Seasonal activity of the Denali caribou herd, Alaska

Boertje, Rodney D.

doi:10.7557/2.5.2.545

Cited by 29 publications

(23 citation statements)

References 4 publications

(7 reference statements)

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“…Proportions of wild reindeer feeding and lying during daytime and nighttime for no-insect and insect days in SetesdalRyfylke, Norway, in summer 1997and 1998 hypothesis that the ratio of active to inactive time calculated from one active-resting cycle is equivalent to the ratio of active to inactive time over the entire 24-h period is synonymous with polycyclicity. Our data for no-insect days support Boertje's (1985) hypothesis. Differences in the polycyclic pattern between day and night, in number, amplitude, or periods of bout peaks, for example, do not necessarily contradict Boertje's (1985) hypothesis.…”

Section: Feeding and Lying Patternssupporting

confidence: 85%

Twenty-four-hour feeding and lying patterns of wild reindeer <i>Rangifer tarandus tarandus</i> in summer

Colman¹,

Pedersen²,

Hjermann³

et al. 2001

Can. J. Zool.

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We tested whether sunlight and insect harassment were important proximate factors (Zeitgebers) controlling feeding and lying patterns of wild reindeer (Rangifer tarandus tarandus) in summer. With no insect harassment, feeding and lying each exhibited a polycyclic rhythm with, on average, 4 bouts at equal intervals during each 24-h period (unit-sum constraints in a polycyclic rhythm). When insects were absent, the activity percentages were 50 ± 4% feeding (mean ± SE) and 33 ± 4% lying for daytime and 44 ± 3% feeding and 47 ± 4% lying for nighttime, i.e., the percentage of time spent feeding was equal for daytime and nighttime (nychthemeral), while for lying it was not. With insects present, percentages of time spent feeding and lying were 18 ± 3 and 13 ± 3% for daytime and 45 ± 8 and 41 ± 8% for nighttime, respectively, i.e., neither feeding nor lying exhibited a nychthemeral pattern. During periods of insect harassment, 24-h feeding patterns had no cyclic rhythm, whereas lying remained cyclic, but the percentages of time spent lying during peak bouts (amplitude) and at peak duration (period) were unequal between night and day. Reindeer did not attune their activity to the set points of sunrise and sunset (not crepuscular), demonstrating that daylight is most likely not a powerful Zeitgeber for reindeer during summer.Résumé : Nous avons vérifié si la lumière solaire et le harcèlement des insectes constituent des facteurs immédiats importants (Zeitgebers) du contrôle des rythmes de l'alimentation et du repos chez des Rennes (Rangifer tarandus tarandus) sauvages en été. Sans le harcèlement des insectes, l'alimentation et le repos suivent un rythme polycyclique d'en moyenne 4 épisodes de périodes égales par 24 h (contraintes reliées à la somme des unités dans un rythme polycyclique). En l'absence d'insectes, les pourcentages d'activité sont répartis comme suit 50 ± 4 % (moyenne ± erreur type) du temps consacré à l'alimentation et 33 ± 4 % au repos durant le jour, 44 ± 3 % à l'alimentation et 47 ± 4 % au repos durant la nuit, i.e., le pourcentage de temps consacré à l'alimentation est le même le jour et la nuit (nycthé-méral), alors que ce n'est pas le cas pour le repos. En présence des insectes, ces pourcentages sont respectivement de 18 ± 3 % et de 13 ± 3 % durant le jour, et de 45 ± 8 % et de 41 ± 8 % la nuit, i.e., ni l'alimentation, ni le repos ne suivent de rythme nycthéméral. Avec le harcèlement des insectes, les patterns d'alimentation sur 24 h ne sont plus cycliques, alors que le repos reste cyclique, mais les pourcentages de temps consacrés au repos diffèrent en amplitude et en durée entre le jour et la nuit. Les rennes n'ajustent pas leur activité en fonction du lever ou au coucher du soleil (pas crépusculaire), ce qui démontre que la lumière solaire n'est probablement pas un Zeitgeber très fort pour les rennes en été.[Traduit par la Rédaction] 2175Colman et al.

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Section: Feeding and Lying Patternssupporting

confidence: 85%

Twenty-four-hour feeding and lying patterns of wild reindeer <i>Rangifer tarandus tarandus</i> in summer

Colman¹,

Pedersen²,

Hjermann³

et al. 2001

Can. J. Zool.

