Churchill Community of Knowledge
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An online resource of data and media about the Town of Churchill, its people, Wapusk National Park, and the extensive research supported by the Churchill Northern Studies Centre. This Digital Archive is hosted by the Yorkspace Institutional Repository, York University, Toronto. The first collection in the project celebrates the life and work of Professor Bob Jefferies, who carried out field research in ecology in and near Churchill, for 30 years.
Robert L. Jefferies Collection
How to submit an item: Undigitized items (lke your old Kodachrome slides) can be sent to Ms. Netta Untershats and her team for digitizing.
We will send you a receipt for the items, and send them back to you after they are digitized. Please include any information about the item - in the case of photos, what, where, when and who? And, please remember to confirm in writing in an email or letter, that you are the owner of the image.
QUESTIONS? For items related to Bob Jefferies and other La Pérouse Bay research and to send digitized items, please contact:
Dawn Bazely: dbazely@yorku.ca
Netta Untershats: nettauntershats@osgoode.yorku.ca
For items relating to the broader Churchill community: Mike Goodyear and Leeann Fishback of the Churchill Northern Studies Centre, can advise you about items that do not directly relate to Prof. Jefferies’ life and research, but which do relate to the broader Churchill community, including the Studies Centre.
goodyear@churchillscience.ca
fishback@churchillscience.ca
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Browsing Churchill Community of Knowledge by Author "1c2fe4c8d356d377c535b805cb1373fb"
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Item Open Access A comparison of the Characteristics and Fate of Barrow's Goldeneye and Bufflehead Nests in Nest Boxes and Natural Cavities(University of California Press, 2002) Evans, M.R.; Lank, D.B.; Boyd, W.S.; Cooke, F.Abstract. Barrow's Goldeneye (Bucephala islandica) and Bufflehead (B. albeola) are cavity-nesting waterfowl that have received considerable attention in studies using nest boxes, but little is known about their nesting ecology in natural cavities. We found larger clutch size, lower nesting success, and different major predators for Barrow's Goldeneyes nesting in boxes versus those nesting in natural cavities, but few differences for Bufflehead. These differencesa re attributedt o the location and physical differencesb etween Barrow's Goldeneyen est boxes and naturalc avities that affect theirc onspicuousnesst o predatorsa nd conspecific nest-parasitizingfe males. Goldeneyeb oxes were concentratedin highly visible locations such as trees at water or forest edge. Natural cavity nests, on the other hand, were often abandoned Pileated Woodpecker (Dryocopus pileatus) cavities, which were more dispersed throughout the forest interior and concealed under dense canopy cover. Bufflehead natural cavity nests were typically closer to edges, which may account for their similarity with boxes. We conclude that in some respects, studies of Barrow's Goldeneye that use nest boxes may not be representativeo f birds nesting in naturalc avities, whereast hose of Bufflehead are more likely to be so.Item Open Access A genetic analysis of Lesser Snow Goose families.(University of California Press, 1972) Cooke, F.; Mirsky, P.J.Item Open Access Age-specific costs of first-time breeding(University of California Press, 1995) Viallefont, A.; Cooke, F.; Lebreton, D.We investigated the cost of first-time breeding in a population of Lesser Snow Geese (Anser caerulescens caerulescens) nesting at La Perouse Bay, Manitoba, Canada. We estimated local survival and capture probabilities of female geese by capture-recapture analysis. We first found that birds were less likely to be recaptured one year after their first successful breeding than on later occasions. Since only successfully nesting birds are captured, this suggests that first-time breeding affects the ability of nesting the next year. We then show that this effect of first breeding is much more severe for birds nesting at age 2 (the youngest age at which Lesser Snow Geese can breed) than for birds starting to breed at an older age. Finally, we compare the mean expected lifetime reproductive success for birds breeding for the first time as two-year-olds or as three-year-olds, conditionally on their survival until age 4. On average, birds first nesting as two-year-olds produce similar numbers of offspring in a lifetime as birds starting at age 3.Item Open Access Body size and fecundity in lesser snow geese: response to Alisauskas and Ankney.(University of California Press, 1990) Cooke, F.; Davies, J. C.; Rockwell, R. F.Item Open Access Body size variation and fitness components in lesser snow geese Chen caerulescens caerulescens.