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Impact of Red Fox Predation on the Sex Ratio of Prairie Mallards

Table 4: Various Indices of Red Fox Densities and Estimated Spring Population of Red Fox Families

Table 4. Various indices of red fox densities in the reference area and estimated spring population of red fox families, 1963-73.

Year	Township census^a	Rural mail carrier survey^b	Strychnine-baited draw stations^c	Estimated spring population^d
1963	-	-	5,880	13,528
1964	-	2.519	7,647	16,669
1965	-	1.990	4,980	13,403
1966	-	0.680	2,731	5,316
1967	-	0.942	-	6,934
1968	-	1.054	-	7,625
1969	28	0.537	-	4,717
1970	38	0.908	-	6,401
1971	55	1.332	-	9,265
1972	69	1.711	-	11,624
1973	80	1.974	-	13,477

^a Number of fox families in six townships
^b Weighted average, of six strata encompassing the Prairie Pothole Region, of sightings of adult foxes seen per 1,609 km traveled during a 3-day period in April.
^c Total foxes recovered at strychnine-baited stations reported by the U.S. Fish and Wildlife Service, Division of Wildlife Services, Bismarck.
^d Number of fox families in our reference area.

Previous Section-- Table 3: Definitions of Rates Associated with the Equations in Table 2
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