SEASONAL AND DIURNAL TRENDS OF CHORUSING HUMPBACK WHALES WINTERING IN WATERS OFF WESTERN MAUI

A portable data logger controlled by a Tattletale 7 microcontroller was used to record humpback whale choruses during the 1998 humpback whale winter season in Hawaii. The data logger sampled the sounds for four minutes every half hour using a digitizing rate of 2 kHz, and the data were stored on a hard disk. The results between January and April showed a peak in the sound pressure level between mid-February and mid-March. This peak of approximately 120 dB re 1 μPa coincided with the peak in the number of whales sighted by aerial survey on 7 March 1998. The choruses had spectral peaks at 315 Hz and 630 Hz. Some of the sounds at 630 Hz were second harmonics of the 315 Hz peak and others were not. The data also indicated a diurnal pattern in the sound pressure level, with levels at night significantly louder than the daytime levels. The sound levels began to increase during sunset and remained relatively high until sunrise, when they progressively decreased to a minimum. The nighttime peak occurred within an hour before and after midnight, and the daytime minimum occurred between 1100 and 1500. That more humpback whales appear to sing at night may reflect a switch to sexual advertisement as the primary male mating strategy at this time. It may also indicate that daylight and vision play key roles in the formation of competitive groups. It is suggested that the relative number of humpback whales in a given locale may be estimated by monitoring changes in sound pressure levels.     

ABUNDANCE AND POPULATION TREND (1978-2001) OF WESTERN ARCTIC BOWHEAD WHALES SURVEYED NEAR BARROW, ALASKA

The 2001 survey of western Arctic (Bering, Chukchi, and Beaufort seas) bowhead whales was conducted from 5 April to 7 June near Barrow, Alaska. Visual observers recorded a total of 3,295 “new” (not seen before) and 532 “conditional” (possibly seen before) whales in 1,130 h of watch effort, including 121 new calves (3.7% of the new whales). Concurrent with the visual survey, passive acoustic surveillance was conducted almost continuously from 16 April to 31 May, resulting in 27,023 locations of vocalizing bowhead whales. The estimated number of whales within 4 km of the perch (N₄) was 7,025 (SE = 1,068). The estimated proportion of the whales within 4 km of the perch (P₄) was 0.862 (SE = 0.044, computed by a moving blocks bootstrap). Combining these, the abundance estimate (N₄/P₄) for 2001 is 10,470 (SE = 1, 351) with a 95% confidence interval of 8, 100–13, 500. The estimated annual rate of increase (ROI) of the population from 1978 to 2001 is 3.4% (95% CI 1.7%‐5%). Reports from hunters and results of an aerial survey in June 2001 indicate whales continued to pass Barrow after the survey had ended. In 2001 51% (572 h) of the watch was scored as occurring during “fair‐excellent” visibility conditions, somewhat lower than the average for all surveys since 1978. Sea ice in the leads and fog were the principle environmental factors affecting visibility for all years. The estimated rate of increase and the fact that the number of calves counted in 2001 is the highest ever recorded suggest a steady recovery of this population. Other populations of large balaenids, notably the North Atlantic right whale, have failed to recover despite 70 yr of protection. The recovery of the howhead whale is likely attributable to low anthropogenic mortality, a relatively pristine habitat, and a well‐managed subsistence hunt. Nonetheless, offshore oil development, increasing shipping traffic, changes in the Bering Sea ecosystem, sea ice retreat, and possibly killer whale predation within its range could impact this bowhead population and should be carefully monitored.     