(University of California Press, 1988) Davies, J.C.; Rockwell, R.F.; Cooke, F.We examined the potential action of selection on body size in a population of Lesser Snow Geese (Chen caerulescens caerulescens) breeding in the Canadian subarctic. We evaluated the genetic basis of phenotypic variation in body size and examined the association of body size and components of fitness related to fecundity and viability. There was a heritable component to body size in this population derived in part from the action of additive genes. There was no relation between adult body size and the number of eggs laid, the number of eggs surviving predation, the number of goslings that left the nest, or the number of goslings fledged. Small birds entered the breeding population at a younger age. They did so with no reduction in viability and may actually live longer than large birds. The heritable variation in body size combined with the directional selection gradient should lead to a gradual reduction in adult body size in this population. We found no evidence for such a change over 5 generations. We discuss this in terms of additional fitness components, the retarding effects of age structure on the response to selection, and the interaction of selection and gene flow. Received 6 October 1987, accepted 8 May 1988.Item Open Access Body weight and feather growth of male Barrow's Goldeneye during wing molt.(University of California Press, 2000-02) Van der Wetering, D.; Cooke, F.We studied the timing, duration, and rate of wing molt of male Barrow's Goldeneye (Bucephala islandica). The mean daily change in primary feather length was 2.6%, which is consistent with rates reported for other waterfowl species. The mean length of the flightless period was 31 days (range: 27-34 days), excluding the pre-shedding interval. Wing molt extended from early July to mid-September. Peak wing molt occurred between 20 July and 23 August. The mean body weight of adult males decreased significantly during wing molt. Heavier birds had greater remigial growth rates and experienced more substantial declines in body weight than lighter birds, suggesting that body reserves may be used to increase the rate of remigial growth.Item Open Access Changes in Survival Rates of Lesser Snow Geese with Age and Breeding Status(University of California Press, 1992) Francis, C.M.; Richards, M.H.; Cooke, F.; Rockwell, R.F.Survival rates of Lesser Snow Geese (Chen caerulescens caerulescens) were examined based on recoveries and recaptures of about 350,000 geese banded at breeding colonies in northern Canada, at migration stopover points in the Dakotas and Missouri, and on the wintering grounds in Louisiana and Texas. First-year survival rates for goslings banded on the breeding grounds varied from 10 to 70% of adult survival rates. Much of the juvenile mortality occurred on the breeding grounds or early on the first migration. Young geese that reached migration stopovers or the wintering grounds were more vulnerable to hunters than adults, but had only slightly lower survival rates than adults. Greater vulnerability and lower survival continued through the second year of life, even though yearlings do not breed. In contrast, older birds that did not breed, or failed early in a nesting attempt, were much less vulnerable to hunters in the following hunting season than successful breeding adults, but did not appear to have higher survival as a result. Geese captured for the first time as breeding adults had slightly lower survival rates than geese that had been recaptured at the colony at least once, suggesting experienced breeders have higher survival. Although there was some evidence that older birds were slightly more vulnerable to hunters, there were no signs of any changes in survival rate with age in older geese, indicating that senescence, if it affects survival, does not do so for at least the first 10 to 15 years of age. With current hunting levels, less than 5% of Lesser Snow Geese are likely to live beyond this age. Our study demonstrates a variety of statistical methods for testing hypotheses about age-specific survival using both recovery and recapture data, even when the data do not permit estimation of the exact survival rates.Item Open Access Colonial Nesters in a Deteriorating Habitat: Site Fidelity and Colony Dynamics of Lesser Snow Geese(University of California Press, 1998) Ganter, B.; Cooke, F.Birds that exhibit a high degree of natal and breeding philopatry and normally breed in stable environments may suffer costs of philopatry if their habitat deteriorates. Female Lesser Snow Geese (Chen caerulescens caerulescens) are highly site faithful; however, recent increases in numbers of breeding birds have resulted in widespred habitat destruction in some colonies. Using capture-recapture modeling techniques on multiple resightings of marked individuals, we examined whether breeding-site fidelity of adult