Natural Nests Research Articles

Understanding dispersal patterns can inform future translocation strategies: A case study of the threatened greater stick‐nest rat (Leporillus conditor)

AbstractDispersal behaviour and sociality are significant factors influencing survival at both the individual and population levels. In translocation and breeding programmes, social structure and sex‐biased philopatry and dispersal should be considered in order to maximise population viability and conservation outcomes. Here, we use the greater stick‐nest rat (Leporillus conditor), a native Australian rodent, as a case study to understand how knowledge of social structure and dispersal can inform conservation and translocation programmes. We combine high‐throughput DNA sequencing with field trapping data from a translocated population of greater stick‐nest rats at Arid Recovery Reserve, South Australia, to provide the first empirical evidence of female philopatry and male‐biased dispersal in this species. Males were found to disperse, on average, 1.5 km from the natal nest, while females typically did not disperse beyond 500 m. Further, recapture data showed that females demonstrated a higher degree of nest fidelity than males over time. Based on these findings, we make two key recommendations for future translocations of the species. Firstly, founders should be harvested in small groups at adjacent nest sites with groups separated by a minimum of 1.5 km allowing family group structure to be retained during translocation while simultaneously maximising genetic diversity. Secondly, translocated individuals should be released in family cohorts into patches of optimal habitat that contain adequate shelter substrates interspersed over short distances (~300–500 m, the maximum dispersal distance of females found in this study), thereby facilitating nest establishment and maintenance of family groups. The results of this study have implications for conservation and reintroduction biology as a whole; we highlight the importance of considering spatial genetic structure during all stages of translocations to improve outcomes, and the value of combining genetic and field data to better understand species’ social and spatial preferences.

Nest temperature assessment in an American crocodile (Crocodylus acutus) population on the central coast of Oaxaca, Mexico.

The temperatures at which eggs of crocodilians are incubated plays an important role in embryo survival, rate of embryonic development and sex definition. The aim of this study was to assess the nest temperatures of an American crocodile (Crocodylus acutus) population on the central coast of Oaxaca state in Mexico. The fieldwork was carried out from February to June 2018at Palmasola Lagoon, Oaxaca. Ten natural nests of C. acutus were carefully excavated to determine clutch size. When putting the eggs back in the nests, we placed a data logger in the center of the egg mass to determine the temperature parameters in the nest chamber environment, as well as the variation in temperature during the incubation period. All nests were revisited to count the number of hatched eggs (NHE) and to determine the hatching success (HS), along with the duration of the incubation period (IP). Hatching success was 89.04%. The mean clutch size in the American crocodile nests was 30.7±7.83 eggs (ranging from 17 to 46 eggs), and the mean incubation period was 77.6±5.89 days. The mean nest incubation temperature throughout the reproductive season was significantly different among nests. Based on the average temperature during the middle third of the incubation period, the nests should have produced both sexes, but with a higher proportion of males. This study tried to elucidate the impact of nest temperatures during the incubation period on embryo survival, as well as hatchling sex ratio in a local climate on the central coast of Oaxaca.

Natural nest substrates influence squamate embryo physiology but have little effect on hatchling phenotypes.

Vertebrate embryos require access to water; however, many species nest in terrestrial habitats that vary considerably in moisture content. Oviparous, non-avian reptiles have served as models to understand how environmental factors, like moisture availability, influence development because eggs are often exposed to prevailing environments in the absence of parental care. Though much research demonstrates the importance of water absorption by eggs, many ecological factors that influence moisture availability in natural nests have received little attention. For example, the type of substrate in which nests are constructed is understudied. We experimentally incubated eggs of the brown anole lizard (Anolis sagrei) in 2 naturally occurring nest substrates that were treated with varying amounts of water to determine how natural substrates influence development at different moisture concentrations. One substrate consisted of sand and crushed seashells and the other was mostly organic material (i.e. decayed plant material). Both are common nesting substrates at our field site. When controlling for water uptake by eggs, we found that egg survival and hatchling phenotypes were similar between substrates; however, embryos developed more quickly in the sand/shell substrate than the organic substrate, indicating substrate-specific effects on embryo physiology. These results demonstrate that different natural substrates can result in similar developmental outcomes if the water available to eggs is comparable; however, some aspects of development, like developmental rate, are affected by the type of substrate, independent of water availability. Further study is required to determine how natural substrates influence embryo physiology independent of water content.

