Bioacoustics of Chrysocyon brachyurus

Breeding. Females enter estrus once per year for approximately five days. Peak breeding season is from April to June. There are numerous published accounts of breeding behavior in captivity, but little information is available from wild populations. In captivity, the frequency of vocalizations (roar-bark) and scent marking increases during the weeks prior to mating, and the amount of time a pair spends in close proximity increases significantly during the estrous period. Courtship is characterized by frequent approaches, mutual anogenital investigation, and playful interactions. Mounting may occur frequently during estrus; successful breeding includes a copulatory tie that may last several minutes. In Emas National Park, Brazil , a breeding pair observed at night for approximately three and a half hours foraged together and vocalized frequently whenever one partner was out of sight. The male marked with urine or feces wherever the female marked. A breeding display lasting ten minutes concluded in a two-minute copulatory tie, after which the pair continued to forage together. Gestation length is approximately 65 days, the majority of births occurring from June to September, during the dry season. One female gave birth to three pups in a bed of tall marsh grass. At 45 days of age the pups had notyet left the den and weighed 2 kg (females) and 2-25 kg (males). All dens found in the wild have been above ground, sheltered by natural features such as shrub canopies, rock crevices, gullies, and dry mounds in marshy, tall-grass areas. In captivity, an analysis of 361 births indicated that parturition peaks in June (winter), and the average litter size is three (range 1-7). Birth weights average 390-456 g (n = 8). In captive animals, nursing bouts begin to decline after the first month, and weaning is complete at c. 15 weeks. Pups begin consuming solids regurgitated by the parents at about four weeks of age; regurgitation has been recorded up to seven months after birth. Females with 7-14-week-old pups have been observed hunting for continuous periods of eight hours over 3 km from their den sites and pups. Pups stay in the mother’s home range for approximately one year, when they begin to disperse. Juveniles attain sexual maturity at around the same time, but usually do not reproduce until the second year. One of the many unknown aspects of Maned Wolf behavioris the role the male plays in rearing pups. Pups have been seen accompanied by two adults , and a female with pups was seen accompanied by a male many times. In captivity, males increase pup survival rates and are frequently observed regurgitating to pups and grooming them. Nonetheless, direct confirmation of male parental care in the wild isstill lacking.

Movements, Home range and Social organization. Maned Wolves appear to be facultatively monogamous. Pairs are not often seen together, although researchers have observed pairs resting, hunting, and traveling together. Home ranges ofpairs in Serra da Canastra National Park averaged 25-2 km ? (21- 7-30 km ? n = 3 pairs). Home ranges studied elsewhere are larger, averaging 57 km ? ( 15:6-104-9 km ? n = 5) in Aguas Emendadas Ecological Station and 49-0 km? ( 4-7-79-5 km ? n = 5) in Emas National Park. Home range boundaries appear stable over time and are defended against adjacent pairs. Termite mounds are preferentially used as urine-markingsites, and more marks are placed on the upwind side of objects than on the downwind side. Floater individuals without territories appear to move along territory boundaries and do not scentmark. The most frequently heard vocalization is a loud roar-bark, which may occur during any time of the day or night throughout the year.

BEHAVIOR . Anestrus in captive maned wolves is characterized by mutual avoidance and minimum levels of scent marking and vocalization. Proestrus is a period of social approximation culminating in estrus. Individual distance increases during gestation, but mutual use of space remains high suggesting that females regulate the extent to which males participate in rearing their offspring ( Dietz, 1984 ). Captive males may help females during parturition and in rearing of the young ( Bartmann and Nordhoff, 1984 ). However, the contribution to parental care by free-living males is unknown. Signals such as barks, visual displays, and locus-specific defecation carry well over long distances and may be related to spacing of individuals through avoidance ( Kleiman, 1972 ). Longdistance vocalization in the wild and in captivity is most common during the breeding season ( Brady, 1981 ; Dietz, 1984). Interaction sequences in juvenile maned wolves, characterized by wrestling and frequent switching of behavioral categories, resemble those described for Canis species and are not divergent with respect to sex ( Biben, 1983 ). GENETICS . The diploid number of chromosomes for Chrysocyorı is 38 ( Newnham and Davidson, 1966 ). From this and other karyological information the species appears most closely related to Canis , Lycaon , Atelocynus , Dusicyon , and Speothos ( Chiarelli, 1975 ) . Dürr and Schmitt (1970) examined the electrophoretic differentiation of serum proteins for the maned wolf and found that this species differed from Canis familiaris , C . aureus , C . lupus , Speothos venaticus , and Lycaon pictus in the mobilities of five globulin components of the transferrin complex.