Seasonal variation in the range areas of the diurnal rodent Octodon degus

Both breeding activity and abundance and quality of available food are expected to influence daily movements of animals. Animals are predicted to range over large areas to meet high energy demands associated with reproduction (females) or to increase mating success (males). However, animals should expand their range areas whenever food conditions deteriorate. To examine the extent to which breeding activity versus food availability influence space use, we compared the size and location of range areas (home ranges) of the degu (Octodon degus), a diurnal rodent from semiarid environments of north-central Chile, during the austral winter and summer seasons. Degus produce young during the austral spring (September-October) when high-quality food is readily available. In contrast, degus do not breed during the austral summer (January-March) when food is scarce and of low quality. We predicted that degus would range over smaller areas in winter if the availability of food has a greater influence on space than breeding activity. Individuals were radiotracked in winter and the following summer over a 3-year period. Surveys of herbaceous cover were conducted during winter and summer to determine seasonal changes in the abundance and quality of primary food. In summer degus expanded and moved the location of their range areas to locations with available food. Given that preferred food was less abundant in summer than winter, we suggest that degu range areas are strongly influenced by food conditions.     

Seasonal home range changes of the Sichuan snub-nosed monkey (Rhinopithecus roxellana) in the Qinling Mountains of China

The seasonal changes in home range and habitat use of the Sichuan snub-nosed monkey, Rhinopithecus roxellana, have been studied by radio tracking and direct observation in the Qinling Mountains of China. The home range size was 14.1 km(2) in spring, 9.5 km(2) in summer, 12.1 km(2) in autumn and 12.3 km(2) in winter; the total area used was 22.5 km(2). The area of the home range is closely correlated with the distribution and abundance of food resources. Seasonal change in the home range area is correlated with the phenology of the vegetation. An unusually large home range is a unique characteristic of this monkey.     

Seasonal variations in feeding range and flock structure of the Rook Corvus frugilegus in eastern Ireland

The feeding range and flock structure of Rooks showed temporal variations caused mainly by the dispersion of food and reproductive behaviour.
Feeding range was restricted in spring, autumn and early winter when food availability was high and Rooks were reproductively active. A large feeding range occurred in late summer and late winter, when food availability was either generally low or locally distributed and when Rooks were reproductively inactive. The occurrence of flocks common to several rookeries mirrored variations in feeding range; mixed rookery flocks were more common in late summer and late winter. Similarly, the size of the rookery (as measured by the number of nests) was related to feeding range only when Rooks were reproductively inactive and at such times larger rookeries had greater feeding ranges.
Flock structure showed similar seasonal variations; small widely spaced flocks predominated in summer, autumn, early winter and spring, whereas large dense flocks occurred in late winter. Diurnal variations in flock structure occurred within any one season. Both seasonal and diurnal variations in flock structure may be determined by the dispersion of the prey and the feeding strategy used to obtain it, reproductive behaviour and the risk of predation.     

Not only annual food abundance but also fallback food quality determines the Japanese macaque density: evidence from seasonal variations in home range size

Previous studies on Japanese macaque (Macaca fuscata) densities suggest that both total annual food abundance and the quality of fallback foods in the winter bottleneck period affects density. We reviewed data on the seasonal changes in home range size to explain how both factors affect density. In general, home range was large in summer or autumn and small in spring or winter, indicating that density is determined by the home range size in the seasons before winter. The main foods in these seasons are fruits and seeds. If these foods are not abundant, macaques need to range over a larger area, thus decreasing density. Macaques survive the winter by depending on the fat deposited before winter through eating these high-quality foods. If the food condition in winter is severe and the amount of required fat deposition is large, macaques need a larger home range before winter, and thus density becomes lower.     

Spatial behaviour of adult male Alpine ibex<Emphasis Type="Italic">Capra ibex ibex</Emphasis> in the Gran Paradiso National Park,Italy

During a two year preliminary study, the spatial organization of a group of male Alpine ibexCapra ibex ibex Linnaeus, 1758 was examined in the Gran Paradiso National Park, Western Italian Alps, Italy. From December 1995 to January 1998 we measured annual, seasonal home range and home range during the rut, plus altitudinal migration of 13 radio-collared adult Alpine ibex. The small annual home range size showed a traditional use of space, confirmed by the high overlapping values between home ranges of consecutive years: the ibex used the same places from year to year. This was also true during periods of rut. Home ranges closely overlapped in consecutive ruts, while their size changed from winter to winter. Snow cover limited the movements of the ibex; winter and spring home ranges were smaller than those in summer and autumn. Mean vertical movement patterns were similar in the two years, showing the highest values in summer and the lowest in spring. Space use was never proportional to availability for each altitudinal range.     

