The use of nutrient reserves by breeding male lesser snow geese Chen caerulescens caerulescens C. DAVISON ANKNEY
Can. J. Zool. Downloaded from www.nrcresearchpress.com by McMaster University on 11/21/14 For personal use only.
Department o f z o o l o g y , University of Western Ontario, London, Ont., Canada N6A 5B7 Received July 8, 1977
ANKNEY,C. D. 1977. The use of nutrient reserves by breeding male lesser snow geese Chen caerulescens caerulescens. Can. J . Zool. 55: 1984-1987. Breeding male lesser snow geese were collected at the McConnell River, Northwest Territories, and the size of their nutrient reserves (fat and protein) were indexed. The males use these reserves during nesting but protein use is less than that reported for females. It is argued that males use food available on the territory and thus remain in better condition than females. This allows them to protect the female and to become guardian of the family after hatch. ANKNEY,C. D. 1977. The use of nutrient reserves by breeding male lesser snow geese Chen caerulescens caerulescens. Can. J . Zool. 55: 1984-1987. Des petites oies blanches miles en Ltnt de se repmduire ortt & t i caprurees dans la rivitre McConnell. dans les temtoires du Nord-Ouesr. ct I'importance de leurr; kse-wes nutritives (graisses et pmtiines) a i t k evalute. Idesmiles ulilisent leurs kserves durant la nidation. mais la dcpense en proteines est moins grande que celle qu'on peut enregistrer chez Ies femefles. I1 semblc que le mile utilise la noumture disponihle sur le territoire, se gardant ainsi e n meilleure condition que la ferneHe. ce qui lui permet de protegerla femelle el de tlevenirgardine de la famille apres I'tclosion. [Traduit par le journal]
Introduction Male birds, unlike females, require little energy for gonadal growth (King 1973). Nevertheless, males of many species lose weight during the breeding season. Although little is known about the physiological stresses incurred by breeding males (Roseberry and Klimstra ]971), male weight loss is thought to reflect the demands of courtship and (or) territory defense (e.g. Anderson 1972; Brenner 1968; "anson 1962; ~~~t~~ et al. 1974; Oring 1969; Ryder 1975). In certain species incubation is an energetic cost for males (El-Wailly 1966). Weight loss by breeding males is usually assumed to reflect fat utilization, although in spruce grouse (Dendragupus cansdensis) male weight changes primarily reflect changes in mass (Pendergast and Boag 1973). Tundra-nesting geese are heavy and have large fat reserves on arrival at the breeding grounds and show reduced feeding during egg laying and incubation 1962, 1967; Coach 19-58; Hanson 1962; Ryder 1970, 1975). Weight loss, by both sexes, occurs during breeding in several species (brant Branfa bernicla) (Barry 1962); canada goose (B. anadensis) (Hanson lesser snow geese (Chen caeruzescens caerulescens) (Cooch 1958); Ross' goose (C.
rossi) (Ryder 1970, 1975). Ankney and MacInnes (unpublished manuscript) showed that weight loss in nesting female lesser snow geese from Use of nutrient reserves (mainly fat and protein) for egg production and incubation. However, detailed information about changes in the weight of nutrient reserves of male geese been published. My purposes are to has Present such data for male lesser snow geese (which here includes the blue and white color phases) and to explain their significance to the rep'flductive Strategy of this species+These data provide some support for Ryder's hy" pothesis about the evolution of territory size for colonia1 nesting geese.
Methods Data are from male lesser snow geese collected from mid-May through midJuly, 1971 and 1972, at the nesting E O I O ~ at~ the mouth of the McConnell Rlver (60 LO' N, 9 4 2 5 ' W), Northwest Territories, Canada. The area was described by Maclnnes (1962). Bxeding he no logy and t~mingof collection periods were nearly identical ~n thc 2 years (Table 1) and the data have bWn combined. I assig~led hirdg to the following catcgorles (collection methods are given I,y ~ n k n e f 1 9 7 4 ) : nrriuin~,males arriving on the breeding ground: Iujbing,males mated to "males that had just compfeted laying: ear/)' incubation. males mated to females that had incubated &I1 days (incubating geese were collected from nests with known histories); /ate incubation, males mated to females that
TABLE 1. Breeding phenology and collection periods
Can. J. Zool. Downloaded from www.nrcresearchpress.com by McMaster University on 11/21/14 For personal use only.
