Reproductive ecology of black-tailed prairie dogs in Montana

Reproductive ecology of black-tailed prairie dogs ( Cynomys ludovicianus ) was studied on the Charles M. Russell National Wildlife Refuge in northeastern Montana (1978–1980 and 1985). Breeding took place from early March through early April in most years. Persistent snow cover and below normal temperatures in February and March of 1978 delayed the start of breeding. Litter size averaged 4.4 but varied significantly among years. Average yearly litter size was correlated (r 2 = 0.986) with summer (June-September) precipitation prior to the breeding season. Largest average yearly litter size (5.0) followed record precipitation, while the smallest average yearly litter size (3.8) followed extreme drought. More than half the yearling females failed to breed while 88% of the females two years and older bred. Testes weights were greatest early in the breeding season and regressed rapidly during April.     

Population and reproductive biology of the mud crab,Macrophthalmus hirtipes (Jacquinot, 1853) (Ocypodidae), from marine and estuarine habitats

Summary

Monthly samples of the burrowing mud crab, Macrophthalmus hirtipes (Jacquinot 1853) were collected from February 1978 to April 1979 from a marine inlet, Governors Bay (43°38′S, 172°39′E) and from the Avon-Heathcote Estuary (43°33′S, 172°44′E), New Zealand. The estuarine population was generally unimodal and had an annual cycle of population change sustained by a concentrated summer recruitment. In contrast, the bay population was unimodal and bimodal at different times, and recruitment occurred thoughout the year with no clear peak. Both populations had equal sex ratios and were dominated by immature individuals (crabs?10·0 mm carapace width). Estuarine crabs were generally smaller than marine crabs.

At both sites, ovigerous females were found from late May to early March; the smallest egg-bearing female measured CW 10·0 mm at the estuary and CW 10·5 mm at the bay. Cycles of ovarian and embryological development were similar at the two localities. Three peaks of egg oviposition occurred within one breeding season and mature females were capable of producing successive broods. Fecundity was related exponentially to female carapace width and did not alter during the breeding season. Estuarine females carried more eggs than marine females of similar size. Egg volume was related to time of oviposition and eggs laid at the start of the breeding season were significantly larger than those deposited during the second half; however, estuarine eggs showed less reduction in size at this time than did marine eggs.

Estuarine sediments had higher levels of chlorophyll ‘a’, ATP, and microorganism activity and productivity than marine sediments. As M. hirtipes is a detritus feeder, the differences in food resources are believed to account for the elevated fecundity of estuarine crabs. At the bay, salinities were high with little tidal and seasonal variation, whereas in the estuary sea water was diluted significantly both daily and seasonally. The differences in salinity characteristics between the sites may be affecting larval distribution; recruitment in the estuary was concentrated to the summer and in the bay it was almost continuous.     

Seasonal abundance and life cycle of Archaeomysis articulata (Crustacea: Mysidacea) on a sandy beach of western Hokkaido,Japan

Abundance and life cycle of the sandy beach mysid Archaeomysis articulata Hanamura were investigated based on seasonal collections over 2 years in the surf-swept intertidal zone of an open sandy beach in Ishikari Bay, western Hokkaido, Japan. The number of mysids in the intertidal zone increased from winter to spring, reaching its maximum in summer to autumn (average >2500 ind. m^-2), and decreased considerably towards the end of the year. The abundance was maintained at a minimal level (<200 ind. m^-2) throughout the winter. The breeding season was March to November, during which the liberation of young was most intensive from late April to mid-October. Three alternate generations, including overwintering, spring and summer generations, were suggested from field observations. Archaeomysis articulata is primarily iteroparous; only a restricted number of breeding females could produce more than two broods. The life span was estimated to be 7–9 months for the overwintering generation and 2.5–3.5 months for the spring–summer generations. The sex ratio fluctuated at samplings, with a tendency toward female dominance (overall mean=54%). The number of embryos carried by a single female ranged from 16 to 94, tending to increase with increasing size of females. The size of egg-like embryos varied seasonally from 0.45 to 0.54mm, being largest in spring and smallest in summer, with no correlation to the length of females; water temperature is considered an important factor in regulating the size of eggs. The embryonic development time was estimated to be 1.5 months for the spring generation (water temperature 5–10°C), and much shorter than this for the summer and overwintering generations. The mortality rate during embryonic development was estimated to be 7–18%.     

