Persistence Hunting Research Articles

Hunting and the Likelihood of Extinction of Amazonian Mammals

Species inhabiting tropical forests are thought to be on the verge of mass extinction. Much work has focused on extinction rates caused by deforestation; however, many of the recorded extinctions that have occurred since 1600 were a result of overhunting. We collected data on the relative abundance of large‐bodied mammals in the northeastern Peruvian Amazon in areas with persistent hunting pressure and in areas with infrequent hunting pressure. We quantified the effects of hunting by calculating the change in abundance of species between the infrequently and persistently hunted sites. We report that in Amazonian mammals weighing more than 1 kg the degree of population declines caused by hunting is correlated with the species’ intrinsic rate of natural increase (rmax ), longevity, and generation time. Our results show that species with long‐lived individuals, low rates of increase, and long generation times are more vulnerable to extinction than species with short‐lived individuals, high rates of increase, and shorter generations.

Convariation of Spider Egg and Clutch Size: The Influence of Foraging and Parental Care

The purpose of this study was to investigate the effects of body size, foraging mode, and parental care on the relationship between clutch size and egg size in spiders. Specifically, covariation of egg size and clutch size with body size was investigated, using data from the literature, in 156 species of North American spiders from 22 families. Variance in clutch size and egg size was found to be mainly attributed to differences among genera. I therefore conducted a comparative analysis at the generic level. Results indicated that clutch and egg size were influenced by body size. Spiders from genera with larger body sizes produced larger offspring and more offspring per reproductive event than spiders from genera with smaller sized species. Relative egg number was inversely related to size of eggs produced, indicating a reproductive trade—off. Web building spiders produced more and smaller eggs than cursorial hunting spiders of a similar body size. Furthermore, cursorial spiders that guard and carry their young produced more young than those that only guard the eggs before hatching or do not guard. However, residual clutch size or residual egg size (residuals from regressions of clutch size and egg size, respectively, against female body size) did not differ among parental care groups. This study suggests that the method of food acquisition and type of parental care contributed to the offspring are associated with clutch size and egg size in spiders.

Responses of Bull Elk to Simulated Elk Vocalizations during Rut

We studied the responses of mature, bull elk (Cervus elaphus nelsoni) to repeated bugling that simulated a technique used by hunters to harvest elk. Our study was conducted on the Forbes Trinchera Ranch in southcentral Colorado during September and October 1988-89. We repeatedly approached and bugled at individually radio-collared bulls. To instill negative reinforcement, treatment bulls were harassed by the sound of a shot after bugling sessions; control bulls were not. We used a logistic regression model to test the bulls' ability to learn to avoid hunter vocalizations after repeated harassment. A model that fit the observed data included previous harassment (P = 0.030, 1988; P < 0.0001, 1989), suggesting that repeatedly harassed bulls can learn to avoid a bugling hunter. J. WILDL. MANAGE. 55(3):396-400 Several hypotheses regarding the function of bugling by bull elk have been suggested. Bulls may bugle to advertise to cows (Struhsaker 1967, Geist 1982), to bring harem members closer together (Bowyer and Kitchen 1987), or to assess the fighting ability of other bulls (Clutton-Brock and Albon 1979). During rut some bulls will respond to bugling by searching out and chasing off intruders (Geist 1982, Bowyer and Kitchen 1987); others will try to threaten the intruder with bugles of their own (Harper et al. 1967, Lincoln et al. 1970, Clutton-Brock and Albon 1979). These responses are regularly exploited by hunters during rut. Because the number and proficiency of hunters attempting to harvest bull elk during rut has increased, wildlife managers are concerned that this technique could result in an overharvest or excessive disturbance of bulls during a time of year when they are highly vulnerable. Shooting in the immediate proximity of an elk may cause it to run several kilometers (Skovlin 1982) or to move off into distant, heavily-timbered areas (Ward 1973, Wright 1983). Batcheler (1968) thought that persistent hunting in New Zealand caused a shift in habitat use and an increase in nocturnal activity. If bulls did not develop an avoidance response to hunter bugling, concern about further behavioral and physiological effects of heavy hunting pressure during the rut might be warranted. Artificial bugling by hunters represents a unique type of disturbance, the effects of which have not been determined. Our objective was to determine whether individual bulls learn to cease responding when they are repeatedly harassed after approaching a simulated bugle. We administered the aversive stimulus of firing a blank from a revolver to treatment bulls to experimentally test bull

Peregrine falcon and merlin predation on small shorebirds and passerines in Alberta

