Terrestrial Nests Research Articles

Arboreal or terrestrial: Oviposition site of Zhangixalus frogs affects the thermal function of foam nests.

Temperature is essential for the survival and development of eggs. Some anurans have evolved and developed foam nesting traits, with thermal insulation considered to be among their functions. Foam-nesting frogs tend to exhibit reproductive plasticity. For example, they oviposit on both trees and the ground. How such plasticity affects foam nest function is of major relevance and is likely related to the adaptation of foam nesting frogs. However, this has not been well studied. In this study, we examined the interaction between foam nest site, foam nest function, and egg fate using the Japanese green tree frog, Zhangixalus arboreus, and analysed how nest site differences (arboreal or terrestrial) affect the thermal function of foam nests. We compared the thermal functions of foam nests between arboreal and terrestrial oviposition sites of Z. arboreus. We artificially replaced half of the arboreal nests with terrestrial environments and recorded temperature in and outside of the experimental terrestrial nest and original arboreal nests. We also examined egg survival and hatching rates for all the nests. The results indicated superior heat insulation in terrestrial nests, with warmer temperatures inside than outside the nests, especially at night, which led to a high egg survival rate. Therefore, terrestrial ovipositing should be valid under cold weather conditions. This may be related to the evolutionary history of oviposition site plasticity of this genus, which originally had an arboreal oviposition trait but evolved into terrestrial site use owing to global cooling. Our novel insights into the evolution and adaptivity of foam nesting and oviposition site use in Z. arboreus make an important contribution to animal ecology.

Hatching plasticity is associated with a more advanced stage at hatching in an Ambystoma with terrestrial eggs.

Hatching plasticity allows animals to initiate hatching in response to environmental cues including predation, flooding, and hypoxia. In species with terrestrial eggs but aquatic larvae, hatching plasticity often manifests as extended development of embryos when water is not available. Although these effects are taxonomically widespread, little attention has focused on differences in plasticity across closely related species with terrestrial and aquatic embryos. We propose that the terrestrial embryonic environment favors slower and prolonged development and, consequently, that we should see differences in development between closely related species that differ in where they lay their eggs. We test this hypothesis by comparing embryonic development between two mole salamanders, Ambystoma opacum and A. annulatum. Most Ambystoma lay eggs submerged in ponds but A. opacum lays its eggs on land, where hatching is triggered when eggs are submerged by rising pond levels. Embryos of both species were reared under common laboratory conditions simulating both aquatic and terrestrial nest sites. Consistent with our hypothesis, we found that A. opacum embryos exhibited slower development and took longer to hatch than A. annulatum embryos in both rearing environments. Furthermore, we observed in A. opacum a plasticity in hatching stage that was absent in A. annulatum. Our results indicate that the terrestrial-laying A. opacum has evolved slower and prolonged development relative to its aquatic-laying congener and suggest that embryonic survival in the unpredictable terrestrial environment may be facilitated by developmental plasticity.

Decay rates of arboreal and terrestrial nests of Easternchimpanzees (Pan troglodytes schweinfurthii) in the Bugoma Central Forest Reserve, Uganda: Implications for population size estimates.

Chimpanzees were once thought to sleep primarily in the trees, but recent studies indicate that some populations also construct terrestrial night nests. This behavior has relevance not only to understanding the behavioral diversity of Pan troglodytes, but also to the conservation of the species, given that nest encounter rates are often used to estimate great ape population densities. A proper estimate of decay rates for ground nests is necessary for converting the encounter rate of nests to the density of weaned chimpanzees. Here we present the results of the first systematic comparative study between the decay rates of arboreal and terrestrial chimpanzee nests, from the Bugoma Central Forest Reserve in western Uganda. We followed the decay of 56 ground and 51 tree nests in eight nest groups between April 2020 and October 2021. For 15 of the ground and 19 of the tree nests, we collected detailed information on the condition of the nests every two weeks; we checked the remaining 73 nests only twice. On average, ground nests lasted 238days versus 276 days for tree nests (p = 0.05). Of the 107 total nests surveyed, 51% of tree and 64% of ground nests had disappeared after six months. Based on our results, we propose a modification of the formula used to convert nest density into chimpanzee density. Our results highlight the importance of taking into account potential differences in decay rates between ground versus tree nests, which will likely influence our understanding of the distribution of ground nesting behavior in chimpanzee across tropical Africa, as well as our estimations of the densities of ground nesting populations.

