圈养小熊猫的昼夜活动节律

Daily activity rhytlms of three radio-collared captive red pandas were monitored individually at 15 minute intervals for 3 euntinuous days each month at Yele Nature Reserve, Xiangling Mountains, June- October 1995. Our data indicated that mean rate of activity [0.51 ) of captive red pandas was lower than that of wild red pandas. Three captive red pandas showed similar daily activity patterns, being least active during night and more active during daytime. Mean rate of activity during daylight (0.58)was higher than during nighttime (0.41). Daily mean durations of activity and rest were 12.21 hours and 11.79 hours, respectively. Active times of captive red pandas accounted for 50.6% of each 24 hours, of which 66.5% were recorded during daylight and 33.5% during night. Two active peaks appeared at07: 30-09: 15 and 17: 30- 19: 00. We recorded a mean of 2.17, 2.13 and 0.88 long, mid-length, and short resting bouts daily, which had mean durations of 3.47, 1.65 and 0.87 hour, respectively.Among these long rests, 46.1% occurred during daytime and 53.8% during nighttime.     

Feeding biology of Aplocheilichthys normani, Ahl, a small Cyprinodontidae from West Africa

Aplocheilichthys normani is a small Cyprinodontidae endemic in tropical Africa from Senegal to central Sudan. Analysis of the gut content of two populations from Guinea reveals that it feeds mainly on small crustaceans and chironomid larvae. Experimental investigations into its predatory capacity vis-á-vis the larvae of Aedes aegypti show that there is a significant difference between the daily feeding rates in adult versus subadult specimens. Moreover, significant 24 h variations were also observed. The feeding rate is also related to the stage of the larvae, i.e. the predatory capacity is greater for smaller prey. The 24h feeding rate variations show that A. normani feeds both during the daylight hours and at night, with a slightly higher predatory activity during the daylight hours. The peak in feeding activity occurs during the two hours before dark. Tests on feeding preferences show that the fish prefers, in descending order, Aedes, Anopheles and Culex larvae. Its larvivorous activity against mosquito larvae was corroborated by small-scale field studies. We propose that this species be considered for possible use in the biological control of mosquito larvae in West Africa.     

Use of visual landmarks by young trout (Salmo trutta) during their diel downstream post-emergence displacement in experimental channels

The diel timing of displacement of emerging brown trout ( Salmo trutta ) was studied by trapping the alevins at the downstream end of three experimental channels. The presence of phosphorescent landmarks on the substrate delayed the catches during the first hours of complete darkness, but increased them during twilight. During daylight, the presence of the landmarks was associated with greatly increased numbers of free-swimming fishes.     

Activity budget of Geoffroy's marmoset (Callithrix geoffroyi) in an Atlantic forest in southeastern Brazil

This report describes the activity budget of a group of Callithrix geoffroyi in a patch of Atlantic forest on the Brazilian coast, between February 1993 and January 1994, using the scan sampling methods. On average, the group rested for 29% of the daylight hours, fed for 21%, moved for 20%, and foraging and gouging occupied 14% and 13% of this period, respectively. A greater proportion of time was spent resting during the wet seasons (32.1%) than the dry seasons (17.8%), but the reverse observed for time spent foraging (9.7% and 20.6% of the group's daylight hours during wet and dry seasons, respectively). The time allocated to feeding was greater in the first hours of the day. Gum consumption showed two peaks, a larger one in the early morning and a minor one in the afternoon. Animal prey foraging occurred throughout the day, but was more intense during the hottest hours. The increase in foraging and decrease in resting during the dry season was related to a decrease in the availability of insects. Am. J. Primatol. 46:333–340, 1998. © 1998 Wiley-Liss, Inc.     

Diel activity of the pink shrimp Penaeus duorarum

Twelve juvenile pink shrimp, Penaeus duorarum Burkenroad, were tested individually for 3-day periods in electronic shuttleboxes to determine their diel patterns of locomotor activity, in relation to a natural summer photoperiod. Nocturnal activity was twice that exhibited during the daytime; however, a bimodal pattern was evident with crepuscular peaks occurring at dawn and dusk. The dusk peak was more pronounced, with activity increasing markedly before sunset (indicative of an endogenous circadian rhythm component), and continuing during the initial hours of darkness, gradually declining later during the night with a secondary peak at dawn falling off to minimal activity during daylight. Crepuscular activity (mean of dawn and dusk) was twice the nocturnal average.     