This study describes and compares hunting techniques and predatory efficiency of peregrine falcon (Falco peregrinus) and merlin (Falco columbarius) preying on small shorebirds and passerines in open agricultural lands around Beaverhills Lake, Alberta, during spring and fall, 1965–1987. Hunting methods were divided into four categories: (i) surprise attacks with less than six swoops at prey initially on the ground, (ii) short pursuits with less than six swoops at flying prey, (iii) persistent, long-range pursuits with more than six swoops, and (iv) other or unknown methods. They made up, respectively, 73.9, 17.2, 2.5, and 6.4% of 647 hunts by peregrines, and 72.3, 16.1, 4.5, and 7.1 % of 354 hunts by merlins. Persistent pursuits of prey were significantly more successful than surprise attacks by merlins (62.5 vs. 9.4%, P &lt; 0.00001), but not by peregrines (18.8 vs. 8.8%, P = 0.40). I postulate that peregrines and merlins employ persistent hunting techniques only if surprise attacks are unproductive because of (i) lack of expertise of the falcon, (ii) scarcity of prey, (iii) unsuitable habitat, and (iv) effective early warning by flocking prey. Peregrines captured 50 shorebirds of 11 species, and 3 passerines of 2 species. Merlins captured 28 shorebirds of 8 species, and 16 passerines of 5 species. Adult male merlins were significantly more successful than immatures and adult females combined (38.7 vs. 9.1%, P &lt; 0.00001). Adult peregrines were not significantly more successful than either spring or fall immatures (9.2 vs. 7.2 and 4.9%, P = 0.21, P = 0.24, respectively). Merlins were significantly more successful than peregrines in hunting small passerines (12.2 vs. 3.8%, P = 0.04), but not significantly more successful in hunting small shorebirds (12.6 vs. 8.8%, P = 0.10).

Hunting Ability and Reproductive Success Among Male Ache Foragers: Preliminary Results

Hunting Ability and Reproductive Success Among Male Ache Foragers: Preliminary Results

Factors affecting abundance of bowhead whales Balaena mysticetus in the eastern arctic of North America, 1915–1980

The severely depleted bowhead whale Balaena mysticetus has failed to recover from overexploitation during the 18th and 19th centuries in the Eastern Arctic. Although commercial whaling for bowheads ended in this region about 1915, bowhead whaling by native people has continued until recently in parts of the Eastern Arctic. Low-level but persistent hunting by Inuit (Eskimos) may have inhibited bowhead population increase. Two natural mortality factors can be documented—ice entrapment and predation by killer whales Orcinus orca. There is little direct evidence of ice-related mortality but a strong circumstantial argument that ice conditions affect survival. Killer whales are known to prey on most species of large whales, and we believe bowhead whales and right whales Eubalaena glacialis are especially vulnerable. The bowhead's apparent failure to recover in the Eastern Arctic may be due to a combination of continued low-level hunting, habitat instability, and predation. Complete protection from all forms of hunting is necessary to ensure the bowhead's survival. Environmental disturbances due to industrial development in the Arctic may have direct and indirect impact on bowhead habitat and behaviour, creating an urgent need for further study.

An equation for prediction of energy expenditure of walking and running.

An equation for prediction of energy expenditure of walking and running.

Heat of evaporation of sweat: thermodynamic considerations.

Heat of evaporation of sweat: thermodynamic considerations.

Reactors in hydroelectric stations

The advantages and limitations in the use of current limiting reactors in hydroelectric stations are not so well recognized or understood as they are in steam turbine stations, but it is now coming to be realized that their use may be quite as justifiable and necessary in the former as in the latter. The two beneficial results of reactance, protection and localization, are distinct; the former being associated with the square, and the latter with the first power of the reactance. Of two detrimental results of reactance, or limitations to its use, one, that of voltage drop, is well understood but the other, the reduction of synchronous stability is not so well understood. The installation of reactance usually results in a decrease in the stability of synchronism. Such stability may be expressed in terms of the angular phase displacement between two groups, due to a sudden load disturbance. Practically, complete instability or asynchronism occurs in a large station when the phase angle exceeds 90 deg. The asynchronizing effect of a sudden load change is approximately twice that of a gradual change of the same magnitude. The origination of a power surge by sudden loss of load and the accompanying hunting oscillation is described. Increased reactance increases the amplitude of both the power surge and the phase-angle oscillation and also increases the period. A certain amount of reactance will result in complete asynchronism immediately following the load disturbance, and a smaller amount may cause troublesome and persistent hunting by forced harmonic oscillation of the turbine governors in combination with certain hydraulic conditions, such as long penstocks. It is shown that these phenomena form a practical limitation to the use of reactance, in that the reactances necessary to create the conditions described are of the same magnitude as those often indicated for protective and localizing purposes. The actual occurrence of a surge is described.