Threat-sensitive Nest Preferences in Male Upland Bullies,Gobiomorphus breviceps

A male's ability to acquire and defend a nest site against competitors is an important requirement for successful breeding in many fish species. In the upland bully Gobiomorphus breviceps (Eleotridae), not all males are successful in gaining ownership of nesting rocks; therefore, male-male competition may be important in nest acquisition. Although larger nests have the potential to hold more eggs, in nature there is a preferred nest size well below the maximum available. I found that in over 88% of dyadic contests, the larger male was successful in acquiring the single nesting site provided. When males were individually given a choice of two artificial nest rocks, they consistently preferred the larger nest. These results suggest that larger males have the ability to occupy the largest nests. In the presence of a trout predator, males preferred nests with three closed sides 93% of the time. This preference disappeared when the threat was a conspecific. This shows that while males were choosing the larger nests their decisions were also threat-sensitive.     

Potential consequences of angling on nest-site fidelity in largemouth bass

Breeding site fidelity has evolved in many vertebrate taxa, suggesting both that site selection has an important influence on fitness potential and that the decision to reuse a nesting site is related to the individual’s prior nesting success at that location. For a species that provides parental care, such as the Largemouth Bass Micropterus salmoides, catch-and-release angling impacts individual nesting success and fitness through physiological disturbance and by removing the nest-guarding male from its brood, thereby allowing temporary access to eggs and hatchlings by brood predators. To assess the impact of catch-and-release angling on nest site fidelity, we compared the consequences of angling on individually marked (i.e., with passive integrated transponders) nest-guarding male Largemouth Bass in Ontario. An extremely high degree of nest site fidelity in year two was observed for males that were angled only once during year one (87% within 10 m of the previous year’s nest), 96.7% of which remained on the nest and completed parental care activities. There was significantly lower fidelity in year two, however, for males that were angled multiple times during year one (27% within 10m of the previous year’s nest), only 5.6% of which remained on the nest and completed parental care activities. This observed difference suggests that angling nesting bass may cause them to avoid previously used nest sites and instead search for alternative sites during future reproductive seasons. This human-induced impact on nest site choice may impact the future reproductive success of those Largemouth Bass.     

Determinants of reproductive success and offspring sex in a turtle with environmental sex determination

Despite the importance of maternal effects in evolution, and knowledge of links among nest site choice, timing of nesting, offspring sex, and reproductive success in animals with environmental sex determination, these attributes have not been rigorously studied in a combined and natural context. To address this need we studied the relationships between three maternal traits (nest site choice, lay date, and nest depth) and two fitness‐related attributes of offspring (hatchling sex and embryonic survival) in the riverine turtle Carettochelys insculpta, a species with temperature‐dependent sex determination, for four years. Predation and flooding were the major sources of embryonic mortality in 191 nests. Embryonic survival was influenced by both lay date and nest site choice: in one year when nesting began later than average, nests laid later and at lower elevations were destroyed by early wet season river rises. In other years early nesting precluded flood mortality. However, turtles did not nest at the highest available elevations, and a field experiment confirmed that turtles were constrained to nest at lower elevations where they could construct a nest chamber. The principal determinant of hatchling sex in 140 nests was lay date, which in turn was apparently related to the magnitude of the previous wet season(s). Clutches laid earlier in the season (a female's first clutch) produced mainly males, while later clutches (her second clutch) yielded mostly females, due to seasonal increases in air temperatures. Accordingly, later nesting produced female‐biased hatchling sex ratios in 1996, while earlier nesting resulted in sex ratios near unity in the other years. However, all‐female nests were more likely to be flooded than mixed‐sex or all‐male nests in years when nesting was late. In conclusion, we found evidence that the position of two maternal trait distributions (elevation of the nest site and lay date), associated with the reproductive strategy of C. insculpta, reflect a combination of natural selection, physical constraints, and phenotypic plasticity. © 2004 The Linnean Society of London, Biological Journal of the Linnean Society, 2004, 81 , 1–16.     