Peak of arrival Collected arriving 33 Peak of laying Collected laying 3d Collected early incubation 33 Collected failed nesters 66 Collected late incubation $3 Peak of hatch Collected posthatch 33 had incubated at least 17 days of the 23-day incubation period; posrhatch, males collected 7-14 days after the peak of the egg-hatching period; failed nesters, males mated to females that were collected feeding, away from the colony, at the end of incubation. I used body weight, i.e., the fresh weight of a gander minus the weight of intestinal contents, as an overall index of its nutrient reserves. The protein reserve index (protein RI) is the total dry weight of sternal muscles (pectoralis, supracoracoideus, and coracobrachialis), leg muscles (all muscles having either their origin or insertion on the femur or tibiotarsus), and gizzard (minus contents). The fat reserve index (fat RI) is the total wet weight of subcutaneous, mesenteric, and abdominal fat. Sternal and leg muscles were excised unilaterally and dry weights were doubled to compute the protein RI. Muscles were freezedried in 1971 and oven-dried (22 h at 105'C) in 1972; these techniques did not remove significantly different amounts of water from comparable samples (Ankney 1974). The components of the protein R I are presented separately and in total as they did not show simultaneous weight changes. I did not measure intracellular fat in the muscles for two reasons. Firstly, most intracellular fat is not an energy reserve (Hoar 1966). Secondly, Hanson (1962) showed that variation in intracellular fat content of leg and breast muscles of Canada geese accounted for little of their weight changes. Statistical tests follow Sokal and Rohlf (1969); significance was set at the 5% level.
Results Breeding male lesser snow geese used nutrient reserves after arrival on the breeding ground (Table 2). Mean body weight was highest at arrival (Table 2); in laying males, collected an average of 7 days later, mean body weight was lower, but not significantly (0.1 > p > 0.05). Mean body weight decreased significantly during the nesting period (weight loss averaged 2 0 x from arriving through late incubation) but no change occurred during posthatch. The fat RI decreased significantly during successive periods and was depleted by the middle of posthatch (Table 2). The only significant change in the protein RI occurred between early and late
27 May-28 May 23 May-29 May 28 May- 3 June 30 May- 1 June 5 June-15 June
-
26 June-27 June 27 June-29 June 6 July-13 July
26 May-27 May 23 May-31 May 27 May- 2 June 30 May- 7June 5 June-14 June 22 June-24 June 19 June-26 June 26 June-28 June 6 July -1 3 July
incubation. However, changes in the components of the protein RI were sometimes in different directions and thus cancelled each other (e.g. between arriving and laying, and between late incubation and posthatch). I compared failed nesters with late incubation males as both groups were collected during the same period (Table 1). They differed significantly ( p < 0.05) only in mean gizzard weight; the heavier gizzards of failed nesters result from increased feeding by these birds (Ankney 1977). Discussion Feeding by male lesser snow geese declines after they arrive on the breeding ground until midway through incubation but increases late in incubation (Ankney 1977). Males arrived with large nutrient reserves and used them, especially fat, during the breeding season (Table 2). Nutrient reserve use by a male reflects the demands of territory maintenance plus his existence energy; courtship and copulation are completed before lesser snow geese arrive and males do not incubate (Cooch 1958). The energy cost of establishing and defending a territory must be relatively high for these geese because they nest in colonies (often more than 1000 pairs/km2 (C. von Barlowen, personal communication)); fights between neighboring males are common during egg laying and incubation. The decline in protein reserves during incubation was considerably less in males (14% (Table 2)) than in females (35% (Ankney and MacInnes, unpublished manuscript)) even though males are more active than females during incubation. There are two, not mutually exclusive, explanations for that: (1) the nitrogen conserving effect of androgens inhibits protein catabolism in males; and (2) males probably feed more than females during incubation (Ankney 1977) and the oxalacetate required for fat metabolism is
1986
CAN. J. ZOOL. VOL. 55, 1977
TABLE 2. Changes in body and nutrient-reserve weights (grams) of breeding males. Mean
Body weight Protein R I Gizzard Breast muscle Leg muscle Fat RI
Arriving ( N = 45)
Laying ( N = 18)
Early incubation ( N = 18)
2810k40 246.2k4.7 34.1k0.7 135.5+ 3.2 76.6k2.0 398.5k18.1
2680 k 60 247.2k9.3 29.2k1.1 136.9k5.8 81.1k3.2 272.3k24.3
2400 + 40 228.7k5.3 27.0k 1 . O 124.223.6 77.2f3.2 116.1+17.9
Pa
Late incubation ( N = 22)
f SE
Pa
Posthatch ( N = 22)
aP = probability (from one-way ANOVA between each pair of adjacent means) that means in adjacent columns are different by chance * p < 0.05, * * p < 0.01, *'*p < 0.001, NS indicates P > 0.05.
