Fred H. Harrington

Pack size and wolf pup survival: their relationship under varying ecological conditions

SummaryThe relationship between pack size and two parameters of reproductive success (litter size at 7–8 months and pup weights at 5–6 months) were determined for two wolf (Canis lupus) populations in northern Minnesota. Pup weights were not correlated with pack size for either population. Litter size, however, was correlated with pack size, but the direction of the relationship varied between the two study populations.In the superior National Forest, where prey were scarce and the wolf population was declining from high densities, litter size and pack size were inversely related. Pairs produced more surviving pups than did larger packs with one or more potential helpers. In the Beltrami Island State Forest, where prey were relatively abundant and the wolf population was increasing, pack size and litter size were positively correlated. The results suggest that ecological factors, such as prey availability, affected the ability or willingness of various pack members to provide food or other care for the pups.The lack of correlation between number of auxiliaries and number of pups in canid populations with low and declining prey densities may be explained on the basis of heterogeneous prey density resulting in drastic annual variation in litter production. No study to date has measured the actual benefit that pups derive from helping by auxiliaries, and the costs and benefits of it. The relationships discussed herein can be considered valid only after such research is completed.

Individually distinct vocalizations in timber wolves, Canis lupus

Abstract Howls were recorded from seven captive wolves temporarily individually isolated from their pack-mates. Sound spectrograms of these recordings were then digitized and 14 variables were measured and subjected to multivariate statistical analyses. Both principal components analysis and discriminant analysis indicated that individuals could be reliably discriminated primarily on the basis of the fundamental frequency of howls and the variability of frequency within howls. The significance of the presence of vocal signatures in this long distance vocalization is discussed in the context of wolf social organization.

Urine-Marking and Caching Behavior in the Wolf

The relationship between urine-marking and caching was studied in two captive groups of wolves (Canis lupus). It was found that urine-marking never occurred when a cache was stocked, rarely occurred during later investigations if some food was still present, but usually occurred soon after the cache was emptied. The animal marking an empty cache was often not the one which had exploited it. Once an empty cache was marked it received little further attention, as opposed to caches that were empty but not urine-marked. These results suggest that urine-marking may enhance foraging efficiency in wolves by signalling that a site contains no more edible food despite the presence of lingering food odors.

Aggressive howling in wolves

Abstract During two studies that investigated the responses of wolf packs to either human simulations or pre-recorded playbacks of wolf, Canis lupus , howling, single adult wolves from five different packs approached my location and howled on a total of six occasions. The howls uttered by these close-approaching wolves were significnatly deeper in pitch than comparable samples of howls recorded from animals that did not approach. In addition, howls of two of the five animals differed in structure from most of the other howls recorded during both studies. These close-approach howls were characterized by the presence of harmonically unrelated frequency sidebands near the end of the howl. This feature was rate in howls recorded during occasions when wolves kept their distance. These results indicate that the structure of wolf howling during aggressive interactions with strange wolves follows Mortons (1977) motivation-structural rules, which state that natural selection will favour the use of low-frequency, harsh sounds by hostile animals. This relationship follows from the physical constraints of vocal production: animals of larger size can produce sounds of lower pitch and harsher tonal quality. As body size is a primary determinant in the outcome of aggressive interactions, vocalizations signalling size (i.e.low-pitched, harsh sounds) will be of selective value for individuals engaged in aggressive interactions.

Wolf pack spacing: Howling as a territory-independent spacing mechanism in a territorial population

SummaryHowling is a principle means of spacing in wolf populations. The relationship between a packs responses to howling (replies, movements) and its location within its home range, was studied using human-simulated howling in a territorial population in northeastern Minnesota. The results indicated the responses were independent of the packs location, or the locations of the pack and playback relation to the territory center. These results indicate that howling serves as a territory-independent spacing mechanism, that will result in the use of exclusive territories when coupled with strong, year-round site attachment, but with floating, exclusive, buffer-areas about migratory packs.

Demography of decline of the Red Wine Mountains Caribou Herd

The causes of decline of woodland caribou (Rangifer tarandus caribou) populations remain incompletely understood. We compared population characteristics of woodland caribou of the Red Wine Mountains Herd (RWMH) in central Labrador before (1981-88) and during a population decline (1993-97). During the 1980s, population estimates were 751 (no error estimation) animals in 1981, 736 ± 172 (x ± SE) in 1983, 610 ± 9 in 1987, and 741 ± 165 in 1989. By 1997, the herd declined to 151 animals (95% CI = 65-251). The decline was not associated with changes in parturition rate or in mean age of >1-year-old females, but the decline was associated with significantly lower recruitment, a greater proportion of females in the >1-year-old population, increased mortality of >1-year-old females, and emigration to the parapatric George River Caribon Herd. Throughout the study. predation by gray wolves (Cauis lupus) remained the most frequent cause of mortality of >1-year-old caribou. We hypothesize that wolves may mediate the population dynamics of sed entary woodland caribon when associated with high densities of moose (Alces alces) and migratory caribon, but that the management implications of such a triad remain unclear.