Genetic structure at three spatial scales is consistent with limited philopatry in Ricord's Rock Iguanas (Cyclura ricordii)

Cyclura ricordii is an endemic iguana from Hispaniola Island and is threatened on the IUCN Red List. The main threats are predation by introduced mammals, habitat destruction, and hunting pressure. The present study focused on two nesting sites from Pedernales Province in the Dominican Republic. The hypothesis that natal philopatry influences dispersal and nest‐site selection was tested. Monitoring and sampling took place in 2012 and 2013. Polymorphic markers were used to evaluate whether natal philopatry limits dispersal at multiple spatial scales. Ripley's K revealed that nests were significantly clustered at multiple scales, when both nesting sites were considered and within each nesting site. This suggests a patchy, nonrandom distribution of nests within nest sites. Hierarchical AMOVA revealed that nest‐site aggregations did not explain a significant portion of genetic variation within nesting sites. However, a small but positive correlation between geographic and genetic distance was detected using a Mantel's test. Hence, the relationship between geographic distance and genetic distance among hatchlings within nest sites, while detectable, was not strong enough to have a marked effect on fine‐scale genetic structure. Spatial and genetic data combined determined that the nesting sites included nesting females from multiple locations, and the hypothesis of “natal philopatry” was not supported because females nesting in the same cluster were no more closely related to each other than to other females from the same nesting site. These findings imply that nesting aggregations are more likely associated with cryptic habitat variables contributing to optimal nesting conditions.     

Nesting habitat use and partitioning of three sympatric ninespine sticklebacks (genus <Emphasis Type="Italic">Pungitius</Emphasis>): implications for reproductive isolation

The nest site characteristics and distribution patterns of nests of three sympatric ninespine sticklebacks, the brackish- and fresh-water types and Pungitius tymensis, were investigated in the Shiomi River, eastern Hokkaido, Japan. In this river, most of the males of the brackish-water type were found to build their nests in the lower reach with higher salinity (mean 13.5‰) and water temperature (mean 13.3°C), whereas the males of the freshwater type and P. tymensis built their nests in the upper reach with lower salinity (mean 0.6 and 0.8‰, respectively) and water temperature (both mean 11.3°C). The ranges of their nesting areas, however, overlapped within the river, because the nests of the brackish-water type were widely distributed in the river. A comparison of the nest site characteristics in the area where nest overlapped indicated that there were no significant differences for all of five characteristics (the distance from the nest to the shore, the distance from the nest to the bottom, the distance to the nearest nest, the nest density and the amount of cover around the nest). Using canonical discriminant analysis, the nests of the three sticklebacks could not be distinguished using the five nest characteristics. These results suggest that habitat isolation through physical factors functions as an important mechanism of reproductive isolation between the brackish-water type and the other two sticklebacks.     

Nest‐site fidelity in parental male bluegill Lepomis macrochirus: spatial patterns and the influence of prior mating success

A 4 year mark–recapture study examined the pattern of nesting site fidelity of parental‐type male bluegill Lepomis macrochirus. The study results indicated that iteroparous male L. macrochirus choose new nest sites near their own previously used sites. The scale of site fidelity varied, but generally males choose to renest within shoreline areas rather than specific or exact nest locations (94% within‐year, 86% among‐years). Iteroparous males also displayed no preference to nest in proximity to neighbouring males from previous colonies to suggest social fidelity. Contrary to expectation, manipulating males' reproductive success had no significant effect on the pattern or scale of male reproductive site fidelity.     

Spatial and temporal patterns of nest distribution influence sexual selection in a marine fish

In many species, the natural distribution of material resources important for reproduction can profoundly impact reproductive success among individuals and, hence, the opportunity and intensity of sexual selection. Here, we report on a field‐based experiment investigating the effects of nest aggregation on sexual selection in a fish, the sand goby Pomatoschistus minutus. We found that the distribution of potential nests (sparse versus aggregated nest treatments) affected patterns of nest colonization and reproductive success. Specifically, in the treatment with aggregated nesting resources, a greater proportion of nests remained unoccupied by sand goby males. Although the size of nesting males did not differ between treatments, eggs accumulated more rapidly when nests were sparsely distributed. We found that the opportunity for selection decreased over time with the accumulation of eggs in the nests in both the aggregated and sparse treatments. Moreover, the effect of male size on reproductive success was influenced by an interaction between nest distribution and time, with the selection gradient being highest right after nest colonization when nests were aggregated, while the opposite pattern was observed in the sparse nest treatment. Such findings highlight the vital role that environmental and social factors can play in determining the importance of male phenotypic traits (in this case, male size). More broadly, our results also underscore how the natural distribution of resources, both in space and time, can impact the strength of sexual selection acting on wild animal populations.     

