether changes in nest box occupancy were attributed to wildfires, nest box design, land cover type, or some combination of these variables. Occupancy surveys before and after these wildfires revealed changes in habitat selection at the nest scale. Occupancy increased during the study, reaching its highest point after the fires. Owls were found breeding in recently burned areas that were previously unoccupied and modeling results showed that nest box occupancy had a positive relationship with burned areas, particularly with edges of the fire perimeter. Barn owls also consistently showed a strong preference for taller nest boxes that were surrounded by more grassland than other land cover types and a moderate selection for wooden over plastic boxes. These results illustrate an incentive for the conservation of uncultivated habitat, particularly grassland, in vineyard ecosystems, and they provide an example of a mobile pest predator’s response to wildfire disturbance. In this case, results suggest an agroecosystem service made resilient to wildfire by the owls’ selection of burned and uncultivated habitats.

Insulated nest boxes provide thermal refuges for wildlife in urban bushland during summer heatwaves

Abstract In urban bushland, the installation of nest boxes is widely used to compensate for the loss of natural tree hollows. However, current nest box designs may not provide thermal refuges for wildlife during summer heatwaves, particularly if internal temperatures exceed the upper critical temperatures of wildlife. We investigated whether the addition of roofing insulation to nest boxes deployed for sugar gliders (Petaurus breviceps) and squirrel gliders (Petaurus norfolcensis) in urban bushland would reduce internal nest box temperatures during summer heatwaves. We measured temperatures of 44 insulated and 47 uninsulated nest boxes during one of the hottest summers on record (2018–2019) in the Lake Macquarie region of NSW, Australia, a period during which several prolonged heatwaves occurred. Over the 90-day study, maximum temperatures were, on average, 3.1°C lower in insulated boxes than in uninsulated boxes. The addition of insulation significantly lowered nest box temperatures regardless of aspect (north or south facing) or day of measurement. Temperatures exceeded the upper critical temperature (35.1°C) of gliders more frequently in uninsulated nest boxes (28% of days) than in insulated nest boxes (8% days). Although the addition of insulation to nest boxes lowered their internal temperatures, during heatwaves spanning 23 days, nest box temperatures exceeded the upper critical temperatures of gliders on 58% and 23% of days in uninsulated and insulated nest boxes respectively. These findings underscore the importance of retaining natural hollows in urban bushland to provide thermally suitable refuges for wildlife during extreme heat events.

Rapid colonisation, breeding and successful recruitment of eastern barn owls (

Abstract Context The introduced house mouse (Mus domesticus) causes significant economic damage to Australia’s agricultural enterprises. As part of the Marna Banggara Rewilding Project on the southern Yorke Peninsula (SYP), the present study focused on the eastern barn owl (Tyto alba delicatula) as a potential bio-controller of mice, by providing nesting spaces where natural hollows are limited. Aims To design an appropriate pole-mounted wooden nest box, and to enhance barn-owl-breeding and house-mouse-hunting capacity on farmland adjacent to remnant native vegetation. Methods A prototype nest box was collaboratively designed with a nest box manufacturer using data from previous barn owl studies and anecdotal reports. Eleven pole-mounted wooden boxes with platforms were installed at distances &gt;1.4 km apart on properties near Warooka, southern Yorke Peninsula (SYP), and monitored over a 6-month period using external trail cameras. Key results Of the 11 nest boxes installed, 55 percent were colonised within a month after establishment, and 82 percent were colonised within 7 months. Occupied nest boxes were actively used by paired owls for mating, breeding and rearing of chicks, which resulted in up to 35 fledgling owlets. Conclusions The nest box design successfully supported eastern barn owl colonisation and reproduction on the SYP. The inclusion of the platform not only provided easy, minimally invasive monitoring of barn owl activity and prey intake by researchers, but also increased usable space for barn owl behaviours, such as copulation and wing flapping. Implications The important nest box design elements featured in this paper, such as the platform, high entrance hole, predator-proof pole and rear door access, can be implemented in barn owl conservation, research and on farms where alternative nesting sites are limited.

