Prolonged Breeding Season Research Articles

Vocalization and territorial behaviour of Phyllomedusa nordestina Caramaschi, 2006 (Anura: Hylidae) from southern Bahia, Brazil

Territoriality is common among amphibians with a prolonged breeding season and can be expressed through the defence of territories with vocalizations and aggressive interactions. The present study aims to describe the territorial behaviour of male Phyllomedusa nordestina, test whether the physical characteristics of males influence the results of disputes, and describe the vocalizations of the species. The study was conducted at temporary and permanent ponds located in the Ecological Reserve Michelin, Igrapiúna, Bahia, Brazil. Male P. nordestina defended territories and showed aggressive behaviour, consisting of vocal disputes, chasing and physical fighting. Winners were not bigger, heavier, or in better condition than the losers. The victory may be associated with the vocalization activity. Three types of vocalizations were recorded: the advertisement call, composed of one or two multipulsed notes, and two types of territorial calls. We also report on male patrolling behaviour and habitat use.

The superpopulation approach for estimating the population size of 'prolonged' breeding amphibians: Examples from Europe

AbstractIndividual members of a population of 'prolonged' breeding amphibian species are asynchronously present at their breeding sites. Therefore, population size estimates can be misleading when based on commonly used closed or open-population capture-mark-recapture approaches. The superpopulation approach, a modified Jolly-Seber model, has been successfully applied in taxa other than amphibians with distinct migratory behaviour and where individuals are asynchronously present at the sampling site. In this paper, we suggest that the superpopulation approach is a useful population size estimator for 'prolonged' breeding amphibian species. Two case studies on European anurans show that superpopulation estimates are much higher than simple population counts. A simulation study showed that superpopulation estimates are unbiased but that accuracy can be low when either survival or detection probabilities (or both) are low. We recommend the superpopulation approach because it matches the natural history and phenology of amphibian species with prolonged breeding seasons.

Impact of Weather on Breeding Success of the Eurasian KestrelFalco tinnunculusin a Semi-Arid Island Habitat

In semi-arid ecosystems, rainfall and temperature induce changes in the food chain and affect breeding conditions of raptors. We examined the influence of rainfall and temperature on the breeding success of the Eurasian Kestrel Falco tinnunculus inhabiting xerophytic scrub on Tenerife Island, Canary Archipelago. Reproductive performance was recorded during five years, and food availability (arthropods, lizards, mice and birds) was monitored monthly during a wet and a dry breeding season. We found that increased rainfall in the previous autumn was associated with an earlier laying date and a more prolonged breeding season. Mean clutch size showed a positive correlation with rainfall in the month prior to laying. Hatching and fledgling success did not vary significantly between a wet and a dry year. Temperature did not influence breeding parameters. Despite the advanced laying date and larger clutch size observed, high prey availability during egg formation in the wet year did not result in higher overall breeding success. Stable between-year number of fledglings coincided with stable prey availability during the nestling or fledgling periods. Food conditions in the dry year were more stable and attuned to harsh weather conditions regardless of rainfall during the previous autumn and pre-breeding period.

Interspecific variation in fear responses predicts urbanization in birds

Urbanization and domestication share features in terms of characters that are favored by selection. These include loss of fear of humans, reduced corticosterone levels, prolonged breeding seasons, and several others. Here, I test the hypothesis that urbanization results from differential colonization of urban areas by species with heterogeneous levels of fear in the ancestral rural populations, followed by a reduction in variance in fear responses with a subsequent increase in diversity of fear responses as urban populations become adapted to the urban environment. Using information on variance in flight initiation distances (FIDs) when approached by a human, I show that rural populations of birds characterized by short mean flight distances and large variances in flight distances differentially colonized urban areas. As a consequence of this urban invasion, urban populations lost variation in FID. The variance in FID was initially larger in rural than in urban populations but eventually became larger in urban populations with time since urbanization. This secondary increase in variance in FID of urban populations was associated with an increase in population density of urban populations, suggesting that as birds became adapted to urban areas, they secondarily gained variance in behavioral flexibility.

