Spatiotemporal pattern of local sexual segregation in a tree-dwelling temperate bat Myotis daubentonii

Sexual segregation is a common phenomenon in temperate bats, but little is known about driving forces or spatiotemporal patterns. Sexual segregation of the tree-dwelling Daubenton’s bat (Myotis daubentonii) was analyzed. Day roosts and foraging areas of radio-tracked animals were recorded during late spring, early summer, and late summer. Home ranges were calculated for each sex based on identified locations. Distance analysis between sex-specific roosts and foraging areas was conducted for each period. Mixed colonies were confirmed by trapping at roosts. Home range of males was larger (47.3 km²) than of females (9.7 km²). During late spring, distances between male and female roosts were larger (median = 715 m) than during early (median = 474 m) and late summer (median = 489 m). Distances between sex-specific foraging areas were larger during early summer (median = 2,134 m) than during both late spring (median = 1,116 m) and late summer (median = 628 m). The proportion of males in mixed groups increased from late spring (0.2 ± 0.1) to late summer (0.5 ± 0.2). These results show that sexual segregation is not static, but depends on energetic demand of individuals and mating willingness. A high energetic demand in females and low mating willingness in both sexes leads to distinct sexual segregation during late spring. When mating willingness increases, despite an increasing energy demand in males, sexes aggregate to mate.     

Costs of breeding status in the European badger, Meles meles

Compared with other mammals, reproduction is expected to be particularly costly for European badgers ( Meles meles L.) since both the gestation and mating periods occur in the winter when the animals are inactive and feed little. This paper assesses the costs of breeding status in both male and female badgers, in terms of body condition, ectoparasite load, haematology and mortality. By the end of the lactation period (May), breeding females had suffered a marked loss in body condition, although there was no such cost associated with gestation. However, females regained the weight that they had lost by the autumn following lactation. Lactating two-year-olds experienced a higher age-specific mortality than those that did not breed, but there was no difference among older females. No costs of breeding status could be detected among males at the end of the spring mating period. However, breeding males sustained testicular activity later into the summer than non-breeders, and by the autumn they had acquired more bite wounds and become anaemic. This suggests that there was a physiological cost associated with extended testicular activity in breeding males.     

Seasonal influence on fecal immunoreactive testosterone concentrations of male Formosan black bears (<Emphasis Type="Italic">Ursus thibetanus formosanus</Emphasis>)

We investigated the effect of seasonal influence and geographic location on the testosterone concentrations of three adult male Formosan black bears kept at a Low Altitude Experimental Station, simulating natural breeding conditions. Estimations of fecal testosterone for males 1, 2, and 3 were made during January to October 2000, April 2001 to December 2003, and April 2002 to December 2003, respectively, using non-invasive enzyme-linked immunosorbent assays. Results indicated that fecal immunoreactive testosterone recrudesces after winter and ceases after summer. Mating behaviors were observed both before and after the fecal immunoreactive testosterone peak of March–May. In addition, fecal immunoreactive testosterone concentrations were significantly (p < 0.01) higher during January to June than from July to December. As expected, levels corresponded to the longer and earlier breeding seasons of subtropical zones. Formosan black bears appear to be seasonal breeders who breed primarily in spring, synchronized with sunlight and ambient temperature. The aim of this study was to determine if testosterone concentrations respond to seasonality thereby reflecting bear mating demands. Baseline parameters established in this study will help to evaluate endocrine information applicable for guidelines in future management and preservation of Formosan black bears in the field. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Spatio-temporal ecology and density of badgers <Emphasis Type="Italic">Meles meles</Emphasis> in the Swiss Jura Mountains

This study reports for the first time data on the spatio-temporal ecology of badgers living in a cold and wet mountain region (Swiss Jura Mountains). The home range, movements, activity patterns and habitat use of three badgers (two males, one female) were examined using radiotelemetry. Average home range size was 320 ha (MCP 100%), but the ranging behaviour of badgers varied at a seasonal scale. As in other regions, badgers were strictly nocturnal or crepuscular and showed a marked reduction of activity in the winter period. From spring to autumn, animals were active for an average (±SD) of 8.1 ± 2.4 h and travelled up to 9,460 m each night (mean±SD, 5,160 ± 2,600 m). The nightly distance travelled by badgers was positively correlated with their travel speed, the duration of the activity period and the used area, but not with night length. Year-round, the radio-collared animals avoided pastures and the vicinity of houses during their night trips. In winter and spring, individual badgers used forests and wooded pastures more than expected according to their availability, whereas cereal fields were actively selected in summer and autumn. Den-watching, night-lighting and radio-tracking data suggest that badgers live in pairs in this wet and cold region. Population density estimates range from 0.4 to 1.5 individuals/100 ha. We discuss the importance of trophic resources and climate as factors influencing badger behavioural ecology.     

