Dennis R. Voigt

ELIMINATION OF RABIES FROM RED FOXES IN EASTERN ONTARIO

The province of Ontario (Canada) reported more laboratory confirmed rabid animals than any other state or province in Canada or the USA from 1958–91, with the exception of 1960–62. More than 95% of those cases occurred in the southern 10% of Ontario (≈100,000 km2), the region with the highest human population density and greatest agricultural activity. Rabies posed an expensive threat to human health and significant costs to the agricultural economy. The rabies variant originated in arctic foxes: the main vector in southern Ontario was the red fox (Vulpes vulpes), with lesser involvement of the striped skunk (Mephitis mephitis). The Ontario Ministry of Natural Resources began a 5 yr experiment in 1989 to eliminate terrestrial rabies from a ≈30,000 km2 study area in the eastern end of southern Ontario. Baits containing oral rabies vaccine were dropped annually in the study area at a density of 20 baits/km2 from 1989–95. That continued 2 yr beyond the original 5 yr plan. The experiment was successful in eliminating the arctic fox variant of rabies from the whole area. In the 1980s, an average of 235 rabid foxes per year were reported in the study area. None have been reported since 1993. Cases of fox rabies in other species also disappeared. In 1995, the last bovine and companion animal cases were reported and in 1996 the last rabid skunk occurred. Only bat variants of rabies were present until 1999, when the raccoon variant entered from New York (USA). The success of this experiment led to an expansion of the program to all of southern Ontario in 1994. Persistence of terrestrial rabies, and ease of elimination, appeared to vary geographically, and probably over time. Ecological factors which enhance or reduce the long term survival of rabies in wild foxes are poorly understood.

Changes in Summer Foods of Wolves in Central Ontario

Feeding habits of wolves (Canis lupus) in central Ontario compared with results from the early 1960s indicated variation in use of prey species between nearby areas. A total of 1,943 scats was collected between May and September, 1963 to 1972, in 3 study areas in central Ontario. The occurrence of beaver (Castor canadensis) hair in scats increased and of deer (Odocoileus virginianus) hair in scats decreased as follows: Algonquin Park, beaver 7 to 55 percent, deer 76 to 33 percent; Pakesley, beaver 59 to 75 percent, deer 27 to 11 percent; Marten River, beaver 37 to 74 percent, deer 42 to 1 percent. Moose (Alces alces) hair in scats collected from all three areas occurred infrequently. Juvenile deer and moose generally were selected over adults. The change in foods of wolves apparently resulted from a decrease in availability of deer in all areas. A concurrent increase in beaver occurred on only one

EFFECTS OF SELECTION CUTTING ON BIRD COMMUNITIES IN CONTIGUOUS EASTERN HARDWOOD FORESTS

Abstract We used point counts to sample bird communities in hardwood forest stands following single-tree selection harvest to determine the impacts on birds of this harvesting system. We sampled at 1–5 years post-harvest (n = 24), 15–20 years post-harvest (n = 23), and in reference stands subjected only to natural disturbances for >30 years (n = 24). White-throated sparrow (Zonotrichia albicollis), chestnut-sided warbler (Dendroica pensylvanica), and mourning warbler (Oporornis philadelphia) abundances were significantly higher in recently logged stands than in other treatments. Ovenbird (Seiurus aurocapillus) abundance was about 50% lower in recently logged stands and in stands logged 15–20 years previous than in reference stands. Black-throated blue warbler (Dendroica caerulescens) and yellow-bellied sapsucker (Sphyrapicus varius) abundances were similar in reference and recently logged stands but significantly lower in stands harvested 15–20 years previously. Redundancy Analysis (RDA) identified 6 habitat variables associated with changes in avian abundances. Percent shrub and slash cover were higher in recently logged stands than in older logged and reference stands. Deciduous canopy cover and basal area of living deciduous trees were greater in reference stands than in both logged treatments. Although the abundance of some bird species were statistically lower in selection cut stands, the implications to population persistence will require data on reproductive success in combination with population modeling with varying proportions of the forested landscape committed to selection cutting.

WILD CARNIVORE ACCEPTANCE OF BAITS FOR DELIVERY OF LIQUID RABIES VACCINE

A series of experiments are described on the acceptance, by red foxes (Vulpes vulpes) and other species, of two types of vaccine-baits intended to deliver liquid rabies vaccine. The baits consisted of a cube of sponge coated in a mixture of tallow and wax, or a plastic blister-pack embedded in tallow. All baits contained tetracycline as a biological marking agent: examination of thin sections of carnivore canines under an ultraviolet microscope revealed a fluorescent line of tetracycline if an individual had eaten baits. Baits were dropped from fixed-wing aircraft flying about 100 m above ground at approximately 130 km/h. Flight lines followed the edges of woodlots midway between parallel roads. Baits were dropped at one/sec, resulting in one bait/36 m on the ground, or 17 to 25 baits per km2. Crows (Corvus brachyrhynchos) removed many baits, but did not appear to lower the percent of the fox population which took bait. Dropping baits only into corn and woodland to conceal baits, to reduce depredation by crows, reduced acceptance by foxes. Acceptance by foxes ranged between 37 and 68%. Meat added as an attractant did not raise acceptance. Presence, absence, color and perforations of plastic bags did not alter bait acceptance. Dispersal by juvenile foxes probably lowered the estimates of bait acceptance. It took 7 to 17 days for 80% (n = 330) of foxes to eat their first bait. The rapidity with which foxes picked up their first bait appeared more affected by unknown characteristics of years or study areas than by experimental variables. Skunks (Mephitis mephitis) and raccoons (Procyon lotor) also ate these baits, but acceptance was lower. Small mammals contacted baits, but rarely contacted the vaccine, which had the potential for vaccine-induced rabies in some species. Aerial distribution of baits was more cost-effective than ground distribution as practiced in Europe. This system has potential for field control of rabies, although higher acceptance will be desirable.

Locating Pup-Rearing Dens of Red Foxes with Radio-Equipped Woodchucks

Techniques to locate pup-rearing dens of red fox (Vulpes vulpes) have included aerial surveys (Sargeant et al. 1975), questionnaires (Lemke and Thompson 1960), ground searches (Scott and Selko 1939), and monitoring radio-collared foxes (Sargeant 1972, Storm et al. 1976). The 1st 3 methods rely on observing foxes or dens and are difficult to use in forested areas. The 4th method requires extensive fieldwork. This paper describes use of radioequipped prey to locate fox dens. The technique was used successfully in an ecological study of red foxes in southern Ontario.