Differences in feeding between 1+ and 2+ hatchery brown trout exposed to low water temperature

Both 1 + and 2+ brown trout fed during the day and at night when held in hatchery tanks at low temperatures (2·7–3° C). Over 60% of the daily ration was consumed during daylight hours, but there were differences in feeding behaviour between fish of the two age groups: the 1 + trout had greater feeding activity at night than the 2+ fish.     

Effects of seismic surveys on New Zealand fur seals during daylight hours: Do fur seals respond to obstacles rather than airgun noise?

The responses of New Zealand fur seals (Arctocephalus forsteri) during a three‐dimensional marine seismic survey were recorded in the first quantified investigation of the effects of seismic exploration operations on otariid seals. The survey was over the continental slope off southern New Zealand, where fur seals dive to forage at night and rest on the surface during daylight hours. Data were restricted to daylight sightings from the source vessel while towed seismic gear was fully deployed, with comparisons made between fur seal responses when airguns were off and when airguns were operating at full power. Results were inconclusive. Comparisons were confounded because both sighting rate and distance first seen decreased with deteriorating sea state. The key finding of this study was that the source vessel and towed gear created physical obstacles that often generated responses from fur seals. A more thorough investigation is recommended in order to differentiate between responses to airgun noise and responses to physical obstacles, and improvements are suggested to rectify shortfalls in data collection that should generate conclusive outcomes.     

Diel activity of a boreal water beetle (Dytiscus alaskanus: Coleoptera; Dytiscidae) in the laboratory and field

SUMMARY. 1. The diel activity of Dytiscus alaskanus (Coleoptera: Dytiscidae) was studied by trapping in the field and by direct observation of behaviour (mounting, chasing, grappling, swimming and surfacing) in the laboratory.
2. In the field in the number of beetles trapped during the dark hours was approximately fifty-fold greater than trapped during daylight hours.
3. In the laboratory, there was a marked increase in mounting, chasing and grappling when the ambient light level fell below 0.41mm⁻². Swimming showed only a slight diel pattern and surfacing none at all.     

Diurnal activity patterns of three heron species in Queen Elizabeth National Park,Uganda

Kasoma, P.M.B. 2000. Duirnal activity patters of three heron species in Queen Elizabeth National Park, Uganda. Ostrich 71(1): 127–130.

Observations of activities were carried out over 12 h periods on the Goliath Heron, Grey Heron and Great White Egret along the shores of Lake Edward and Kazinga Channel. Behaviour was classified into three major categories: foraging, loafing and other behaviour. For all three species, foraging went on throughout the daylight hours but the level was variable both in the dry and wet seasons and between species. For all three species, foraging basically consisted of standing-and-waiting. The Great White Egret spent more time foraging than the other two species. Overlap between species in foraging activity on an hourly basis was high during most hours of the day implying that ecological separation through temporal partitioning of daylight hours is negligible.     

Larval behavior in Lymantria dispar increases risk of fungal infection

Late-instar larvae of the forest defoliator Lymantria dispar display relatively unusual behavior for Lepidoptera. Late instars move down from the tree canopy and wander and rest in dark locations during daylight hours. When we sampled the area extending from below 3 m and within 200 cm of tree trunks during daylight hours, 71% of L. dispar late instar larvae were found at ground level. Providing dark resting locations on the soil surface where there was no litter resulted in rapid location and colonization of these sites by late instar larvae. L. dispar larvae were always more prevalent in leaf litter 0-50 cm from tree trunks compared with 50-200 cm away. In an area where the fungal insect pathogen Entomophaga maimaiga is established, larvae were caged on tree trunks, in the foliage, or on top of soil during photophase or scotophase to determine in which locations risk of infection was greatest. At both times of day, highest infection levels always occurred on the soil, with least infection among larvae caged in the foliage. Infection levels were greater during photophase than scotophase. When larvae were exposed to soil for shorter periods during daylight hours to mimic wandering, 4.7 and 6.1% became infected after 30- and 60-min exposure intervals, respectively, with increasing infection associated with longer exposure times. The high levels of infection by E. maimaiga that have been documented in L. dispar populations since this pathogen was first found in North America are consistent with the strong litter-dwelling behavior of late-instar L. dispar larvae. Rarity of other lepidopteran larvae at ground level could help to explain the host specificity of this pathogen in the field.     

