Previous Reproductive Success Research Articles

Previous reproductive success and environmental variation influence nest‐site fidelity of a subarctic‐nesting goose

AbstractNest‐site fidelity is a common strategy in birds and is believed to be adaptive due to familiarity with local conditions. Returning to previously successful nest sites (i.e., the win‐stay lose‐switch strategy) may be beneficial when habitat quality is spatially variable and temporally predictable; however, changes in environmental conditions may constrain dispersal decisions despite previous reproductive success. We used long‐term (2000–2017) capture‐mark‐reencounter data and hierarchical models to examine fine‐scale nest‐site fidelity of emperor geese (Anser canagicus) on the Yukon–Kuskokwim Delta in Alaska. Our objectives were to quantify nest‐site dispersal distances, determine whether dispersal distance is affected by previous nest fate, spring timing, or major flooding events on the study area, and determine if nest‐site fidelity is adaptive in that it leads to higher nest survival. Consistent with the win‐stay lose‐switch strategy, expected dispersal distance for individuals that failed their nesting attempt in the previous year was greater (207.7 m, 95% HPDI: 151.1–272.7) than expected dispersal distance for individuals that nested successfully in the previous year (125.5 m, 95% HPDI: 107.1–144.9). Expected dispersal distance was slightly greater following years of major flooding events for individuals that nested successfully, although this pattern was not observed for individuals that failed their nesting attempt. We did not find evidence that expected dispersal distance was influenced by spring timing. Importantly, dispersal distance was positively related to daily survival probability of emperor goose nests for individuals that failed their previous nesting attempt, suggesting an adaptive benefit to the win‐stay lose‐switch strategy. Our results highlight the importance of previous experience and environmental variation for informing dispersal decisions of a long‐lived goose species. However, it is unclear if dispersal decisions based on previous experience will continue to be adaptive as variability in environmental conditions increases in northern breeding areas.

The female effect-how female receptivity influences faecal testosterone metabolite levels, socio-positive behaviour and vocalization in male Southern white rhinoceroses.

Testosterone is known to be essential for sexual maturation as well as for the display of behavioural traits linked to reproduction. At the same time, external factors such as the presence of receptive females may affect testosterone levels, stressing the hormone's substantial role in reproductive success. It is therefore of major interest to investigate the links between androgens, behaviour and the social environment especially in species that rely on a resilient reproduction rate, such as the white rhinoceros (WR). We collected faecal samples of 16 male Southern WR (Ceratotherium simum simum) aged between 1 and 44years from 11 European zoos. Audio and video recordings were simultaneously taken from five of the study males that were sexually mature and had direct contact with receptive females. Our results showed a positive correlation of faecal testosterone metabolite (fTM) concentrations and progressing age up until adulthood followed by a decline in older males. While previous reproductive success did not show any effect, the access to receptive females resulted in higher fTM levels. Thereby, fTM concentrations remained at the same level regardless of the receptivity phase, while social cohesion with respective females, affiliative behaviour as well as call rates of Pant and Hiss distinctly peaked during the receptive compared to the non-receptive periods. Conclusively, the immediate presence of receptive females poses a female effect that enhances the overall androgen levels in males and, thus, might facilitate their reproductive success. However, androgens do not seem to be the main driver of behavioural changes during courtship or mating. By linking endocrinological and socio-behavioural factors, we were able to provide an applicable basis for non-invasive monitoring of reproductive behaviour in male WR in captivity, thereby contributing to deeper understanding of potential reproduction impairments in a species whose population in captivity remains not fully self-sustaining.

Exploring causal components of plasticity in grey seal birthdates: Effects of intrinsic traits, demography, and climate.