Life cycle and population structure of the terrestrial isopod Hemilepistus klugii (Brandt, 1833) (Isopoda: Oniscidea) in Iran

The life cycle and population structure of Hemilepistus klugii were studied in a population in Varamin, Iran. The population was sampled monthly (or fortnightly during the breeding season) from February 2008 to June 2009 and a total of 7015 individuals, comprising 1069 males, 1079 females and 4867 juveniles, were collected. As in other Hemilepistus species, five distinct phenophases, namely pair formation, gestation, hatching, growth and stationary, were recorded during the life cycle of H. klugii. The overall sex ratio was 1 : 1 but varied over time. Ovigerous females were observed only in April, indicating a seasonal and very short breeding period. With a short lifespan after breeding, females demonstrated true semelparity. The mean cephalothorax width for ovigerous/post-ovigerous females was higher in 2008 than in 2009. These females attained the largest size in the population throughout the year. The number of eggs per female ranged from 28 to 147 (mean ± SE, 78 ± 1.8). There was a positive correlation between female size and fecundity. Recruitment occurred in late April and resulted in the highest population density in this month, whereas the lowest densities were observed during November to January. Despite a high percentage of ovigerous females carrying undeveloped eggs (72.3%), intramarsupial mortality was low (3.5%).     

Growth and development of the western harvest mouse, Reithrodontomys megalotis megalotis

Growth rates, gestation period, litter size, reproductive age, sex ratios, and development were studied on 198 litters of Reithrodontomys megalotis megalotis (Baird). Growth was characterized by several standard skull and body measurements and was partitioned into four phases of 1 &ndash; 3, 4 &ndash; 12, 13 &ndash; 22, and 23 &ndash; 70 days. Growth was best described by measurements of tail length, ear length, and dried eye - lens weight. Reproductive activity began as early as 38 days for females and 59 days for males. The gestation period was 22 days, and the mean litter size was 3.83 (range 1 &ndash; 7). Sex ratio was 53.49 percent males to 46.51 percent females. Reproductive efficiency was 53.53 percent. The development of R. m. megalotis was very similar to that of R. m. dychei. Early breeding, postpartum estrous, year - round breeding, high reproductive efficiency, and a short gestation period contribute to a high reproductive potential in R. m. megalotis. &nbsp;     

Population structure and breeding season of the hermit crab Diogenes brevirostris Stimpson, 1858 (Decapoda,Anomura, Diogenidae) from southern Mozambique

In this study the population dynamics of the diogenid hermit crab Diogenes brevirostris is evaluated focusing on size structure, sex ratio and breeding season. Crabs were randomly taken on a monthly basis from January to December 2003 at Costa do Sol, Maputo Bay, southern Mozambique. A total of 622 crabs was obtained of which 290 were males (46.6%), 170 were non‐ovigerous females (27.3%) and 162 were ovigerous females (26.1%). The overall size frequency distribution was unimodal for males, non‐ovigerous females and ovigerous females. The overall sex ratio (1:1.15) differed from the expected 1:1 ratio. Sexual dimorphism was evidenced by the larger size attained by males in relation to both ovigerous and non‐ovigerous females. Breeding took place year‐round with three peaks of spawning (March, August and December). Despite the high reproductive activity, young recruits were scarce in the population. The present results suggest that the study area is suitable for reproduction and growth whereas recruitment may take place in different areas from that occupied by the adults.     