Testing ecological and behavioral correlates of nest predation

Variation in nest predation rates among bird species are assumed to reflect differences in risk that are specific to particular nest sites. Theoretical and empirical studies suggest that parental care behaviors can evolve in response to nest predation risk and thereby differ among ecological conditions that vary in inherent risk. However, parental care also can influence predation risk. Separating the effects of nest predation risk inherent to a nest site from the risk imposed by parental strategies is needed to understand the evolution of parental care. Here we identify correlations between risks inherent to nest sites, and risk associated with parental care behaviors, and use an artificial nest experiment to assess site-specific differences in nest predation risk across nesting guilds and between habitats that differed in nest predator abundance. We found a strong correlation between parental care behaviors and inherent differences in nest predation risk, but despite the absence of parental care at artificial nests, patterns of nest predation risk were similar for real and artificial nests both across nesting guilds and between predator treatments. Thus, we show for the first time that inherent risk of nest predation varies with nesting guild and predator abundance independent of parental care.     

Divergent life histories among smallmouth bass Micropterus dolomieu inhabiting a connected river–lake system

Annual reproductive surveys monitored nesting location, reproductive success and the age and size of individually tagged male smallmouth bass Micropterus dolomieu that reproduced in Millers Lake, a 45 ha widening of the Mississippi River, Ontario, and in a 1·5 km pool and riffle section of the river directly upstream. The vast majority of males displayed fidelity to either the river or the lake as reproductive habitat throughout their lifetimes. Nearly, half of the males that reproduced in successive years exhibited strong nest‐site fidelity by nesting within 20 m of their previous year’s nest site. In most years, when compared to those in the lake, reproductive males in the river differed significantly in reproductive characteristics including age and size at maturation and nesting success rates. A 3 year telemetry project identified two distinct habitat use patterns: lake‐resident fish remained in the lake throughout the year and potamodromous individuals migrated from the lake to upriver spawning habitat in the spring and then returned to the lake prior to the onset of winter. Integration of habitat use and reproductive data suggests that there are significant differences in the life‐history strategies of fish that reproduce in the river v. the lake.     

Testing models of female reproductive migratory behaviour and population structure in the Caribbean hawksbill turtle, Eretmochelys imbricata, with mtDNA sequences

Information on the reproductive behaviour and population structure of female hawksbill turtles, Eretmochelys imbricata , is necessary to define conservation priorities for this highly endangered species. Two hypotheses to explain female nest site choice, natal homing and social facilitation, were tested by analyzing mtDNA control region sequences of 103 individuals from seven nesting colonies in the Caribbean and western Atlantic. Under the social facilitation model, newly mature females follow older females to a nesting location, and subsequently use this site for future nesting. This model generates an expectation that female lineages will be homogenized among regional nesting colonies. Contrary to expectations of the social facilitation model, mtDNA lineages were highly structured among western Atlantic nesting colonies. These analyses identified at least 6 female breeding stocks in the Caribbean and western Atlantic and support a natal homing model for recruitment of breeding females. Reproductive populations are effectively isolated over ecological time scales, and recovery plans for this species should include protection at the level of individual nesting colonies.     