Latitudinal variation in parental energy expenditure during brood rearing in the great tit

The variation in time and energy allocation of female great tits, Parus major, was studied in five different European populations across a latitudinal gradient. Daily energy expenditure (DEE) was measured in females tending 12-day-old broods. The number of daylight hours used by the parents to collect food for the brood increased with latitude, while DEE and feeding rate per brood tended to level off with latitude. Individual variation in DEE could be explained by variation in ambient temperature (–), the duration of activity period (+) and area, but not by brood size, female body mass, brood mass or feeding rate. When the effect of ambient temperature and the duration of the activity period on the day of energy expenditure measurements were controlled for, female DEE still tended to level off with latitude. Temperature and activity alone can thus not explain the observed pattern. The present study suggests that parents at southern latitudes may be under a time constraint and do not increase energy expenditure because they have no more daylight hours available for foraging, while birds at northern latitudes may be under an energy constraint because they do not make full use of the long daylight period available. Received: 25 May 1999 / Accepted: 08 September 1999     

Ultrastructure of the Budgerigar testis during a photoperiodically induced cycle

Summary Spermatogenesis in the Budgerigar can be arrested by reducing the birds' photoperiod to 8 hours of daylight or less. When this occurs, Sertoli cell cytoplasm shows a great increase in the size and number of residual bodies, while the smooth endoplasmic reticulum is reduced. If the bird is kept at 8 hours of daylight for some weeks large lipid droplets are seen in Sertoli cytoplasm, and degenerated spermatids are apparently phagocytosed. The interstitium shows fewer active Leydig cells, a paucity of lipids and occasional ovoid mitochondria. The basal lamellae of the tubule which are thick and convoluted before and during spermatogenesis become thinner and straighter. It is thought that these morphological changes reflect changes in metabolic activity.This work was partly supported by a grant from the World Health Organisation for investigation of testicular carcinogenesis.I am grateful to Professor D. Bellamy for provision of laboratory facilities and to A. Stevenson, C. Winter and S. Jones for technical assistance.     

Daylight and absenteeism – Evidence from Norway

Based on administrative register data from Norway, we examine the impact of hours of daylight on sick-leave absences among workers. Our preferred estimates imply that an additional hour of daylight increases the daily entry rate to absenteeism by 0.5 percent and the corresponding recovery rate by 0.8 percent, ceteris paribus. The overall relationship between absenteeism and daylight hours is negative. Absenteeism is also sensitive to weather conditions. Heavy snowfall raises the incidence of absence during the winter, while warm weather reduces the probability of returning to work during the summer.     

Field and laboratory studies provide insights into the meaning of day-time activity in a subterranean rodent (Ctenomys aff. knighti), the tuco-tuco

South American subterranean rodents (Ctenomys aff. knighti), commonly known as tuco-tucos, display nocturnal, wheel-running behavior under light-dark (LD) conditions, and free-running periods >24 h in constant darkness (DD). However, several reports in the field suggested that a substantial amount of activity occurs during daylight hours, leading us to question whether circadian entrainment in the laboratory accurately reflects behavior in natural conditions. We compared circadian patterns of locomotor activity in DD of animals previously entrained to full laboratory LD cycles (LD12:12) with those of animals that were trapped directly from the field. In both cases, activity onsets in DD immediately reflected the previous dark onset or sundown. Furthermore, freerunning periods upon release into DD were close to 24 h indicating aftereffects of prior entrainment, similarly in both conditions. No difference was detected in the phase of activity measured with and without access to a running wheel. However, when individuals were observed continuously during daylight hours in a semi-natural enclosure, they emerged above-ground on a daily basis. These day-time activities consisted of foraging and burrow maintenance, suggesting that the designation of this species as nocturnal might be inaccurate in the field. Our study of a solitary subterranean species suggests that the circadian clock is entrained similarly under field and laboratory conditions and that day-time activity expressed only in the field is required for foraging and may not be time-dictated by the circadian pacemaker.     

金黄滴虫细胞同步分裂的诱导

无菌培养的金黄滴虫在25℃及连续通气的条件下,经12小时光照(2500Lux)和12小时黑暗的相间处理,可连续出现三次同步分裂,同步分裂率最高可达92％,即细胞数在一小时内可陡增92％。 细胞核动态的观察表明,在黑暗处理期中细胞被阻止于细胞分裂的前期。当黑暗处理11小时后,前期细胞突破阻拦,实现了同步分裂。     