Reproductive ecology of a Tibetan frog Nanorana parkeri (Anura: Ranidae)

Endemic to the Tibetan Plateau, Nanorana parkeri figures among the highest altitude amphibians in the world. The present work, which was conducted in an alpine marsh at 4300 m altitude, is the first report of the species’ reproductive ecology. The breeding season, as indicated by the presence of amplectant pairs and fresh eggs in ponds, lasted from early Mary to early July. The ratios of adult male to female were 1.3 in hibernation ponds and 2.3 in spawning ones. Males were smaller than females. Amplexus was typically axillary (81.7%), with a few exceptional amplexus in which a male clasped another male or object rather than gravid females. Scramble competition occurred in 6.8% of the normal amplexus located. The body sizes of amplexed couples correlated positively. Deposited eggs were attached to submerged plants solitarily (60.5%) or in small clusters (39.5%), and the scattered arrangement of individual eggs could be a strategy to ensure embryonic development in oxygen-poor environments. Clutch size averaged 189 [standard deviation (SD) = 64], and correlated positively with female body size; egg size averaged 2.18 mm (SD = 0.10), independent of female body size; both traits within a clutch were negatively related with each other even controlling for female body size. Relatively few and large eggs laid by the Tibetan frogs, compared with those by lowland aquatic-spawning anuran species, should be adaptive to the harsh high-altitude conditions. Larvae hatched from eggs after 16.4 days on average (SD = 5.8). Froglets emerged between late July and early August, but some tadpoles were present in winter. These findings may help to understand the evolution of amphibians in extreme environments and to protect these remote species.     

Breeding biology of the Sayaca Tanager (Thraupis sayaca) in southeast Brazil

ABSTRACT

Thraupis is a genus of the American endemic Thraupidae (subfamily Thraupinae), comprising seven species that inhabit tropical forests to urban centres. The Sayaca Tanager (Thraupis sayaca) is a disturbance-tolerant species of high representativeness in plant-frugivore networks, but information on its breeding biology is scarce and often restricted to non-systematic surveys. We studied the breeding biology of the T. sayaca, following 39 active nests in a periurban area of southeast Brazil during two breeding seasons (2017/2018, 2018/2019). The breeding season ranged from early September to middle December, and the nests were placed in native and exotic plants and human buildings (nest height above ground: 3.35 ± 1.73 m, mean ± SD). Only females incubated and brooded, but both adults built the nests, fed the nestlings, and removed their faecal sacs. Clutch size was 2.86 ± 0.38 eggs and nest attentiveness was 71.2%. The incubation and nestling periods were, respectively, 13.4 and 17.4 days. Males and females did not differ on nestling provisioning and nest sanitation rates. Nestling provisioning (13.35 ± 6.25 trips/hour) increased with nestling age, while mean brooding time was 37.2% and decreased with nestling age. Apparent nest success was 38.7%, and nest survival according to the Mayfield method was 27.2%. Five nests (20.8%) were parasitised by the Shiny cowbird (Molothrus bonariensis), and we recorded five events of nest-site reuse. We concluded that the most remarkable breeding traits of T. sayaca in comparison with close-related tanagers are the use of anthropogenic nest sites, the higher clutch size and number of feeding trips, and the longer nestling period.     

Breeding biology and population structure of the intertidal crab Petrolisthes laevigatus (Anomura: Porcellanidae) in central-southern Chile

The present study describes the seasonal reproductive cycle and population structure of the porcellanid crab Petrolisthes laevigatus, a typical inhabitant of the rocky intertidal. A total of 960 individuals (including 372 females) was collected in monthly samples from October 1993 to December 1994 in central-southern Chile. Ovigerous females were present between August and December, and were absent between January and July. The breeding season started during late winter (August), and females with embryos close to hatching occurred between October and end of spring (December). Considering the gonadosomatic index and the duration of the incubation period, it is concluded that P. laevigatus has a markedly seasonal breeding period with probably two successive spawnings per female per season. Our results compared with previous studies in temperate intertidal porcellanids suggest a lower structural variability of the population during the sampling period, but a pronounced seasonal variation in both sex ratio and abundance. The influence of environmental habitat conditions (i.e. temperature) is suggested to be responsible for the lower variation in the crab population size structure in ovigerous females, and the almost constant size distribution observed in males.     

Studies on the biology and ecology of the northern scorpion, Paruroctonus boreus (Girard)

An investigation to elucidate some facets of the biology and ecology of Paruroctonus boreus (Girard), in southeast Idaho, was conducted from 21 March to 13 October 1972. Three hundred and eighty - five observations were made on 202 scorpions captured in covered pitfalls and by ultraviolet light. The greatest activity occurred at 2130 hours. Surface activity was not observed when ambient temperature was below 10 C, and, as ambient temperature increased, an increase in surface activity was noted. Male scorpions frequently moved as much as 30 m between observations, while females seldom moved more than five m. Sex ratios varied considerably depending on time of year and method of sampling. Of 142 scoipions observed by blacklight, 92 were males, and 50 were females (1.84 males/female). Limited data suggest a mean litter size of 34 &plusmn; 11.     