Nest site selection in leatherbacks, Dermochelys coriacea: individual patterns and their consequences

We determined individual nest placement patterns for female leatherbacks nesting at Awa:la-Ya:lima:po, French Guiana, by measuring distance from the nest to several landscape features, such as the highest spring tide line (HSTL) and the vegetation line. Distance from the nest to the HSTL differed significantly between females, indicating the existence of individual nesting patterns. There was a significant repeatability of nest site choice relative to the HSTL, indicating that females showed within-individual consistency in their nest placement. Despite individual preferences, there was much within-individual variation and a lack of predictability in the nesting patterns; that is, the locations of subsequent nests could not be predicted based on knowledge of previous nest choices, indicating a certain degree of scatter. The significant repeatability suggests that nest choice behaviour in female leatherbacks is heritable and may show the potential for further evolution. We tested sea-finding ability of hatchlings, a potential consequence of nest site choice, in Matapica, Suriname, by using orientation arenas to quantify the strength and direction of travel after emergence. The orientation tests showed that hatchlings were unable to move seaward in vegetated arenas, providing evidence that vegetation acts as a strong selective pressure driving nest placement seaward. It appears that leatherbacks have adopted a regional rather than a local optimum for nest placement patterns, possibly resulting from their weak beach fidelity and the frequent erosion and destruction of their nesting beaches. We discuss the evolutionary and conservation implications for this species in the context of current environmental changes.     

Colony Development and Serial Polygyny in the Primitively Eusocial Wasp Belonogaster juncea juncea (Vespidae: Polistinae)

In Cameroon, the social ropalidiine wasp Belonogaster juncea juncea mostly selects human constructions for nesting, but nests installed in the shelter of large boulders were also noted. Nests were founded throughout the year by one female (25.5%) or by associations of two to eight females. Among the 49 colonies studied from foundation, 24 produced at least one adult, and only 5 produced males among the eight that succeeded in producing sexual individuals. After the first dominant female disappeared (died or abandoned the nest, from 77 to 196 days after foundation) the remaining females fought among themselves, leading to a drastic decrease in the total number of brood. They completely abandoned 22 of 24 surviving nests, over a mean colony cycle lasting about 7 months. Hence the colony and nesting cycles were congruent, illustrating that determinate nesting corresponds to the majority of the cases in this species. In the other two nests, some females remained on the nest and began a new colonial cycle illustrating semi-independence between colony and nesting cycles. Up to four successive cycles were completed in this way in the same nest, thus illustrating the phenomenon of serial polygyny (intermediate between determinate and indeterminate nesting cycles). Serial polygyny in independent founding polistine wasps, previously documented only once, has implications for studies attempting to identify factors involved in regulating the colony and nesting cycles in tropical social wasps.     

Mutual benefits of associations between breeding and non-breeding White-fronted Geese Anser albifrons

The relationships between yearlings and adult pairs of White-fronted Geese Anser albifrons were studied during pre-nesting, laying and early incubation in the central Canadian Arctic. Prior to nesting, females of lone pairs spent 75–81% of their time feeding, while males spent only 42–47% of time feeding and 46–50% alert. In pairs with one or more associated yearlings, both females and males fed significantly more and spent less time vigilant. Yearlings spent significantly less time (59%) feeding when alone compared with 71–76% when with pairs. Associations between yearlings and paired adults were most frequent before adult females began prospecting for nest sites. No prospecting pairs were associated with yearlings. After the egg-laying period, groups of geese, predominantly yearlings, made distraction flights over humans and terrestrial predators approaching nests, in contrast to the more cryptic behaviour of nesting pairs. The presence of groups of geese associated with some nest sites suggests that continuing parent-offspring relationships may involve assistance with nest defence.     

Nest predation increases with parental activity: separating nest site and parental activity effects.

Alexander Skutch hypothesized that increased parental activity can increase the risk of nest predation. We tested this hypothesis using ten open-nesting bird species in Arizona, USA. Parental activity was greater during the nestling than incubation stage because parents visited the nest frequently to feed their young during the nestling stage. However, nest predation did not generally increase with parental activity between nesting stages across the ten study species. Previous investigators have found similar results. We tested whether nest site effects might yield higher predation during incubation because the most obvious sites are depredated most rapidly. We conducted experiments using nest sites from the previous year to remove parental activity. Our results showed that nest sites have highly repeatable effects on nest predation risk; poor nest sites incurred rapid predation and caused predation rates to be greater during the incubation than nestling stage. This pattern also was exhibited in a bird species with similar (i.e. controlled) parental activity between nesting stages. Once nest site effects are taken into account, nest predation shows a strong proximate increase with parental activity during the nestling stage within and across species. Parental activity and nest sites exert antagonistic influences on current estimates of nest predation between nesting stages and both must be considered in order to understand current patterns of nest predation, which is an important source of natural selection.     