Evaluating the reproductive cost of migration for females in a partially migrating pond‐breeding amphibian

AbstractPopulations of animals with resident and migratory individuals provide an ideal system for addressing questions concerning the evolution of migration. Partially migratory populations may persist because residents and migrants have equal fitness or because migration is based on conditional asymmetries. Studies measuring the costs and benefits of migration provide empirical data to test hypotheses concerning the maintenance of partial migration within a population. In this study, we measured the reproductive differences between resident and migrant females in a pond‐breeding amphibian, the red‐spotted newt Notophthalmus viridescens. We used large field enclosures to repeatedly sample egg laying over the prolonged breeding season of this species. Resident females did not lay a greater number of eggs or begin laying eggs earlier, despite beginning the breeding season earlier and having a higher mass than migrant newts. The only difference in reproduction we detected was that the eggs of resident females hatched into larger larvae compared with the larvae of migrant females. We discuss this result in the context of other potential trade‐offs between residency and migration. This study illustrates the phenology of egg laying of N. viridescens and our results contribute to understanding the population dynamics of partially migratory species.

Superb fairy-wren males aggregate into hidden leks to solicit extragroup fertilizations before dawn

Female superb fairy-wrens Malurus cyaneus initiate extragroup fertilizations by forays to the territory of preferred males, just before sunrise, 2--4 days before egg laying. Over a prolonged breeding season, males advertise their availability to foraying females by singing during the dawn chorus. Here, we show that 1) males commence dawn advertisement at the same time of the year regardless of their quality or status; 2) subordinate males advertise by singing in close proximity to the dominant, or by using the dominant's song perch, despite inevitable punishment; 3) low-quality dominants and their helpers sing from the boundary of their own territory, which increases their proximity to attractive neighboring dominants; 4) each spatial cluster of males use a common dialect of a song that is implicated in extragroup choice, despite the ability of individual males to sing several dialects; and 5) there is leakage of paternity to lower-quality helpers and neighbors as a result of their satellite behavior. Collectively, these data suggest that Wagner's hidden lek hypothesis (Wagner RA, 1998. Hidden leks: sexual selection and the clustering of avian territories. In: Parker PG, Burley NT, editors. Avian reproductive tactics: female and male perspectives. Ornithological Monographs No. 49. Allen Press. p. 123--145) can be extended to birds that defend year-round all-purpose territories and that mating induced by parasitic behavior of low-quality satellites can be one explanation for polyandry in birds. Copyright 2009, Oxford University Press.

Pattern of Wing Moult and Its Relationship to Breeding in the Eurasian Stone-CurlewBurhinus oedicnemus

The timing, duration and pattern of the poorly documented wing moult in the Eurasian Stone-curlew Burhinus oedicnemus were described and related to the breeding cycle. Between 1998 and 2007, 141 birds were trapped in the Taro River Regional Park (Parma, Italy) both while incubating and during the post-breeding season. The timing of primary moult was estimated according to the method of Underhill & Zucchini (1988) and Underhill et al. (1990). Primary moult was very slow and overlapped most of the breeding season, beginning in early May and ending in October. Secondary moult was much more irregular and was not completed within a single moult cycle. Innermost and outermost secondaries were more likely to be shed than those at the centre of this tract. Juvenile secondaries were not shed during the first winter. The study provides the first detailed analysis of wing moult in the Eurasian Stone-curlew and suggests some useful ageing criteria based on the pattern of secondary moult. The extensive overlap between breeding and moulting is relatively uncommon compared to other waders. This could be interpreted as a way to maximize breeding success through renesting potential (up to 4 attempts), i.e. by spreading the cost of moult over a prolonged time period. A between-species comparison using independent contrasts was consistent with this hypothesis: species with a prolonged breeding season also showed considerable overlap in the timing of primary moult and breeding activities.

Seasonal reproduction in male pichis Zaedyus pichiy (Xenarthra: Dasypodidae) estimated by fecal androgen metabolites and testicular histology

Poaching poses a threat to a wide variety of wildlife, and basic information about the biology of hunted species needs to be collected before their populations decline to the extent that requires drastic human intervention. As the survival of a species is related to its ability to reproduce, data on its reproductive cycle are necessary for the development of management strategies. The hypothesis was tested that the reproductive season of pichis ( Zaedyus pichiy), small hibernating armadillos that inhabit arid environments in Argentina and Chile, is limited to spring months. Gonadal competence of semi-captive and wild-caught male pichis of Mendoza Province, Argentina was studied, by measuring fecal immunoreactive testosterone concentrations and evaluating spermatogenic activity. Results suggest that Z. pichiy is a seasonal breeder that regulates reproduction through photoperiodic cues. Gonadal competence was limited to a period of 3–5 months in spring and early summer and was reflected in enlarged testes, increased spermatogenesis, and significantly elevated fecal immunoreactive testosterone concentrations. The reproductive season for males from southern Mendoza was almost 6 weeks shorter than in the north. This fact, along with significant morphological differences between both groups, suggests that northern and southern pichis belong to two distinct populations. It is concluded that prolonged breeding seasons and more favorable environmental conditions in northern Mendoza favor a prolongation of the reproductive season that may allow pichis to breed later in the year, thus maximizing reproductive opportunities.