KILLER WHALES AND MARINE MAMMAL TRENDS IN THE NORTH PACIFIC—A RE-EXAMINATION OF EVIDENCE FOR SEQUENTIAL MEGAFAUNA COLLAPSE AND THE PREY-SWITCHING HYPOTHESIS

Springer et al . (2003) contend that sequential declines occurred in North Pacific populations of harbor and fur seals, Steller sea lions, and sea otters. They hypothesize that these were due to increased predation by killer whales, when industrial whaling's removal of large whales as a supposed primary food source precipitated a prey switch. Using a regional approach, we reexamined whale catch data, killer whale predation observations, and the current biomass and trends of potential prey, and found little support for the prey-switching hypothesis. Large whale biomass in the Bering Sea did not decline as much as suggested by Springer et al ., and much of the reduction occurred 50–100 yr ago, well before the declines of pinnipeds and sea otters began; thus, the need to switch prey starting in the 1970s is doubtful. With the sole exception that the sea otter decline followed the decline of pinnipeds, the reported declines were not in fact sequential. Given this, it is unlikely that a sequential megafaunal collapse from whales to sea otters occurred. The spatial and temporal patterns of pinniped and sea otter population trends are more complex than Springer et al . suggest, and are often inconsistent with their hypothesis. Populations remained stable or increased in many areas, despite extensive historical whaling and high killer whale abundance. Furthermore, observed killer whale predation has largely involved pinnipeds and small cetaceans; there is little evidence that large whales were ever a major prey item in high latitudes. Small cetaceans (ignored by Springer et al .) were likely abundant throughout the period. Overall, we suggest that the Springer et al . hypothesis represents a misleading and simplistic view of events and trophic relationships within this complex marine ecosystem.     

FEEDING, SOCIAL AND MIGRATION BEHAVIOR OF BOWHEAD WHALES, BALAENA MYSTICETUS, IN BAFFIN BAY VS. THE BEAUFORT SEA—REGIONS WITH DIFFERENT AMOUNTS OF HUMAN ACTIVITY

This paper compares the behavior of bowhead whales of the Davis Strait/Baffin Bay stock, as observed along the east coast of Baffin Island in 1979–1986, with behavior of the Bering/Chukchi/Beaufort Sea stock observed in the Beaufort Sea in 1980–1986. All data used here were collected during late summer and early autumn in the absence of acute human disturbance. The behavioral repertoires of the two populations were similar. However, quantitative differences were found for whales engaged in all three activities studied: (1) Bowheads feeding in deep water off Isabella Bay, Baffin Island, had longer dives and surfacings, on average, than noted for bowheads feeding in the Beaufort Sea. (2) Among whales socializing in shallow water, we saw sexual interactions more often at Isabella Bay than in the Beaufort Sea. Calls emitted by socializing whales off Baffin Island were similar to those heard in the Chukchi and Beaufort Seas. However, pulsed tonal calls were longer off Baffin Island, and previously undescribed mechanical "crunch" sounds were recorded there near socializing bowheads. (3) During autumn migration, "fluke-out" dives were less common, and dive durations were longer, in the Beaufort Sea than off Baffin Island (P<0.001). Multivariate and other analyses indicated that some but not all differences can be ascribed to regional differences in the natural environment or in whale activities, However, during 1974–1986, Bering/Chukchi/Beaufort bowheads were exposed to more industrial, hunting and other human activity than Davis Strait/Baffin Bay bowheads. The "inconspicuous" behavior during autumn migration in the Beaufort may have been attributable to human activities, but causative links cannot be isolated.     

THE DISTRIBUTION OF BOWHEAD WHALES, BALAENA MYSTICETUS, IN THE CHUKCHI SEA

Under a U.S.-U.S.S.R. cooperative Marine Mammal Project, shipboard cruises were made in 1979, 1980 and 1982, primarily to determine whether there is a substock of western Arctic bowhead whales ( Balaena mysticetus ) that summers in the western Chukchi Sea instead of migrating to the Beaufort Sea. More than 100 bowheads were sighted along the north Chukotka coast of Siberia in October 1979, and more than 200 bowheads were sighted there in September 1980. None were seen anywhere in the Chukchi Sea in late July and August 1982. We conclude that the September and October sightings were of animals returning early from the Beaufort Sea and that, other than occurrences peripheral to the main migration, there are no large concentrations in the Chukchi in the summer and there is apparently no western Chukchi substock.     