Habitat availability,social attraction and nest distribution patterns in longear sunfish (Lepomis megalotis peltastes)

Synopsis Two forces, limited availability of preferred habitat and social attraction between conspecifics were hypothesized to explain nest aggregation in male longear sunfish. In the laboratory, males cluster their nests within a small segment of a much larger uniform area of nesting habitat. In the field, large areas of unused habitat suitable for nesting were found, suggesting that nesting aggregations are not formed as a result of limited preferred habitat. Males appear to be socially attracted during breeding, and social nesting presumably is a successful reproductive strategy for at least a portion of the population.     

Size-mediated dominance and aggressive behavior of male Japanese fluvial sculpin Cottus pollux (Pisces: Cottidae) reduce nest-site abundance and mating success of conspecific rivals

Despite growing evidence for plasticity in the mating patterns of nest-holding animals in relation to the changes in nest abundance, the effects of aggressive interaction by dominant males on nest availability for conspecific rivals remains unclear. To quantify the effects of male–male competition on nest-site choice and mating success of the male Japanese fluvial sculpin Cottus pollux, we conducted experiments on 5 males from different 5 size classes under both sufficient and shortage nest-abundance conditions. Nest-choice experiments showed that both male size class and nest-abundance condition had significant effects on the nesting rates of males. Following the nest-choice experiments, 10 gravid females were added in the experimental tanks. Mating experiments revealed that male size, nesting rate before addition of females, and the number of courtship attempts on females were valid variables of male mating success, regardless of nest-abundance conditions. After achieving initial mating success, the largest nesting male exhibited more frequent aggressive interaction with other conspecific males than he did before obtaining eggs in his nest. Our results suggest that size-mediated dominance and aggressive behavior of males may disrupt nest acquisition of other conspecific males, and may consequently result in extreme variation in mating success among males even under sufficient nest-abundance conditions.     

Nest-Building by Chimpanzees (Pan troglodytes verus) at Seringbara, Nimba Mountains: Antipredation, Thermoregulation, and Antivector Hypotheses

The construction of nests (or beds) for sleeping is a chimpanzee universal, yet little is known about the adaptive function of nest-building. We present an in-depth study of nest-building by unhabituated chimpanzees at the Seringbara study site in the Nimba Mountains, Guinea, West Africa. We recorded 1520 chimpanzee nests over 28 mo during three study periods between 2003 and 2008. We investigated where chimpanzees built their nests, both across the home range and in nest trees, and assessed how altitude and habitat type affected nest site selectivity. We examined whether or not chimpanzees were selective in nest tree choice regarding physical tree characteristics and tree species and assessed plant species preference for both tree- and ground-nesting. We tested three, nonmutually exclusive, hypotheses for the function of arboreal nest-building. We assessed whether selectivity for nest tree characteristics reflected an antipredator strategy, examined whether nesting patterns (both arboreal and terrestrial) and nesting height were influenced by variation in climatic conditions (temperature, humidity, wind), and measured mosquito densities at ground level and in trees at 10 m and related mosquito densities to nesting patterns. Chimpanzees preferred to nest above 1000 m and nested mainly in primary forest. They preferred relatively large trees with a low first branch, dense canopy, and small leaves and showed preference for particular tree species, which was stable across years, whereas plant choice for ground-nesting was largely based on plant availability. We found no support for the antipredation hypothesis, nor did mosquito densities explain arboreal nest-building. The thermoregulation hypothesis was supported, as both nesting patterns and nest-height variation across seasons reflected a humidity-avoidance strategy. Chimpanzees nested higher in trees and at higher altitudes in the wet season. In sum, chimpanzees were selective in their choice of nest sites, locations, and materials, and tree-nesting patterns at Seringbara were best explained by a thermoregulation strategy of humidity avoidance.     