Recent Advances in the Behavioral Ecology of Tropical Birds

Tropical birds offer unique opportunities to test ecological and evolutionary theory because their life history traits are so diverse and different from temperate zone models upon which most empirical studies are based. We review recent studies on the behavioral ecology of tropical birds, studies that explore new advances in this field. Life histories and their evolution remain the focus of research on tropical birds. Clutch size manipulations in two species showed that food limitation does not explain small clutch size. In antbirds, enlarged clutches decreased post-fledging survival whereas in thrushes, enlarged broods were costly due to high nest predation. Small clutches may be favored via different ultimate selective forces and shared underlying tradeoffs between the immune, metabolic, and endocrine systems in the body may account for the commonly observed ‘slow pace of life’ in tropical birds. The physiological tradeoff between testosterone and immunocompetence may explain the evolution of low testosterone levels in tropical passerines where adult survival is paramount. In contrast to life history theory, few studies have explored temperate-tropical differences in territoriality, mating systems, and song function. The idea that low breeding synchrony in tropical birds is associated with low levels of extra-pair fertilizations was supported by several new paternity studies conducted on tropical passerines. Seasonally breeding tropical birds have higher testosterone levels than tropical birds with prolonged breeding seasons, although it is unclear if this pattern is driven by mating systems per se or selection from pathogens. Recent work on relations between pair members in permanently paired tropical passerines focuses on the question of mate defense versus territorial defense and the extent of cooperation versus selfish interests in inter-sexual relations.

Resolving the population status of Ascension FrigatebirdFregata aquilausing a ‘virtual ecologist’ model

The Ascension Frigatebird is an island endemic whose conservation status was subject to confusion owing to difficulties in counting and misinterpretation of data. Accurate nest counts for this species are problematic owing to their extremely prolonged breeding seasons, high nest failure rates, turnover of individuals at nest‐sites, replacement laying and biennial breeding. We conducted repeated complete censuses of Ascension Frigatebird eggs at the species’ sole colony of Boatswainbird Island, and collected data on laying phenology and nest survival rates within sample quadrats, throughout the 2001 and 2002 breeding seasons. We used these data to develop an individual‐based model that predicted the number of Frigatebird nests present on each day an actual census occurred assuming an arbitrary 1000 breeding females bred there. We then divided the number of nests counted in these virtual censuses by 1000 to quantify bias, and used this figure to correct real census totals. The model revealed that the population numberedc.6250 breeding females andc. 9350 mature females in 2001–2, and that numbers have not changed significantly since the late 1950s. Productivity, at 0.34 chicks/pair, was high compared to previous studies of Ascension Frigatebirds and most of those of congeners elsewhere.

Reproductive Season of the Scalloped Spiny Lobster Panulirus homarus Along the Coast of Oman: Management Implications

The spiny lobster Panulirus homarus is widely distributed in the Indo-West Pacific. Along the coast of Oman it supports an artisanal fishery using traps and tangle nets. The egg-bearing incidence of females caught between 1989 and 2006 were analysed relative to month, lobster size and location of capture. The smallest female with external eggs had a carapace length (CL) of 54.6 mm, but only 9–18% of females of 60–69 mm CL carried eggs. This percentage increased significantly above 70 mm CL, and on average, 63% of individuals >90 mm carried eggs. Egg-bearing increased seasonally at the onset of the SW monsoon in May and June, when wind-driven upwelling reduces inshore water temperatures and increases primary productivity. The reproductive season extended over a 9-month period up to January, with a pause in February to April. No geographical gradient in egg-bearing seasonality was observed. The prolonged breeding season with multiple broods in large females conforms with the typical pattern of tropical palinurids. The 2-month open fishing season (15th October to 15th December) falls within the breeding season, and may be more optimally placed in February to April.

Individual Male Calling Pattern and Male Mating Success in the European Treefrog (Hyla arborea): Is there Evidence for Directional or Stabilizing Selection on Male Calling Behaviour?