Drought‐induced relocation of ant colonies and its consequences for the long‐term spatial ecology of a population under stress

Abstract Maintaining a central refuge such as a nest or burrow can offer protection against environmental stressors but comes at the expense of the capacity to disperse to new locations. This trade‐off with mobility can be detrimental when environmental conditions become adverse for extended periods, necessitating animals to relocate in order to track shifting niche envelopes. Long‐lived ant colonies that invest in the construction of large nests are especially susceptible to changing environmental conditions. The Australian meat ant, Iridomyrmex purpureus, build large terrestrial nests at sites that balance shade and solar exposure. Long‐term study of a population of meat ants showed low nest turnover and a stable spatial distribution of nests across typical rainfall years. With the onset of drought, a dramatic surge in the production of new nests occurred through a process of budding that far exceeded historic trends. This appears to have allowed colonies to relocate nests into areas with more favourable microclimate conditions in a strategy reminiscent of the production of runners in stressed plants. The consequence has also been the packing of nests into a narrow habitable zone that has resulted in an apparent increase in competition among large rival colonies. Following the break in drought and the thinning of some nests through abandonment, competition has progressively eased in later years. The surge in nest budding triggered by acute environmental stress in this population offers a possible strategy for long‐lived colonies to effectively migrate across the landscape. With changes in environmental conditions becoming more frequent and severe with the climate crisis, any strategy available to central place foragers to track windows of preferred conditions is likely to become increasingly important. Read the free Plain Language Summary for this article on the Journal blog.

The Nemesia trapdoor spider fauna of the Maltese archipelago, with the description of two new species (Araneae, Mygalomorphae, Nemesiidae)

Contrary to what its name suggests, Nemesia arboricola is not strictly arboreal in habit. Here we compare female specimens of N. arboricola collected from arboreal and terrestrial nests. We furthermore describe the male of N. arboricola for the first time as well as two recently discovered species of Nemesia (N. maltensis sp. nov. and N. cominensis sp. nov.). Nemesia maltensis is described from both sexes, N. cominensis is described from the female and a juvenile male specimen. For N. cominensis we discuss the sexual dimorphism of juvenile male and female spiders. Field observations and laboratory observations show remarkable features of the Maltese Nemesia fauna that are unknown from Nemesia species found elsewhere. Particularly, the arboreal dwellings of N. arboricola and the absence of a trapdoor to close off the burrow entrance in N. maltensis appear to be exceptional. The composition of the Maltese Nemesia fauna, as located in the central Mediterranean, is finally discussed in relation to the different Nemesia species-complexes occurring in the eastern and western Mediterranean basin.

Tadpoles' Resistance to Desiccation in Species of Leptodactylus (Anura, Leptodactylidae)

Desiccation may increase egg and tadpole mortality of anurans that reproduce in temporary ponds. Tadpoles of some species, however, can survive temporarily out of water. Among leptodactylids, desiccation-resistant tadpoles were reported only for species that use terrestrial foam nests for reproduction. To test whether Leptodactylus tadpoles' ability to survive out of water represents an exclusive trait of species with terrestrial nests, we compared survival and resistance to hydric stress of tadpoles of six different species of the Leptodactylus groups and one Physalaemus. We also present an exploratory discussion about the evolutionary association between dehydration-tolerant tadpoles, egg-laying microhabitat, and nitrogen excretion type. Tadpoles were divided into two groups, one staying in 100 mL of water and another subjected to hydric stress on moist paper substrate. Our results indicate that tadpoles resistant to desiccation are not common for all species tested, as only the species with terrestrial nests survived longer and lost less body mass than the other related species. As an estimate, tadpoles of terrestrial-nesting frogs were seven times more resistant to desiccation than those with eggs/nests placed directly into the water. A possible dehydration-resistance mechanism is the premetamorphosis ureotelism that has been shown in terrestrial breeding species with tadpoles that survive some time out of water. Therefore, the capacity of tadpoles to survive a few days after pool drying probably arose from the evolutionary association between terrestrial reproduction and the tadpole ability to prevent body dehydration by a mechanism such as ureotelism.