Urinary hormone analysis assists reproductive monitoring and sex identification of bell frogs (Litoria raniformis)

With the world currently facing a global amphibian extinction crisis, the development of techniques to help meet the needs of conservation managers and researchers studying the reproductive biology of amphibians is needed. Here, we developed enzyme immunoassays to measure estrone, testosterone, and progesterone hormone metabolites in the urine of Litoria raniformis, the southern bell frog. Concentrations of urinary estrone, testosterone, and progesterone increased during the breeding season for females (P < 0.05). Concentrations of urinary testosterone and progesterone increased for males during the breeding season compared with that for months where no reproductive behaviors were observed (P < 0.05). Furthermore, urinary estrone concentrations proved to be a reliable sexing tool for adult frogs, with no overlap between the sexes in 98% of cases, regardless of season. There was no difference in estrone (P = 0.204) or testosterone (P = 0.485) metabolite concentrations between samples taken immediately upon capture and those taken 12 to 24 h later from the same individual. Progesterone metabolite concentrations were lower on Day 2 than upon collection (P = 0.004). This is the first study to show that urinary hormone analysis can be a useful technique for reproductive monitoring in an amphibian. Additionally, hormone metabolite measures offer promise as sex identification tools for monomorphic species and for those whose secondary sex characteristics are visible only during the breeding season.     

Characteristics and seasonal variation in the semen of Markhoz bucks in western Iran

The aims of the present study were to evaluate if seasonality in semen characteristics and plasma testosterone concentrations exist in Markhoz male goats. Ten Markhoz (Angora) bucks were housed and fed according to standard recognized practices. During the observation period, semen was collected monthly with the aid of an electro-ejaculator and examined microscopically immediately after collection. Physical parameters of semen and the semen index were recorded. Blood samples were also taken monthly throughout the observation period and the plasma testosterone concentration monitored. Bucks demonstrated a higher semen quality (P < 0.05) in autumn and summer (semen index of 965 × 10⁶ and 752 × 10⁶ ml⁻¹, respectively), compared to spring and winter (semen index of 606 × 10⁶ and 512 × 10⁶, respectively). This coincided with a higher (P < 0.05) plasma testosterone concentration in autumn and summer (8.1 and 10.1 ng ml⁻¹, respectively), compared to that obtained in spring (3.0 ng ml⁻¹) and winter (2.5 ng ml⁻¹). During autumn and summer, the ejaculate volume (average of 1.2 and 1.0 ml), sperm output (1159 × 10⁶ and 1005 × 10⁶ sperm ml⁻¹), sperm mass motility (4.2 and 4.3), sperm progressive motility (83.9 and 82.0%) and percentage live sperm (90.7 and 88.2%, respectively) of the bucks were higher (P < 0.05) than in the spring (0.6 ml, 880 × 10⁶ sperm ml⁻¹, 3.3, 71.5% and 80.2%) and winter (0.7 ml, 863 × 10⁶ sperm ml⁻¹, 4.0, 71.5% and 84.9%, respectively). During autumn and summer, the percentage of sperm abnormalities (5.0 and 9.2%) was significantly lower than that in spring (12.9%) and winter (11.2%). The semen pH was slightly alkaline being significantly (P < 0.05) lower in the autumn (7.1) than in spring (7.3). Data showed season of the year to influence all semen parameters evaluated—indicating that optimal buck performance may be obtained in late summer and autumn. It can thus be said that Markhoz bucks have distinct seasonal spermatogenic activity, with poorer semen characteristics being recorded during winter and spring. This may be a critical obstacle when implementing an intensive breeding system of three kidding seasons in 2 years, with natural mating being implemented.     