AbstractIn anurans, call properties are commonly classified based on within‐male variability as being either static or dynamic. Numerous playback experiments in the laboratory have indicated that female preferences based on dynamic call properties are usually strongly directional, while female preferences based on static call properties are often stabilizing or weakly directional. However, there are only few studies demonstrating that female preferences for high values of dynamic call properties indeed exert directional selection on male calling behaviour in natural populations. Moreover, field studies investigating whether female preferences for values of static call properties around the mean of the population lead to currently operating stabilizing selection on male calling patterns in natural populations are completely lacking. Here I investigate for two consecutive breeding seasons male calling patterns and male mating success in a population of individually marked European treefrogs (Hyla arborea), a hylid frog with prolonged breeding season and a lek mating system. Individual male calling pattern as analysed in terms of seven temporal and spectral call properties did not differ between males that survived from one breeding season to the next and those not surviving. None of the seven call properties investigated differed significantly between mated and unmated males, indicating that there is no strong directional selection on male calling behaviour in the study population. However, in one study season males that produced calls with a number of pulses around the mean of the population were significantly more likely to obtain matings than males that produced calls with a number of pulses at the low or high end of the distribution. Thus, this study provides preliminary evidence for the operation of stabilizing selection on a static call property (i.e. the number of pulses per call) in a natural population of an anuran amphibian.

Sexual selection in the lek-breeding European treefrog: body size, chorus attendance, random mating and good genes

Variation in male reproductive performance and success was studied over 2 years in a population of individually marked European treefrogs, Hyla arborea , a hylid frog with prolonged breeding season and a lek mating system. Reproductive success in males was not related to body size, age or growth rate, and there was no evidence for size- or age-assortative mating. Male mating success was significantly correlated with chorus attendance, that is, the number of nights spent calling at the breeding site. There were no significant differences with regard to body size, age or growth rate between males surviving to the next breeding season and those not surviving. However, surviving males showed a significantly higher chorus attendance than nonsurviving males, which is a novel finding for lekking anurans. Furthermore, males that survived from the previous breeding season spent significantly more nights calling at the breeding site than males that were observed for the first time. Since calling in frogs is costly, these results suggest that chorus attendance reflects male quality. The distribution of male mating success did not differ from a Poisson distribution, indicating a random mating pattern. Since male quality is related to chorus attendance, females that mate randomly are likely to mate with high-quality males and thereby gain indirect genetic benefits without incurring costs of extended mate searching and mate assessment. We suggest that a similar mating pattern is found in many lek-breeding hylid frogs in which male mating success is mainly determined by chorus attendance.

Vocalizations and Reproductive Behavior of Male Pickerel Frogs, Rana palustris

I performed playback trials with and recorded vocalizations of male Pickerel Frogs, Rana palustris, in 1992–1993 and 1998–2000 at sites in Delaware and Pennsylvania. I also conducted a mark-recapture study of one population throughout its 1998 breeding season at the Ashland Nature Center, Delaware. Rana palustris had a prolonged breeding season with chorusing occurring over more than one month on nights that the air temperature was at least 8°C. Individual males during the breeding season participated in most choruses, were faithful to specific calling sites, and lost body mass. In the playback trials, I recorded male vocalizations during control conditions and after the playback of one conspecific advertisement call. Males had a complex vocal repertoire consisting of at least three call types: an advertisement call and two additional calls (“snicker” and “growl”) that were elicited by the playback stimulus or exchanged during natural male-male interactions. The three call types had distinct combinations of duration and pulse rate, and the snicker and growl had similar dominant frequencies that were significantly lower than those of the advertisement call. All males in the playback trials eventually returned to advertisement calling; however, these calls differed from the calls emitted during the control period in that they had shorter durations, longer rise times, and a shift of energy toward lower frequencies. Several males responded to the stimulus by emitting a series of underwater calls before returning to the water's surface and calling into the air. Overall, R. palustris has a complex communication system in terms of number of call types, the ability to alter call properties, and the ability to vocalize in both air and underwater.