Home range patterns of male fallow deer<Emphasis Type="Italic">Dama dama</Emphasis> in a sub-Mediterranean habitat

From 1996 to 2000 the home ranges of 14 male fallow deerDama dama (Linnaeus, 1758) were studied in the San Rossore Preserve (Italy) using radio-telemetry. Mean size of annual home ranges was 588.9 ± 278.9 ha, calculated by MCP, and 337.5 ± 178.9 ha, using Kernel method, and was larger than that reported in published literature to date. The size of the seasonal home range estimated with the MCP method was 90.6 ± 129.1 ha during spring, 73.7 ± 67.9 ha in summer, 465.0 ± 230.6 ha in fall, and 65.6 ± 60.6 ha in winter. The Kernel method gave 84.7 ± 140.2 ha in spring, 61.3 ± 64.6 ha in summer, 306.0 ± 170.5 ha in fall, and 46.5 ± 44.0 ha during winter. The seasonal analysis suggested that bucks tended to occupy the same particular area from winter to summer, which was related to rich trophic resources, even despite of anthropic disturbance. During autumn, males reached the rutting site (a lek) that was 4 km distant from the areas occupied during the other three seasons. The lekking behaviour was the main factor influencing home range size.     

Seasonal home range use by Japanese monkeys in the snowy Shiga heights

Between December 1974 and November 1975 (157 days), it was found that seasonal home range changes in the Shiga C troop were closely related to food changes, vegetation, and the existence of neighbouring troops. The detailed points clarified may be summarized as follows: (1) The seasonal home range sizes from winter to autumn were 1.23 km², 1.46 km², 1.69 km², and 1.21 km², respectively, and the annual size was 3.66 km²; (2) The food changed from bark and buds of trees in winter to young leaves and stems of grasses and trees in spring and summer, and fruits in autumn; (3) Each home range clearly changed according to the phenology of the plants used as food at each season; (4) The food abundance for the monkeys was extremely poor in winter, relatively poor in summer, plentiful in spring, and the best in autumn; and (5) The Shiga C troop and the neighbouring Shiga B₂ troop overlap in their home ranges in spring and autumn, but are separated during winter and summer.     

Reproductive biology of Philodryas patagoniensis (Snakes: Dipsadidae) in south Brazil: male reproductive cycle

The male reproductive cycle of Philodryas patagoniensis in south Brazil was described through morpho‐anatomical and histological analysis of individuals deposited in zoological collections. Spermatogenesis occurred during late autumn–winter (June–September) and spermiogenesis occurred in spring–summer (October–March). The volume of the testes was smaller (quiescent) in winter, while the tubular diameter and the epithelial height of the seminiferous tubule were larger in summer (January–March). The ductus deferens presented spermatozoa all over the year and had no seasonal variation in diameter. The length of the kidney was larger in winter–spring (July–December), although the tubular diameter and epithelium height of the sexual segment of the kidney (SSK) were larger only in winter (July–September). Total testicular regression was observed in late autumn (May), simultaneously with the peak in SSK. Therefore, at the individual level, males exhibit a discontinuous cyclical reproduction. Considering the population level, the reproductive cycle is seasonal semisynchronous, with most of the individuals showing a reproductive peak in spring–summer (October–March). Here, we present evidence to support the importance of the microscopic approach to reproductive cycle studies. Finally, we discuss the intrinsic and extrinsic factors influencing P. patagoniensis reproductive patterns.     

食物季节性对野生藏酋猴家域利用的影响

食源植物的分布与食物的可获得性影响灵长类动物的家域动态。研究灵长类动物家域利用及其影响因素,对揭示野生动物的生态适应性与行为复杂性有重要意义。2020年9月—2021年8月,利用GPS技术、直接跟踪观察等方法,对黄山低海拔地区的野生藏酋猴群的家域范围进行研究。结果发现藏酋猴家域面积从春季到冬季依次递减,分别为7.16 km²、5.09 km²、3.85 km²、0.35 km²,面积与食物资源可得性呈显著正相关;猴群月平均漫游距离 (d= 1735.67 m ± 288.35 m, n = 12) 与食物可得性呈正相关,且月平均漫游距离在7月最长、1月最短。猴群偏好利用的生境类型为针阔混交林和常绿落叶阔叶混交林,春季主要偏好利用毛竹林和常绿落叶阔叶混交林,夏季和冬季为针阔混交林 (马尾松),秋季为常绿落叶阔叶混交林。结果表明,藏酋猴会根据食物资源分布、食物可得性等因素来优化家域的时空利用以适应低海拔地区。     