Seasonal and spatial pattern of shelter use by badgers<Emphasis Type="Italic">Meles meles</Emphasis> in Białowieża Primeval Forest (Poland)

In 1997–2001, we investigated the use of day-time shelters by radio-collared badgersMeles meles (Linnaeus, 1758) in the Białowieża Primeval Forest, eastern Poland. Each social group of badgers utilised, on average, 9 different shelters per territory (range: 4–20). The main setts, occupied for breeding and winter sleep, were also most frequently used for day-time rest throughout the year (73% of days). Badgers living in the pristine oldgrowth stands utilised larger number of shelters and spent more days in hollow trees (mainly limeTilia cordata), compared to badgers inhabiting younger secondary tree stands. Number of shelters used by individuals varied between seasons and depended on sex and age of animals. In summer, badgers used more shelters than in spring and autumn. In winter, they stayed in their main setts only. Adult males occupied more shelters and spent fewer days in the main sett than other badgers. In spring, females rearing young used only the main setts. The average underground space used by badgers within the main sett was 128 m². It was largest in summer and smallest in winter, and also varied between males and females. We proposed that, in a low-density population, badgers used several setts and other daily shelters to reduce energy expenditure when exploring their large territories and foraging. Furthermore, setts may play a role of marking sites. Analysis of the biogeographical pattern of sett use by European badgers showed that the number of setts used by social groups increased with increasing territory size, whereas the density of setts (n setts/km²) was negatively correlated with territory size. We proposed that different factors could shape the utilisation of setts by badgers in low- and high-density populations.     

雄性大熊猫褪黑素与睾酮季节性变化

褪黑素通过调控下丘脑-垂体-性腺内分泌轴使季节性繁殖动物在适宜的季节进行繁殖活动.大熊猫(Ailuropoda melanoleuca)在春季集中繁殖.为探究雄性大熊猫褪黑素和睾酮的季节性变化规律,本研究选取成都大熊猫繁育研究基地3只成年雄性大熊猫作为实验对象,在自然光照下对这3只大熊猫进行每周1次为期1年(2018年...     

Female receptivity, embryonic diapause, and superfetation in the European badger (Meles meles): implications for the reproductive tactics of males and females

The European badger Meles meles is thought to mate throughout the year with two mating peaks occurring in late winter/spring and summer/autumn. After mating, fertilized ova enter embryonic diapause (delayed implantation) at the blastocyst stage, which lasts up to eleven months. Even if mating is successful, however, the estrous cycle may continue during embryonic diapause, which suggests that female badgers are capable of superfetation (conception during pregnancy). This may increase female fitness by facilitating polyandry, and reduce the risk of infanticide by resident males through paternity confusion. Detailed understanding of female receptivity, specifically the association of superfetation with embryonic diapause, may explain field observations of seemingly inconsistent reproductive tactics of male badgers with regard to, for instance, whether or not they guard mates or defend territories. The combination of embryonic diapause and superfetation may occur in other mustelids; if so, the sociobiology of mustelids will need reevaluating, and the Mustelidae may prove to be a good model taxon for studies of sexual conflict in the reproduction of eutherian mammals.     

Environmental and seasonal adaptations of the adrenocortical and gonadal responses to capture stress in two populations of the male garter snake, Thamnophis sirtalis

Stress and reproduction are generally thought to work in opposition to one another. This is often manifested as reciprocal relationships between glucocorticoid stress hormones and sex steroid hormones. However, seasonal differences in how animals respond to stressors have been described in extreme environments. We tested the hypothesis that garter snakes, Thamnophis sirtalis, with limited reproductive opportunities will suppress their hormonal stress response during the breeding season relative to conspecifics with an extended breeding season. The red-sided garter snake, T.s. parietalis, of Manitoba, Canada, has a brief breeding season during which males displayed no change in either plasma levels of testosterone or corticosterone, which were both elevated above basal levels, in response to capture stress. During the summer, capture stress resulted in increased plasma corticosterone and decreased testosterone. During the fall, when mating can also occur, males exhibited a significant decrease in testosterone but no increase in corticosterone in response to capture stress. The red-spotted garter snake, T.s. concinnus, of western Oregon, has an extended breeding season during which males displayed a stress response of increased plasma corticosterone and decreased testosterone levels. The corticosterone response to capture stress was similar during the spring, summer, and fall. In contrast, the testosterone response was suppressed during the summer and fall when gametogenesis was occurring. These data suggest that male garter snakes, in both populations, seasonally adapt their stress response but for different reasons and by potentially different mechanisms. J. Exp. Zool. 289:99-108, 2001.     

