Biology and Behavior of Tub-Nesting Canada Geese

Abstract

A 3-year study (1961-64) of a sedentary flock of Canada geese (Branta canadensis maxima) is reported. A detailed study of full-winged birds was possible because each was individually colormarked and of known age and sex. Most pairs nested in elevated wash tubs which provided protection from predators during the laying period. Courtship, density of nests, and territorial requirements are discussed. Ten percent of yearling males nested. Females became productive in their second year with one-third of them nesting. Ninety percent or more of males 2 years and older and females 3 years and older paired. Polygamy was not uncommon. Nesting territories were selected by the females and defended primarily by the males. Females had an affinity for their nest sites in subsequent years. The rate of laying was one egg each 11/2 days. There was a direct relationship between age of females and initiation of laying; older females nested first. Eggs of maxima were similar to those of other subspecies. Egg size was related to age of females; 5-year-old birds laid the largest eggs. Down appeared most often with the fourth egg. Clutches of successful tub-nesting females averaged 5.5 eggs while successful ground-nesting females averaged 4.6 eggs. Older females laid larger clutches and hatched a larger percentage of their eggs than did younger females. The duration of breeding season was influenced primarily by renesting. Females incubated 28 days; males anticipated hatching. Females incubated dead eggs 1.5 times normal length. Goslings were held in the tubs about 24 hours after hatching and became imprinted to their parents. Broods were called from the tubs by their parents, and the nesting territory was abandoned as the new family swam away. Loss of production in tub nests was primarily because of desertions and in ground nests because of destructions. Renests were of two types: continuation nests, which were located an average of 96 yards from destroyed nests, and true renests, which were located an average of 243 yards away. Clutch sizes were the same in original and renests but were smaller in continuation nests. The average renesting interval was 13 days and was directly related to the number of eggs in the original nest. Seventy-three percent of incubated eggs hatched, 5 percent were infertile, and 22 percent died during incubation. Broods retained their identity for about 7 days, then gradually formed creches of increasing size. Creches were accompanied by both productive pairs and nonbreeding females. Gosling mortality averaged 32 percent. Resident geese were almost as wild as migrants during the fall but were quite tame during the postmolting period. Canada geese are prized game birds of considerable trophy value. They are widely distributed over the North American continent and hunted in some way almost 10 months of each year. Much has been learned about goose management on the wintering grounds, but because of the remoteness of most of their nesting area and the bird's wide dispersal within that area, far less is known about their breeding biology and nesting behavior. Previous behavior studies have dealt with pinioned or confined birds, and most nesting studies have been concerned with gross aspects of population productivity. The purpose of this study was to learn facts about the nesting biology and behavior of full-winged, unconfined, nonmigratory Canada geese. The objective was to determine whether these birds were suitable for restocking purposes and productive enough to warrant annual harvests. The study was conducted over a 3-year period from 1961 to 1964 at the Trimble Wildlife Area, Trimble, Clinton County, Missouri. The area, developed in 1950-51 with Federal Aid funds, is located in northwest Missouri between Kansas City and St. Joseph. Its 1,200 acres include a reservoir of 160 acres and 10 adjacent marshes totaling 175 acres. About 680 acres of upland are available for cultivation. The primary objective of management is to provide suitable habitat for ducks, nesting geese, and fish, with the ultimate goal of providing public recreation. In January, 1952, 24 pinioned Canada geese, now identified as B. c. maxima, were 'A Federal Aid to Wildlife Restoration Project, Surveys and Investigations Projects, Missouri 13-4.