红腹角雉取食栖息地选择的研究

１９９３年１１月－１９９４年１０月,在以无线电遥测技术对贵州省仙人山地区红腹角ｒｕｇｏｐａｎ ｔｅｍｍｉｎｃｋｉｉ的活动范围,栖息选择及食性研究的基础上,对其取食栖息地的选择作了探讨。红腹角雉遥测位点和粪便相对集中分布。表明对栖息一半存在明显的选择,对食物分布的样方分析表明其活动特点与食物密切相关。红腹角雉各季节我灌木与草本植物的沟谷带上段,春冬季主要取食草本及蕨类植物,活动范围较大小二对二得的物     

Seasonal home range patterns of the reintroduced and rewild female Père David’s deer Elaphurus davidianus

To learn the seasonal home range pattern and its role in the ecological adaptation of rewild Père David’s deer, we took the investigation from spring to winter in three-collared females that released into the coastal wetlands of the Yellow Sea, China. Using GPS collars, minimum convex polygons and fixed kernel estimation, we recorded the movement and estimated the home ranges of the deer. The results showed that the collared deer inhabited only 42.85% of the coastal wetland habitat that had been designated for them. The home ranges were larger during winter and spring than in autumn and summer. In summer and autumn, the collared deer remained in the reserve, which was dominated by spartina grass. In the spring and winter, they were lured by the green leaves of wheat in the farmlands outside the reserve but were then driven back by people. Home range patterns reflected the seasonality of the availability of food resources and human activity. In addition to the frequently utilized habitats, much larger wetland areas are required for such deer. As the population density increases gradually, more available space will be needed to meet the fundamental needs of the seasonal dispersal of rewild Père David’s deer.     

Seasonal fluctuations in androgen levels in females of the hermaphroditic gag, Mycteroperca microlepis, with an emphasis on juvenile animals

Androgens are known to play many roles in the reproductive physiology of teleosts, but less information exists on the role that they play in the development of larval and juvenile fish. This study examines an observed seasonal cycle of 11-ketotestosterone (11KT) in females of the hermaphroditic gag grouper (Mycteroperca microlepis). Otoliths, gonads, and plasma samples from gag were collected quarterly (spring, summer, fall, and winter), with complete data (age, sex, and androgen levels) obtained from a total of 225 individuals. Ages ranged from zero to 11 years, and all individuals were female. Testosterone (T) peaked in the spring, coincident with spawning, and was low throughout the remainder of the year. The androgen 11KT peaked in summer and declined through the following spring. 11KT levels were negatively correlated with fish size in both the summer and winter, while T was negatively correlated in the summer and positively correlated in the winter. T levels showed little seasonal variation in juveniles (0-1 and 2-3 age groups), but showed a seasonal increase from fall through spring in older fish (4-5 and 6+ age groups). Age 0-1 fish had significantly higher levels of 11KT than the age 4-5 group during the summer and both the 4-5 and 6+ age groups in the winter. The gag is a protogynous hermaphrodite that goes through several ontogenetic shifts during its life, and this seasonal fluctuation in plasma levels of 11KT may play a role in the growth and development, behavior, or control of sex change of gag.     

官山白颈长尾雉活动区域海拔高度的季节变化及其影响因素

2005年7月至2006年12月,采用无线电遥测的方法在江西官山国家级自然保护区内对5只白颈长尾雉（Syrmaticus ellioti）的活动区域进行了跟踪监测,结合GIS技术和样方法分析其活动区域的海拔高度随季节变化的影响因素。结果表明：海拔400-600m为白颈长尾雉全年最适活动带,其主要活动区域的海拔高度呈现明显的季节变化：夏秋季最高,春季次之,冬季最低。水源是其冬季喜欢在低海拔区域活动的最主要原因;而距林缘距离、灌木数量、灌木种数、灌木盖度等与增加食物丰富度和隐蔽度相关的因子是促使它们在春季和夏秋季倾向于在高海拔区域活动的主要因素。     

Early life history timings in marbled rockcod (Notothenia rossii) fingerlings from the South Shetland Islands as revealed by otolith microincrement