Change in breeding phenology is often a response to environmental forcing, but less is known of the mechanism underlying such changes and their fitness consequences. Here, we report on changes in the breeding phenology from a 27‐year longitudinal study (1991–2017) of individually marked, known‐aged grey seals (Halichoerus grypus) on Sable Island, Nova Scotia, Canada. We used generalized linear mixed models and a 3‐step process to develop a model that includes interactions between intrinsic and extrinsic covariates and to test hypotheses about the influence of fixed factors (maternal age, parity, previous reproductive success, pup sex, colony density, Atlantic Multidecal Oscillation (AMO), North Atlantic Oscillation (NAO), and Sea Surface Temperature) and a random factor (female identity) on parturition dates. We also examined the consequences of the shift in birthdates on maternal energy allocation in offspring as measured by pup weaning mass. Birthdates were known for 2,768 pups of 660 known‐age females. For 494 females with ≥2 parturition dates, repeatability as measured by the intraclass correlation was high (mean = 0.66). 87% of the variation in birthdates was explained by a mixed‐effects model that included intrinsic and extrinsic fixed effects. Most of the explained variation was associated with the random effect of female identity. Parity was the most important intrinsic fixed effect, with inexperienced mothers giving birth later in the season than multiparous females. Over almost 3 decades, mean birthdates advanced by 15 days. The mixed model with intrinsic effects and population size, the detrended AMO from the previous year and mean NAO in the previous 3 years explained 80% of the variation with 21% of variation from the fixed effects. Both primiparous and multiparous individuals responded to the climate forcing, and there was strong evidence for heterogeneity in the response. Nevertheless, the shift in birthdates did not impact pup weaning mass.

Feather corticosterone in Northern Bald Ibis Geronticus eremita: a stable matrix over time able to predict reproductive success

Measuring corticosterone concentrations in feathers (FCC) has been increasingly used as an integrated index of bird’s response to stressors, offering valuable insights into subsequent carry-over effects. However, it is still unclear to what extent corticosterone levels deposited in feathers during the moulting period relate to individual physiology in high-energetic demanding situations. In addition, the stability and repeatability of FCC over the same feather generation and across successive generations are still unresolved questions. In this study, we assessed FCC in 24 captive Northern Bald Ibis, Geronticus eremita. We sampled body feathers on three occasions during two consecutive years (2015–2016) to explore within-individual stability of FCC in feathers grown during the same generation and test whether FCC was repeatable or varied between two consecutive generations. Then, we explored whether FCC (a) was associated with individual health status, (b) correlated with previous reproductive success and (c) was related to future reproductive success. Results showed high stability of FCC among feathers of the same generation, while FCC differed between successive generations. We also observed that FCC, age and health status were negatively associated with subsequent reproductive success the following season, while no association was found with previous reproductive success. Overall, our study supports the use of feathers as a stable measure of corticosterone over the same feather replacement generation and emphasizes the usefulness of FCC as a biomarker of subsequent reproductive success.

Cumulative reproductive costs on current reproduction in a wild polytocous mammal.

The cumulative cost of reproduction hypothesis predicts that reproductive costs accumulate over an individual's reproductive life span. While short‐term costs have been extensively explored, the prevalence of cumulative long‐term costs and the circumstances under which such costs occur alongside or instead of short‐term costs, are far from clear. Indeed, few studies have simultaneously tested for both short‐term and cumulative long‐term reproductive costs in natural populations. Even in mammals, comparatively little is known about cumulative effects of previous reproduction, especially in species with high variation in offspring numbers, where costs could vary among successful reproductive events. Here, we quantify effects of previous short‐term and cumulative long‐term reproduction on current reproduction probability and litter size in wild female yellow‐bellied marmots (Marmota flaviventer) and test how these effects vary with age and between two contrasting environments. We provide evidence for cumulative long‐term effects: females that had both reproduced frequently and weaned large litters on average in previous years had decreased current reproduction probability. We found no evidence for short‐term reproductive costs between reproductive bouts. However, females weaned larger litters when they had weaned larger litters on average in previous years and had lower current reproduction probability when their previous reproductive success was low. Together these results suggest that, alongside persistent among‐individual variation, long‐term reproductive history affects current reproductive success.

Which male and female characteristics influence the probability of extragroup paternities in rhesus macaques, Macaca mulatta?