Influence of intrinsic and extrinsic attributes on neonate survival in an invasive large mammal

Understanding factors influencing survival of neonates for wild species is important for successful management, particularly for determining drivers of population dynamics. Wild pigs (Sus scrofa) are invasive and populations are rapidly increasing in part due to high reproductive capacity. Survival of adults is generally high, however, survival of piglets, and particularly neonates, is largely unknown. We located neonates at the natal nest and quantified survival in relation to individual and maternal biological attributes, and environmental variables. During 2017–2020, we captured 50 neonates from 13 litters and documented 28 mortalities (56%) over six weeks. Survival was positively influenced by pelage coloration, likely as a form of camouflage from predators. Male neonates had higher survival. They were born larger than females, which could be beneficial for thermoregulation and competition for milk. Neonates born to larger sows had lower survival. Sow size was positively correlated with litter size, and this finding may reflect the increased nutritional demands of sustaining large litters, or difficulties in defending more neonates against predators. Neonates born in warmer months had higher survival than those born in cooler months. Neonates are inefficient thermoregulators, thus being born in warmer months could be beneficial for maintaining homeostasis as well as access to more food resources. These are the largest and most complete data for neonate wild pig survival and will inform population models for the development of management strategies to reduce negative impacts of this destructive invasive species on native ecosystems.

Urban rooftop-nesting Common Nighthawk chicks tolerate high temperatures by hyperthermia with relatively low rates of evaporative water loss

Abstract Heat tolerance for many birds under climate and land use change scenarios could be compromised in the future. Common Nighthawks (Chordeiles minor) belong to the Caprimulgiformes, a generally heat-tolerant order, but few studies have assessed heat tolerance in Caprimulgiform chicks, which might be particularly susceptible to heat stress. In the midwestern United States, nighthawks primarily nest on flat graveled rooftops in urban areas, as natural nesting habitats are limited. Urban rooftop-nesting nighthawks are likely exposed to higher environmental temperatures than birds nesting at more thermally buffered natural sites, and evaporative cooling might be impeded by the typically high summer humidity in their Midwest breeding range. This combination of heat and humidity might negatively impact heat tolerance of nighthawk chicks. We exposed 7- to 14-day-old nighthawk chicks (n = 15) from rooftop nests to ambient temperatures (Tas) up to 51°C and at typical summer dew points. Chicks initiated gular flutter at a mean ambient temperature of 42.4 ± 3.4°C (mean ± SE). Evaporative water loss (EWL) rates increased significantly with increasing temperature above 44.0 ± 1.5°C. Chicks showed little evidence of lower and upper bounds of the thermal neutral zone over the range of temperatures (30–44°C) for which we measured oxygen consumption. Body mass loss was significantly positively correlated with temperature during heat exposure trials. Chicks tolerated Tas up to 51°C and body temperatures (Tbs) up to 48°C, which, along with the high temperatures at which gular flutter and high rates of EWL were initiated, suggest that nighthawk chicks are tolerant of high ambient temperatures, even with relatively high humidity. Given the high rates of mass loss and high Tbs at hot ambient temperatures, chick heat tolerance mechanisms could be detrimental for rooftop-nesting nighthawks given projected increasing trends for both heat and humidity in the midwestern United States.

How deep is deep enough? Analysis of sea turtle eggs nest relocation procedure at Chagar Hutang Turtle Sanctuary.

Sea turtle eggs incubation involves natural and artificial incubation of eggs, and indeed the depth will be varied and presumably affect the development of hatchlings. For nest relocation, the researcher needs to decide on the depth to incubate the eggs. Sea turtle eggs clutches may vary between 40 and 120 eggs for the green turtle, thus using a single value as the standard procedure might affect the quality of hatchlings. Here we quantify the dimension of the natural (in-situ) nest constructed by the nester and the artificial (ex-situ) built by our ranger during nest relocation. We suggest a linear regression calculation of Y = 0.2366X + 59.3267, better predict a more accurate nest depth based on the number of eggs to imitate the natural nest.

Zero-Inflated Generalized Linear Mixed Models: A Better Way to Understand Data Relationships

Our article explores an underused mathematical analytical methodology in the social sciences. In addition to describing the method and its advantages, we extend a previously reported application of mixed models in a well-known database about corruption in 149 countries. The dataset in the mentioned study included a reasonable amount of zeros (13.19%) in the outcome variable, which is typical of this type of research, as well as quite a bit of social sciences research. In our paper, present detailed guidelines regarding the estimation of models where the data for the outcome variable includes an excess number of zeros, and the dataset has a natural nested structure. We believe our research is not likely to reject the hypothesis favoring the adoption of mixed modeling and the inflation of zeros over the original simpler framework. Instead, our results demonstrate the importance of considering random effects at country levels and the zero-inflated nature of the outcome variable.