Can. J. Zool. Downloaded from www.nrcresearchpress.com by McMaster University on 11/21/14 For personal use only.
*None had a measurable amount of fat.
mostly derived from dietary carbohydrates rather than from protein catabolism (see Hanson 1962 for a review of avian intermediary metabolism). The former explanation may give a proximate factor in less use of protein reserves by males, but the latter one suggests an ultimate factor: that males establish territories large enough to provide some food during incubation because it is important that they remain physically strong. Ryder (1975) hypothesized that, in colonial nesting geese, a male should acquire a territory small enough to defend against conspecifics but large enough to provide him with supplemental food. He argued that supplemental food was necessary so that the gander would not have to leave the territory and thus leave the incubating goose undefended from attacks by neighboring ganders. Attacks by ganders on undefended females are a maior cause of nest desertion in Canada geese and Boag 1972). I agree with Ryder and suggest that food that the male gets on his territory enables him to maintain the large muscles which are important for defending the female. I have no evidence that males ever deplete their reserves to the point where starvation is the alternative to leaving the territory to feed. Starved males have not been found and reserves of failed nester males were not lower than those of late incubation males. This is not so in females because they occasionally starve to death (Harvey 1971; Ankney 1975) and failed nester females have significantly smaller reserves than late incubation females (Ankney and MacInnes, unpublished manuscript). Even successful females are extremely emaciated at the end of incubation. In lesser snow geese the strategy of nutrient reserve use during reproduction is as follows. Females rely almost solely on their nutrient
c wasc chuck
reserves for egg production and energy during incubation. This allows them to devote maximal attention to the eggs but they complete incubation in poor physical condition. Males also use nutrient reserves during nesting but that use is mitigated by food eaten on the territory. The gander thus is able to defend the territory and is in relatively good condition at hatch. That is important because he then becomes the guardian of the female and brood and this allows the female to spend much time feeding (Harwood 1975). As a result, females gain weight after hatch (mean increase = 11% (Ankney and MacInnes, unpublished manuscript)) but males do not (Table 2). Thus, large nutrient reserves are very important to breeding lesser snow geese; the male-female 'cooperation' in using these reserves is noteworthy.
Acknowledgements I am grateful to Charles MacInnes for advice, encouragement, and assistance during this study. Larry Patterson provided excellent field assistance. This research was supported by the Canadian Wildlife Service, the National Research Council of Canada, and the University of Western Ontario. D
ANDERSON, W. L. 1972. Dynamics of condition parameters and organ measurements in pheasants. Ill. Nat. Hist. Surv. Bull. 30: 455-497. ANKNEY, C. D. 1974. The importance of nutrient reserves to breeding blue geese (Anser caerulescens caerulescens). Ph.D. Thesis, University of Western Ontario, London. -1975. Neckbands contribute to starvation in female lesser snow geese. J. Wildl. Manage. 39: 825-826. 1977. Feeding and digestive organ size in breeding lesser snow geese. Auk, 94: 275-282. BARRY,T. W. 1962. Effects of late seasons on Atlantic brant reproduction. J. Wildl. Manage. 26: 19-26. 1967. The geese of the Anderson River delta,
Can. J. Zool. Downloaded from www.nrcresearchpress.com by McMaster University on 11/21/14 For personal use only.