Snow Geese has changed over time in a colony that has grown rapidly and in which habitat quality has declined severely during the past two decades. In addition, we examined the age structure of breeding birds to investigate natal-site fidelity to formerly central areas of the colony. Only slight changes in adult breeding-site fidelity were detected over 10-year periods, despite the deterioration of nesting and brood-rearing habitats in and near the investigated areas. However, increasing mean ages of breeding birds in formerly central areas of the colony indicated a lack of recruitment into those areas; young birds must have preferred to settle at the colony periphery even when vacant spaces in the center were available. Together with a small amount of movement by adult birds, the settlement pattern of young birds has led to a long-term shift in the colony location as a whole.Item Open Access Differential timing of spring migration in wood warblers (Parulinae).(University of California Press, 1986-07) Francis, C.M.; Cooke, F.Spring migration patterns of 18 species of paruline warbler at Prince Edward Point, Ontario showed that males arrived earlier than females in all species. Adult males arrived significantly earlier than second-year males in American Redstarts (Setophaga ruticilla), and there was evidence for a similar trend in other species. The difference in mean arrival dates between the sexes was greatest in species that arrived earliest. Similarly, within species, the difference between sexes was greatest in years when the males arrived earliest. For individuals within a species there was a significant negative correlation between arrival date and wing length; however, males of a particular size generally arrived earlier than females of the same size. Thus, larger size may be an advantage to early arrival, but is not sufficient to explain the difference in arrival between sexes. Species that winter furthest north arrived earliest, but sexual differences in wintering grounds have not been reported. These results are consistent with the hypothesis that males are selected to arrive as early as food resources or climatic conditions are adequate, whereas females arrive later, closer to the time when they can successfully begin nesting.Item Open Access Does sex ratio vary with egg sequence in Lesser Snow Geese?(University of California Press, 1983-01) Cooke, F.; Harmsen, R.Item Open Access Dominance, brood size and foraging behaviour during brood-rearing in the lesser snow goose: an experimental study.(University of California Press, 1995-02) Mulder, R.S.; Williams, T.D.; Cooke, F.We investigated the relationship between brood size and social dominance during the brood-rearing period in Lesser Snow Geese (Anser caerulescensc aerulescens) by experimentally manipulating food availability to create high-biomass food patches. A total of 128 social interactions were subsequently observed in experimental areas; the rate of interactions was significantly higher in experimental high-biomass plots (9.6 hr-1) than in control, low-biomass, areas (0.4 hr-1). During social interactions families (pairs with one or more goslings) were always dominant over pairs without goslings. However, there was no clear dominance hierarchy among families in relation to brood size. Neither aggressiveness (the number of interactions initiated) nor the proportion of successful interactions varied consistently with brood size. We conclude that, during brood rearing, dominance ranking is determined more by individual variation in aggressiveness of adult (parent) birds, rather than by any "motivational" effect of offspring or by brood size per se. Geese fed longer in the high biomass plots (mean 19.2 min per visit) than in control plots (2.9 min), and birds "defended" high biomass areas: 32% of all interactions involved a social unit inside the experimental plot driving off a social unit which was trying to enter the plot from outside. This suggests that geese derived benefits from monopolization of good quality food patches. The behavior of foraging geese varied in relation to food availability: birds took fewer steps per minute during both feeding and non-feeding bouts in the experimental plots and females, but not males, had shorter feeding bouts in experimental plots, i.e., they adopted the vigilant head-up posture more frequently. We suggest that the benefits of utilizing high biomass food patches during brood-rearing include higher intake rates, decreased energetic costs of foraging and reduced predation risk through increased vigilance behavior by parents and greater cohesion of the family unit.Item Open Access Egg-Laying Time and Laying Interval in the Common Eider(University of California Press, 1993-11) Watson, M.D.; Robertson, G.J.; Cooke, F.We determined the time of day at which eggs were laid and the laying interval (time between laying of successive