Natural history of the Lined Seedeater Sporophila lineola (Aves: Thraupidae) in southeastern Brazil

The Lined Seedeater (Sporophila lineola) is a migratory species that inhabits a variety of open habitats in South America. We studied the breeding biology and territorial behaviour of a colour-banded population of the species in the Universidade Federal de Viçosa, Campus Florestal (1–19,8808ºS, –44,4136ºW), during two breeding seasons (2014/2015 and 2015/2016), which spans from December to April. We monitored 74 nests of this species. The nest is a low cup supported between a fork. Nests are mainly built with grass stems and rootlets, with spider-web used to hold the material together and to bind the nest to its supporting plant. Females are solely responsible for nest building and incubation, which is synchronic, and also for feeding nestlings to a large extent. Males are responsible for defending the territory, which corresponds to a small portion of the home range restricted to the nest environs, and also feed the nestlings. Mean clutch size is two eggs (78% of nests monitored), with clutches of three (20.3%) and four (1.7%) eggs also observed. Eggs are whitish, covered with dark brown blotches and spots to a variable extent. Mean incubation period, considered as the period between the onset of incubation and hatching of the first egg, is 11 days. Nestling period, considered as the period between hatching of the first egg and fledging of the last young, is 10 days. During the first breeding season, the simple percentage of successful nests was 34.1%, while the Mayfield success was 29.8%, with slightly higher values observed during the second breeding season, with 39.4% and 35.7%, respectively. We recorded, for the first time, three cases of polygamy in the species. We also recorded breeding site fidelity for the first time in the species, with males returning to the same territory owned in a previous breeding season.     

Western Scrub-Jay breeding biology in central Colorado

The breeding ecology of the Western Scrub-Jay ( Aphelocoma californica ) in the midwestern United States is relatively unknown compared with Aphelocoma species in other geographic regions. We examined Western Scrub-Jay breeding biology in Colorado between 1970 and 1992. Incubation was initiated in early April and lasted 16 days, while the nestling stage lasted approximately 17-18 days. Clutch size averaged 4.0 eggs per nest, reproductive success was 25%, and productivity averaged 0.66 fledglings per nest. The low reproductive success and productivity measures may be due to high predator densities in the surrounding suburban landscape. Western Scrub-Jays preferred nesting in eastern red cedar ( Juniperus virginianus ) with nests placed on southern exposures. Western Scrub-Jays bred monogamously and were more similar in their breeding biology to the Island Scrub-Jay ( Aphelocoma insularis ) than to the Florida Scrub-Jay ( Aphelocoma coerulescens ).     

Leucocytozoon toddi in British sparrowhawks Accipiter nisus: observations on the dynamics of infection

Leucocytozoon infection was studied in a breeding population of sparrowhawks Accipiter nisus in the British Midlands. Almost all transmission was apparently ‘vertical’ from adults to young, at the nest site. Parasites largely disappeared from the blood between October and April, reappearing in a ‘spring relapse’ during the nesting season. Infected birds remained infected for life; there was no evidence of reduced longevity in infected birds once they had dispersed from their natal nest site. There was no assortative mating between infected or uninfected males and females. It is postulated that the concentration of birds at the nest site allows transmission by a non-specific vector breeding in the same vicinity. At other times of year the birds are more regularly dispersed and transmission in unlikely to occur.     

Notes on the occurrence and biology of Xenoclarias Greenwood (Siluriformes: Clariidae) in Lake Victoria,East Africa

Summary

Xenoclarias inhabits the deeper (>50 m) waters of Lake Victoria. Specimens captured in a bottom trawl ranged in size from 10–22 cm TL (mode, 15–18 cm) and females grew to a larger size than males. Length-weight relationships between sexes were different only in the Kenya waters and resulted in significantly different KTL. Based on gonadal stages, Xenoclarias matured between 14–16 cm (age 1). Fecundity of 6 specimens (Stage VI) ranged from 744–1357 (mean 1009) and egg size from 1·45 to 1·98 mm (mean 1·79 mm).