Disease influences male advertisement and mating outcomes in a critically endangered amphibian

The sublethal effects of infectious disease on reproductive behaviour and mating success are not well understood. Here, we investigated predictors of male mating success in one of Australia's most critically endangered vertebrates: the northern corroboree frog, Pseudophryne pengilleyi. Using a genomic approach to assign parentage, we explored whether infection with the amphibian chytrid fungus Batrachochytrium dendrobatidis (Bd), a pathogen responsible for amphibian declines globally, influenced male calling behaviour and mating success. We also explored whether male mating success was predicted by phenotypic traits (age, body size, coloration, call characters) that potentially signal genetic quality, and the soil moisture (water potential) of male-constructed terrestrial nests, which may directly impact offspring survival. We found that Bd significantly influenced male advertisement; Bd-infected males produced calls with significantly higher pulse repetition rates than uninfected males. Older males had a higher probability of mating; however, variation in the number of eggs in a nest was most strongly explained by an interaction between male Bd infection status and call pulse repetition rate. We propose that these relationships may result from either pathogen-mediated changes to host behaviour or host-mediated changes to behaviour (e.g. terminal investment). Regardless of the mechanism, this is the first evidence that male mating success in an amphibian can be influenced by male Bd infection status, highlighting a novel mechanism through which this virulent pathogen can affect amphibian fitness. More broadly, these findings add to a growing body of evidence that pathogens can alter the reproductive biology of their hosts. From a conservation perspective, increased consideration of how sexual selection operates in altered environments has the potential to assist with the management of threatened amphibians worldwide.

Modeling Onset of Hourly Nesting Activity in a Freshwater Turtle Using Abiotic Variables and Physiological Capacity

Nesting is an essential, yet variable, reproductive behavior in most oviparous organisms. Although many factors conceivably influence nesting behaviors, it is unclear which factors strongly influence terrestrial nest timing in aquatic nonavian reptiles. As climate is changing rapidly, understanding the relative influences of biotic and abiotic factors on nesting behaviors may yield important information on future changes in daily and seasonal nesting activity. We collected hourly data to examine the significance of local weather conditions to the timing of within-season nesting activity in a large population of Painted Turtles (Chrysemys picta). We quantified nesting activity as the ratio of females who nested to all females who could nest in each hour, adjusting the size of the denominator to include the time required to shell a subsequent egg clutch. We then used zero-inflated models to identify potential weather predictors of presence/absence of nesting activity and strength of nesting responses (i.e., the fraction of turtles nesting that could nest). Higher temperatures and rainfall predicted stronger nesting responses, whereas lower temperatures and no rainfall predicted the absence of nesting activity, indicating that both temperature and rainfall are important cues in within-season nesting phenology. Our study enhances our understanding of abiotic influences on the terrestrial nesting behavior of aquatic organisms.

Key roles of paternal care and climate on offspring survival of an Amazonian poison frog.

In poison frogs (Dendrobatoidea), usually the males are territorial, care for terrestrial nests and later transport their offspring to waterbodies where they complete larval development. In some species, mothers care for their offspring or may exhibit flexible care to compensate for father absence. We conducted a multi-season field experiment with the Amazonian species Allobates paleovarzensis, in which it was possible to study the joint impact of paternal care and the El Niño climatic anomaly on offspring survival. The experiment consisted of two treatments: non-removal, and removal of the father from their territories. We observed that parental care was performed exclusively by the father, and none of the mothers of the 21 monitored nests transported the tadpoles. We also observed that the severe drought in a year under the influence of the El Niño event caused such a high mortality in all pre-metamorphic stages, that the role of parental care became irrelevant for offspring survival during that season. We found that pre-metamorphic Allobates paleovarzensis are highly vulnerable to the loss of paternal care. In addition, we showed that paternal care, when present, does not prevent offspring death under these increasingly frequent climatic anomalies.