eggs in a clutch) in the Hudson Bay race of the Common Eider( Somateria mollissima sedentaria), at La Perouse Bay, Churchill, Manitoba (58 24'N, 94 24'W). Nests were found at the one-egg stage and were subsequently visited three times daily.Analysis of the nest contents at each visit allowed us to estimate mean egg-laying times as well as the mean time at which eggs were lost to predators. The estimated mean egg-laying hour was 13:49( CST,9 5%C L 12:30-15:06). We detected no selective advantage to laying at this time based on the timing of egg predation. The average egg-laying interval was2 7.7 +/- 3.4 hr. Laying intervals decreased with increasing clutch sizes. For clutches of four and five eggs, the estimated interval between the last two eggs was significantly longer than that for intervals between all other eggs, all other comparisons between intervals were not significantly different. If last-laid eggs were excluded the mean laying interval for all eggs was2 6.1 +/- 4.3 hr, confirming that the last egg in a clutch takes longer to produce. We suggest that longer laying intervals of last-laid eggs may be related to hormonal changes associated with the onset of incubation.Item Open Access Evidence of former allopatry of the two colour phases of Lesser Snow Goose (Chen caerulescens caerulescens).(University of California Press, 1988) Cooke, F.; Parkin, D.T.; Rockwell, R.F.Plumage color is distributed clinally in the Gulf Coast population of the dimorphic Lesser Snow Goose (Chen caerulescens caerulescens); the white phase predominates in the west, and the blue phase in the east. A similar distribution occurs in the breeding colonies of this population. Historical evidence, stretching back to the mid-18th century, shows that the two phases were almost allopatric until the third decade of the 20th century. Allozyme variants at 6 loci also support the conclusion that the morphs were until recently two distinct taxa. The recent merging of the taxa probably is due to a change in winter feeding habits that allowed birds of both morphs to meet in the rice-growing areas of inland Texas and Louisiana. Because pair formation occurs at this time, this change permitted gene flow to occur between the morphs. There is no evidence of reduced fitness among mixed pairs, and interbreeding among the morphs is common. We know of no other case of a historically documented merging of two formerly allopatric taxa of birds where interbreeding is so widespread and where there is no evidence of reduced fitness of the hybrids. Received 30 January 1987, accepted 26 February 1988.Item Open Access Fitness Consequences of Parental Behavior in Relation to Offspring Number in a Precocial Species: The Lesser Snow Goose. Churchill, 1994.(University of California Press, 1994) Williams, T.D.; Loonen, M.J.J.E.; Cooke, F.We investigated the relationship between parental behavior and brood size, and the consequences of this relationship in terms of parental fitness (timing of molt and body mass at onset of molt in same year as breeding, and probability of return, timing of breeding, and clutch size in following year) in the precocial Lesser Snow Goose (Chen caerulescens caerulescens) at La Pérouse Bay, Manitoba. The percentage of time parent birds spent feeding decreased with increasing brood size, from greater than 90% for pairs without offspring to less than 80% for broods of seven and eight. The number of vigilant (head-up) postures per minute by parental birds increased up to brood size five and then decreased. Parental females also spent significantly less total time feeding and more time in alert behavior as brood size increased from one to five goslings. The relationship between parental behavior and brood size remained significant for small brood sizes even if pairs without goslings were excluded (range one to five goslings), and this relationship was independent of female age. Males (but not females) rearing larger broods molted later than those with smaller broods, although only by one to two days. This was directly related to rearing of offspring; in both sexes, birds that hatched four or more goslings and subsequently lost one or more goslings during brood-rearing molted significantly earlier than birds rearing all of their hatched goslings. There was no relationship, in either sex, between number of goslings reared and the adult mass five to six weeks posthatch (molt) in the same year, or probability of return or timing of breeding (laying date or hatch date) in the following year. Partners of males that reared the largest number of goslings laid significantly larger clutch sizes the following year, suggesting that these were "better-quality" pairs. Over the range of naturally observed brood sizes, the effect of increasing brood size on parental behavior does not appear to be associated with any negative effects on residual parental reproductive effort or