Training and usage of detection dogs to better understand bumble bee nesting habitat: Challenges and opportunities.

Bumble bees are among the most imperiled pollinators. However, habitat use, especially nest site selection, remains relatively unknown. Methods to locate nests are invaluable to better understand habitat requirements and monitor wild populations. Building on prior study findings, we report constraints and possibilities observed while training detection dogs to locate bumble bee nests. Three conservation detection dogs were initially trained to three species of bumble bee nest material, first within glass jars concealed in a row of cinder blocks, then placed in the open or partially hidden for area searches. The next intended training step was to expose the dogs to natural nests located by community science volunteers. However, significant effort (> 250 hrs), yielded only two confirmed, natural nests suitable for dog training purposes. Although the dogs did not progress past the formative training stage valuable insight was gained. Maximum observed detection distance for bumble bee nest material during initial controlled training was 15 m, which decreased significantly (< 1 m) once training progressed to buried samples and natural nests. Three main considerations around future training and usage of detection dogs were identified. First, dogs might benefit from transitional training via exposures to known natural nests, regardless of species. However, it may be too difficult for people to find natural nests for this, and prior work demonstrated the ability of dogs to generalize and find natural nests after testing to artificially-buried nest material. Second, confirming a dog’s nest find, via resident bee presence, is nuanced. Third, future study design and objectives must harness strengths, and reflect limitations of detection dog surveys and search strategies, as extensively discussed in this paper. Prospective studies involving detection dogs for locating bumble bee nests would benefit from considering the drawbacks and opportunities discussed and can mitigate limitations through incorporating these considerations in their study design.

Courtship with two spoons-Anatomy and presumed function of the bizarre antennae of Cardiocondyla zoserka ant males.

Mating in ants often occurs on the wing during nuptial flights or on the ground when scattered female sexuals attract males by pheromones. In both scenarios, there is little opportunity for males to engage in prolonged aggressive competition or elaborate courtship displays. Male morphology is therefore adapted to locating female sexuals and mating, and it lacks specific weapons or other traits associated with courtship. In contrast, sexuals of the ant genus Cardiocondyla typically mate in their natal nests. As a consequence, in many species winged males have been replaced by wingless fighter or territorial males, which kill or expel rival males with their strong mandibles and show complex mating behavior. However, no wingless males are known from Cardiocondyla zoserka from West Africa, and instead, winged males have evolved a bizarre secondary sexual trait: uniquely shaped antennae with spoon‐like tips that show heavily sculptured ventral surfaces with numerous invaginations. We here report on the courtship behavior of C. zoserka males and describe antennal glands with class 3 gland cells, which presumably secrete a close range sex pheromone. Antennal glands have not yet been found in males of other ant species, including a close relative of C. zoserka, suggesting that in ants with intranidal mating sexual selection can rapidly lead to highly divergent adaptations and the evolution of novel structures.

Worker ants promote outbreeding by transporting young queens to alien nests

Choosing the right mating partner is one of the most critical decisions in the life of a sexually reproducing organism and is the basis of sexual selection. This choice is usually assumed to be made by one or both of the sexual partners. Here, we describe a system in which a third party – the siblings – promote outbreeding by their sisters: workers of the tiny ant Cardiocondyla elegans carry female sexuals from their natal nest over several meters and drop them in the nest of another, unrelated colony to promote outbreeding with wingless, stationary males. Workers appear to choose particular recipient colonies into which they transfer numerous female sexuals. Assisted outbreeding and indirect female choice in the ant C. elegans are comparable to human matchmaking and suggest a hitherto unknown aspect of natural history – third party sexual selection. Our study highlights that research at the intersection between social evolution and reproductive biology might reveal surprising facets of animal behavior.