SIZE-AND AGE-CLASS SEGREGATION OF BOWHEAD WHALES SUMMERING IN NORTHERN FOXE BASIN: A PHOTOGRAMMETRIC ANALYSIS

To determine whether Hudson Bay-Foxe Basin bowhead whales segregate on the basis of age, whales summering in northern Foxe Basin, were aerially photographed in August of 1996, 1997, and 1998. Image lengths on either the negatives or contact prints were measured and total body lengths were estimated. In all three years the majority of whales photographed were ≤13.5 m long. Calves and juveniles made up 89.3%, 96.6%, and 79.3% of the total number of measured whales in 1996 (n = 28), 1997 (n = 30) and 1998 (n = 29) respectively. The number of bowheads >13.5 m, the approximate size at which females reach sexual maturity, that were photographed was directly proportional to the number of calves photographed. Our results indicate that northern Foxe Basin bowheads are part of a more widely distributed stock. Adult males and resting adult females apparently summer in another part of the range, probably northwestern Hudson Bay. Northern Foxe Basin appears to be used as a summer feeding area by cows with young-of-the-year calves and by juveniles.     

AIRCRAFT SOUND AND DISTURBANCE TO BOWHEAD AND BELUGA WHALES DURING SPRING MIGRATION IN THE ALASKAN BEAUFORT SEA

Short‐term behavioral responses of bowhead whales (Balaena mysticetus) and beluga whales (Delphinapterus leucas) to a Bell 212 helicopter and Twin Otter fixed‐wing aircraft were observed opportunistically during four spring seasons (1989–1991 and 1994). Behaviors classified as reactions consisted of short surfacings, immediate dives or turns, changes in behavior state, vigorous swimming, and breaching. The helicopter elicited fewer detectable responses by bowheads (14% of 63 groups) than by belugas (38% of 40). Most observed reactions by bowheads (63%) and belugas (86%) occurred when the helicopter was at altitudes ≤150 m and lateral distances ≤250 m. Belugas reacted significantly more frequently during overflights at lateral distances ≤250 m than at longer lateral distances (P= 0.004). When the helicopter was on the ice with engines running, 7 of 14 groups of belugas reacted, up to 320 m away, sometimes with small‐scale (≤100 m) diversion; only 1 of 8 groups of bowheads reacted. For the fixed‐wing aircraft, few bowheads (2.2%) or belugas (3.2%) were observed to react to overflights at altitudes 60–460 m. Most observed reactions by bowheads (73%) and belugas (70%) occurred when the fixed‐wing aircraft was at altitudes ≤182 m and lateral distances ≤250 m. However, the proportions reacting, especially to low‐altitude flights (e. g., ≤182 m), were underestimated for both species because observation opportunities were brief. Even so, reactions were more common when the aircraft was low (≤182 m): P= 0.009 for belugas, P= 0.06 for bowheads. There was little if any reaction by bowheads when the aircraft circled at altitude 460 m and radius 1 km. Aircraft sounds measured underwater at depths 3 m and 18 m showed that a Bell 212 helicopter was 7–17.5 dB noisier than a Twin Otter (10–500 Hz band). Bell 212 sound consisted mainly of main rotor tones ahead of the helicopter and tail rotor tones behind it. Twin Otter sound contained fewer prominent tones. Peak sound level as received underwater was inversely related to aircraft altitude, and received levels at 3 m depth averaged 2.5 dB higher than at 18 m depth. The dominant low‐frequency components of aircraft sound are presumed to be readily audible to bowheads. For belugas, these components may be inaudible, or at most only weakly audible. Mid‐frequency sound components, visual cues, or both, are probably important in eliciting beluga reactions to aircraft.     