CHORUS HOWLING BY WOLVES: ACOUSTIC STRUCTURE, PACK SIZE AND THE BEAU GESTE EFFECT

ABSTRACT A variety of structural parameters were measured from wolf choruses recorded in the Superior National Forest, Minnesota, USA. Mean duration of 60s did not vary with pack size or composition. Packs replied to simulated howling after an average of 40s, often interrupting the stimulus howls. Choruses began with simply-structured howls, which became increasingly modulated as the chorus progressed. Little difference in mean fundamental frequency or other howl parameters was found among the choruses from packs of various sizes and compositions. In particular, choruses produced by single adult pairs did not differ from those of larger packs accompanied by pups. The lack of relationship between chorus parameters and pack size or composition indicates there is little useful information concerning a packs size to be found in its chorus howling. The observation that chorus howling by adult pairs is often perceived as that of larger groups with pups suggests that chorus structure has evolved to exaggerate t...

Fuzzy structure and spatial dynamics of a declining woodland caribou population

Examining both spatial and temporal variation can provide insights into population limiting factors. We investigated the relative spatial and temporal changes in range use and mortality within the Red Wine Mountains caribou herd, a population that declined by approximately 75% from the 1980s to the 1990s. To extract the spatial structure of the population, we applied fuzzy cluster analysis, a method which assigns graded group membership, to space use of radio-tracked adult females, and compared these results to a hard classification based on sums-of-squares agglomerative clustering. Both approaches revealed four subpopulations. Based on the subpopulation assignments, we apportioned the number of animals, radio-days, calving events and mortalities across subpopulations before and after the decline. The results indicated that, as the herd declined, subpopulations were disproportionately affected. In general, subpopulations with the greatest range overlap with migratory caribou from the George River herd experienced comparative reductions in activity and increased mortality. The subpopulation with the least overlap exhibited the converse pattern. The infra-population imbalances were more pronounced when hard clustering was employed. Our results reiterate that refugia from other ungulates may be important in the persistence of taiga-dwelling caribou. We propose that changes across time and space are valuable assays of localised demographic change, especially where individuals exhibit spatial hyperdispersion and site fidelity.

The Pet Relationship Scale: Replication of Psychometric Properties in Random Samples and Association With Attitudes Toward Wild Animals

AbstractRecent interest in the human-companion animal bond (HCAB) has been reflected in increased efforts to develop self-report attitudinal scales about affectionate relationships with pet Animals. A recent review and critique of pet attitude assessments indicated that most scale development efforts used small nonrandom samples, did not report psychometric characteristics, and paid inadequate attention to concurrent validation of the resulting measures. This article reports on the continued refinement and validation of the Pet Relationship Scales (PRS) in a large random sample independent from the two samples used to develop the scales. The random sample showed distinct differences in responses as compared with the two previously used samples, highlighting the need to test animal attitudes in samples drawn from the general population, and to examine them in greater detail in relation to other personal and situational factors that might mediate the influence of attitudes on behavior directed toward animals.

6 – Wolf Vocalization1

Publisher Summary This chapter provides an overview of wolf vocalization. Many different sounds have been listed in the literature: barks, howls, growls, squeaks, whines, whimpers, songs, snarls, yelps, yips, yaps, and combinations such as growl-barks, bark-growls, and bark-howls. Theberge and Falls (1967) pared the list to six basic types; Joslin (1966) used four—howl, bark, whimper, and growl—and considered the others merely subclasses of the four. The growl is a deep, coarse sound, with energy spread between 250 and 1500 hertz (Hz) and emphasis around 800 Hz (Tembrock, 1963). Whimpering includes vocalizations variously classified as whines, whimpers, and squeaks. All are characterized by their high pitch and relatively pure tone. The bark is a short, explosive sound, usually no more than .1 second long. The wolf vocalization that comes quickest to mind is the howl. Spontaneous group howling sessions follow both daily and seasonal trends in frequency. The study of wolf vocalization is in its infancy. Detailed acoustic studies of each sound form, its variations, and possible correlations with behavioral and ecological contexts are lacking for most wolf vocalizations. For howling, some preliminary work has been completed, but there is still not a complete understanding of these rich and varied vocalizations.