ANKNEY
Northwest Temtories. Ph.D. Thesis, University of Alberta, Edmonton. BRENNER, F. 1. 1968. Energy flow in two breeding populations of redwing blackbirds. Am. Midl. Nat. 79: 289-310. C o o c ~F. , G. 1958. The breeding biology and management of the blue goose Chen caerulescens. Ph.D. Thesis, Cornell University, Ithaca. EL-WAILLY, A. J. 1966. Energy requirements for egg laying and incubation in the zebra finch Taeniopygia castonotis. Condor, 68: 582-594. EWASCHUK, E., and D. A. BOAG.1972. Factors affecting hatching success of densely nesting Canada geese. J. Wildl. Manage. 36: 1097-1 106. HANSON, H. C. 1962. The dynamics of condition factors in Canada geese and their relation to seasonal stresses. Arct. Inst. North Am. Tech. Pap. No. 12. J. M. 1971. Factors affecting blue goose nesting HARVEY, success. Can. J. Zool. 49: 223-234. J. 1975. The feeding strategies of blue geese, HARWOOD, Anser caerulescens. Ph.D. Thesis, University of Western Ontario, London. HOAR,W. S. 1966. General and comparative physiology. Prentice-Hall, Englewood Cliffs. p. 226. KING,J. R. 1973. Energetics of reproduction in birds. In
1987
Breeding biology of birds. Edited by D. S. Farner. Natl. Acad. Sci., Washington, D.C. pp. 78-107. MACINNES, C. D. 1962. Nesting of small Canada geese near Eskimo Point, Northwest Territories. J. Wildl. Manage. 26: 247-256. and A. J. ISAACSON. MURTON, R. R., N. J. WESTWOOD, 1974. Factors affecting egg weight, body weight and moult of the woodpigeon, Columbia palurnbus. Ibis, 116: 52-73. ORING,L. W. 1969. Summer biology of the gadwall at Delta, Manitoba. Wilson Bull. 88: 44-54. PENDERGAST, B. A., and D. A. BOAG.1973. Seasonal changes in the internal anatomy of spruce grouse in Alberta. Auk, 90: 307-317. J. L., and W. D. KLIMSTRA. 1971. Annual ROSEBERRY, weight cycles in male and female bobwhite quail. Auk, 88: 116-123. RYDER,J . P. 1970. A possible factor in the evolution of clutch size in Ross' goose. Wilson Bull. 82: 5-13. 1975. The significance of temtory size in colonial nesting geese-an hypothesis. Wildfowl, 26: 114-1 16. SOKAL,R. R., and F. J. ROHLF.1969. Biometry. W. H. Freeman, San Francisco.
Can. J. Zool. Downloaded from www.nrcresearchpress.com by McMaster University on 11/21/14 For personal use only.
Department o f z o o l o g y , University of Western Ontario, London, Ont., Canada N6A 5B7 Received July 8, 1977
ANKNEY,C. D. 1977. The use of nutrient reserves by breeding male lesser snow geese Chen caerulescens caerulescens. Can. J . Zool. 55: 1984-1987. Breeding male lesser snow geese were collected at the McConnell River, Northwest Territories, and the size of their nutrient reserves (fat and protein) were indexed. The males use these reserves during nesting but protein use is less than that reported for females. It is argued that males use food available on the territory and thus remain in better condition than females. This allows them to protect the female and to become guardian of the family after hatch. ANKNEY,C. D. 1977. The use of nutrient reserves by breeding male lesser snow geese Chen caerulescens caerulescens. Can. J . Zool. 55: 1984-1987. Des petites oies blanches miles en Ltnt de se repmduire ortt & t i caprurees dans la rivitre McConnell. dans les temtoires du Nord-Ouesr. ct I'importance de leurr; kse-wes nutritives (graisses et pmtiines) a i t k evalute. Idesmiles ulilisent leurs kserves durant la nidation. mais la dcpense en proteines est moins grande que celle qu'on peut enregistrer chez Ies femefles. I1 semblc que le mile utilise la noumture disponihle sur le territoire, se gardant ainsi e n meilleure condition que la ferneHe. ce qui lui permet de protegerla femelle el de tlevenirgardine de la famille apres I'tclosion. [Traduit par le journal]
Introduction Male birds, unlike females, require little energy for gonadal growth (King 1973). Nevertheless, males of many species lose weight during the breeding season. Although little is known about the physiological stresses incurred by breeding males (Roseberry and Klimstra ]971), male weight loss is thought to reflect the demands of courtship and (or) territory defense (e.g. Anderson 1972; Brenner 1968; "anson 1962; ~~~t~~ et al. 1974; Oring 1969; Ryder 1975). In certain species incubation is an energetic cost for males (El-Wailly 1966). Weight loss by breeding males is usually assumed to reflect fat utilization, although in spruce grouse (Dendragupus cansdensis) male weight changes primarily reflect changes in mass (Pendergast and Boag 1973). Tundra-nesting geese are heavy and have large fat reserves on arrival at the breeding grounds and show reduced feeding during egg laying and incubation 1962, 1967; Coach 19-58; Hanson 1962; Ryder 1970, 1975). Weight loss, by both sexes, occurs during breeding in several species (brant Branfa bernicla) (Barry 1962); canada goose (B. anadensis) (Hanson lesser snow geese (Chen caeruzescens caerulescens) (Cooch 1958); Ross' goose (C.