Based on gravid and spawning females, Xenoclarias spawned prior to the rainy season (January–March) in Kenya and Uganda waters. During periods of increased reproductive activity females were consistently more numerous in samples (2:1) than males. Local meteorological and hydrological conditions may explain the apparently different spawning season in Tanzania waters of the Lake. This genus of small fish is not affected by the artisinal gillnet fishery but may be by the expansion of a bottom trawl fishery in Lake Victoria.     

Reproductive pattern in the southernmost populations of South American redbelly toads

Anurans can be classified as explosive or prolonged breeders. In species with short breeding periods, intensive competition for females is expected. We analyse the temporal breeding pattern of Melanophryniscus aff. montevidensis, a bufonid inhabiting grasslands of Argentina, whose breeding is concentrated in events of short duration. Males are active during more than one breeding event per season, whereas most females take part in a single event per season. Active males outnumbered females by up to 14 times at one event, operational sex ratio (OSR) ranged from 0.07 to 0.75 and intensity of sexual selection (I _s) from 0.69 to 24. We found a negative association between I _s and OSR, but no correlation between number of active males per event and OSR or I _s. The OSR is the key that regulates the intensity of sexual selection, nevertheless, and in spite of being explosive breeders, females would potentially have chances to select their mate.     

Sperm viability in the reproductive tract of females in a population of Sceloporus mucronatus exhibiting asynchronous reproduction

Asynchronous reproduction is a common phenomenon in high-elevation populations of lizards from Central México. Sperm storage in the reproductive tract of females is the mechanism for making oocyte fertilization possible. Our study addresses questions related to functional oviductal sperm storage of females mating on different dates throughout the reproductive season. A population of Sceloporus mucronatus with copulation in the summer and ovulation in the fall was chosen for this experiment. Eleven females that copulated in the field during June and 13 females that copulated in captivity during August were maintained in the laboratory until parturition. The number of pregnant females and the litter sizes produced in each experimental group were indicative of the viability of the stored sperm. Sperm stored in the reproductive tract of females were able to fertilize eggs after 4 months. No significant differences were found in the number of pregnant females between the 2 experimental groups nor in the litter sizes that they produced. We found that the amount of time sperm were held in the female reproductive tract (ca. 3 months) had no effect on the capacity of sperm to fertilize eggs. Histological examination of 8 oviducts collected before the mating season eliminated the possibility of sperm storage from one year to the next. In this system, sperm retention could have evolved as a response mechanism to deal with the asynchrony between sexes in the reproductive cycles. However, we cannot rule out alternative hypotheses.     

Not every drought is bad: quantifying reproductive effort in the harlequin frog Atelopus laetissimus (Anura: Bufonidae)

Atelopus laetissimus is an endemic and threatened harlequin frog from the high mountain forests of Sierra Nevada de Santa Marta, Colombia. Knowledge of its reproductive biology is essential for understanding the intraspecific interactions that can help the conservation of Atelopus species. We quantified the energy, measured in body weight, invested by males and females of A. laetissimus for reproduction, and how this energetic investment is related to the survival of individuals and rainfall conditions in habitats during two years (2014 and 2015). Our results show plasticity in terms of reproductive phenology linked to rainfall with short- and long-duration breeding strategies. The first year of this study, 2014, had a precipitation level in accordance with the annual averages at the area. During this time frogs exhibit a short breeding period. Contrary to 2014, 2015 was a year with little precipitation, below the annual averages, which probably facilitated the females’ quick spawning in the creeks and a consequent reduction in the duration of amplexus and low breeding efforts by males. This, in turn, was related to a long breeding period that favors the survival and reproduction of males during the entire year. In 2014 we found a decrease of 25% to 30% body weight of potentially reproductive males, which may be attributed to a prolonged duration of amplectant events.     