Extragroup paternity (EGP) is found across a wide range of species and may entail reproductive benefits, but may also entail costs to both sexes. While population and group parameters affecting the degree of EGPs are relatively well established, less is known about the individual characteristics that make males and females engage in alternative reproductive tactics such as EGP. Applying a combination of long-term demographic and genetic data from the rhesus macaque population of Cayo Santiago (Puerto Rico, U.S.A.), we investigate which male and female characteristics influence the probability of EGP to better understand the circumstances that shape the distribution and occurrence of EGP. Our results show that, against our expectations, higher-ranking females were more likely to produce EGP offspring than lower- ranking females. The probability of producing extragroup offspring was not significantly related to female or male age, male tenure or previous reproductive success. Furthermore, genetic relatedness between the parents did not affect the production of extragroup offspring, but extragroup offspring were more frequently produced early rather than late in a given mating season. Altogether, our analysis suggests that individual attributes and seasonal aspects create different opportunities and preferences for engaging in EGP as an alternative reproductive tactic. The observed patterns of EGP in rhesus macaques appear to be consistent with female mate choice for genetic benefits, which needs to be confirmed in future studies.

The individual courtship behaviour of male European mink (Mustela lutreola) is a good indicator for their breeding success

Conservation breeding of the critically endangered European mink (Mustela lutreola) is a challenge, because the genetically prioritised breeding pairs often fail to mate during the staged breeding attempts. For this study the courtship and mating behaviour of 33 males and the response behaviour of 28 females was observed and recorded throughout two breeding seasons at Tallinn Zoo using an ethogram. The behavioural patterns of the male European mink differed significantly depending upon their previous reproductive success and the outcome of the breeding attempt. “Clucking”, “flehmen”, “chase”, “anal drag”, “neck bite” and “mounting” were observed significantly more often among males that sired a litter during the study (“breeding males”) and during attempts that ended with copulation. More than half (61%) of the males were “non-breeding males”: they never sired a litter or copulated with a female. Females “chirped” significantly less often in attempts with “non-breeding males”. The male “clucking” sound was the best indicator to predict 1) a males ability to sire a litter and 2) whether a breeding attempt would end with copulation. The absence of species-specific courtship and mating behaviour in the “non-breeding males” threatens the conservation goal to maintain the genetic heterozygosity of the captive population. From a practical point of view, behavioural indicators could be used as a potential screening method for identifying successful future breeders. In an experimental setup, males were presented with scent cues from an oestrous female but without the opportunity for direct contact. In this experimental context 64% of “breeding males” responded with “clucking” and also presented “flehmen”, “rubbing” and “approach to the female/her nest box door” significantly more often than the “non-breeding males”.

Hydrosalpinx in dairy goats: Occurrence, ultrasound diagnosis, macro- and microscopic characterization

Hydrosalpinx is an oviduct disease that can compromise female fertility. This study describes the occurrence and characterization of hydrosalpinx in dairy goats and proposes a new approach for an accurate diagnosis of hydrosalpinx by using transrectal ultrasonography (US). The data were collected from 2579 goats subjected to US exams. Six goats had their reproductive tracts collected post mortem and macroscopically and microscopically examined. A total of 28 cases of hydrosalpinx (1.1%) were detected: 27 Saanen goats and one Alpine goat. Among these, 22.2% (6/27) had previously shown other reproductive disorders such as spontaneous abortion (3.7%), follicular cysts (3.7%) and hydrometra (14.8%). Only the oldest goat (12 years old) was pluriparous with history of previous reproductive success, while 27 nulliparous females ranged in age from one to eight years old. The US exams revealed a fluid-filled, rounded structure ( >24 mm) formed by the accumulation of fluid inside the oviduct lumen of the affected goats. The infundibulum was the most commonly affected region, and contained rounded structures up to 100 mm in diameter. The ampulla was the second most commonly affected structure, and minor changes were observed in the isthmus. In one of the 28 positive cases, the presence of bilateral hydrosalpinx was identified. Microscopically, at the infundibulum and ampulla, a decrease and/or absence of the mucosal folds with subsequent reduction of the epithelial surface area was noted. In conclusion, hydrosalpinx may be successfully diagnosed in goats via transrectal US. The occurrence rate of hydrosalpinx in this study reveals the importance of an accurate diagnosis and a strong possibility that hydrosalpinx has been underdiagnosed and neglected in this species.