西湖湖西浮游与着生藻类季节变化及相互关系

2014年11月至2015年8月调查了西湖湖西沿岸带浮游藻类和不同基质(植物、石块和底泥)上着生藻类的群落结构及季节变化, 分析了着生丝状藻与浮游丝状藻的相互关系以及它们与环境因子的相关性, 探讨湖西生态修复过程中季节性暴发的丝状藻水华的原因。结果表明浮游藻类和植物、底泥、石头上着生藻类中均以硅藻门种类数(分别占52.5%、60.4%、86.7%和72.7%)最多, 蓝藻门(分别占10.1%、8.9%、6.7%和15.2%)和绿藻门(分别占26.3%、19.8%、5.6%和10.6%)次之, 其他门类相对较少, 浮游藻类与着生藻类优势种季节差异较大。附植丝状藻密度显著高于附泥和附石丝状藻, 且狐尾藻上着生丝状藻密度与浮游丝状藻密度呈显著正相关, 表明狐尾藻着生丝状藻可能是浮游丝状藻较重要的来源之一, 该结果可为西湖丝状藻水华的控制提供一些参考。相关性分析表明, 着生藻类和丝状藻与各理化因子(水深、透明度、溶解氧、水温、pH、TN、SRP、TP等)均无显著相关性。     

川西平原农田啮齿动物群落动态：年间变动和季节变动

为了研究农田啮齿动物群落的动态规律,用标志重捕的方法给出了川西平原农田的啮齿动物群落的物种数、结合种群密度、生物量、物种多样性的Shannon指数与Simpson指数等5个变量的时间序列资料,并分析了这些时间序列的年间变动和季节变动的特点。结果表明：（1）5个变量总是处于不断的变化之中,特别是年间交替升降十分明显;（2）群落的全部8个物种从未同时出现过,同一个月最多有5个物种,最少只有1个物种;（3）5个变量季节变动的幅度均较大并各具有1至3个不等的明显的峰值,而年间变动的幅度则相对较小;（4）5个变量的最大值均出现在夏季,最小值则出现在春季、夏季或冬季;（5）5个变量的季节性均不强;（6）优势种大足鼠（Rattus nitidus)的种群密度分别与群落结合种群密度、生物量的年间变动和季节变动均具有相似的变动规律;此外,优势种大足鼠的种群密度、生物量分别占群落结合种群密度、生物量的比例均较高,而且这两个比例季节变动的幅度都较大而年间变动则较为稳定。     

THE ROLES OF LIFE‐HISTORY SELECTION AND SEXUAL SELECTION IN THE ADAPTIVE EVOLUTION OF MATING BEHAVIOR IN A BEETLE

Although there is continuing debate about whether sexual selection promotes or impedes adaptation to novel environments, the role of mating behavior in such adaptation remains largely unexplored. We investigated the evolution of mating behavior (latency to mating, mating probability and duration) in replicate populations of seed beetles Callosobruchus maculatus subjected to selection on life‐history (“Young” vs. “Old” reproduction) under contrasting regimes of sexual selection (“Monogamy” vs. “Polygamy”). Life‐history selection is predicted to favor delayed mating in “Old” females, but sexual conflict under polygamy can potentially retard adaptive life‐history evolution. We found that life‐history selection yielded the predicted changes in mating behavior, but sexual selection regime had no net effect. In within‐line crosses, populations selected for late reproduction showed equally reduced early‐life mating probability regardless of mating system. In between‐line crosses, however, the effect of life‐history selection on early‐life mating probability was stronger in polygamous lines than in monogamous ones. Thus, although mating system influenced male–female coevolution, removal of sexual selection did not affect the adaptive evolution of mating behavior. Importantly, our study shows that the interaction between sexual selection and life‐history selection can result in either increased or decreased reproductive divergence depending on the ecological context.     