The nocturnal activity of a commonly housed rodent: How African pygmy dormice (Graphiurus murinus) respond to an enriched environment?

Exotic rodents are becoming increasingly popular in industry; however, there is limited empirical evidence to guide husbandry practices. African pygmy dormice (Graphiurus murinus) are typical in this respect. This research aimed to determine the effect of environmental enrichment on the behavior (including stereotypical scratching at the glass walls of the enclosure) and space use of a group of eight African pygmy dormice at Sparsholt College Hampshire, UK. An apple-wood climbing grid and three raised (at various heights above the substrate) woven-wicker nest boxes were provided. Instantaneous scan sampling was used to record 150 hours of nocturnal behavior (19:00–07:00 daily) over five experimental phases (phase 1 baseline; phase 2 climbing grid provided; phase 3 lower nest box provided; phase 4 middle nest box provided; phase 5 higher nest box provided). Space use was determined using the modified Spread of Participation Index. Nest box use was recorded continually. The provision of the climbing grid significantly increased the groups' time spent eating, digging, gnawing, and climbing and significantly decreased stereotypic scratching at glass. It also significantly changed the use of all enclosure zones, with mice utilizing the highest zones as soon as they were accessible. The addition of raised nesting opportunity saw the highest zones of the enclosure become those preferentially used. It also totally diminished stereotypic scratching at glass. The highest nest box was preferentially used and use of terrestrial nest boxes (those placed directly on top of the substrate) reduced significantly when raised alternatives were provided. This study suggests those working with African pygmy dormice should provide an enriched enclosure via “arboreal” opportunity to increase active behaviors and reduce stereotypy.

Responses to terrestrial nest predators by endemic and introduced Hawaiian birds.

Birds free from nest predators for long periods may either lose the ability to recognize and respond to predators or retain antipredator responses if they are not too costly. How these alternate scenarios play out has rarely been investigated in an avian community whose members have different evolutionary histories. We presented models of two nest predators (rat and snake) and a negative control (tree branch) to birds on Hawaiʻi Island. Endemic Hawaiian birds evolved in the absence of terrestrial predators until rats were introduced approximately 1,000 years ago. Introduced birds evolved with diverse predator communities including mammals and snakes, but since their introduction onto the island approximately one century ago have been free from snake predation. We found that (a) endemic and introduced birds had higher agitation scores toward the rat model compared with the branch, and (b) none of the endemic birds reacted to the snake model, while one introduced bird, the Red‐billed Leiothrix (Leiothrix lutea), reacted as strongly to the snake as to the rat. Overall, endemic and introduced birds differ in their response to predators, but some endemic birds have the capacity to recognize and respond to introduced rats, and one introduced bird species retained recognition of snake predators from which they had been free for nearly a century, while another apparently lost that ability. Our results indicate that the retention or loss of predator recognition by introduced and endemic island birds is variable, shaped by each species' unique history, ecology, and the potential interplay of genetic drift, and that endemic Hawaiian birds could be especially vulnerable to introduced snake predators.

THE TADPOLE OF ZACHAENUS CARVALHOI IZECKSOHN, 1983 (ANURA: CYCLORAMPHIDAE).

The genus Zachaenus Cope is the least specious within Cycloramphidae, including two species: Z. carvalhoi Izecksohn, and Z. parvulus (Girard). Both are leaf litter species distributed across Atlantic forest remnants in Southeastern Brazil. Zachaenus carvalhoi occurs westerly in the states of Espírito Santo and Minas Gerais, and Z. parvulus easterly in the states of São Paulo, Rio de Janeiro, and Espírito Santo (Verdade et al. 2009; Motta et al. 2010; Salles Maciel 2010; Oliveira et al. 2012; Guedes et al. 2019; Frost 2019). Both species build terrestrial nests, and larval development is endotrophic nidicolous (reproductive mode 21 after Haddad Prado 2005; Lutz 1944; Thibaudeau Altig 1999; Zocca et al. 2014). In this work, we describe the tadpoles of Z. carvalhoi, and discuss morphological aspects regarding other endotrophic tadpoles.