WEDDELL SEAL UNDERWATER CALLING RATES DURING THE WINTER AND SPRING NEAR MAWSON STATION, ANTARCTICA

Underwater vocalization monitoring and surveys, both on ice and underwater, were used to determine if Weddell seals ( Leptonychotes weddellii ) near Mawson Station, Antarctica, remain under the fast ice during winter within close range of breeding sites. Daytime and nighttime underwater calling rates were examined at seven breeding sites during austral winter and spring to identify seasonal and diel patterns. Seals rarely hauled out at any of the sites during winter, although all cohorts (adult males, females, and juveniles) were observed underwater and surfacing at breathing holes throughout winter (June–September) and spring (October–December). Seal vocalizations were recorded during each sampling session throughout the study ( n = 102 daytime at seven sites collectively, and n = 5 24-h samples at each of two sites). Mean daytime calling rate was low in mid-winter (July) (mean = 18.9 ± 7.1 calls/min) but increased monthly, reaching a peak during the breeding season (November) (mean = 62.6 ± 15.7 calls/min). Mean nighttime calling rate was high throughout the winter and early spring (July–October) with mean nocturnal calling rate in July (mean = 61.8 ± 35.1 calls/min) nearly equal to mean daytime calling rate in November (during 24-h daylight). Reduced vocal behavior during winter daylight periods may result from animals utilizing the limited daylight hours for nonvocal activities, possibly feeding.     

The diel activity pattern of mountain hare (Lepus timidus) on managed heather moorland in Scotland

The research presented in this paper provides an insight into the behavioral ecology of mountain hares on heather moorland in the Lammermuir Hills of southeast Scotland. We examine the seasonal and diel activity patterns using camera traps over a period of 12 months. The rate of camera detections was calculated for the different divisions of the 24‐hr cycle (daylight, dusk, night, and dawn). During autumn and winter (October–February), the activity pattern was crepuscular with greater activity at dusk than at dawn. Daylight activity was relatively low, and there was a regular pattern of small peaks of activity during the night. In spring and summer (March–September), peaks of crepuscular activity remained evident but daylight activity was much more prevalent than during autumn and winter, and night activity was lower. We discuss the problematic definition of twilight and present an explanation for seasonal changes in the pattern of diel activity that is linked to the reproductive cycle of the mountain hare.     

Spatial and temporal patterns in Arvicanthis niloticus (Desmarest, 1822) as revealed by radio-tracking

Arvicanthis niloticus was radio‐tracked in the grasslands of the Queen Elizabeth National Park in Uganda. Home range sizes calculated by Ranges V^® using the Minimum Convex Polygon Method (at 95%) were on average 5.5 times larger in the bushland–grassland mosaic than those in the Abutilon guineense–Ocimum suave bushland. An inverse relation between home range size and population density was found. In both habitats the species was highly active during daylight hours but differed in activity patterns.     

Activity pattern of the brown howler monkeyAlouatta fusca,Geoffroy 1812, in a forest fragment of southeastern Brazil

A group of six brown howlers was studied during a year in the Santa Genebra Reserve, a 250ha-forest fragment near the city of Campinas, State of São Paulo, southeastern Brasil. On average, the group rested for 64% of the daylight hours and feeding and moving occupied 18% and 13% of this period, respectively. A greater proportion of time was spent feeding during dry season (24%) than the wet season (15%), and the reverse observed for time spent resting (59% and 69% of the group's daylight hours during dry and wet seasons, respectively). The increase of resting and decrease of feeding during wet season were related to the percentage of leaves in the group's diet, high even during the fruiting season (wet season). However, additional data of other groups are necessary to draw conclusions about the effects of habitat disturbance on this population.     

Female pre-nesting foraging and male vigilance in Common Eider Somateria mollissima

Foraging activity and behaviour of paired female Common Eider from arrival to laying at Saltholm, Denmark, was studied during the spring of 1994 and 1995 to assess the importance of female resource accumulation just prior to egg-laying. Ovary development was studied in paired females collected in 1995, 1996 and 1998. Male activity and behaviour were recorded in 1996 in order to assess the importance of mate-guarding in optimizing female resource acquisition. From arrival at the colony in late March until laying in mid-April, female Eiders allocated on average 62% of the daylight hours to foraging by dabbling in inshore waters (<1 m water depth). In offshore waters (1–4 m depth) foraging by diving averaged 74% of the daylight hours. Paired males foraged an average of 17% of the day time in the inshore habitat, and closely attended their females during this time. The males actively defended their females in encounters with other pairs and from single males. Defence events involving encounters with single males increased significantly from 9.2 times per hour to 17.5 times per hour by the time of laying. The frequency of interruption to female foraging did not change significantly as a result of the more frequent encounters towards the time of laying, being 4.0 times per hour before early April and 5.8 times per hour at the time of laying. Female ovary weights showed a significant increase from early April, indicating that resources obtained locally were allocated to egg production. The increase in encounters with single males suggests that extra-pair copulation may be a secondary reproductive strategy in male Eiders at the time their females start to incubate. The present results emphasize the importance of pre-nesting foraging for female Eiders in maximizing the nutrient intake in preparation for reproduction, and the importance of the behaviour of attendant males in protecting female foraging from interruptions from other males.