Territorial behaviour is exhibited by a wide variety of species for reasons such as resource control, mate acquisition, or protection of offspring. Most studies of short-term territorial activity focus on diurnal behaviours. Here, we present evidence of male nocturnal territorial behaviour by a subset of the Leon Springs pupfish population. Approximately half of the males behaved cathemerally, defending their territories during the daytime and continuing to do so through the nighttime hours (Cathemeral Defenders). In contrast, other males did not defend nor spend significant time within their territories at night (Day Defenders). None of the defensive variables examined (male patrols, chasing behaviours, or frequency of conspecific and heterospecific intruders) predicted which male pupfish would exhibit cathemeral territorial behaviour. The absolute number of spawns observed during the day also were not predictive of which males continued to hold nighttime territories, but there appeared to be an inverse relationship with diurnal mating success: males that did not spawn during daytime observations were more likely to maintain nighttime territories. These results indicate that further investigation into cathemeral behaviour is required to understand the optimal expression of territorial behaviour.

A field study on the biparental convict cichlids (Amatitlania siquia) in Lake Xiloá, Nicaragua was conducted to understand how the loss of a parent’s parental care affects the antipredator behavior of both parents and offspring during intruder events. We hypothesized that the combined efforts of two parents would result in increased intruder aggression and decreased offspring dispersion compared to single-parents of either sex, and that single-females and males would differ in their ability to deter predators and manage offspring dispersion. Both parents in a pair chased half the intruders that single-females did and the same number as single-males, suggesting that the presence of a partner deters intruders from encroaching and affords parents more time to engage in other parental care duties. Compared to single-parents, offspring accompanied by both parents were seldom left alone and showed greater shoal cohesion—both of which would presumably lower their risk of predation. Although there were sex differences between single-parents in terms of how often they left their offspring unattended and called to them using pelvic fin-flicks, neither sex was found to be more effective at managing the distribution of their offspring. This field study provides empirical evidence to support the need for biparental care in this species and gives insight into the selection pressures shaping parental investment.

The aim of this study was to further characterize the relationship between small group social experiences and individual behaviour in a pair bonding fish and to explore hormonal factors possibly relating to previous evidence that prior social experience affects pair formation. Behavioural profiles of groups containing one sex differed from those containing both sexes; aggression was heightened in same-sex groups. Dominance, as quantified by aggression, was easily identifiable. Plasma levels of 11-ketotestosterone (11-KT) and 13,14-dihydro-15-keto prostaglandin F2 alpha (PGF2 alpha metabolite) and whole-brain follicle-stimulating hormone (FSH) were measured after group treatment. 11-KT varied across males and differed according to dominance status but not same-sex or mixed-sex social experience. PGF2 alpha metabolite also did not differ among females as a function of social experience. FSH was elevated in subordinate males and females. We did not find clear evidence of a reproductive priming mechanism but did find evidence that social experience can impact hormonal pathways relevant for reproduction, a factor worth considering when using this species for such studies.

In an experimental field study, we examined the effectiveness of territorial defense by male Leon Springs pupfish (Cyprinodon bovinus) in safeguarding eggs from predation. Both Pecos gambusia (Gambusia nobilis) and small C. bovinus intrude into territories to forage and will follow spawning pairs to eat newly deposited eggs. To test whether attacking and chasing these intruders would reduce the number of eggs that territorial males lost to predation, we excluded large males from different portions of their territories but still allowed the smaller fish to access those areas. Males lost many of their eggs to predators, but a similar number and proportion of eggs were lost to predation whether males could or could not defend those portions of the territory. We speculate that the haphazard distribution of egg laying by females may play a more important role than territorial defense in mitigating egg predation and discuss broader concerns of egg predation and habitat loss as threats to the survival of this endangered species.

We considered the relationship between the benefits and costs of territorial defense in a wild population of the Leon Springs pupfish, Cyprinodon bovinus. We defined benefit as the number of eggs deposited on an artificial substratum placed within the defender's territory. Costs included two defensive behaviors. First, males frequently "patrolled" their territories, swimming back-and-forth across their area. Second, males chased intruding Pecos gambusia (Gambusia nobilis) as well as small male and female conspecific C. bovinus from their territories. Both of these species prey on the territorial defenders' eggs; additionally, small male C. bovinus will attempt to "steal" spawns from the territorial defender by spawning with females in the territory. Our analyses revealed that only patrol frequency was related to the reproductive benefit of the territory. Neither chases against gambusia nor conspecifics were predicted by egg numbers on the breeding substrata. We speculate that the frequency of patrolling is an indicator of territorial value and note the qualitative differences in chasing behavior against the different species of intruder.