Development-specific transcriptomic profiling suggests new mechanisms for anoxic survival in the ventricle of overwintering turtles.

Oxygen deprivation swiftly damages tissues in most animals, yet some species show remarkable abilities to tolerate little or even no oxygen. Painted turtles exhibit a development-dependent tolerance that allows adults to survive anoxia approximately four times longer than hatchlings: adults survive ∼170 days and hatchlings survive ∼40 days at 3°C. We hypothesized that this difference is related to development-dependent differences in ventricular gene expression. Using a comparative ontogenetic approach, we examined whole transcriptomic changes before, during and 5days after a 20-day bout of anoxic submergence at 3°C. Ontogeny accounted for more gene expression differences than treatment (anoxia or recovery): 1175 versus 237 genes, respectively. Of the 237 differences, 93 could confer protection against anoxia and reperfusion injury, 68 could be injurious and 20 may be constitutively protective. Most striking during anoxia was the main expression pattern of all 76 annotated ribosomal protein (R-protein) mRNAs, which decreased in anoxia-tolerant adults, but increased in anoxia-sensitive hatchlings, suggesting adult-specific regulation of translational suppression. These genes, along with 60 others that decreased their levels in adults and either increased or remained unchanged in hatchlings, implicate antagonistic pleiotropy as a mechanism to resolve the long-standing question about why hatchling painted turtles overwinter in terrestrial nests, rather than emerge and overwinter in water during their first year. In summary, developmental differences in the transcriptome of the turtle ventricle revealed potentially protective mechanisms that contribute to extraordinary adult-specific anoxia tolerance, and provide a unique perspective on differences between the anoxia-induced molecular responses of anoxia-tolerant and anoxia-sensitive phenotypes within a species.

Reproduction and metamorphosis in the Myristica Swamp tree frog, Mercurana myristicapalustris (Anura: Rhacophoridae).

The reproductive biology of the Myristica Swamp tree frog (Mercurana myristicapalustris), a monotypic rhacophorid frog endemic to the foothills of the Western Ghats mountains of India, has remained unknown since the description of the genus and species. We monitored individuals from parental generation amplexus to the completion of offspring generation tadpole metamorphosis. Surprisingly, our observations revealed that this species exhibits many previously unknown characteristics, including the first ever record of the female, and a diverse call repertoire, consisting of five different call types (the functions of which remain incompletely known). We were also able to determine that reproductive activity peaked during the late pre-monsoon season, that males engaged in intraspecific aggressive encounters to occupy and to defend desirable territories, and that oviposition took place in terrestrial nests made by females. Embryonic development in the unattended nest was followed by tadpole development, which concluded within 40 days. The specific breeding mode employed by Mercurana, which restricts its range to the endangered Myristica swamp ecosystem, likely renders it susceptible to multiple threats, which should be considered jointly in future conservation planning.

Use of sun compass orientation during natal dispersal in Blanding’s turtles: in situ field experiments with clock-shifting and disruption of magnetoreception

