Dietland Müller-Schwarze

Anal gland secretion codes for family membership in the beaver

Abstract We investigated how information about family membership is coded by the individually specific anal gland secretion (AGS) in the beaver, Castor canadensis. Because beavers live in strict family units and relatives share more features in the AGS profile than non-relatives, family members share more AGS features than non-family members. Therefore, family recognition seems to be a natural consequence of the more specific kin recognition. Multivariate statistical analyses revealed two possibilities in coding for family membership using the multi-component AGS: either two (female) to three (male) AGS compounds or many compounds were used, but we were not able to determine which possibility is more likely. Compounds were not equally important in coding family membership information, and the interactions among compounds were complex. We attempted to reconstruct a lineage tree for the relationship among different families using two–three or many compounds. We found there was no significant difference for trees constructed by using few or many compounds in either males or females. However, the trees derived from male compounds and female compounds lacked good congruence.

The social role of scent marking in beaver (Castor Canadensis)

Beaver colonies with close neighbors constructed more “scent mounds” than did isolated colonies, and the number of scent mounds at each active lodge is correlated with the distance to the nearest occupied lodge. The scent mounds were typically located at trails, also on lodges and dams. The beaver rebuilt experimentally removed scent mounds. Experimentally scent-marked unoccupied lodges were less often visited or inhabited than unscented control lodges. Resident beaver responded to artificial scent marks near their lodges with aggressive behavior and increased activity. We conclude that scent mounds serve in delineating family territories and are effective in deterring transient beaver from utilizing existing but uninhabited lodges.

Effects of predator fecal odors on feed selection by sheep and cattle.

The effectiveness of predator fecal odors in modifying feeding selection by sheep and cattle was investigated in two trials. In trial 1, animals could select from feed bins contaminated with coyote, fox, cougar, or bear fecal odor, and oil of wintergreen, or select the control feed. All odors were rejected (P<0.01) by sheep and cattle, except bear odors by sheep. In trial 2, animals could select feed during 10-min periods in an open 11-m × 16-m arena. Fecal odor did not influence approaches to feed bins, or head entries into bins. Only coyote fecal odor reduced (P<0.05) the time spent feeding in the contaminated bin, and increased (P<0.05) consumption from the control bin by both cattle and sheep. Some animals on some test days refused to feed from either feed bin, although cattle and sheep closely inspected bins. Results suggest that fecal odors may not prevent livestock from entering a treated area but may reduce the time spent grazing in such an area.

Pheromonal activity of single castoreum constituents in beaver,Castor canadensis

Behavioral activity of single components of beaver castoreum was demonstrated for the first time. In four experiments samples were presented to free-ranging beaver in their family territories. First, responses to whole castoreum and anal gland secretion (AGS) from males and females were tested. Second, 24 compounds, known to be constituents of beaver castoreum, were individually screened for activity. Four of these consistently released immediate responses during the observation periods. These are the phenols 4-ethylphenol and 1,2-dihydroxybenzene and the ketones acetophenone and 3-hydroxyacetophenone. In the most complete responses, the beaver sniffed from the water, were attracted to the odor, swam toward its source, went on land, and then approached, sniffed, pawed, and scent-marked the artificial scent mound. 4-Ethoxyphenol, a compound not yet found in castoreum, also released these responses. Five additional compounds resulted in a few delayed visits to the samples during the night following the observations, as evidenced by destroyed scent mounds. These are 4-methyl-1,2-dihydroxybenzene, 4-methoxyacetophenone, 5-methoxysalicylic acid, salicylaldehyde, and 3-hydroxybenzoic acid. Third, mixtures of 24 and six compounds were tested. Responses to these mixtures could be as strong as those to whole castoreum. Fourth, the four regularly active compounds were tested in two additional beaver populations and proved to be active there, too. The response was strongest in the densest beaver population.

Osmetrichia: specialized scent hair in black-tailed deer

Black-tailed deer (Odocoileus hemionus columbianus) possess a conspicuous tarsal hair tuft covering the tarsal gland which is located on the inside of the hock. The central hairs of that tuft carry a strong smelling mixture of sebaceous and urinary components. These central hairs are short and stiff in comparison to the outer hair of the tuft and the deers other body hair. These “scent hairs” have large chambers between the cuticular scales, and the scales have comb-like group of ridges. Lipids, in which volatiles are trapped, are held on the hair by these two features. The term “osmetrichia” is proposed for the specialized scent hair. No comparable features were found on hair covering the metatarsal gland of black-tailed deer, the tarsal gland of white-tailed deer (O. virginianus borealis); the subauricular gland of pronghorn (Antilocapra americana); on scalp, axillary, and pubic hair of Homo sapiens; or the ventral gland hair of Mongolian gerbils (Meriones unguiculatus). SEM pictures of the trough-like osmetrichia of the Mongolian gerbil are presented.