AGE-LENGTH RELATIONSHIPS IN HUMPBACK WHALES: A COMPARISON OF STRANDINGS IN THE WESTERN NORTH ATLANTIC WITH COMMERCIAL CATCHES

Strandings of previously identified individuals, while rare, provide an opportunity to examine age-length relationships in humpback whales (Megaptera novacangliae) from the North Atlantic. Ages and lengths of 23 individuals are presented: 11 females and 12 males, 9 of known age and 14 with estimated minimum ages. Lengths ranged from 853 to 1, 430 cm, ages 0.5–17 yr. These individuals were generally smaller and more variable in size at age than reported from commercial catches. Fifteen of the stranded individuals were four years of age or younger, while few of the animals taken by whalers were this young, and these probably represented the larger individuals in these age categories. Thus the data presented herein help to give more definition to the early growth curve for the humpback whale than has previously been available. Growth equations illustrate a difference of about one meter in asymptotic length through age five between stranding and catch data. The close fit of growth models to data from younger and older animals separately and the difficulty of fitting a single growth model to animals of all ages, could indicate that a dynamic or staged growth pattern exists in this species.     

ECOLOGY, BEHAVIOR AND SOCIAL ORGANIZATION OF THE BOTTLENOSE DOLPHIN: A REVIEW

The authors review the literature on bottlenose dolphin ecology, behavior and social organization, focusing on data collected on free-ranging animals. Most bottlenose dolphins studied to date have had definable home ranges, and behavioral, morphological and biochemical information indicates discrete stocks in some areas. Bottlenose dolphins appear to form relatively permanent social groups based on sex and age. Mother—calf bonds are long-lasting. Movement patterns are extremely variable from location to location but are relatively predictable at any given site. Food resources are one of the most important factors affecting movements. Bottlenose dolphin behavior is very flexible, and these dolphins are generally active day and night. Feeding peaks in the morning and afternoon have been observed at several sites. Social behavior is an important component of daily activities. Sharks are the most significant predator on bottlenose dolphins in most areas, but captive and wild studies show that dolphins and sharks frequently live in harmony as well. Human activities may be helpful, harmful or neutral to bottlenose dolphins, but interactions with humans are frequent for these coastal cetaceans.     

短尾猴和日本猴雄性性行为的比较研究

本文比较研究了短尾猴和日本猴的雄性性行为。短尾猴属单次爬跨射精型种类,每次交配平均持续23.2秒,日本猴属多次爬跨射精型种类,每次交配平均持续8.2分,交配期间雄性平均爬跨雌性lO.6次才能达到射精。短尾猴第1顺位雄性是群中的主要交配者,它占有交配总数的70.9 %;而日本猴第5顺位以下的雄性占交配总数的64%。交配中,两种猴雄性间相互打搅行为的发生频率大致相当。短尾猴高顺位雄性的打搅行为能使低顺位雄性的交配中断,但日本猴高顺位的打搅行为只能使低顺位雄性交配的54.3%中断。     

SPERM WHALES IN THE GULF OF CALIFORNIA: RESIDENCY, MOVEMENTS, BEHAVIOR, AND THE POSSIBLE INFLUENCE OF VARIATION IN FOOD SUPPLY

Sperm whale movements, residency, population structure, and behavior were investigated in the Gulf of California in 1998 and 1999. Variations in sperm whale movement patterns and behavior were related to changes in prey abundance (jumbo squid, Dosidicus gigas ) determined by fishery statistics. Photo-identification data revealed that seven female sperm whales moved into the Gulf of California from the Galapagos Islands, traveling up to 3,803 km. These are among the longest documented movements for female sperm whales. There were significant differences in speed and distance traveled during a dive cycle between 1998 and 1999 (low and high squid abundance). In 1999 there were also significant differences in small-scale movements and behavior between the northern and the southern part of the study area (high and low prey abundance). These results suggest that when food resources are low, sperm whales travel in straighter lines, dive for longer periods, travel larger distances during dive cycles, and at higher speed. In 1999 there were significant differences in time spent socializing in areas of high prey abundance versus areas of low abundance. All of these changes in behavior were consistent with increased foraging effort when squid abundance was low. A high proportion of mature males and first-year calves were observed in the Gulf of California, suggesting that it is an important sperm whale breeding ground.