The dominance relationships and associated agonistic postures of Canada geese were studied during the winters 1963-64 and 1964-65 by observation of the behavior of radio-and color-marked families and individuals living in a large, wild flock in southern Illinois. Part I I. Behavior was not significantly altered by color-marking and attachment of trausmitters. 2. Hostile encounters occurred during almost all activities. They varied widely in frequency and intensity and were especially associated with feeding. 3. Success in hostile encounters was directly related to family size, i.e., large family> smaller family > pair > single. 4. Unified action by all members of a family occurred in 8.5 percent of victories and T5 percent of defeats. 5. All members of a family shared equal dominance status but the success of a family in the rank order was most dependent upon the gander. 6. Only once in 26 fights between unmarked family ganders did the gander of the largest family lose. 7. Dominance position of family individuals decreased immediately upon separation and increased upon reunification of family members. 8. Large families were engaged in significantly more conflicts per unit time than were singles, pairs, and small families. 9. Exceptions to the usual dominance hierarchy occurred after pairs were newly formed. The gander of a newly formed pair could dominate family ganders. 10. Intrafamily aggression was rare and of low intensity. 11. Fights rarely occurred; threats and chases were common. 12. In some instances, rank orders based upon individual recognition could exist. However, stable rank orders in most large flocks appear to be based on recognition of different postures and levels of intensity of threat. 13. The dominance order of geese yields benefit in terms of food and space acquisition and freedom from defeat in aggressive encounters for the pairs and their young in direct relation to those most successful at raising a brood. Part II 1. Postures associated with attack or fleeing or simultaneous tendencies to do both are described. These include actual fleeing or attack, Submissive attitude, Erect, Head-pumping, Rolling, Bent-neck, and Forward postures. 2. The Submissive attitude is exhibited mostly by single geese and probably results from the conflicting tendency to approach (but not attack) and flee from other geese at the same time. This posture functions to identify single geese, allow approach, habituation, and ultimately pair formation, and inhibits violent attack. 3. The Erect posture may take either the form of intention movements of escape or attack and represents an ambivalent motivation between these two tendencies. 4. Head-pumping contains alternating intention movements of attacking and fleeing and represents almost a perfect balance between these two tendencies but is of higher intensity and ritualization than the Erect position. 5. Rolling is a complex portion of the Triumph Ceremony but also serves as the most intense threat of Canada geese and is highly ritualized. The spatial relationships of a gander to his mate and family appear most important in motivating Rolling. Intrusion of another high ranking gander or family on those boundaries may result in violent attack. 6. Erect, Head-pumping, and Rolling serve as three different intensity threats which are recognized by other geese and serve to maintain and establish the rank order of geese without undue fighting. 7. Bent-neck and Forward postures may occasionally represent conflicting attack and flee tendencies but often appear to represent a conflict of attack and remain doing another activity such as feeding or preening. These postures serve to maintain and reinforce a rank order but are probably not very important in initial establishment of rank.

No abstract

Food selection by and diet of Cackling Goose (Branta canadensis minima) goslings were studied in relation to the quality and availability of food during brood rearing, 1977-1979. Arrowgrass (Triglochin palustris) was the most important food in the diet of goslings before wing-molt of adults and sometimes during molt. Carex mackenziei was the most common sedge in the diet but was less important than arrowgrass. Leaves of other species were relatively unimportant during premolt. Arrowgrass declined, while Carex seeds and crowberries (Empetrum nigrum) increased, in the diet as brood rearing progressed. Arrowgrass was highly preferred, whereas other sedges and grasses (except C. mackenziei) were avoided in areas for which both availability and consumption were measured. Preference for arrowgrass was related to its higher protein and energy content and lower cell-wall content compared to other forage species. Thus, geese benefitted nutritionally from selecting their preferred diet. Seeds and berries contained high levels of lipids and carbohydrates relative to green leaves. Less arrowgrass was consumed in a year when brood densities were higher than in the other 2 years of the study. Arrowgrass availability declined as brood rearing progressed in another year. Thus, Cackling Geese may have been reducing the availability of their most nutritious food, at least at high brood densities. Food quality in breeding areas may be influencing population dynamics of geese despite the high overall availability of green plants.

The incubation constancy of 11 female Emperor Geese (Chen canagica) was monitored electronically and behavior of both sexes was observed during incubation recesses in 1983 and 1984 at Kokechik Bay, Alaska. Average nest attentiveness of female Emperor Geese was 99.5% during 4,800 h of monitored incubation time. Recesses averaged (±SE) 13.3 ± 0.8 min, and modal recess length was 8 min (n = 107). Recess frequency was 0.54/day. This high degree of nest attentiveness exceeded that reported for any goose species. Nest attentiveness did not vary significantly through the incubation period, but increased in the last 3 days, probably in response to embryo noises and pipping. Most recesses (45%) occurred between 1200 and 1800, the warmest portion of the day. There were no significant differences in recess length at different times of day, however, and recess duration and frequency were not related to differences in daily temperature or wind speed. Females fed for only 14% of the time during their infrequent and brief recesses. Most time (43%) during recesses was spent preening and bathing. Males were alert for 49% of the time females were on recess but were present during only 56% of recesses, reflecting their relative lack of attendance during incubation. Behavior of females during recesses when males were absent did not differ significantly from when males were present. The high incubation constancy, loss of body mass during incubation (20.7%), and relatively large average clutch size (5.2) indicate that Emperor Geese arrive on nesting grounds with an extremely high level of endogenous reserves relative to other geese. Clutch size and incubation behavior also represent trade-offs in energy investment related to body size, egg size, food availability, and feeding needs during incubation. Generally, larger species or subspecies of geese depend more on endogenous reserves than do smaller forms. We believe, however, that this relationship is not satisfactorily explained just by energetic constraints related to body size because Emperor Geese were more attentive to incubation than even larger goose species. Emperor Geese usually can defend their nests from arctic foxes (Alopex lagopus) but, when on incubation recesses, are apparently less efficient in defense against avian predators than sympatric-nesting smaller geese. These smaller species are more vulnerable to foxes but more agile and effective against avian predators. The incubation constancy of geese results from an interaction of predation pressures related to body size and defense capabilities.

During 1979 and 1980, we studied the incubation behavior and body-weight dynamics of captive Canada Geese (Branta canadensis moffitti) with known breeding histories. Females were attentive to their nests for 97.5% of the incubation period and lost 27% of their initial body weight. Heavier females were more attentive to their nests and lost more weight during incubation than did lighter females. Variation in body weight among females was greatest at the onset of incubation and least at hatch, which suggests that females invested maximum reserves in incubation. Recess frequency and duration increased throughout incubation, resulting in more foraging time for the female. Once a lower critical weight of about 3,200 g was reached, the amount of recess time taken increased dramatically, probably because lipid reserves were depleted. Females nesting for the first time began incubation at a lighter body weight and were less attentive than experienced females. All inexperienced females were either 4 or 5 yr old, but their egg production (4 eggs) was that of 2- or 3-yr-old wild females. This indicated that experience rather than age was the important variable affecting acquisition of reserves. Inattentiveness to a nest by a female prolongs the duration of incubation and exposes the nest to a greater risk of predation. The inability of inexperienced females to gain enough reserves to provide for both maximum clutch size and attentiveness during incubation may be a major explanation for the lower hatching success of geese nesting for the first time.