Breeding Success Affects the Apparent Survival of Grassland Passerines

The apparent adult survival rate is one of the key population parameters of migratory birds. The widely used Cormack–Jolly–Seber capture–mark–recapture model has a number of disadvantages, the main one of which is the impossibility of discerning mortality and permanent emigration. The accuracy of survival estimates can be increased using a multistate capture–mark–recapture model, with the help of which it is possible to assess the survival of successful and unsuccessful birds separately. We used this model to estimate the apparent survival rates of adults in local populations of three ground-nesting passerines: Booted Warbler (Iduna caligata), Whinchat (Saxicola rubetra), and Yellow Wagtail (Motacilla flava), all breeding on abandoned agricultural lands. We studied the reproductive success of 472 marked pairs and analyzed individual capture histories of 814 birds. The previous reproductive success was found to influence significantly the apparent survival of adults. This relation was best expressed in the Yellow Wagtail (apparent survival of successful birds, φ = 0.39 ± 0.06, vs. that of unsuccessful birds, φ = 0.19 ± 0.06) and the Whinchat (apparent survival of successful birds, φ = 0.32 ± 0.05, vs. apparent survival of unsuccessful birds, φ = 0.10 ± 0.05), but a little lower in the Booted Warbler (apparent survival of successful birds, φ = 0.33 ± 0.17, vs. apparent survival of unsuccessful birds, φ = 0.16 ± 0.13). Unsuccessful individuals leave the study area for good, while most of the successful birds return there the next year. Thus, the apparent survival rate of passerines evaluated with capture–recapture models is determined to a considerable degree by the previous reproductive success within local populations.

Leucocyte Profiles and Family Size in Fledgling Greylag Geese (Anser Anser)

In precocial species, large brood sizes are usually considered as beneficial and individuals in larger broods grow faster and are more dominant compared to individuals in small broods. However, little is known whether family size also beneficially affects the offspring's physiology. In the present study, we investigated whether leucocyte profiles in fledgling Greylag Geese ( Anser anser) are affected by (1) family size, (2) individual characteristics, i.e. age, body condition or sex, or (3) characteristics of the parents, i.e. previous reproductive success. From spring 2013 to autumn 2015, we collected blood samples from 100 juvenile Greylag Geese from 20 different pairs. From these samples we determined the absolute leucocyte number, an individual's differential blood cells count and an individual's haematocrit (HCT). The number of fledglings in a family and therefore the number of siblings a focal individual had, was positively related to the percentage of basophils, negatively to the heterophils/lymphocytes ratio (H/L), and tended to be negatively related to the percentage of monocytes and eosinophils in a sample. H/L ratio was negatively related to age in days and tended to be negatively related to body condition, whereas the percentage of basophils tended to be positively related to it. Absolute leucocyte number did not differ between individuals depending on family size. However, composition of different leucocyte types (basophils, eosinophils, H/L ratio) was modulated mostly by the social environment (family size) and not by the characteristics of the individual or the parents. In conclusion, even though we did not find clear evidence of a positive health effect, i.e. a better immune system, in fledgling Greylag Geese of large versus small families, our results suggest that family size modulates different components of the immune system hinting at its stress-reducing effect.