Habitat Quality Determines Dispersal Decisions and Fitness in a Beetle – Fungus Mutualism

Delayed dispersal of sexually mature offspring is a fundamental component of cooperative breeding. In ambrosia beetles, female offspring temporarily remain in their natal nest and refrain from reproduction, instead investing in alloparental care. Previous work has demonstrated a link between helping behaviour and the increased need for pathogen defence, arising from their close association with fungal cultivars. In the ambrosia beetle Xyleborinus saxesenii, mature female offspring can effectively fight pathogen infections and manage the microbial composition within the nest by adjusting the frequency of different hygienic and nest maintenance behaviours. This suggests a potential to respond flexibly to the ecology of their nest, which calls for a better understanding of the connection between behaviour and the microbial community thriving within their nests. Here, we studied the significance of the mutualistic fungus garden composition for the beetles’ nest ecology and fitness by experimentally varying substrate quality. We found that the vertically transmitted ambrosia fungus garden is composed of at least two fungus mutualist species and a wide variety of other microbes varying in their relative abundance. This is strongly affected by the moisture content of the substrate, which in nature depends on the age and type of wood. We found that the mutualist fungi complement each other in terms of dryness-resistance, allowing the beetles to utilise a broad range of substrates over prolonged time during which the wood gradually desiccates. Under suboptimal humidity conditions, the interaction between host and multiple fungus species has important ramifications for the behaviour of philopatric helpers, including their alloparental investment, sibling cannibalism and the timing of dispersal. Rearing five generations of beetles consecutively in dry substrate resulted in transgenerational effects on philopatry and alloparental care, probably mediated through the dominance of a particular fungus species that was driven by the experimental habitat condition. Interestingly, the nests of these selection lines produced much more offspring after five generations than any first-generation nest, which may have reflected increased egg laying by non-dispersing daughters. Our study highlights the importance of considering the interactions between the microbial community and their insect hosts for understanding social evolution in cooperatively breeding beetles.

Effect of predicted sea level rise scenarios on green turtle (Chelonia mydas) nesting

There is a growing interest among scientists about climate change and its adverse effects. One of the major adverse effects of climate change is the sea level rise (SLR), which will cause habitat loss for many species and threaten their survival. Sea turtles are an example of animal groups most likely to be threatened by SLR. It is, therefore, critical to predict the effect of SLR on sea turtle habitats to prepare better conservation and management plans that consider the climate change impact. With this aim, we projected the outcomes of SLR on the habitat and nest loss of one of the most important Mediterranean green sea turtle (Chelonia mydas) nesting beaches (Samandag, Turkey) using natural nests between 2008 and 2016 nesting seasons. Under the extreme scenario (1.2 m SLR) one-third of the coastal area and up to 18% of natural nests could be lost at a key green turtle nesting beach for this globally unique population.

Polliniferous flora foraged by Melipona bees along the Rio Negro in the Brazilian Amazon

Undoubtedly, Melipona bees are the most widely managed native American bee species for the production of honey and related products. These bees have been reared since before the arrival of Europeans on the continent. Despite being considered generalists due to their life histories, each stingless bee species has food preferences easily adapting to the available resources. Seeking to contribute to the understanding of the food ecology of Melipona bees, 17 pollen samples from six species found in natural nests along the Rio Negro were analysed. The pollen material was homogenised and prepared following the standard acetolysis technique. Relative frequency, the similarity between diets and correlation of diets with bee body size were determined. Thirty-two pollen types (17 botanical families) were identified, 13 of which were considered attractive, while six promoted temporary specialisation events. The results reaffirmed the potential generalist pattern of these bees with temporary specialisation events, being strongly influenced by local conditions. The diversity of pollen types per pot was not related to bee body size. Also, the number of pollen types found in each nest did not correlate to the number of pots analysed revealing non-neutral determinants for each species pollen richness. With the results obtained, it was clear that certain plants were more as food sources which could support conservation programmes and help meliponiculture in the Amazon.

Nest substrate and tool shape significantly affect the mechanics and energy requirements of avian eggshell puncture.

Some host species of avian obligate brood parasites reject parasitic eggs from their nest whereas others accept them, even though they recognize them as foreign. One hypothesis to explain this seemingly maladaptive behavior is that acceptors are unable to pierce and remove the parasitic eggshell. Previous studies reporting on the force and energy required to break brood parasites' eggshells were typically static tests performed against hard substrate surfaces. Here, we considered host nest as a substrate to simulate this potentially critical aspect of the natural context for egg puncture while testing the energy required to break avian eggshells. Specifically, as a proof of concept, we punctured domestic chicken eggs under a series of conditions: varying tool shape (sharp versus blunt), tool dynamics (static versus dynamic) and the presence of natural bird nests (of three host species). The results show a complex set of statistically significant interactions between tool shapes, puncture dynamics and nest substrates. Specifically, the energy required to break eggs was greater for the static tests than for the dynamic tests, but only when using a nest substrate and a blunt tool. In turn, in the static tests, the addition of a nest significantly increased energy requirements for both tool types, whereas during dynamic tests, the increase in energy associated with the nest presence was significant only when using the sharp tool. Characterizing the process of eggshell puncture in increasingly naturalistic contexts will help in understanding whether and how hosts of brood parasites evolve to reject foreign eggs.