Using anal gland secretion to determine sex in beaver

Controlling beaver (Castor canadensis) populations is a problematic issue for wildlife managers in North America. Management of beaver can be facilitated by determining sex ratio of a population, but this requires ready identification of gender for live and harvested beaver. We developed a technique using color and viscosity of anal gland secretion (AGS) to identify gender of beaver. Inexperienced volunteers inspected AGS from beaver in 3 regions of New York. Using AGS collected and stored in glass vials, 4 volunteers correctly identified sex of 24 beaver (16 M, 8 F) livetrapped during spring 1992; 2 additional pairs of volunteers correctly discriminated 45 beaver (21 M, 24 F) livetrapped in spring 1993 and 1994. Using fresh AGS viewed in the field, 1 volunteer correctly discerned 25 beaver (15 M, 10 F) caught in October 1993; and 2 volunteers distinguished sex of 5 beaver (3 M, 2 F) captured in November 1992 without error. Male AGS was Kraft brown (P55, Marker color system) to sepia (P56) and viscous (490-507 centipoise [cP] at 25.8 C and 60 rpm, Brookfield DV-11 + viscometer), while female secretion was pale to medium olive (P34, P39) or warm gray (P191), less viscous (4-28.7 cP, 23-25.4 C, 50 or 100 rpm) and flowed more (P < 0.001) than male AGS. Secretion color and viscosity were discriminating means of distinguishing the sexes in the field.

Experimental habitat scenting inhibits colonization by beaver, Castor canadensis

Unoccupied beaver (Castor canadensis) sites in New York State were for two years experimentally scented with a mixture of beaver castoreum and anal gland secretion. These sites were colonized less often than unscented control sites. The beaver is the first mammal to have been shown experimentally to use intraspecific odor cues when settling in vacant habitat. Territorial pheromones may be useful as repellents for beaver or other rodents.Unoccupied beaver (Castor canadensis) sites in New York State were for two years experimentally scented with a mixture of beaver castoreum and anal gland secretion. These sites were colonized less often than unscented control sites. The beaver is the first mammal to have been shown experimentally to use intraspecific odor cues when settling in vacant habitat. Territorial pheromones may be useful as repellents for beaver or other rodents.

Castoreum of Beaver (Castor Canadensis): Function, Chemistry and Biological Activity of Its Components

Castoreum, the paste found in the paired castor sacs of both sexes in beaver, Castor canadensis and C. fiber, has been used for medicines and perfumes since time immemorial. The Romans burned castoreum in lamps and believed that the fumes caused abortions (McCully, 1969). Trappers have attracted beaver to castoreum lures for a long time. As for the natural history of castoreum, Audubon first published a trapper’s report of mud piles topped with strong-smelling castoreum that beaver built at the banks of their ponds. Two neighbor colonies alternated in marking, accumulating mud piles up to five feet high (Audubon and Bachman, 1849). To this date, we don’t know the precise role scent mounds play in the behavior, physiology and population ecology of the beaver. Aleksiuk (1968) proposed that scent marks may warn transient beaver away from occupied territories and that scent mounding may be an epideictic display sensu Wynne Edwards (1962) that communicates population density.

The “deer lactone”

Urine of the black-tailed deer is the source of the “deer lactone,” which is deposited on the tarsal gland tufts by “rub-urination.” The enantiomer composition of the lactone from the urine of the female is 89(R)-(−)/11(S)-(+). Responses by deer were strongest toward the synthetic racemic lactone in the social test and toward the natural lactone in the choice test. In both tests, the (−)- lactone released slightly stronger responses than its enantiomer.

Responses of reindeer to interdigital secretions of conspecifics

Adult captive European “forest” reindeer,Rangifer tarandus L., were exposed to hindfoot interdigital (ID) secretion placed on the ground. The animals were tested with blanks and interdigital secretion from themselves and male and female group members, and secretion from excised glands of male and female “mountain” reindeer. Responses to the stimuli consisted of sniffing, licking, and olfactory searching on the ground. With forest reindeer secretions, each sex responded more to its own ID secretion than to that of the opposite sex. Of the mountain reindeer samples, male ID secretion released stronger responses. The responses did not vary systematically from June to October. The functional significance of the ID secretion in free-ranging reindeer is discussed.