fitness in this species.Item Open Access Frequency, Timing and Costs of Intraspecific Nest Parasitism in the Common Eider(University of California Press, 1992-11) Robertson, G.J.; Watson, M.D.; Cooke, F.Intraspecific nest parasitism was studied in the Hudson Bay race of the Common Eider (Somateria mollissima sedentaria), near Churchill, Manitoba (58 24'N, 94 24'W). Nest parasitism was detected by three methods: (1) multiple eggs laid in the same nest on a single day, (2) eggs laid before or after the host's clutch was laid, and (3) large within clutch variances in egg size and color. It was determined that 42.4% (n = 153) of completed clutches were parasitized. Parasitic eggs were laid significantly earlier in the host's laying sequence than expected by chance: 65% of parasitic eggs were laid on the first two days of laying. Number of parasitic eggs laid, as a proportion of all eggs, did not change significantly throughout the laying period. The probability of parasitic and host eggs hatching was not significantly different from that in unparasitized nests. Hosts did not reduce their clutch size in response to parasitism, when data were controlled for initiation date, nor did they hatch any fewer of their own young for a given clutch size than unparasitized nests. Parasitized nests were found in areas with higher densities (number of neighbors within 10 m) at initiation. Parasitism in this species does not appear to be a salvage strategy and may be part of a mixed or conditional strategy.Item Open Access Gene flow between breeding populations of Lesser Snow Geese.(University of California Press, 1975) Cooke, F.; MacInnes, C.D.; Prevett., J.P.Item Open Access Genetic analysis of offspring of a female-female pair in the lesser snow goose (Chen caerulescens caerulescens).(University of California Press, 1989) Quinn, T.W.; Davies, J.C.; Cooke, F.; White, B.N.We used restriction-fragment-length polymorphism (RFLP) analysis to establish the parentage of a clutch of eight eggs being incubated by two female Lesser Snow Geese to determine if both females had contributed to the clutch, and whether a single male had fertilized both females. Genotypes at 30 polymorphic restriction enzyme sites were surveyed with 14 cloned DNA probes. Sexing of all individuals was done both by dissection and by use of a DNA probe that detected the presence of the W chromosome in females. Paternal genotypes were reconstructed from haplotypes of the offspring. We determined that both females had contributed to the clutch, and that each was fertilized by a different male. Received 9 May 1988, accepted 30 September 1988Item Open Access Intraspecific Variation in Commuting Distance of Marbled Murrelets (Brachyramphus marmoratus): Ecological and Energetic Consequences of Nesting Further Inland. Churchill, 2001.(University of California Press, 2001-10) Hull, C.L.; Kaiser, G.W.; Lougheed, C.; Lougheed, L.; Boyd, S.; Cooke, F.Radio transmitters were deployed on Marbled Murrelets (Brachyramphus marmoratus) at Desolation Sound, British Columbia, Canada, during the 1998 breeding season to assess individual variation in distance birds nested from foraging areas, and potential energetic and ecological consequences of commuting those distances. Radio-tracking from a helicopter was used to locate nests, and tracking from the air and boats was used to locate murrelets on the water. Twenty-three nests were found, with active incubation at 16, and active chick-rearing at 12. A minimum of 3 nests fledged chicks, 9 were failures, and 11 were unknown. Nests were at an elevation of 806 ± 377 m and a distance of 39.2 ± 23.2 km (range 12-102 km) from locations on the water. Birds spent an estimated 1.2 ± 0.7 h per day commuting to and from nests (range 0.3-3.5 h per day). It was estimated that birds expended 3,883 ± 2,296 kJ (range 1,200-10,144 kJ) over the breeding season when commuting to those nests, which was 5-41% of their estimated field metabolic-rate during the breeding season. There was no relationship between distance to nests and breeding success. Either Marbled Murrelets can accommodate that additional energy expenditure, or reduce commuting costs by modifying their foraging behavior. They may forage closer to nest sites when provisioning chicks, thereby reducing commuting costs with a payload, or alter nest visitation rates in relation to distance they nest from foraging areas. Nests further inland may also confer advantages that compensate for the added commuting, or birds might replenish body reserves at the end of the breeding season.Item Open Access Is there a positive relationship between body size and fecundity in lesser snow geese?(University of California Press, 1992) Cooch, E. G.; Lank, D. B.; Rockwell, R. F.; Cooke, F.Item Open Access Is there an optimal clutch size in Lesser Snow Geese?(University of Chicago Press, 1987) Rockwell, R. F.; Findlay, C. S.; Cooke, F.