The role of nest‐site selection and cereal production in differential nest predation in Common Quail Coturnix coturnix and hybrid quail C. coturnix × C. japonica

In Europe, farm‐reared quail used for restocking purposes are often hybrids between the Common Quail Coturnix coturnix and the Japanese Quail Coturnix japonica. These hybrids interbreed with wild Common Quail populations and suffer higher rates of nest predation, which would suggest that the two quail types have different nest‐site selection patterns. We monitored 103 radiotagged nesting females (77 wild Common Quail over 18 breeding seasons and 26 hybrid quail over six breeding seasons) and analysed their nest placement behaviour. Our results did not provide any evidence that the quail types showed different nest‐site selection trends, as they all preferred to nest near cereal field margins. The higher nest predation rate experienced by hybrids might therefore be explained by less effective anti‐predator behaviour among hybrid females during incubation. As no edge effect on nest predation was observed, the preference for nesting close to cereal margins could be due to the greater food resources of field margins. Moreover, Common Quail nest predation decreased with a rise in barley straw production, supporting evidence that nest cover plays an important role in the prevention of nest predation in this species. No such relationship was found for hybrid quail, but this result is not conclusive, as the data on barley straw production for hybrid quail covered a much smaller range of interannual variability. Barley straw production in Catalonia decreased significantly between 1992 and 2012, possibly as a result of a change in the barley varieties used. This practice could entail a conservation threat for ground‐nesting bird species.     

Breeding ecology and nest aggregations in a population of Salaria pavo (Pisces: Blenniidae) in an area where nest sites are very scarce

In this paper we present data on the breeding ecology and patterns of nest aggregation in a population of Salaria pavo (Pisces: Blenniidae), in an area where hard substrates are very scarce. The study site was at Ria Formosa, an extensive littoral lagoon on the south coast of Portugal. The only hard materials available are bricks, tiles, stones and debris that clam culturists use to delimit their fields. The males of S. pavo establish nests intertidally in the holes of the bricks where they guard the eggs. Data were collected at low tide inspections of these artificial ridges and underwater behavioural observations during high tide. The main results are: (i) the same male can establish sequentially more than one nest in the same breeding season; the number of males that stay within the bricks increases before the start of the breeding season and declines towards its end; (ii) there is a large excess of mature males that do not establish nests and they are significantly smaller than the nesting males, suggesting very strong competition for nest sites; (iii) the nests of several males occur in adjacent holes of the same brick, sometimes being entirely surrounded by other nests. Thus, in this population, there is virtually no defended territory around the nest, a situation not known for other blenniid species. This pattern of nest aggregation implies both strong competition among males and reduction of aggression between neighbour parental fishes. This can be explained by the extreme scarcity and spatial distribution of available nest sites.     

Size-assortative nest choice in the absence of competition in males of the sand goby,Pomatoschistus minutus

Synopsis Size-assortative choice of nest site is commonly found among fish with paternal care. This pattern can be explained either by the superior competitive ability of large males for preferred large nests, or by a choice of nest size that is related to the male's own body size. Choice of nest size was studied in males of a small marine fish, the sand goby Pomatoschistus minutus, by providing artificial nest sites in laboratory and field experiments. A positive correlation between nest size and male size, indicating a size-assortative nest choice process, was found in both aquarium and field experiments. This is argued to be the outcome of a preference for an optimal nest size and not to be due to competition, as (a) a surplus of nest sites was available to the individuals in nature; (b) in the aquarium experiments, single males of all sizes, when offered a choice between a smaller and a larger nest site, showed a preference for nests in proportion to their body size and not for the largest available nests; and (c) in the aquaria, when single males were offered only a small or only a large nest site, small males abstained from building nests in the large sites, whereas in the small nest sites males of all sizes built nests. My conclusion is that size assortative nest choice occurred in the absence of competition, which thus is not a necessary condition for size-assortative nesting, contrary to what is commonly assumed in many studies. This preference may represent a compromise (or trade-off) between the advantage of a nest large enough to accommodate many eggs and a smaller one with lower maintenance and defence costs.