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“…In response to inferred harassment by mosquitoes and other fly parasites, caribou/reindeer have been reported to seek refuge at such microhabitats as wind-swept mountain tops, barren coastal areas, snow fields and isolated patches of snow (e.g. Pruitt, I960;Kelsall, 1968;Skjenne¬ berg & Slagsvold, 1968;Bergerud, 1971;Thomson, 1971;Gaareetal., 1975;Low, 1976;Boertje, 1985;Sokolov, 1984;Vodop'yanov, 1984;Ion & Kershaw, 1989). However, in the absence of quantitative insect data and identification of species, such a presumptive cause: effect relationship remains mostly conjectural.…”

Section: Introductionmentioning

confidence: 99%

Do reindeer aggregate on snow patches to reduce harassment by parasitic flies or to thermoregulate?

Anderson¹,

Nilssen²

1998

Ran

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During warm, sunny days (Max. temp. 22 °C -25 °C) C02-baited traps operated at sites on and off snow patches (SP's) in subarctic Norway caught significantly fewer culicids, simuliids and tabanids on snow in both 1985 and 1987. However, for overnight catches (18.30 -07.30 h) there was no significant difference in the number of culicids caught on versus off SP's. Analysis of videotapes taken in 1987 showed that defensive anti-fly behaviors of reindeer on and off SP's remained low (< 1/4 min) throughout the day. Based on reindeer anti-fly behaviors, harassment was greatest from 10.30 to 12.30 h (Norwegian Standard Time), but reindeer continued to aggregate on SP's while anti-fly behaviors were lowest (13-30 -20.00 h). Groups of > 150 animals often occupied the entire surface of a snow patch. At the fly densities and climatic conditions encountered it seemed apparent that reindeer intermittently used SP's primarily to thermoregulate following periods of foraging. Almost all reindeer remained on SP's from 11.00 to 12.30 h, but at other times between 08.00 and 19 00 h about half the herd (ca. 800 animals) foraged for about an hour while the other half aggregated on SP's. However, by 20.00 h, during the cooler period when trap catches of mosquitoes were increasing, almost all reindeer had moved off SP's.The small decreases in anti-fly defensive behaviors observed for reindeer on SP's versus animals foraging in snow-free areas indicated that their presence on SP's may have resulted in a minor, coincidental reduction in harassment. Significantly more tabanids were caught during the morning trapping period than at other times, and significantly more mosquitoes were caught during the evening/overnight trapping period than at other times.

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“…Roby (1978) and Thing (1977) noted the lack of nighttime data, emphasizing its importance to conclusions regarding Rangifer behaviour and energetics. Boertje (1985) hypothesized that behaviour budgets based on single active-rest cycles should represent the proportion of time spent in various behaviours throughout the 24 hour period. If true, there would be less need for nighttime observations.…”

Section: Introductionmentioning

confidence: 99%

Twenty-four hour behaviour patterns and budgets of free-ranging reindeer in winter

Collins¹,

Smith²

1989

Ran

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Activities of free-ranging reindeer (Rangifer tarandus) on the Seward Peninsula, Alaska were studied to determine 24-hour behaviour patterns and budgets in winter. Use of daytime active-rest data to predict nighttime behaviour resulted in as much as 37% underestimate of nighttime resting and 37% overestimate of nighttime activity. Three active-rest cycles occurred daily, synchronous with photoperiod.Key words: Rangifer, reindeer, behaviour budgets, 24-hour behaviour patterns. Yhteenveto: Vapaana laiduntavan poron (Rangifer tarandus) aktiivisuutta tutkittiin Sewardin niemimaalla Alaskassa mààrittàmàllà 24 tunnin kayttaytymismallit ja budjetit talvella. Kàyttàmàllâ pàivàajan aktiivisuus -lepo -tietoja yôajan kåyttåytymisen ennustamiseen ne alittivat jopa 30%:lla yollisen lepoajan ja ylittivåt 40%:lla yôajan aktiivisuuden. Påivittain esiintyi kolme aktiivisuus -lepo -sykliå samanaikaisesti valojaksojen kanssa.Rangifer, 9(1): 2-8

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Seasonal activity of the Denali caribou herd, Alaska

Cited by 29 publications

References 4 publications

Twenty-four-hour feeding and lying patterns of wild reindeer <i>Rangifer tarandus tarandus</i> in summer

Twenty-four-hour feeding and lying patterns of wild reindeer <i>Rangifer tarandus tarandus</i> in summer

Do reindeer aggregate on snow patches to reduce harassment by parasitic flies or to thermoregulate?

Twenty-four hour behaviour patterns and budgets of free-ranging reindeer in winter

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