The importance of site to mate choice: Mate and site fidelity in Piping Plovers

Each breeding season, seasonally monogamous birds can divorce or reunite with their previous year's mate, assuming both partners survive and return. We tested a suite of variables related to mate choice and site choice to determine which of 4 prominent mate fidelity hypotheses (better [mate] option, habitat mediated, musical chairs, and bet-hedging) best explained the interyear reunion rate and breeding dispersal of a seasonally monogamous shorebird, Piping Plover (Charadrius melodus), nesting on dynamic sandbars on the Missouri River, USA, 2005–2012. Of 252 pairs in which both members returned to the breeding grounds the following year, only 20% reunited. Pairs with an early-arriving male had the highest mate fidelity. Reunited pairs returned to previous nest sites (median breeding dispersal = 39 m), and divorced and widowed birds tended to move farther (median = 229 m and 193 m, respectively). Overall, site fidelity was higher in males than females. Previous reproductive success of a pair did not predict reunion, but all successful birds, with the exception of divorced females, exhibited high site fidelity, suggesting selection for site based on prior breeding success. Among divorced birds, females had higher-quality mates and higher nest success compared to their former partners, and they nested in areas of similar quality between years, whereas males settled in lower-quality areas following divorce. The benefits that females gained from divorce suggested that females initiated divorce to improve reproductive success, which supports the better option hypothesis. Although females seemed to initiate most divorces, males may have divorced as a safeguard against remaining unmated when there was uncertainty about the survival and return of a former mate, as proposed by the bet-hedging hypothesis.

Effects of climatic variation and reproductive trade‐offs vary by measure of reproductive effort in greater sage‐grouse

Research on long‐lived iteroparous species has shown that reproductive success may increase with age, until the onset of senescence, and that prior reproductive success may influence current reproductive success. Such complex reproductive dynamics can complicate conservation strategies, especially for harvested species. Further complicating the matter is the fact that most studies of reproductive costs are only able to evaluate a single measure of reproductive effort. We systematically evaluated the effects of climatic variation and reproductive trade‐offs on multiple reproductive vital rates for greater sage‐grouse (Centrocercus urophasianus; sage‐grouse), a relatively long‐lived galliforme of conservation concern throughout western North America. Based on over a decade of field observations, we hypothesized that reproduction is influenced by previous reproductive success. We monitored hen reproductive activity from 1998 to 2010, and used generalized linear mixed models to assess effects of climate and previous reproductive success on subsequent reproductive success. Reproductive trade‐offs manifested as chronic effects on subsequent reproduction and were not apparent in all measures of subsequent reproduction. Neither nest initiation nor clutch size were found to be affected by climatic variables (either year t − 1 or t) or previous reproductive success. However, both nest and brood success were affected by climatic variation and previous reproductive success. Nest success was highest in years with high spring snowpack, and was negatively related to previous brood success. Brood success was positively influenced by moisture in April, negatively associated with previous nest success, and positively influenced by previous brood success. Both positive and negative effects of previous reproduction on current year reproduction were observed, possibly indicating high levels of individual heterogeneity in female reproductive output. Our results support previous research in indicating that climatic variability may have significant negative impacts on reproductive rates.

Behavioural cues surpass habitat factors in explaining prebreeding resource selection by a migratory diving duck

Prebreeding habitat selection in birds can often be explained in part by habitat characteristics. However, females may also select habitats on the basis of fidelity to areas of previous reproductive success or use by conspecifics. The relative influences of sociobehavioural attributes versus habitat characteristics in habitat selection has been primarily investigated in songbirds, while less is known about how these factors affect habitat selection processes in migratory waterfowl. Animal resource selection models often exhibit much unexplained variation; spatial patterns driven by social and behavioural characteristics may account for some of this. We radiomarked female lesser scaup, Aythya affinis, in the southwestern extent of their breeding range to explore hypotheses regarding relative roles of habitat quality, site fidelity and conspecific density in prebreeding habitat selection. We used linear mixed-effects models to relate intensity of use within female home ranges to habitat features, distance to areas of reproductive success during the previous breeding season and conspecific density. Home range habitats included shallow water (≤118 cm), moderate to high densities of flooded emergent vegetation/open water edge and open water areas with submerged aquatic vegetation. Compared with habitat features, conspecific female density and proximity to successful nesting habitats from the previous breeding season had greater influences on habitat use within home ranges. Fidelity and conspecific attraction are behavioural characteristics in some waterfowl species that may exert a greater influence than habitat features in influencing prebreeding space use and habitat selection within home ranges, particularly where quality habitat is abundant. These processes may be of critical importance to a better understanding of habitat selection in breeding birds.