When hatchling freshwater turtles emerge from nests and first experience environmental stimuli, they primarily use visual cues to disperse toward nearby open horizons or far dark horizons. Within hours, hatchling Blanding’s turtles (Emydoidea blandingii) develop compass mechanisms to maintain their headings when the initial dispersal targets become invisible. We captured hatchling Blanding’s turtles during dispersal in natural habitat, attached a magnetic or non-magnet disk to each turtle, translocated them into an arena in a visually uniform field of corn, and measured their compass orientation (heading). Hatchlings from the magnet and no-magnet groups were evenly divided into two environmental chambers (6-h clock-shift or non-clock-shift) to create four experimental treatments. After 5 to 11 days hatchlings were re-released in the arena. If hatchlings used a time-compensated sun compass, then clock-shifting would cause a ~90° change in heading. If they used a geomagnetic compass, disruption of magnetoreception would cause wandering. If both compasses were used simultaneously or sequentially, we predicted a range of outcomes. All four treatment groups dispersed directionally during both trials, maintaining their prior headings in natural habitat except for the clock-shift treatment which changed heading ~90° as predicted. The ability of hatchlings to maintain prior headings despite the disruption of geomagnetism supports the absence, inactivity, or disregard of a geomagnetic compass. Only a time-compensated sun compass coupled with an internal clock was necessary and sufficient for hatchlings to maintain compass headings during natal dispersal when relocated from natural prairie habitat to a monoculture habitat with a relatively uniform visual horizon. Individuals moving long distances (e.g., migrating birds or dispersing salamanders) often maintain their movement headings using compass orientation (i.e., a geomagnetic or time-compensated sun compass). When hatchling freshwater turtles emerge from underground terrestrial nests they initiate dispersal in search of wetlands primarily based on visual horizon cues. Because such cues often become obscured by uneven terrain or dense vegetation and because straight-line travel is more efficient and less risky, hatchlings soon develop a mechanism of compass orientation to maintain their dispersal headings. We disrupted their ability to use magnetoreception by attaching magnets to their shells, manipulated their sense of time-of-day with clock-shifting, and then monitored their dispersal in a visually uniform field of mature corn. Our results demonstrated that a sun compass was necessary and sufficient for hatchlings with dispersal experience to maintain their dispersal headings when natural environmental cues were not visible.

Continental Late Cretaceous gastropod assemblages from Uruguay. Paleoecology, age, and the oldest record of two families and a genus

ABSTRACTPaleoecological studies of continental gastropods give valuable information about the depositional environment of the fossil assemblages. In South America, these assemblages from the Late Cretaceous/Paleocene are scarce and poorly studied. Most works focuses on taxonomy, but a paleoecological approach is still missing. We analyzed the assemblages present in the Queguay limestones from Uruguay. The total fossil content consists in freshwater and terrestrial gastropods, characean gyrogonites, ostracods, Neosauropoda eggshells, vegetable remains, insect nests, and pupal chambers. As the precise age and sedimentary environment of the Queguay limestones have been discussed for almost nine decades, a paleoecological study was conducted in order to answer these questions from this point of view. Diversity (Simpson, Shannon-Wiener, equitability) and similarity (Jaccard and Kulczynski) indices were calculated; the analyses showed a close relationship among all locations, and therefore we conclude that there are not differences in fossil content among the localities. Moreover, the data allows to consider them basically of the same environment and age. The presence of Neosauropoda eggshells in several outcrops indicate unquestionably a Late Cretaceous age, and establish the oldest record worldwide for Pupillidae, Orthalicoidea and Biomphalaria.

Foam nests provide context-dependent thermal insulation to embryos of three leptodactylid frogs.

The choice of adequate breeding habitat and its associated thermoregulatory conditions are thought to be important in the evolution of amphibian reproductive strategies. Among leptodactylid frogs, there is a terrestrial cline in the oviposition sites chosen to build foam nests for eggs. Although several functions have been attributed to foam nests, their role in temperature regulation for embryos is unclear. Here we tested the hypothesis that foam nests buffer embryos from variation in air temperature. We examined the degree of terrestrial nest sites in three species, finding a terrestrial cline of sites in terms of distance from water. We tested whether this nest-insulation effect varied among these species that differ in the degree of terrestrial nest sites and whether translocating nests impacted embryonic mortality. Our results demonstrate a negative effect of translocating aquatic nests to land, inferred from the highest hatching success in natural nests sites. All nests attenuated environmental thermal variation, but more terrestrial nests buffered embryos from a greater range of temperatures than did aquatic ones. Altogether, our data indicate that foam nests insulate embryos from daily temperature fluctuations among leptodactylid frogs with different degrees of terrestrial nests, which may well have contributed to the evolution of this reproductive strategy.