Non-infectious diseases and laying hen welfare

Numerous non-infectious conditions can affect commercial layer flocks. Some of these, such as conditions related to bodyweight, fatty liver haemorrhagic syndrome and effects of age are common to all production systems, while some are more common in cage systems (cage layer fatigue, feather pecking) or in cage-free systems (grass impaction, smothering, sunlight exposure, cannibalism, predation and injuries). Many of these conditions are covered in other papers and will not be dealt with in here. In the present paper, emphasis will be placed on grass impaction, smothering, effects of age, exposure to high light intensities, predation and conditions related to overweight/obesity issues. All of these are of considerable welfare concern for the industry. Grass impaction is a particular issue when hens are first released to the range areas and are exposed to vegetation or other fibrous materials. Mortality can be high with this problem. Smothering episodes can be generated by sudden flock disturbances, or from overcrowding in nests or related to nest-box design. Other less well understood triggers for smothering are poorly understood but have been linked to temperature variability, retreating shade in range areas on sunny days, dust-bathing opportunities and things that attract birds to certain points in the shed. The incidence of tumours increases with hen age. Most frequently encountered tumours are leiomyomas and adenocarcinomas, both of which are associated with the reproductive tract and are presumably linked to selection for higher and more sustained egg production. The incidence of these neoplastic conditions will need better understanding if increases in flock persistency of lay are desired. Light intensity is understood to be a possible trigger of increased aggressive behaviour and can lead to increased feather pecking and cannibalism. Predation, while frequently reported, is not regarded as a major cause of loss in most farming circumstances, although individual cases can be serious and it is a major cause of concern. Obesity is becoming more recognised as a problem in layer flocks as research begins to focus on its effects. Reduction in average flock weights will be an objective for further improvement in persistency of lay in the future.

Effects of urbanization and nest-box design on reproduction vary by species in three cavity-nesting passerines in the Okanagan Valley, British Columbia, Canada

Artificial nest boxes provide an important resource for secondary cavity-nesting passerines, whose populations may be limited by the availability of nesting sites. However, previous studies have demonstrated that the design and placement of boxes may affect the reproductive success of the birds that use them. In this study, we asked whether the habitat surrounding a nest box or the type of box influenced reproduction in three cavity-nesting passerines. We studied Western Bluebirds (Sialia mexicana Swainson, 1832), Mountain Bluebirds (Sialia currucoides (Bechstein, 1798)), and Tree Swallows (Tachycineta bicolor (Vieillot, 1808)) breeding in artificial nest boxes at sites across 70 km of the Okanagan Valley of British Columbia, Canada. Sites varied in their degree of urbanization, from relatively undisturbed ranchland, to cultivated vineyards, to frequently disturbed “suburban” habitat, and boxes varied in type of entrance (slot or hole). Western Bluebirds nested earlier in vineyards, and Tree Swallows produced significantly fewer fledglings in suburban habitat. In addition, Tree Swallows nested earlier and produced more fledglings in slot boxes. Our results suggest that conservation actions for cavity-nesting passerines may depend on the target species, which in turn should dictate the appropriate box type and habitat when erecting or replacing nest boxes.

Nest Box Entrance Hole Size Influences Prey Delivery Success by American Kestrels

Nest boxes are a popular tool for research and conservation of American Kestrels (Falco sparverius; hereafter “kestrel”). The size of nest box entrance holes affects occupancy, interspecific competition, and nest predation for a number of bird species, but effects on prey delivery success are unstudied. We used digital video cameras to monitor kestrels using two nest box designs, one with a small circular entrance hole (8.75 cm in diameter; n = 8) and the other with a large U-shaped entrance hole (7.62 cm wide by 12.07 cm high; n = 6), to compare the rates at which kestrels failed to deliver large prey (vertebrates) into the nest box while provisioning nestlings. Across 111 d of monitoring, we observed a significantly higher prey delivery failure rate at the boxes with small holes (8.9%) compared to boxes with large holes (1.6%). Boxes with small holes fledged 4.33 nestlings and boxes with large holes fledged 4.5. These results suggest that kestrels nesting in boxes with small entrance holes may have higher costs while provisioning nestlings, compared to kestrels using boxes with larger entrance holes. We conclude that the ideal entrance hole size for kestrel nest boxes may be a compromise between being small enough to minimize predation, yet large enough to allow kestrels with large prey to easily enter. Future research should investigate whether boxes with higher prey delivery failure rates have lower reproductive success.

A 3D Printed Pollen Trap for Bumble Bee (Bombus) Hive Entrances.

To verify the plant sources from which bumble bees forage for pollen, individuals must be collected to remove their corbicular pollen loads for analysis. This has traditionally been done by netting foragers at nest entrances or on flowers, chilling the bees on ice, and then removing the pollen loads from the corbiculae with forceps or a brush. This method is time and labor intensive, may alter normal foraging behavior, and can result in stinging incidents for the worker performing the task. Pollen traps, such as those used on honey bee hives, collect pollen by dislodging corbicular pollen loads from the legs of workers as they pass through screens at the nest entrance. Traps can remove a large quantity of pollen from returning forager bees with minimal labor, yet to date no such trap is available for use with bumble bee colonies. Workers within a bumble bee colony can vary in size making size selection of entrances difficult to adapt this mechanism to commercially reared bumble bee hives. Using 3D printing design programs, we created a pollen trap that successfully removes the corbicular pollen loads from the legs of returning bumble bee foragers. This method significantly reduces the amount of time required by researchers to collect pollen from bumble bee foragers returning to the colony. We present the design, results of pollen removal efficiency tests, and suggest areas of modifications for investigators to adapt traps to a variety of bumble bee species or nest box designs.

Nest box contentions: Are nest boxes used by the species they target?