Circulating carotenoid levels are negatively associated with previous reproductive success in Florida Scrub-Jays (Aphelocoma coerulescens)

The relationship between individual fitness and antioxidants and oxidative stress has come under increasing scrutiny of late. In particular, associations between oxidative balance indicators and reproductive success in the wild have been inconsistent in the limited prior work on this topic. Studies spanning multiple seasons and antioxidant types are particularly lacking. Here, we examined associations between reproductive success over two breeding seasons and several metrics of circulating antioxidants (antioxidant capacity, uric acid, carotenoids, and vitamin E, measured in the intervening nonbreeding season) in Florida Scrub-Jays (Aphelocoma coerulescens (Bosc, 1795)). We found that carotenoid levels in the nonbreeding season were negatively associated with reproductive success in the preceding breeding season but unassociated with that in the subsequent breeding season. This correlation may be driven by the cost of reproduction (i.e., carotenoid depletion while breeding) or some other unmeasured and intercorrelated variable such as diet. Antioxidant capacity, uric acid, and vitamin E were not associated with reproductive success. These data are consistent with an emerging theme in physiological ecology: that antioxidants and oxidative stress are but one part of a suite of integrative physiological systems that interact and trade-off in complex ways, making full understanding of their ecological roles challenging.

Factors influencing reproductive success and litter size in captive island foxes

AbstractA severe decline of island foxes (Urocyon littoralis) on the northern Channel Islands in the 1990s prompted the National Park Service to begin a captive breeding program to increase their numbers. Using detailed records of all the fox pairs (N = 267) that were part of the program on San Miguel, Santa Rosa, and Santa Cruz Islands from its inception in 2000 through 2007, we identified factors influencing the breeding success of pairs in captivity in the interest of formulating strategies that could increase captive productivity. We compiled a database of variables including litter size, reproductive success, distance to nearest occupied pen during the breeding season, subspecies, exposure, female age, male age, age difference, female and male origin (wild vs. captive born), same versus different origin, years paired, previous reproductive success by the pair, previous reproductive success by the female, mate aggression‐related injuries, male previous involvement in a pair with mate aggression, and female previous involvement in a pair with mate aggression. We used multiple linear regression to identify factors predictive of litter size, and logistic regression to predict the probability of reproductive success. A larger inter‐pen distance, older male age, less exposure, and a smaller intra‐pair age difference positively affected litter size. The probabilities of reproductive success increased with fewer years paired and less exposure. Comparatively, pairs with wild born females (vs. captive born females), and previously successful pairs (vs. previously unsuccessful and new pairs) were most likely to be successful. These results indicate that the optimal situation was to pair wild‐caught females with older males in sheltered pens that were as far from other pens as possible, to maintain successful pairs and repair unsuccessful ones. Published 2013. This article is a U.S. Government work and is in the public domain in the USA.

Breeding dispersal of Eurasian Hoopoes (Upupa epops) within and between years in relation to reproductive success, sex, and age

ABSTRACT. Breeding dispersal is often affected by previous reproductive success, age, and sex. Birds with multiple broods within a season can disperse not only between, but also within, years. Little is known about factors that govern dispersal within a season or how strong it is compared with dispersal between years. We studied breeding dispersal of Eurasian Hoopoes (Upupa epops) in Valais, Switzerland, using capture-recapture data collected over 8 years (n = 712 individuals). We analyzed breeding dispersal probability and distance, both between and within years, in relation to age, sex, and reproductive output, using multistate capture-recapture models and generalized linear models. Between years, females dispersed more often and over longer distances than males (mean distance, females = 1.98 km; males = 0.83 km), but dispersal was only weakly affected by age and previous reproductive success. Dispersal within a year also differed between sexes (mean distance, females = 1.45 km; males = 0.46 km) and var...