Although it has been reported that Notothenia rossii elsewhere hatches in spring, our daily increment back-counting from the capture date in otoliths of fingerlings caught in Potter Cove, South Shetland Islands, in the 2000s, showed two main periods of larval hatching, one in summer (February–March) and another in winter (July). In concordance, the simultaneous presence of two cohorts born the same year was identified in the age/length frequency distribution of fish sampled in spring 2010, which belonged to biological ages 0+ and 1+ and hatched, respectively, in summer and winter–spring. Maximum and minimum ages of pelagic blue-phase and demersal brown-phase fingerlings were, respectively, 227 and 240 days, indicating a demersal settlement after about 8 months from hatching. The estimated growth rate was 0.23–0.33 mm/day, equivalent to that of South Georgia fingerlings and higher than those of other nototheniids of similar size range. Based on early life events associated with the hatching periods, two types of life cycles are hypothesised for South Shetland fingerlings. The pelagic blue-phase fingerlings (6.5–7.6 cm TL, age group 0+) hatched in July (winter cohort), entering in Potter Cove in February–March. The brown-phase fingerlings (6.3–10.6 cm, mostly of age group 0+) hatched in February–March (summer cohort) and were collected in the cove in spring (the smaller specimens) or in summer (the larger ones). Finally, early juveniles (10.7–15.5 cm, age group 1+) hatched in winter, mainly in July (winter cohort), entering in the cove the following year to spend the second winter inshore.     

Metabolic rate and food availability of the Antarctic amphipod <Emphasis Type="Italic">Gondogeneia antarctica</Emphasis> (Chevreux 1906): seasonal variation in allometric scaling and temperature dependence

Among the few existing works on seasonal variation in metabolic rate of polar species, most have been conducted during summer due to logistic constraints and have been focused on species that cease feeding during winter. In this work, we present the first extensive data set on the seasonal variation in metabolic rate of G. antarctica, an abundant amphipod that feeds throughout the year, and its relationship with body size, potential food availability and temperature. We measured the resting metabolic rate (RMR) of groups of individuals during 6 months from late summer through winter at 4 experimental temperatures and for a wide range of body size. RMR had a negative allometric scaling with body size and showed a tendency to increase with temperature as expected. However, temperature and body size effects on RMR showed a significant temporal variation, and an increase in temperature decreased scaling exponents. RMR at the mean seawater temperature throughout the study showed a strong seasonal variation following food availability: RMR decreased from the end of summer through winter, coinciding with a reduction in microphytobenthos stock, but recovered summer values in August, when an epontic algae boom occurred. The seasonal factorial aerobic scope (×2.37) is lower than benthic Antarctic invertebrates that cease feeding during winter, in agreement with what is expected based on theoretical grounds. Results suggest that seasonal variation of RMR would allow G. antarctica to achieve a high efficiency in energy utilization, while maintaining the ability to exploit sudden changes in food supply.     

Population Structure and Ranging Patterns of <Emphasis Type="Italic">Rhinopithecus roxellana</Emphasis> in Zhouzhi National Nature Reserve,Shaanxi, China

We describe the population structure and ranging patterns of a troop of Sichuan snub-nosed monkeys (Rhinopithecus roxellana) based on a study conducted between November 2002 and November 2003 in Zhouzhi National Nature Reserve, Shaanxi Province, China. The troop comprised several 1-male units and an all-male unit. Opportunistic censuses revealed that there were ≥112 individuals in the troop. The adult sex ratio (male vs. female) was 1:3.7. The ratios of adults to immatures and infants to adult females were 1:0.7 and 1:2, respectively. Via a grid system, we estimated the home range of the troop to be 18.3 km², of which 7.4 km² was the core area. The subjects exhibited distinct seasonal ranging patterns. Their movement across the home range was extensive in spring and restricted in autumn. In addition, reuse of quadrats was highest in winter and lowest in spring in comparison with other seasons. The daily path length (DPL) varied from .75 to 5 km, with a mean of 2.1 km. Seasonal analysis showed that DPL is significantly shorter in winter than in spring or summer; however, there is no significant difference between the DPLs of spring and summer or those of spring and autumn. The monkeys occupied elevations 1500–2600 m above sea level; the annual mean of altitudinal range is 2137 m. Contrary to early studies that reported Rhinopithecus roxellana migrates to lower elevations in winter, we found no evidence supporting a seasonal altitudinal shift. Using the highest troop count and home range estimate, and considering the extent of range overlap between neighboring troops, we calculated the population density and biomass of Rhinopithecus roxellana to be 7.2 individuals/km² and 68.3 kg/km², respectively. The temporal and spatial distribution of food resources may be the most important determinant of ranging behavior in Rhinopithecus roxellana, though understanding the relationship between resource distribution and seasonal range use may require further investigation.     