rossi) (Ryder 1970, 1975). Ankney and MacInnes (unpublished manuscript) showed that weight loss in nesting female lesser snow geese from Use of nutrient reserves (mainly fat and protein) for egg production and incubation. However, detailed information about changes in the weight of nutrient reserves of male geese been published. My purposes are to has Present such data for male lesser snow geese (which here includes the blue and white color phases) and to explain their significance to the rep'flductive Strategy of this species+These data provide some support for Ryder's hy" pothesis about the evolution of territory size for colonia1 nesting geese.
Methods Data are from male lesser snow geese collected from mid-May through midJuly, 1971 and 1972, at the nesting E O I O ~ at~ the mouth of the McConnell Rlver (60 LO' N, 9 4 2 5 ' W), Northwest Territories, Canada. The area was described by Maclnnes (1962). Bxeding he no logy and t~mingof collection periods were nearly identical ~n thc 2 years (Table 1) and the data have bWn combined. I assig~led hirdg to the following catcgorles (collection methods are given I,y ~ n k n e f 1 9 7 4 ) : nrriuin~,males arriving on the breeding ground: Iujbing,males mated to "males that had just compfeted laying: ear/)' incubation. males mated to females that had incubated &I1 days (incubating geese were collected from nests with known histories); /ate incubation, males mated to females that
TABLE 1. Breeding phenology and collection periods
Can. J. Zool. Downloaded from www.nrcresearchpress.com by McMaster University on 11/21/14 For personal use only.
Peak of arrival Collected arriving 33 Peak of laying Collected laying 3d Collected early incubation 33 Collected failed nesters 66 Collected late incubation $3 Peak of hatch Collected posthatch 33 had incubated at least 17 days of the 23-day incubation period; posrhatch, males collected 7-14 days after the peak of the egg-hatching period; failed nesters, males mated to females that were collected feeding, away from the colony, at the end of incubation. I used body weight, i.e., the fresh weight of a gander minus the weight of intestinal contents, as an overall index of its nutrient reserves. The protein reserve index (protein RI) is the total dry weight of sternal muscles (pectoralis, supracoracoideus, and coracobrachialis), leg muscles (all muscles having either their origin or insertion on the femur or tibiotarsus), and gizzard (minus contents). The fat reserve index (fat RI) is the total wet weight of subcutaneous, mesenteric, and abdominal fat. Sternal and leg muscles were excised unilaterally and dry weights were doubled to compute the protein RI. Muscles were freezedried in 1971 and oven-dried (22 h at 105'C) in 1972; these techniques did not remove significantly different amounts of water from comparable samples (Ankney 1974). The components of the protein R I are presented separately and in total as they did not show simultaneous weight changes. I did not measure intracellular fat in the muscles for two reasons. Firstly, most intracellular fat is not an energy reserve (Hoar 1966). Secondly, Hanson (1962) showed that variation in intracellular fat content of leg and breast muscles of Canada geese accounted for little of their weight changes. Statistical tests follow Sokal and Rohlf (1969); significance was set at the 5% level.