The reproductive biology and larvae of the first tadpole-bearing frog, Limnonectes larvaepartus.

Most of the reproductive modes of frogs include an exotrophic tadpole, but a number of taxa have some form of endotrophic development that lacks a feeding tadpole stage. The dicroglossid frog genus Limnonectes ranges from China south into Indonesia. The breeding biologies of the approximately 60 described species display an unusual diversity that range from exotrophic tadpoles to endotrophic development in terrestrial nests. There have been mentions of oviductal production of typical, exotrophic tadpoles in an undescribed species of Limnonectes from Sulawesi, Indonesia. Here we examine newly collected specimens of this species, now described as L. larvaepartus and present the first substantial report on this unique breeding mode. Typical exotrophic tadpoles that are retained to an advanced developmental stage in the oviducts of a female frog are birthed into slow-flowing streams or small, non-flowing pools adjacent to the streams.

Density estimates and nesting-site selection in chimpanzees of the Nimba Mountains, Côte d'Ivoire, and Guinea.

We investigated nesting behavior of non habituated chimpanzees populating the Nimba Mountains to document their abundance and their criterions of nesting-site selection. During a 19-month study we walked 80 km of transects and recces each month, and recorded 764 nests (mean group size = 2.23 nests) along with characteristics of vegetation structure and composition, topography, and seasonality. Population density estimated with two nest count methods ranged between 0.14 and 0.65 chimpanzee/km(2) . These values are lower than previous estimates, emphasizing the necessity of protecting remaining wild ape populations. Chimpanzees built nests in 108 tree species out of 437 identified, but 2.3% of total species comprised 52% of nests. Despite they preferred nesting in trees of 25-29 cm DBH and at a mean height of 8.02 m, we recorded an important proportion of terrestrial nests (8.2%) that may reflect a cultural trait of Nimba chimpanzees. A logistic model of nest presence formulated as a function of 12 habitat variables revealed preference for gallery and mountain forests rather than lowland forest, and old-growth forest rather than secondary forests. They nested more frequently in the study area during the dry season (December-April). The highest probability of observing nests was at 770 m altitude, particularly in steep locations (mean ground declivity = 15.54%). Several of the reported nest characteristics combined with the existence of two geographically separated clusters of nest, suggest that the study area constitutes the non-overlapping peripheral areas of two distinct communities. This nest-based study led us to findings on the behavioral ecology of Nimba chimpanzees, which constitute crucial knowledge to implement efficient and purpose-built conservation.

Predators, alternative prey and climate influence annual breeding success of a long‐lived sea duck

1. Perturbations to ecosystems have the potential to directly and indirectly affect species interactions, with subsequent impacts on population dynamics and the vital rates that regulate them. 2. The few long-term studies of common eider breeding ecology indicate that reproductive success is low in most years, interrupted by occasional boom years. However, no study has explicitly examined the drivers of long-term variation in reproductive success. 3. Here, we use encounter history data collected across 41 years to examine the effects of arctic foxes (a terrestrial nest predator), local abundance and spatial distribution of lesser snow geese (an alternative prey source), and spring climate on common eider nest success. 4. Eider nest success declined over the course of the study, but was also highly variable across years. Our results supported the hypothesis that the long-term decline in eider nest success was caused by apparent competition with lesser snow geese, mediated by shared predators. This effect persisted even following a large-scale exodus of nesting geese from the eider colony. Nest success was also lowest in years of low arctic fox index, presumably driven by prey switching in years of low small mammal availability. However, increased snow goose abundance appeared to buffer this effect through prey swamping. The effect of spring climate depended on the stage of the breeding season; cold and wet and warm and dry conditions in early spring were correlated with decreased nest success, whereas warm and wet conditions in late spring increased eider nest success. 5. These results underscore the significance of both trophic interactions and climate in regulating highly variable vital rates, which likely have important consequences for population dynamics and the conservation of long-lived iteroparous species.