Effects of temperature and precipitation on a flood plain isopod community: a field study

Effects of a changing climate at individual, population and community levels on biocoenoses will cause profound changes in ecosystem functioning. Considering detritivore communities, we expect severe impacts on the balance of nutrient input through annual leaf fall and nutrient cycling through leaf litter decomposition. Thus, fluctuations of detritivore populations under changing climatic conditions will affect the degradation of detritus. Monitoring populations of four isopod species, that represent the most abundant detritivores in a floodplain forest near Cologne, Germany, revealed three distinct patterns of breeding phenology. Porcellio scaber and Philoscia muscorum breed early in the season (late spring to summer), while Oniscus asellus breeds during summer and early fall. Hyloniscus riparius appears to have a prolonged breeding season, ranging from spring to fall. Over 5 years, I observed effects of annual variations in temperature and precipitation on isopod populations and the composition of the community of these detritivores. With respect to the onset of breeding and to overall population size, as estimated from the number of captured individuals, summer and winter temperature proved to be particularly important, while temperature during fall and spring had little influence on isopod number or phenology. Considering precipitation, mostly summer and spring were of importance, whereas fall and winter precipitation only played a role in determining phenology but did not influence population densities. Predominant effects of climatic factors were low population densities of P. scaber, P. muscorum and O. asellus after warm winters and moist springs and during dry summers, while moist springs increased numbers of H. riparius. After moist springs, in turn, P. scaber and O. asellus started breeding earlier than after dry springs. According to the present field data, isopods (and maybe other detritivores) will be affected by regional climate change in that numbers will be reduced in response to increasing winter temperature, more intense precipitation during spring and dry summers as predicted by current climate models. Thus, climate change will result in reduced faunal contributions to decomposition processes that, in turn, will lead to slowed-down microbial degradation of detritus and nutrient cycling.

TESTS FOR COMPETITION, CANNIBALISM, AND PRIORITY EFFECTS IN TWO PHYTOTELM-DWELLING TADPOLES FROM MADAGASCAR1

Anurans that breed in plant-held water bodies (phytotelmata) often have larvae with unique modifications for surviving in micro-aquatic environments. These larvae are exposed to severe abiotic conditions (e.g., food limitation, low dissolved oxygen levels, risk of desiccation), and multiple cohorts are frequently found in the same container. To test for cannibalism and interactions among cohorts in two phytotelm-dwelling anuran larvae (Mantidactylus bicalcaratus and M. punctatus) from Madagascar, I reared larvae in experimental microcosms. Larvae of both species had significantly faster growth rates in a high detritus treatment compared to the control (P < 0.0001). The experimental evidence also demonstrated that the larvae of these two species display no cannibalistic behavior, regardless of multiple cohorts, sibling relationships, density, or food and water levels. These data indicate that larvae of both species obtain most or all of their nutrition from eating detritus and the organisms associated with detritus. In M. punctatus, experiments with multiple cohorts indicate that competition for food is strongest within, not among, cohorts, and I found no evidence for a priority effect. Relatively low stage-specific mortality, along with a prolonged breeding season, philopatry, and a lack of predatory behavior, may explain why cannibalistic behavior has not evolved in these species.

Is reproduction of the Australian house mouse (Mus domesticus) constrained by food? A large-scale field experiment.

Food quantity and especially food quality are thought to be key factors driving reproductive changes in the house mouse, Mus domesticus, leading to outbreaks of house mouse populations in the Australian grain-growing region. Characteristic changes during an incipient mouse plague are an early start of breeding, a high proportion of females breeding at a young age and a prolonged breeding season. We conducted a large-scale food manipulation during an incipient mouse plague, which started with early breeding and relatively high spring numbers of mice. We measured background food availability in four farms throughout the study and conducted a food manipulation experiment from November to March in two of them. After harvest in December 100-200 kg/ha spilled grain remained in the stubble. This was depleted by March. In two treatment farms we added high-protein food pellets on a weekly basis between November and March and two farms served as controls. We measured changes in mouse numbers by capture-mark-recapture trappings and changes in reproduction by scoring embryos and recent placental scars at necropsy. Mouse numbers did not differ between treatments and controls. There were no differences in the litter size or the proportion of females breeding between treatments and controls. We observed the normal pattern of high litter size in spring and decreasing litter size towards the end of summer in treatments and controls. In all farms reproduction stopped in March. Mouse numbers were high but not at plague densities. Contrary to our prediction we did not observe food constraint affecting the reproduction of female mice. Our field experiment seems to rule out food quality as the driving factor for improved reproduction and formation of an outbreak of mice. We suggest that physiological mechanisms in mice might not enable them to take advantage of food with a high protein content in arid summers in southeastern Australian grain fields because of the lack of free-standing water.