When multiple species within an ecological community are all threatened or endangered, it may be crucial to understand the interconnected relationships of populations in order to better inform their individual recovery plans. We examined the potential egg predation of the critically endangered Leon Springs Pupfish ( Cyprinodon bovinus) endemic to the Diamond Y Spring system in West Texas. This one spring-fed pool also includes multiple species of invertebrate animals and another endangered fish, the Pecos Gambusia ( Gambusia nobilis). Artificial mats were used to observe individual eggs laid by promiscuous females within the defended territories of various males. These eggs were then monitored over a 24-hour period, with and without protection from nocturnal predators. Analysis revealed that predation of eggs is occurring both diurnally and nocturnally, and examination of the pattern of egg predation suggests that this egg predation is a result of multiple species of predators. The number of eggs at the beginning of the observation period was significantly correlated with the number not preyed upon and present following 24 hours, suggesting that males should be investing considerably in spawning with females to increase their reproductive output. Further study is needed to understand the impact that egg predation is having on the reproductive success of this endangered pupfish.

care involves both parents contributing to offspring, though each parent does not necessarily contribute equally or in the same manner. While offspring benefit from parental care, sexual conflict arises within parental pairs because each sex would benefit from a partner's greater contribution to the young. Nevertheless, each parent may be better suited or have preferences for the type and intensity of care they provide. Here, we examined parental pairs of Texas Cichlids in a naturally occurring population in southwest Texas as they defended their free-swimming fry against potential conspecific and heterospecific predators. Sex differences were apparent, with females generally directing higher levels of aggression at intruding fishes and males spending more time away from the brood of fry. Although parents performed the same activities, they exhibited these activities with different durations and frequencies, with the result that the male parents spent less time with the fry and chased fewer intruders.

Female mate choice can involve a complex assessment process which is hypothesized to have evolved in order for females to maximize their reproductive success. In this laboratory experiment, we examined the mate choices of female convict cichlids ( Amatitlania nigrofasciata ) (who have an extended period of mate assessment and benefit from relatively long phases of biparental care) when presented a dichotomous choice between males that they had previously observed winning or losing a fight or novel males. When winner and loser males were presented to females together, females did not show a general preference for either male, but spent substantial time alone, away from both males. When the winner male was paired with a novel male, females showed an evident preference for the winner male. Females also showed an eventual preference for the loser male when paired with a novel male, but in this case, the female spent initially more time with the novel male before shifting to the loser male. In spite of losing their initial competition, loser males were attractive to females, more so than novel males, illustrating that participation in a fight observed by a female is beneficial to the male, even if he is not ultimately victorious.

Understanding the behavioral ecology of species that involve complex interspecific interactions can significantly contribute to conservation efforts and recovery plans, especially when multiple endangered species are of concern. Here, we continue to explore the heterospecific interactions of the Leon Springs pupfish (Cyprinodon bovinus) and the Pecos gambusia (Gambusia nobilis), two endangered species critically threatened by habitat loss. It is suspected that the C. bovinus pupfish suffers from egg predation by the G. nobilis gambusia, and we therefore hypothesize that territorial male C. bovinus should defend against G. nobilis intruding on their territories. In an analysis of 3 years of observations, we found no evidence that territorial males effectively attack these egg predators, despite evidence that G. nobilis are attracted to and swarm C. bovinus spawning events. Instead, territorial male C. bovinus focus their reproductive efforts on conspecific interactions: pursuing females and aggressively attacking all males that enter the territory. The results of this observational study suggest that recovery plans should consider the lack of defense against G. nobilis and may be relevant to additional pupfish species that cohabitate with invasive species of gambusia.

Although Caribbean mixed-species herbivorous fish groups are an important component to the reef community by helping to crop algae that often overgrow and kill corals, little is known of how they organize their foraging groups. In spite of a highly flexible membership, the basic structure of these groups consists of a “core species,” that leads the group and often is either the striped parrotfish (Scarus iserti) or the ocean surgeon (Acanthurus tractus). These species lead their groups to open areas where they feed largely on low profile turf algae. Other members prefer macro algae and are termed “associate species,” of which the two common species we studied were the stoplight parrotfish (Sparisoma viride) and the redband parrotfish (Sparisoma aurofrenatum). In spite of the large difference in group sizes between Jamaica and Grand Cayman Islands, the relationships between movement patterns and compositional changes were largely consistent. There was no support for the hypothesis that these dramatic and continuous group changes were related to foraging success. Instead, we speculated that these group changes perhaps were designed to maintain cohesion among a membership that was spread over a wide area. We also examined if associates species may be more than just passive followers of core species but rather instigated the attracting or the building of core groups. Both associate species do attract striped parrotfish in open areas and thus appear active in initiating mixed-species groups. Finally, given that associate species seem to derive little foraging benefit from following core species, we tested the hypothesis that associate species joined core groups to gain protection against predators. Associate species do not selectively join the larger groups of striped parrotfish but appear to join core species randomly and the groups they joined resembled the wide assortment of core groups available in the area. Thus, while associates may be joining core groups for protection, this protection was not based on sizes of core groups.