The functional role of sibling aggression and “best of a bad job” strategies in cichlid juveniles

Abstract Siblings often compete for limited resources, such as food provided by their parents. However, although several functions of nonlethal sibling (nonsiblicidal) aggression have been proposed, there is currently little empirical evidence for these, apart from food monopolization. Here, we investigated the functions of nonlethal sibling aggression in the biparental-caring territorial herbivorous cichlid Varibilichromis moorii. We found that the juveniles of this species are highly aggressive and that larger juveniles are more aggressive toward their smaller siblings. Larger juveniles feed on algae more frequently than smaller siblings, thereby indicating a dominance hierarchy. Sibling aggression decreased when algae in the nest was experimentally removed. Furthermore, the removal of smaller juveniles decreased sibling aggression among the remaining larger juveniles, whereas the removal of larger juveniles increased aggression among smaller juveniles. The algal feeding rate of juveniles only increased when larger individuals were removed from the nest. Moreover, larger juveniles attained higher growth rates and remained in natal nests longer than smaller individuals. Our results indicate that sibling aggression may facilitate the monopolization of resources by larger juveniles and extend the parental care period. Interestingly, a small subset of juveniles was observed to migrate to other nests. These juveniles were larger than those of the host brood, and their growth rate increased within the new nests. We suggest that subordinate juveniles may disperse from natal nests and sneak into new nests to enhance their rank, which may represent a novel example of a “best of a bad job” strategy associated with sibling competition.

Cryptic eggs are rejected less frequently by a cuckoo host.

Obligate brood parasitism is associated with huge reproduction costs, forcing hosts to evolve various anti-parasitic strategies against brood parasites, among which egg recognition and rejection is the most effective defense strategy. According to the crypsis hypothesis, non-mimetic yet cryptic eggs in a nest can also deceive their hosts and eventually be accepted. To validate this hypothesis, we conducted field experiments on Oriental reed warblers (Acrocephalus orientalis), a common host for common cuckoos (Cuculus canorus). We firstly tested the egg recognition and rejection abilities of Oriental reed warblers, using black and white model eggs in natural nests. Then we designed a comparison test where the cryptic effects of the two groups of experimental eggs were different. We manipulated the nest lining color and added relatively cryptic and bright model eggs to test warblers' rejection behaviors against cryptic and bright foreign eggs. The results showed that warblers have strong egg recognition and rejection abilities. There is a significant tendency for warblers to prefer to peck and reject relatively distinguishable foreign eggs, which supports the crypsis hypothesis. These findings indicate that even in the host-parasite system of open nests, parasitic eggs that are cryptic enough are prevented from being discovered and rejected by the host, and thus obtain the possibility of successful parasitism.

Nest architecture of stingless bee, Tetragonula gressitti Sakagami from Nagaland, India

Tetragonula gressitti Sakagami is the new species of stingless bee discovered in Nagaland (2020). It was earlier found in Arunachal Pradesh (2013), South West China (2019) and Vietnam in 1978. The nest architecture of this particular species was never studied although there had been regular reports of its presence in forest areas by the local populace and all earlier reports were simply documented on the basis of collected samples from forests. This is the first detailed report on nesting characteristics of the stingless bee, T. gressitti, which were found located in the forest and village areas of Phek district in Nagaland during the early winters of 2019. The natural nests were found in tropical to sub-tropical evergreen forests on tree cavities, commonly at a height of 2.91 m ± 0.21 with a single entrance for each colony. The colonies were naturally active as seen and recorded from the activity of bees at their entrance gates during day time. The nests were extracted carefully with appropriate tools and transported to the experimental site. A total of seven natural nests were located for the study. Out of them, three nests were opened to observe the internal nest structure while the remaining nests were kept intact for further development and pollination studies. The observations revealed that the nest entrance on the external region was free from any wax or cerumen funnel/ tube and was meticulously kept clean by the bees. The nest entrances of all the colonies varied in size and shape. Internally, the entrance was connected to the brood through a waxy passage of 11.42 cm ± 0.73 length till it reached the involucrum. The brood was covered in a partial involucrum of 2.15 cm ± 0.23 thickness. The honey pots and pollen pots were found separated from the brood area and were connected through numerous small openings in the involucrum. The adult bees were observed to be deep black in colour. The required data on size of different cells and castes were also recorded accordingly.