性别、季节和体型大小对吐鲁番沙虎巢域的影响

2008年6月份至2009年5月份对吐鲁番沙虎的巢域进行调查:2008年6月份至2008年8月份为繁殖季节(RS),2008年9月份至2009年5月份(冬眠期除外)为非繁殖季节(NRS)。利用截趾标志重捕法研究吐鲁番沙虎的巢域,共标记283只吐鲁番沙虎,累计繁殖季节24只,非繁殖季节43只重捕超过3次(其中13只个体在繁殖季节和非繁殖季节均够3次以上捕捉次数,为重复个体),可以用于计算个体巢域面积数据。利用软件MapGis计算最小凸多边形法(MCP)巢域面积,并分析性别、体型大小、季节等因素对巢域的影响。结果表明:吐鲁番沙虎非繁殖季节雄性、雌性与幼体各组间的巢域面积差异均显著,繁殖季节巢域面积差异不显著;雌雄个体不同季节或全年合并比较巢域面积差异性均不显著;非繁殖季节面积与吻肛长(SVL)显著相关、全年成体组的巢域面积与吻肛长显著相关;成体巢域面积季节差异显著(U=41,P=0.046),幼体则没有季节差异(U=159,P=0.537)。因而,吐鲁番沙虎的巢域大小受性别因素影响不大,体型大小对巢域面积有显著影响,由于繁殖、食物资源等的季节变化是影响吐鲁番沙虎巢域最重要的因素。     

Age-sex differences in the diets of Sika deer on Kinkazan Island,northern Japan

Dietary differences in the ages and sexes of Sika deer (Cervus nippon) were studied on Kinkazan Island, northern Japan from October 1990 to July 1991. Larger deer consumed more graminoids than smaller deer except in spring, and less dicotyledonous leaves in all the seasons. Fecal nitrogen concentrations were lower in larger deer than in smaller deer in all the seasons. The age-sex differences in foods were smaller in summer and winter when foods were most abundant and scarce, respectively, while they were greater in spring and autumn when food availability was intermediate.     

Long-term variation in fruiting and the food habits of wild Japanese macaques on Kinkazan Island, northern Japan

We studied the relationship between the food habits of Japanese macaques (Macaca fuscata) and the availability of nuts (Fagus crenata, Zelkova serrata, Carpinus spp., and Torreya nucifera) on Kinkazan Island, northern Japan, from 1997 to 2005 to examine the long-term variations in both food habits and availability. The food habits of the monkeys showed clear seasonal changes: the staple foods were woody leaves and flowers in spring (May and June), woody leaves and seeds or fruits other than nuts in summer (July and August), nuts and seeds or fruits other than nuts in fall (September-November), and herbaceous plants in winter (December-April). The availability of nuts, combinations of masting species, and energy production varied among years. Food habits varied among years, but the magnitude of variability of food habits differed among seasons, with large variability during summer and winter, and small variability in spring. Food availability was poor in summer and winter, but in several years the monkeys were able to consume nuts during those seasons. We emphasize the importance of conducting long-term studies on both food availability and the food habits of animals in the temperate zone.     

Variation in the diet of the viperine snake Natvix mama in relation to prey availability

The diet of the viperine snake was compared with food availability in the Ebro Delta, a wetland largely occupied by rice fields, in 1990 and 1991. Snake selection of prey type and size was studied seasonally and by snake group: males, females and immature snakes. Overall, feeding activity (percentage of individuals with prey and number of prey per stomach) increased with food availability. Diet analysis showed that viperine snakes mainly foraged on the green frog Rana perezi (adults and tadpoles) and the carp Cyprinus earpio. Conversely, viperine snakes rejected the mosquito fish Gambusia holbroki which is the most abundant species in autumn, when Natrix maura has a low feeding activity. Statistical comparisons between viperine snake diet and prey availability showed that males selected small carp, immature snakes selected tadpoles and, in spring, females selected frogs. The selection of small carp by males may reflect a sexual divergence of trophic niche related to sexual size dimorphism, as females are larger than males. As tadpoles are presumably easier to catch than fish, tadpole selection by immature individuals may reflect variance in capture abilities. In spring, the selection of frogs by females overlapped with vitellogenesis, suggesting that females compensate for the cost of reproduction by selecting green frogs, which have a greater biomass and higher energy content than fish. Carps eaten in spring were smaller than in summer. Moreover, in summer viperine snakes selected smaller carp than the available mean size. This divergent tendency between carp size selection and carp size availability reveals how seasonal diet shifts in prey size selection may be a response to an increase in prey size.