Operational sex ratio (OSR) is predicted to influence the direction and intensity of sexual selection. Thus, as the relative numbers of reproductively active males vs females change, the behavioural competition among males and their differences in reproductive success are also predicted to change. While these outcomes seem intuitively obvious, there have been few experimental tests that examine these predictions. Here, we experimentally tested the relationship between OSR and reproductive behaviour in sheepshead minnows (Cyprinodon variegatus) competing in laboratory-based pools. Males and females were assigned to one of three OSRs (female-biased, equal, or male-biased). We monitored aggression, territory size, and number of eggs acquired by the most aggressive male, termed the “focal male,” in the pool. We used microsatellite analyses to determine the parentage of the eggs within the focal males’ territories. Focal males, by definition, were the most aggressive individual in their pools, but the degree of their aggressiveness and number of spawning sites they controlled were not influenced by OSR. Compared to focal males in the equal and male-biased OSRs, focal males in the female-biased OSR did receive more eggs but the OSR did not appear to influence the percentage of eggs they fathered on their own spawning sites. We speculate that a focal male’s competitive ability is more important to reproductive success than the number of other males and females present.

The decline in herbivorous fishes is an important contributing factor to the degradation of coral reefs, because their reduction contributes to macro algae overgrowth, which can have harmful effects on corals. Herbivorous fish often form mixed-species groups to locate foraging sites and for defense. The movements and compositions of these groups are dependent on the relative numbers of different species present. Some species, such as the striped parrotfish (Scarus iserti) and ocean surgeonfish (Acanthurus bahianus), serve as core species that lead mixed-species groups. Others, such as the redband (Sparisoma aurofrenatum) and stoplight parrotfishes (Sparisoma viride), follow core species as their associates. Despite the potential importance and abundance of mixed-species groups on reefs, little attention has been given to their composition and movements. Our intent was to determine whether the social dynamics of mixed-species groups in Jamaica were similar to those of Grand Cayman. The overall sizes of mixed-species groups were smaller in Grand Cayman. Focal striped parrotfish in Grand Cayman formed smaller groups, changed composition less, and moved less frequently than in Jamaica. Although probably more abundant than striped parrotfish, the ocean surgeonfish in Grand Cayman did not function as a core species but rather attached themselves as associates to the smaller striped parrotfish groups. Redband parrotfish moved less often in Grand Cayman, and appeared to be more dependent on striped parrotfish groups than stoplight parrotfish. While previous studies on herbivorous reef fish have shown that changes in foraging patterns can change with location, perhaps related to structural heterogeneity and resource distribution, this study illustrates that social interactions between common members of mixed-species groups also change. We suggest that the intra and interspecific social interactions in Grand Cayman are less attuned to finding erratically located high quality resources than those in Jamaica. Other plausible explanations are also considered.

Previous studies, largely on avian species, have suggested that pairs that are permanently monogamous and have biparental care develop a coordination over time that enhances offspring survival. If this is the case, we predicted that a parent involved in biparental care would develop a pattern of biparental care specific to a particular mate and remain consistent in that pattern over time but would lose this pattern if it were to change mates. We tested this prediction with the convict cichlid fish (Amatitlania nigrofasciata) which has biparental care that is both complex and flexible. In this species, each parent can perform all parental roles but typically shows a division of labor in which males typically defend against offspring predators while the female typically provides direct care to the offspring. At various times, the parents briefly switch roles. Our experiments revealed that pairs that remained together for two consecutive broods were more consistent in their parental behaviors, including time they spent near the intruder and in the nest compared to pairs that were comprised of individuals that had previously mated with other partners. Also individuals that remained with the same partner were also more consistent as a parental unit, maintaining their sex-specific roles of males defending aggressively against an intruder and females spending more time directly caring for young. While our experiment clearly support our prediction that individuals do develop unique coordination with specific individuals, convict cichlids in nature appear to be largely serially monogamous in which they mate only once before changing partners. Thus, it is likely this coordination may be available in many species that have biparental care but become adaptive when repeated matings become common.

Monogamy can be either long-term or serial, with new pairs formed with each breeding bout. Costs and benefits are associated with each strategy. Because biparental convict cichlids (Amatitlania nigrofasciata) typically switch mates, exhibiting serial monogamy, we tested for the costs associated with forcing individuals to remain with the same mate. Convict cichlids were observed over two successive breeding bouts, either with the same or a new, equally experienced, mate. Parental behavior did not differ between breeding bouts, nor did brood size. Surprisingly, fish that remained with their original partner for a second bout took significantly longer to produce a brood compared to fish that paired with new partners. New partners were also more likely to successfully produce a second brood than re-mated partners. This is in contrast to the majority of bird studies that show many benefits to staying with the same partner for multiple broods. In convict cichlids, there seems to be no benefit associated with remaining with the same partner and switching mates reduces duration between broods for both males and females, potentially increasing overall reproductive success.