Life-history strategies of native and introduced fish species from a Mediterranean lake

AbstractSeven life-history traits were used to describe the life-history strategies of 12 native and introduced species from a permanent lake in Spain. Multivariate analysis identified a continuum of life-history patterns between two extremes: 1) species with one or few spawnings per year, short breeding season, long generation time, large size, high fecundity, and no parental care. This set of life-history traits corresponded to the periodic life-history strategy described by Winemiller (1989) and Winemiller and Rose (1992); and 2) species with multiple spawnings per year, prolonged breeding season, short generation time, small size, low fecundity, parental care, and small to medium size of eggs. This association of life-history traits corresponded to the opportunistic life-history strategy described by Winemiller (1989) and Winemiller and Rose (1992). It seems that there were no apparent differences in life-history strategies between native and introduced species in Lake Banyoles. Native and introduced species were found among periodic and opportunistic strategists. Observed differences in the success of native and introduced species with comparable life-history strategies seems to suggest that the success of fish species in Lake Banyoles could not be explained on the basis of life-history features. Nevertheless, it seems that successful invasive species in Lake Banyoles display a suite of traits such as high fecundity, late maturity, and large body size. These characteristics may perhaps be viewed as biological predictors of successful invaders but more information is needed about life-history features of successful introduced species from other ecosystems.

THE VOCAL BEHAVIOUR OF MALE EUROPEAN TREEFROGS (HYLA ARBOREA): IMPLICATIONS FOR INTER- AND INTRASEXUAL SELECTION

[Calls and calling behaviour were studied over two years in a population of individually marked European treefrogs ( Hyla arborea ), a hylid frog with a prolonged breeding season and a lek mating system. A mean daily air temperature of 4.5°C and a nightly water temperature of 9°C were found to represent lower thresholds for nightly calling activity. Large choruses started calling earlier and showed a longer nightly duration of calling activity than small choruses. Temporal properties of advertisement calls were determined mainly by water temperature, which explained up to 88% of the observed variation. Dominant frequency was determined mainly by male body weight, which explained 20% of the observed variance. Within-bout call rate, call duration, pulse period, number of pulses per call and dominant frequency showed little within-male variability, but overall call activity and the number of calls per call bout varied considerably between different recordings of the same individual males. Statistically significant differences between different males were found for withinbout call rate, call duration, number of calls per call bout, number of pulses per call, and dominant frequency. Observed patterns of variability in call properties are discussed in the context of possible implications for female mate choice and male-male recognition., Calls and calling behaviour were studied over two years in a population of individually marked European treefrogs ( Hyla arborea ), a hylid frog with a prolonged breeding season and a lek mating system. A mean daily air temperature of 4.5°C and a nightly water temperature of 9°C were found to represent lower thresholds for nightly calling activity. Large choruses started calling earlier and showed a longer nightly duration of calling activity than small choruses. Temporal properties of advertisement calls were determined mainly by water temperature, which explained up to 88% of the observed variation. Dominant frequency was determined mainly by male body weight, which explained 20% of the observed variance. Within-bout call rate, call duration, pulse period, number of pulses per call and dominant frequency showed little within-male variability, but overall call activity and the number of calls per call bout varied considerably between different recordings of the same individual males. Statistically significant differences between different males were found for withinbout call rate, call duration, number of calls per call bout, number of pulses per call, and dominant frequency. Observed patterns of variability in call properties are discussed in the context of possible implications for female mate choice and male-male recognition.]

Reproduction in an Introduced Population of the Brown Anole, Anoles sagrei, from O'ahu, Hawai'i

The reproductive cycle of an introduced population of the brown anole, Anolis sagrei, from O'ahu, Hawai'i, was studied from a histological examination of monthly samples collected July 1999 to June 2000. Males undergo a seasonal testicular cycle in which all males > 38 mm snout-vent length are in spermiogenesis from January to August. Although some ovarian activity was found in all months, the period of greatest ovarian inactivity was October- December, which corresponds to the time of male gonadal regression. The reproductive cycle of A. sagrei in Hawai'i resembles that of populations in Belize, Florida, and Jamaica, where minimum gonadal activity was recorded from November through February. Body sizes at reproductive maturity were similar in all four localities. Anolis sagrei in Hawai'i has an ovarian cycle typical of other Anolis lizards with a prolonged breeding season and production of single eggs in succession. Because A. sagrei has been in Hawai'i for only approximately 20 yr, sufficient time has not elapsed to allow evolution of its reproductive cycles, but this study presents baseline reproductive data that can be used for future studies to see if the A. sagrei reproductive cycles are modified as the lizards adapt to the environmental conditions of their newly colonized range.