Implications of nest relocation for morphology and locomotor performance of green turtle (Chelonia mydas) hatchlings

Sea turtle scute abnormalities are observed in higher proportion in hatchlings compared to adults, suggesting that hatchlings with a non-modal scute pattern (NMSP) have a lower chance of surviving to adulthood. In this study, we collected 732 newly emerged hatchlings from Redang Island, Malaysia, and compared their scute classification, size, and mass to fitness correlates (self-righting ability, crawling speed, and swimming speed). We investigated the proportion of hatchlings from each nest with NMSP to determine if there was a correlation with incubation duration or clutch relocation. We found relocated clutches at Chagar Hutang Turtle Sanctuary had a significantly shorter incubation duration with a higher proportion of NMSP compared to in situ clutches. Hatchlings’ mass were significantly heavier from in situ clutches compared to relocated clutches, although there were no significant differences of hatchling speed based on scute classification or clutch type. The difference of hatchling mass between in situ and relocated clutches could affect predation and mortality rates on recently emerged hatchlings. These findings have important conservation implications, suggesting that relocation should only be implemented on clutches with a high potential to be disrupted or with a low chance of survival if left in situ. Our findings highlight the need for a standard procedure when clutch relocation is used as a conservation strategy. Relocation should replicate natural nest dimensions by duplicating both nest width and depth, and clutches should be relocated to similar shade conditions as the natural nest.

Limits to host colonization and speciation in a radiation of parasitic finches

Abstract Parasite lineages vary widely in species richness. In some clades, speciation is linked to the colonization of new hosts. This is the case in the indigobirds and whydahs (Vidua), brood-parasitic finches whose nestlings mimic the phenotypes of their specific hosts. To understand the factors limiting host colonization and, therefore, speciation, we simulated the colonization of a host using cross-fostering experiments in the field. Despite DNA barcoding suggesting that host species feed their chicks similar diets, nestling Vidua had low survival in their new host environment. Nestling Vidua did not alter their begging calls plastically to match those of the new hosts and were fed less compared to both host chicks and to Vidua chicks in their natural host nests. This suggests that a key hurdle in colonizing new hosts is obtaining the right amount rather than the right type of food from host parents. This highlights the importance of mimetic nestling phenotypes in soliciting feeding from foster parents and may explain why successful colonizations tend to be of hosts closely related to the ancestral one. That nonmimetic chicks are fed less but not actively rejected by host parents suggests how selection from hosts can be sufficiently intense to cause parasite adaptation, yet sufficiently relaxed that parasitic chicks can sometimes survive in and colonize new host environments even if they lack accurate mimetic phenotypes. The difficulties of soliciting sufficient food from novel foster parents, together with habitat filters, likely limit the colonization of new hosts and, therefore, speciation in this parasite radiation.

The influence of egg presence and eggshell colour in the attraction of visually oriented predators to nests of a tropical forest bird

Several hypotheses have been proposed to account for the function of eggshell pigmentation. One predicts that patterns of colour and markings provide camouflage against visually oriented nest predators. However, the effectiveness of any anti‐predatory function of eggshell colour may be reduced if predators can use the nests per se as foraging cues (nest‐crypsis hypothesis). Here, we tested whether eggshell pigmentation, and a set of concurrent variables, could explain nest predation in natural nests of the Atlantic Forest endemic Blue Manakin Chiroxiphia caudata containing plasticine eggs. Nests were continuously monitored for predator identification using infra‐red camera traps, and we considered the nest‐crypsis hypothesis by testing the premise that if predators can use nests as visual cues, they would be recorded checking empty nests at rates similar to those containing eggs. Six bird species were identified as visually oriented predators of nest contents, and predation frequencies were low and not influenced by eggshell colour. Empty nests and nests containing eggs were visited by predators at similar frequencies, independently of eggshell colour, which provided the first direct support for the nest‐crypsis hypothesis. It suggests that for this tropical forest, open‐nesting passerine, selective forces driving nest concealment and nest camouflage may be stronger than selection for eggshell colour variation.