1. Translocation of endangered species fromcaptivity into thewild is a common conservation practice used to bolster populations, expand natural ranges, and restore species that have been extirpated. 2. Often little is known of the fate of organisms after they are released, and extended monitoring of reintroduced populations is necessary for understanding the efficacy of this method. 3. Thought to have become extinct, the endangered Leon Springs pupfish (Cyprinodon bovinus) was rediscovered in 1965. Recently, conservation efforts have focused on renovating their natural habitat and reintroducing C. bovinus from a captive colony established in 1976 back into the ancestral habitat. 4. A reintroduction was performed in 2015, and the population was monitored over the next 14 months to ascertain whether territorial males were behaving typically for the species, and whether there were any changes in social behaviour over time. 5. An established population in nearby Diamond Y Spring was used as a benchmark for typical social behaviour, and as an indicator for any expected seasonal differences in behaviour. 6. The development of a typical social system at Monsanto Deep Pool was evident almost immediately, as males started to establish breeding territories, defend them from intruders, and participate in reproductive activities, such as courtship and spawning. The presence of juveniles within a year indicated that individuals were successfully reproducing. 7. It appears that the translocated C. bovinus are developing into a stable and reproductively successful population.

The island of Jamaica is often cited as an example of how overfishing has dramatically reduced the sizes of coral reef fishes. To examine the change in fish sizes over a 36-year period, we analyzed data from systematic surveys conducted in 1977 and 2013/14 of the sizes and relative abundances of four common algae-grazing fishes in the shallow backreef habitats of Jamaica and Grand Cayman. The four species are: striped parrotfish (Scarus iseri), stoplight parrotfish (Sparisoma viride), ocean surgeon (Acanthurus tractus) and the blue tang (Acanthurus coeruleus). We predicted that all four species would be larger in Grand Cayman than in Jamaica in 1977 as well as in 2013/14, because Grand Cayman has been cited as having less fishing pressure than Jamaica. For the same reason, we expected all four species would have declined in size over the 36 years in Jamaica but not in Grand Cayman. Furthermore, we predicted that the compressed body shape of the ocean surgeon and the blue tang would have made them especially vulnerable to net and trap fishing compared to the two parrotfishes, and that accordingly the effects of overfishing would be greater in these two species. We rejected this hypothesis. The size distributions of the laterally compressed species changed significantly on both islands over the 36-year time span, although not as predicted. At both islands, the blue tangs shifted toward smaller sizes and the ocean surgeons shifted toward larger sizes. There were no size distribution changes detected in the two fusiform species. There was also no support for the prediction that the sizes of these four species were larger in Grand Cayman than in Jamaica during either time period.

Social eavesdropping can guide mate choice and the assessment of competitor quality. In the endangered Leon Springs pupfish ( Cyprinodon bovinus ), males establish breeding territories that they defend from conspecifics and heterospecific egg predators. Females enter the breeding area to assess males and spawn in their territories. It was hypothesized that male and female C. bovinus eavesdrop on social interactions within male territories to evaluate each territorial male’s ability to exclude intruders and attract potential mates. Using a repeated design, a bottle containing either a female C. bovinus , a non-territorial male C. bovinus , a swarm of G. nobilis , or water was placed at the centre of a male’s territory. Territorial males received more spawns and females spawned more frequently per visit when a female stimulus was present. These results suggest that females eavesdrop to inform their mating decisions, but this may be limited to the assessment of extra-pair females within territories.

Damselfishes are well known for their aggressive, territorial behaviour during which the use of vocalization behaviour has been well documented. However, agonistic acoustic signalling has been understudied in particular when the vocalizations are interspecific. In this study, we characterize and compare the previously undescribed vocalization behaviour of longfin damselfish (Stegastes diencaeus), in an agonistic context, with the closely related and sympatric dusky damselfish (Stegastes adustus). Next, we examined if these congeneric species modulate their vocalizations in a similar pattern to previously described aggressive behaviour patterns. Audio field recordings of territorial males were obtained in response to three separate stimuli: (1) conspecific male damselfish, (2) heterospecific male damselfish and (3) a common intruder, the slippery dick wrasse (Halichoeres bivittatus). The vocal repertoires of both longfin and dusky damselfish comprised the same three distinct call types: chirps, pops and pulse trains. However, temporal measures of the calls showed significant differences between species. Additionally, dusky damselfish were more vocal overall, producing more calls and spending more time calling than longfin damselfish. These responses were stimulus and species dependent, as the two species modulated acoustic response by modulating pulse number based on intruder species. These results suggest that these closely related species of damselfish use vocalization behaviours that are both unique and context dependent.