Reproductive biology of Scinax fuscomarginatus (Anura,Hylidae) in south‐eastern Brazil

The present study describes the reproductive biology of Scinax fuscomarginatus in a remnant of Cerrado in south‐eastern Brazil. Observations were made between September 2002 and March 2004 at Estação Ecológica de Itirapina, State of São Paulo, south‐eastern Brazil. Breeding activities occurred in lentic and temporary bodies of water during the rainy season. Scinax fuscomarginatus exhibited a prolonged breeding pattern and a lek mating system. Males were smaller than females and defended individual calling areas through acoustic and physical interactions. Resident males consistently won encounters, but did not differ in size or mass from intruder males. Satellite behaviour was observed, but no female or amplected pair interception was registered. Scinax fuscomarginatus exhibited low operational sex ratios and the general reproductive mode in which eggs are laid in the water and tadpoles are aquatic. Amplexus was axillary and the eggs were deposited at the bottom of temporary ponds. Details on oocytes, egg masses, and eggs are included.     

Life history of the Lahontan cutthroat trout, Salmo clarki henshawi, in Pyramid Lake, Nevada

Normal 0 false false false EN-US X-NONE X-NONE MicrosoftInternetExplorer4 st1\:*{behavior:url(#ieooui) } /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin:0in; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-fareast-font-family:"Times New Roman"; mso-fareast-theme-font:minor-fareast; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:"Times New Roman"; mso-bidi-theme-font:minor-bidi;} The Pyramid Lake Lahontan cutthroat trout ( Salmo clarki henshawi ) population was sampled on a monthly basis from November 1975 through December 1977. A subsample of 676 trout, stratified by fish size and lake habitat, provided biological data. The entire population is presently derived from hatchery production, stocked at lengths of approximately 75 to 300 mm. Peak annulus formation occurs in March and April, followed by the period of maximum growth. Scale patterns illustrate a variable growing season. Maximum growth in length is in the first three years of life; after that males begin to grow faster than females. Males attained a greater age in our sample; i.e., the oldest male was seven years old compared to six years for females. The Pyramid Lake Lahontan cutthroat trout exhibit nearly isometric growth. The legal sport fishery removed 380 mm); other decimating factors are poorly understood. No evidence of the following diseases or pathogens was found in the Pyramid Lake population, presuming a carrier incidence of 2 percent at the 95 percent confidence level: infectious pancreatic necrosis, infectious hematopoietic necrosis, viral hemorrhagic septicema, bacterial kidney disease, enteric redmouth, furunculosis, whirling disease, blood fluke; however, 7 of 235 (&asymp;3 percent) adults sampled at the Marble Bluff fishway were positive for furunculosis. Small trout feed primarily on zooplankton and benthic invertebrates; cutthroat trout >300 mm are piscivorous, feeding almost exclusively on tui chub ( Gila bicolor ). The spawning migration of Pyramid Lake cutthroat trout to the Marble Bluff egg taking facility in spring 1976 and 1977 peaked in April and May. Females mature at three or four years (352&ndash;484 mm), and males mature at two or three years (299&ndash;445 mm). Mean diameter of mature eggs is 4.51 mm; both ovum size and fecundity are a function of fish size. Fecundity ranges from 1241 to 7963 eggs, with a mean of 3815. Lahontan cutthroat trout comprise     

Hispid cotton rat ( Sigmodon hispidus ) in Nebraska: distribution, reproduction, and seasonal activity

The hispid cotton rat ( Sigmodon hispidus ) has occurred in Nebraska for about 50 years and entered the state from the south via northward movements through Kansas. However, little is known about its status or distribution in the state in recent decades. We conducted surveys for S. hispidus in southern Nebraska at historical sites and sites without previous records to determine its current status. From 2004 to 2008, we documented cotton rats at 9 of 12 historical sites in south-central and extreme southeastern parts of the state, and we captured this species at 13 new sites in southwestern and south-central Nebraska. In the past 3 decades, the distribution of S. hispidus has expanded westward but not northward in the state. An explanation for such a shift is unclear. At this northern edge of its geographical range, pregnant females were captured from early April to early October, and nonreproductive females were captured from November to January. Males with enlarged testes occurred from late March to September. Aspects of its natural history in Nebraska are similar to those reported in Kansas.