The tempo-spatial variations of phytoplankton diversities and their correlation with trophic state levels in a large eutrophic Chinese lake

Lake Chaohu is one of the most eutrophic lakes in China. Research on this lake's seasonal and spatial variations in phytoplankton diversity is needed to understand the distribution of eutrophication, as well as to find appropriate comprehensive biodiversity indices to assess the eutrophication status of the lake. The present study indicated that the Margalef index of all samples was as low as 0.799 ± 0.543 in summer (August 2011) and as high as 1.467 ± 0.653 in winter (February 2012). The Margalef index of the river samples had a high mean value and substantial variation compared with the lake samples. The Peilou index of the lake samples was higher than that of the river samples in summer and autumn (November 2011) but lower than that of the river samples in winter. In spring (May 2012), the Peilou index of the western samples was lower than that of the eastern samples. The spatial distribution of the Shannon–Wiener index was more similar to that of the Peilou index in autumn and winter, while in spring and summer, the spatial distribution was affected by both species richness and evenness. High eutrophication levels occurred in the western lake in spring and summer, whereas high levels occurred in the eastern lake, especially in the middle of the lake, in autumn and winter. The total trophic state index (TSI) in all samples exhibited a significant negative correlation with the Margalef (r = −0.726) and Peilou (r = −0.530) indices but a significant positive correlation with the Shannon–Wiener (r = 0.654) index. The partial correlation analysis results implied that these phytoplankton biodiversity indices could serve as synthetic ecological indicators to assess the eutrophication condition of Lake Chaohu.     

Spatial organization of the fat dormouse (Glis glis) in an oak-hornbeam forest during the mating and post-mating season

Home range (HR) size and overlap, movements, and nest site use of fat dormice Glis glis (Linnaeus, 1766) were studied by live-trapping and radiotracking in the Bialowieza Forest in north-eastern Poland. The study was conducted during a mast year of oak Quercus robur (2001) and hornbeam Carpinus betulus (2002). Average HR size measured by 100% minimum convex polygons varied from 3.6 to 7.0 ha in males and from 0.55 to 0.76 ha in females. HR size in males was significantly larger in the hornbeam mast year than in the oak mast year, which was probably due to the lower energy value of hornbeam mast. Males had significantly larger HRs and used more nest sites than females. In contrast to females, HRs of males overlapped extensively. In the mating season, core areas of males overlapped significantly more and they shared their core areas with more males than in the post-mating season. During the mating season, males were found to share nest sites with other males or with a single female. Additionally, groups of 2–3 males were observed aggregating around a female during the mating season. Our data suggest that fat dormice have a promiscuous mating system where the females are territorial, and the non-territorial males directly compete for access to receptive females during the mating season.     

Partial migration of the nurse shark, <Emphasis Type="Italic">Ginglymostoma cirratum</Emphasis> (Bonnaterre), from the Dry Tortugas Islands

Nurse sharks have not previously been known to migrate. Nurse sharks of the Dry Tortugas (DRTO) mating population have a highly predictable periodic residency cycle, returning to the Dry Tortugas Courtship and Mating Ground (DTCMG) annually (males) or bi- to triennially (females) during the June/July mating season. For 23 years we have followed the movements of 76 recaptured adults of a total of 115 tagged adults. Telemetry detections of 40 females tagged with acoustic transmitters show that most tagged and presumably post-partum females are continuously present in the DRTO in the fall, winter and early spring following the June mating season but these females depart in late March to early May. Detections reveal these females avoid the DTCMG completely during the next mating season, returning from late summer to fall. Telemetry records of nine of 17 adult males that co-habited with these females in the DTCMG depart DRTO waters every July. Both sexes may overwinter in the DRTO. Between 2011 and 2016 three males and five females with transmitters were detected to move up the west coast of Florida outside of the mating season as far north as the waters off Tampa Bay (335 km). Six others were only detected in the lower Florida Keys (292 km). Nine sharks returned to DRTO; one returned six times. Some overwintered and some resumed courtship in June, demonstrating both resident and migratory contingents within their population, partial migration and an ability to navigate with high spatial and temporal precision.     