Social and life history correlates of litter size in captive colonies of precocial spiny mice (Acomys)

Litter size is an important component of life history contributing to reproductive success in many animals. Among muroid rodents, spiny mice of the genus Acomys are exceptional because they produce large precocial offspring after a long gestation. We analyzed data on 1,809 litters from laboratory colonies of spiny mice from the cahirinus-dimidiatus group: Acomys cahirinus, Acomys cilicicus, Acomys sp. (Iran), and Acomys dimidiatus. Generalized mixed-effect models revealed that litter size increased with maternal body weight and/or number of immature females present in the family group. Thus, both maternal body reserves and presence of immature descendants demonstrating previous reproductive success enhance further reproduction in this social rodent.

Context-dependent risk tolerance of the bicolour damselfish: courtship in the presence of fish and egg predators

Reproductive behaviours such as courting, copulation, parental care and mate guarding often entail a cost of increased predation risk, either to the individual itself or to the offspring under its care. Because of this, males of several species reduce courting effort in the presence of a predator. The degree to which reproduction is curtailed may depend upon the magnitude of potential benefits as well as the current and previous reproductive success of the male. We presented male bicolour damselfish, Stegastes partitus, with females in the presence and absence of fish and egg predators and tracked the realized fecundity of the males over the course of a spawning cycle to evaluate the degree to which courting reductions depend on the size of the female being courted, the type of predator involved and the previous and current mating success. We found that males increased courting towards larger females and that this courting was reduced in the presence of a fish or an egg predator for small females but not for large ones. We found no relationship between courting reduction and either past or current reproductive success for the fish or egg predator treatments, respectively. Our results demonstrate that male S. partitus do show context-dependent courting behaviour and seem to balance risk and reward in courting decisions.

Reproductive success and female preference in the amazonian cichlid angel fish, Pterophyllum scalare (Lichtenstein, 1823)

The angel fish, Pterophyllum scalare is a cichlid native to the Amazon Basin of Brazil and is exported as an ornamental fish. In this study the importance of the experience and previous reproductive success of males in mate selection was investigated. In order to investigate reproductive experience, six pairs of males (experienced and inexperienced) and six females were used. Males were placed in an aquarium, where one female was released. Mate selection was verified by the time spent by a female near one of the males. To evaluate reproductive success, six pairs of males were tested, each pair consisting of a successful male and an unsuccessful one. Again, time spent with one of the males was considered as an indication of preference by the female. Each female was then paired with an unsuccessful male and their reproductive success was assessed. Females preferred larger, aggressive, territorial and experienced males. Correlations between male aggressiveness, aeration and egg survival were significant. During larval care, male aggressiveness was significantly related to larvae survival. Furthermore, intrabucal care and larval survival showed significant correlations with care provided by the experienced, mated and isolated fish. Survival of offspring resulted from mating with experienced and inexperienced males showed significant differences. Correlations between time spent by females with successful males during reproduction and survival rate of eggs and larvae were significant. Females assess the capacity and willingness of males in investing efforts to raise the offspring through their courtship behavior. Experienced and successful males are preferred by females and thereby achieve greater reproductive success.

INFLUENCE OF PREDATION ON NEST-SITE REUSE BY AN OPEN-CUP NESTING NEOTROPICAL PASSERINE

Abstract Nest-site fidelity is associated with previous reproductive success in birds but is thought to be rare among territorial, open-cup nesting passerines. I investigated nest reuse decisions by Spotted Antbirds (Hylophylax naevioides) in central Panama. A quarter of all nest attempts were located at a previously used nest site, often within an extant nest structure. Within a breeding season, pairs preferred to reuse previously successful nest sites overall and were more likely to return to these sites for a consecutive nest attempt than they were to previously depredated nest sites. The fates of two nest attempts at the same location, however, were not associated with each other. The preference of Spotted Antbirds for reusing successful nests may be a short-term strategy to avoid sites recently discovered by predators, as pairs did reuse previously depredated nest sites for later nest attempts and did not prefer successful nest sites from previous breeding seasons. Influencia de la Depredacion sobre ...