Results Breeding male lesser snow geese used nutrient reserves after arrival on the breeding ground (Table 2). Mean body weight was highest at arrival (Table 2); in laying males, collected an average of 7 days later, mean body weight was lower, but not significantly (0.1 > p > 0.05). Mean body weight decreased significantly during the nesting period (weight loss averaged 2 0 x from arriving through late incubation) but no change occurred during posthatch. The fat RI decreased significantly during successive periods and was depleted by the middle of posthatch (Table 2). The only significant change in the protein RI occurred between early and late
27 May-28 May 23 May-29 May 28 May- 3 June 30 May- 1 June 5 June-15 June
-
26 June-27 June 27 June-29 June 6 July-13 July
26 May-27 May 23 May-31 May 27 May- 2 June 30 May- 7June 5 June-14 June 22 June-24 June 19 June-26 June 26 June-28 June 6 July -1 3 July
incubation. However, changes in the components of the protein RI were sometimes in different directions and thus cancelled each other (e.g. between arriving and laying, and between late incubation and posthatch). I compared failed nesters with late incubation males as both groups were collected during the same period (Table 1). They differed significantly ( p < 0.05) only in mean gizzard weight; the heavier gizzards of failed nesters result from increased feeding by these birds (Ankney 1977). Discussion Feeding by male lesser snow geese declines after they arrive on the breeding ground until midway through incubation but increases late in incubation (Ankney 1977). Males arrived with large nutrient reserves and used them, especially fat, during the breeding season (Table 2). Nutrient reserve use by a male reflects the demands of territory maintenance plus his existence energy; courtship and copulation are completed before lesser snow geese arrive and males do not incubate (Cooch 1958). The energy cost of establishing and defending a territory must be relatively high for these geese because they nest in colonies (often more than 1000 pairs/km2 (C. von Barlowen, personal communication)); fights between neighboring males are common during egg laying and incubation. The decline in protein reserves during incubation was considerably less in males (14% (Table 2)) than in females (35% (Ankney and MacInnes, unpublished manuscript)) even though males are more active than females during incubation. There are two, not mutually exclusive, explanations for that: (1) the nitrogen conserving effect of androgens inhibits protein catabolism in males; and (2) males probably feed more than females during incubation (Ankney 1977) and the oxalacetate required for fat metabolism is
1986
CAN. J. ZOOL. VOL. 55, 1977
TABLE 2. Changes in body and nutrient-reserve weights (grams) of breeding males. Mean
Body weight Protein R I Gizzard Breast muscle Leg muscle Fat RI
Arriving ( N = 45)
Laying ( N = 18)
Early incubation ( N = 18)
2810k40 246.2k4.7 34.1k0.7 135.5+ 3.2 76.6k2.0 398.5k18.1
2680 k 60 247.2k9.3 29.2k1.1 136.9k5.8 81.1k3.2 272.3k24.3
2400 + 40 228.7k5.3 27.0k 1 . O 124.223.6 77.2f3.2 116.1+17.9
Pa
Late incubation ( N = 22)
f SE
Pa
Posthatch ( N = 22)
aP = probability (from one-way ANOVA between each pair of adjacent means) that means in adjacent columns are different by chance * p < 0.05, * * p < 0.01, *'*p < 0.001, NS indicates P > 0.05.
Can. J. Zool. Downloaded from www.nrcresearchpress.com by McMaster University on 11/21/14 For personal use only.
*None had a measurable amount of fat.
mostly derived from dietary carbohydrates rather than from protein catabolism (see Hanson 1962 for a review of avian intermediary metabolism). The former explanation may give a proximate factor in less use of protein reserves by males, but the latter one suggests an ultimate factor: that males establish territories large enough to provide some food during incubation because it is important that they remain physically strong. Ryder (1975) hypothesized that, in colonial nesting geese, a male should acquire a territory small enough to defend against conspecifics but large enough to provide him with supplemental food. He argued that supplemental food was necessary so that the gander would not have to leave the territory and thus leave the incubating goose undefended from attacks by neighboring ganders. Attacks by ganders on undefended females are a maior cause of nest desertion in Canada geese and Boag 1972). I agree with Ryder and suggest that food that the male gets on his territory enables him to maintain the large muscles which are important for defending the female. I have no evidence that males ever deplete their reserves to the point where starvation is the alternative to leaving the territory to feed. Starved males have not been found and reserves of failed nester males were not lower than those of late incubation males. This is not so in females because they occasionally starve to death (Harvey 1971; Ankney 1975) and failed nester females have significantly smaller reserves than late incubation females (Ankney and MacInnes, unpublished manuscript). Even successful females are extremely emaciated at the end of incubation. In lesser snow geese the strategy of nutrient reserve use during reproduction is as follows. Females rely almost solely on their nutrient
c wasc chuck
reserves for egg production and energy during incubation. This allows them to devote maximal attention to the eggs but they complete incubation in poor physical condition. Males also use nutrient reserves during nesting but that use is mitigated by food eaten on the territory. The gander thus is able to defend the territory and is in relatively good condition at hatch. That is important because he then becomes the guardian of the female and brood and this allows the female to spend much time feeding (Harwood 1975). As a result, females gain weight after hatch (mean increase = 11% (Ankney and MacInnes, unpublished manuscript)) but males do not (Table 2). Thus, large nutrient reserves are very important to breeding lesser snow geese; the male-female 'cooperation' in using these reserves is noteworthy.