Effects of seasonal variation on the biology and morphology of the dusky cotton bug,Oxcarenus laetus (Kirby)

The dusky cotton bug (Oxycarenus laetus, KIRBY) a pest of several crops. The effects of winter and summer on the biology and morphology was investigated. The sampled eggs of dusky cotton bug (DCB) were kept under controlled environment for biological and morphological investigations. In winter, the mating duration of DCB was observed longer significantly (74.2 days), egg development period (3.93 days), an egg laying period (3.6 days) and hatching period (6.66 days) noted longer in winter season. Interestingly, average number of hatched egg (16.8 days) observed significantly higher in summer and the percentage of the hatching of eggs (81.95%) were also observed higher in summer as compare to winter. Whereas, the longevity of all nymph stages in winter longer days as compare to summer nymph stages. Moreover, differences were also observed between male and female development days between winter and summer. In the winter, female DCB development was suggestively higher as compare to summer (24 days). Whereas, the developmental days were noted considerably more in winter for males as compare to summer (14.93 days). On other hand, for morphological parameters, no differences were observed between winter and summer population of DCB.     

The influence of androgens on hibernation phenology of free-living male arctic ground squirrels

Free-living ground squirrel species are sexually dimorphic in hibernation phenology. The underlying causes of these differences are not yet known. Androgens, testosterone (T) in particular, inhibit hibernation. To determine the influence of endogenous androgens on annual timing of hibernation we first measured circulating levels of T and dehydroepiandrosterone (DHEA), an adrenal androgen implicated in non-mating season aggression in other species, in free-living male arctic ground squirrels (Urocitellus parryii, AGS). We also manipulated endogenous androgen levels by surgical castration, and consequently compared body temperature records from intact (n = 24) and castrated (n = 9) males to elucidate the influence of endogenous androgens on annual body temperature cycles. The highest T levels (0.53 ± 0.10 ng/mL) were in reproductively mature male AGS in spring; whereas, both immature males in spring and all males in late summer had T levels an order of magnitude lower (0.07 ± 0.01 and 0.06 ± 0.00 ng/mL, respectively). DHEA levels were higher in males during the late summer compared to reproductively mature males in spring (120.6 ± 18.9 and 35.9 ± 2.3 pg/mL, respectively). Eliminating gonadal androgens via castration resulted in males delaying euthermy by extending heterothermy significantly in spring (Apr 22 ± 2.9) than reproductive males (Mar 28 ± 3.9) but did not change the timing of hibernation onset (castrate: Oct 12 ± 1.0 vs. intact: Oct 3 ± 3.1). We conclude that while androgens play a significant role in spring hibernation phenology of males, their role in fall hibernation onset is unclear.     

Experimentally elevated testosterone increases status signalling in male Greylag geese (<Emphasis Type="Italic">Anser anser</Emphasis>)

Testosterone modulates male vertebrates sexual and social behaviour. We experimentally investigated the testosterone-sensitive behaviours in male greylag geese (Anser anser) by implanting silastic tubes containing crystalline testosterone during the mating season (February; 5 implanted and 5 control males) and in the early winter (November; 7 and 7). Focal animals were part of a semi-tame, unrestrained flock with fully intact social relationships. Excreted testosterone and corticosterone immunoreactive metabolites (TM, BM) were determined by enzyme immunoassay. Individual faecal samples and behavioural protocols were collected daily over a period of 5 weeks, including 1 control week before implantation. In February, no significant behavioural effects of the supplemental testosterone were observed, which may be due to the naturally occurring high systemic androgen levels in spring. In November, however, implanted males had higher TM excretion rates and performed status signalling behaviour (beak up) more frequently than control males. No differences between implanted and control males were found with respect to BM, agonistic interactions or vigilance behaviour. Furthermore, during the second week after implantation, TM positively correlated with the frequency of beak up of implanted males, whilst their female partners were attacked with lower latency by other members of the flock than the females of control males. Hence, status signalling in greylag ganders seems to be testosterone-sensitive year-long and inappropriate status signalling of males may draw attacks towards their females.     

Plasmatic protein values in captive adult Iberian red deer stags (<Emphasis Type="Italic">Cervus elaphus hispanicus</Emphasis>)

The aim of this study was to assess the time trend of plasmatic proteins in red deer stags. Blood samples were taken monthly from 17 male red deer for 22 months. Total plasmatic determination and protein electrophoresis were performed. Plasmatic proteins showed minimum values during spring and summer and a maximum at the peak of the mating period. Total globulins, β and γ, followed a pattern similar to that observed for total proteins, whereas α1 and α2 globulins showed no seasonal variations. Albumin showed higher values in early spring and summer and lower values at the beginning of autumn, coinciding with the mating season. These seasonal changes in plasmatic proteins should be taken into account when assessing blood protein analysis results.     