SummaryNest boxes have grown in popularity as a habitat management tool in Australia during the last decade. This management use remains contentious because some studies suggest nest boxes are ineffective. There are three recent contentions: (i) nest boxes mostly benefit common species, (ii) exotic species may be dominant users of nest boxes, and (iii) species of conservation concern use nest boxes infrequently. We address these contentions using data from 1865 nest boxes involving eight nest box designs. These nest boxes were installed predominantly &lt;200 m from a road in association with highway duplication and re‐alignment across 16 projects in New South Wales. The Common Brushtail Possum (Trichosurus vulpecula) is the species of most relevance to contention 1. It used 9% of boxes overall including 26% of ‘possum’ designated boxes. The most frequent nest box users were small petaurid gliders (mostly Sugar Gliders, Petaurus breviceps) which used 63% of ‘small glider’ designated boxes. This nest box and another suited to the Sugar Glider comprised 40% of all boxes installed, so it is not surprising that this species might be a common user. Exotic species were uncommon users of the nest boxes enabling contention 2 to be rejected. Active hives of Feral Honeybees (Apis mellifera) occupied just 1% of boxes, and another 1% of boxes were used by introduced rodents and birds. The Squirrel Glider (Petaurus norfolcensis) is the species most relevant to contention 3. It was seen in 80 boxes across 11 projects, representing 7% of the three types most frequently used. These observations are not consistent with the third contention. Nest boxes can provide many important insights about the requirements and interactions of hollow‐dependent fauna. However, they are not intended as an alternative to retaining hollow‐bearing trees.

Relative preference for wooden nests affects nesting behaviour of broiler breeders

Optimising nest design for broiler breeders has benefits for both the animals and the producers. The welfare of the hens will increase by providing preferred housing, while also reducing eggs laid outside the nests. These floor eggs cause economic losses by compromised automatic egg collection and reduced saleability and hatchability. Attractiveness of nests can involve factors such as seclusion, material and microclimate. In this study, four nest box designs were offered in a relative preference test: a plastic control nest, a plastic nest with a partition to divide the nest in two areas, a plastic nest with a ventilator underneath to create air flow inside the nest and a wooden nest. Six groups of 100 hens and 9 roosters had access to these four nests in a randomised location during the ages of 20 to 34 weeks. Nest and floor eggs were collected five days a week. Camera images from inside the nests made during the ages of 24–25 weeks and 26–27 weeks were analysed for behaviour. This included general activity, nest inspections, nest visits and social interactions. At 32 weeks of age the wooden nests were closed, and the subsequent response of the hens was monitored in terms of number of eggs. We found a clear preference in number of eggs for the wooden nest (69.3 ± 1.0%) compared to the control nest (15.1 ± 0.8%), partition nest (10.2 ± 0.5%) and the ventilator nest (5.4 ± 0.4%; p<0.0001 for difference between all nest designs). The preference for the wooden nest was also reflected in an increased time spent sitting, together with fewer nest inspections and visits per egg laid in the wooden nest. The preference for the wooden nest led to crowding, which caused an increased amount of piling, nest displacement, aggression and head shaking. The fact that the hens were willing to accept the crowded circumstances in these nests, underlines the strength of this preference. After the wooden nests were closed, the hens chose a new nest based on a combination of nest design and location. The control nest was still preferred over the other two plastic designs, although the neighbouring nests were overall preferred to the non-neighbouring nests. This study shows how the material used for nests is an important factor in suitability and should therefore be taken into account when designing nests.

Nest box design for a changing climate: The value of improved insulation

SummaryMean air temperatures and the frequency, intensity and duration of extreme weather events such as heatwaves are increasing due to climate change. Nest boxes experience more variable and extreme temperatures than natural cavities, which may reduce survival and reproductive success of the species which utilize them, but little is known about the factors which drive nest box temperature profiles. We quantified the potential for retrofitted insulation on nest boxes to modify internal temperatures and to mimic the thermal characteristics of natural cavities more closely. We tested three types of materials with insulative or reflective properties which were easy to retrofit to nest boxes: 3‐cm‐thick polystyrene, pleated foil batts and reflective paint. We found that polystyrene and foil batts reduced mean nest box temperatures during the day by 0.31 ± 0.01°C and 0.17 ± 0.01°C, respectively (but up to 5.84°C and 4.02°C). The effects of all insulation types were dependent on the time of day, and only polystyrene had a significant effect at night, with a greater capacity to retain heat (mean 0.21 ± 0.01°C warmer). Contrary to expectations, reflective paint caused a small increase in temperature during the late afternoon. In our study, the temperature modulation provided by insulation was able to match or exceed that due to variation in nest location and surrounding vegetation canopy cover. Our findings show that polystyrene and foil batts may offer effective and tractable means to mitigate the effects of extreme temperatures in nest boxes and thereby help achieve temperature profiles more similar to natural cavities.