Acknowledgements I am grateful to Charles MacInnes for advice, encouragement, and assistance during this study. Larry Patterson provided excellent field assistance. This research was supported by the Canadian Wildlife Service, the National Research Council of Canada, and the University of Western Ontario. D
ANDERSON, W. L. 1972. Dynamics of condition parameters and organ measurements in pheasants. Ill. Nat. Hist. Surv. Bull. 30: 455-497. ANKNEY, C. D. 1974. The importance of nutrient reserves to breeding blue geese (Anser caerulescens caerulescens). Ph.D. Thesis, University of Western Ontario, London. -1975. Neckbands contribute to starvation in female lesser snow geese. J. Wildl. Manage. 39: 825-826. 1977. Feeding and digestive organ size in breeding lesser snow geese. Auk, 94: 275-282. BARRY,T. W. 1962. Effects of late seasons on Atlantic brant reproduction. J. Wildl. Manage. 26: 19-26. 1967. The geese of the Anderson River delta,
Can. J. Zool. Downloaded from www.nrcresearchpress.com by McMaster University on 11/21/14 For personal use only.
ANKNEY
Northwest Temtories. Ph.D. Thesis, University of Alberta, Edmonton. BRENNER, F. 1. 1968. Energy flow in two breeding populations of redwing blackbirds. Am. Midl. Nat. 79: 289-310. C o o c ~F. , G. 1958. The breeding biology and management of the blue goose Chen caerulescens. Ph.D. Thesis, Cornell University, Ithaca. EL-WAILLY, A. J. 1966. Energy requirements for egg laying and incubation in the zebra finch Taeniopygia castonotis. Condor, 68: 582-594. EWASCHUK, E., and D. A. BOAG.1972. Factors affecting hatching success of densely nesting Canada geese. J. Wildl. Manage. 36: 1097-1 106. HANSON, H. C. 1962. The dynamics of condition factors in Canada geese and their relation to seasonal stresses. Arct. Inst. North Am. Tech. Pap. No. 12. J. M. 1971. Factors affecting blue goose nesting HARVEY, success. Can. J. Zool. 49: 223-234. J. 1975. The feeding strategies of blue geese, HARWOOD, Anser caerulescens. Ph.D. Thesis, University of Western Ontario, London. HOAR,W. S. 1966. General and comparative physiology. Prentice-Hall, Englewood Cliffs. p. 226. KING,J. R. 1973. Energetics of reproduction in birds. In
1987
Breeding biology of birds. Edited by D. S. Farner. Natl. Acad. Sci., Washington, D.C. pp. 78-107. MACINNES, C. D. 1962. Nesting of small Canada geese near Eskimo Point, Northwest Territories. J. Wildl. Manage. 26: 247-256. and A. J. ISAACSON. MURTON, R. R., N. J. WESTWOOD, 1974. Factors affecting egg weight, body weight and moult of the woodpigeon, Columbia palurnbus. Ibis, 116: 52-73. ORING,L. W. 1969. Summer biology of the gadwall at Delta, Manitoba. Wilson Bull. 88: 44-54. PENDERGAST, B. A., and D. A. BOAG.1973. Seasonal changes in the internal anatomy of spruce grouse in Alberta. Auk, 90: 307-317. J. L., and W. D. KLIMSTRA. 1971. Annual ROSEBERRY, weight cycles in male and female bobwhite quail. Auk, 88: 116-123. RYDER,J . P. 1970. A possible factor in the evolution of clutch size in Ross' goose. Wilson Bull. 82: 5-13. 1975. The significance of temtory size in colonial nesting geese-an hypothesis. Wildfowl, 26: 114-1 16. SOKAL,R. R., and F. J. ROHLF.1969. Biometry. W. H. Freeman, San Francisco.