Nonbreeding season pairing behavior and the annual cycle of testosterone in male and female downy woodpeckers, Picoides pubescens

Studies in birds show that testosterone (T) concentrations vary over the annual cycle depending on mating system and life history traits. Socially monogamous species show pairing behavior throughout the year and low levels of male-male aggression and are underrepresented in these studies, yet the function of testosterone could be particularly important for sexual and social interactions occurring outside the breeding season. We measured fecal T concentrations over the annual cycle and the frequency of interactions between male and female downy woodpeckers (Picoides pubescens) from late fall through early spring. We validated the fecal assay by collecting blood in conjunction with a subsample of our fecal samples: fecal T correlated with circulating levels in the blood. The annual peak level of T in males was relatively low and short-lived, similar to that of other bird species with low levels of male-male aggression and high paternal care. The annual cycle of female T resembled the male pattern, and the ratio of male T to female T was close to 1.0. Likewise, the frequency of aggression among females was similar to the frequency among males. Overall, testosterone levels in both sexes were variable, even in winter. In other bird species, sexual behavior during nonbreeding periods correlates with circulating levels of T in males. Based on this observation, we tested the hypothesis that T in winter was positively related to the frequency of interaction between mated downy woodpeckers. The results showed no such relationship. We discuss this finding and further relate the annual cycle of T in both males and females to behaviors that appear to facilitate mate choice and retention of the pair bond during conspecific challenge.     

Seasonal and age-related changes in blood parasite prevalence in Dark-eyed Juncos (Junco hyemalis, Aves, Passeriformes)

We determined seasonal changes in blood parasite infections in a free-living population of Dark-eyed Juncos (Junco hyemalis) breeding in interior Alaska (65 degrees N; 148 degrees W). The common parasites found in blood smears were Leucocytozoon fringillinarum (56%), Trypanosoma avium (33%), and Haemoproteus fringillae (9%). In males, parasite prevalences were relatively high at arrival on breeding grounds and increased during the breeding season. Intensity of infection with Leucocytozoon also increased between spring and summer, and then decreased at the time of migration (September). This decrease did not occur in adult females. Elevated prevalences during the breeding season probably reflected the addition of new cases via vector activity to positive status resulting from spring relapse. We observed neither an association between parasite species nor a consistent relationship between parasite intensity and body condition. To further study relationships between reproductive system activity and parasite infections, we compared prevalences in adult males that were undergoing their first cycle of gonadal development and regression (males in their second calendar year, or SY) with those of older males (males in their third or more calendar year, i.e., after-second-year males or ASY). Circulating testosterone concentrations declined in both groups between arrival on breeding grounds (end of April-early May) and the end of the reproductive period (July), and they were higher in May in ASY than in SY males. At the peak of the breeding season (June), ASY males also had a higher parasite prevalence than SY males. This difference may have resulted from immunosuppressive effects of gonadal hormones and/or from behavioral differences between SY and ASY males such that older males were exposed to more insect vectors than younger males. .     

Seasonal effect in expression of AQP1, AQP3 and AQP5 in skin of Murrah buffaloes

Aquaporins are transmembrane protein channels which are known to help the passage of water and solutes across the cell membranes. AQP1, AQP3 and AQP5 are isoforms of aquaporin known to aid in transepithelial water movement. AQP3 is also known to aid in glycerol transport. The present study was conducted to investigate the role of AQP1, AQP3 and AQP5 in thermoregulation of buffaloes by probing the expression of the genes in skin of buffaloes during different season viz. winter, spring and summer. The skin tissue samples were collected from the neck region of Murrah buffaloes (n = 12) and analyzed for gene expression by RT-PCR and immunolocalization. The physiological responses including respiration rate, rectal temperature and neck skin temperature observed during summer were significantly higher than winter and spring seasons. The study revealed the expression of AQP1, AQP3 and AQP5 genes in skin samples. The relative mRNA expressions of AQP1, AQP3 and AQP5 in skin relative to spring season were 1.41 ± 0.47, 1.95 ± 0.22 and 6.77 ± 1.02 folds during summer which were significantly higher than other seasons. The up-regulation of the expression of the studied AQPs were concomitant with the increase in physiological responses including skin temperature and sweating rate during summer. During summer season, AQP1 were mostly immunolocalized in the walls of skin blood capillaries, while AQP3 were observed mostly in the epidermal layer of the skin. The immunolocalization of AQP5 were mostly observed in the secretory glands of skin. The up-regulation of AQP1, AQP3 and AQP5 in skin during summer season indicates their role in thermoregulation of buffaloes.