Comparative Response of Rangifer Tarandus and Other Northern Ungulates Colman for Critical Review of Earlier Drafts of the Manu- Norway

Home , Norwegian red deer, Svalbard reindeer

Conclusions tine studies. Nordic Council for Wildlife Research, Foetus growth rate in wild reindeer up to around age Stockholm. 1977. 27 pp. 130 days and weight 550-750 g appears not to be Lenvik, D. & Aune, I. 1988. Selection strategy in domes- influenced by the mothers body weights. Later in tic reindeer. 4. Early mortality in reindeer calves related pregnancy females in very poor condition (mean car- to maternal body weight. – Norsk Landbruksforskning 2: cass weights around 25 kg) support a foetus growth 71-76. rate which is significantly lower than among females Nissen, Ø. 1994. NM - Statpack. Norges landbruk- with mean carcass weights of 29 kg or above. Foetus shøgskole. weight variations within areas and years indicate Reimers, E. & Nordby, Ø. 1968. Relationship between that conception in two year or older females mostly age and tooth cementum layers in Norwegian reindeer. occur within two eustrous cycles. Yearling females – J. Wildl. Manage. 32: 957-961. conceive within a week later than older females Reimers, E. 1972. Growth in domestic and wild reindeer while calves apparently conceive 3-4 weeks later. in Norway. – J. Wildl. Manage. 36: 612-619. Reimers, E. 1983a. Growth rate and body size differences in Rangifer, a study of causes and effects. – Rangifer 3 (1): Acknowledgments 3-15. I am indebted to two anonymous referees and J. E. Reimers, E. 1983b. Reproduction in wild reindeer in Comparative response of Rangifer tarandus and other northern ungulates Colman for critical review of earlier drafts of the manu- Norway. – Can. J. Zool. 61: 211-217. to climatic variability script. Financial support was provided by E. Reimers Reimers, E. 1997. Rangifer population ecology: A Reindeer Research Fund. Scandinavian perspective. – Rangifer 17: 105-118. Reimers, E., Klein, D.R. & Sørumgård, R. 1983. Calving Robert B. Weladji1*, David R. Klein2, Øystein Holand1 & Atle Mysterud3 time, growth rate, and body size of Norwegian reindeer References on different ranges. – Arctic and Alp. Res. 15: 107-118. 1Department of Animal Science, Agricultural University of Norway, P.O. Box 5025, N-1432 Ås, Norway. Eloranta, E. & Nieminen, M. 1986. Calving of the exper- Røed, K. H. 1986. Genetisk struktur i norske villrein. – 2Institute of Arctic Biology, University of Alaska Fairbanks, P.O. Box: 757000, Fairbanks, AK 99775, USA. imental reindeer herd of Kaamanen during 1970-85. – Hognareinen 2: 4-6. 3Department of Biology, Division of Zoology, University of Oslo, P.O. Box 1050 Blindern, N-0316 Oslo, Norway. Rangifer Spec. Issue No. 1: 115-121. Rognmo, A., Markussen, K. A., Jacobsen, E., Grav, H. *corresponding author ([email protected]). Espmark, Y. 1980. Effects of maternal pre-partum under- J. & Blix, A. S. 1983. Effects of improved nutrition in nutrition on early mother-calf relationships. – In: E. pregnant reindeer on milk quality, calf birth weight, Abstract: To understand the factors influencing life history traits and population dynamics, attention is increasingly Reimers, E. Gaare & S. Skjenneberg. (eds.). Proceedings growth and mortality. – Rangifer 3 (2): 10-18. being given to the importance of environmental stochasticity. In this paper, we review and discuss aspects of current from the 2nd International Reindeer/Caribou Symposium, Ropstad, E., Lenvik, D., Bø, E., Fjellheim, M. M. & knowledge concerning the effect of climatic variation (local and global) on population parameters of northern ungu- Røros, Norway, 1979. Direktoratet for vilt og ferskvanns- Romsås, K. 1991. Ovarian function and pregnancy lates, with special emphasis on reindeer/caribou (Rangifer tarandus). We also restrict ourselves to indirect effects of cli- fisk, Trondheim, pp. 485-496. rates in reindeer calves (Rangifer tarandus) in southern mate through both forage availability and quality, and insect activity. Various authors have used different weather vari- Holthe, V. 1975. Calving season in different populations of Norway. – Teriogenology 36: 295-305. ables; with sometime opposite trends in resulting life history traits of ungulates, and few studies show consistent wild reindeer in South Norway. – In: J. R. Luick, P. C. Ropstad, E., Forsberg, M., Sire, J. E., Kindahl, H., effects to the same climatic variables. There is thus little consensus about which weather variables play the most sig- Lent, D. R. Klein & R. G. White. (eds.). Proceedings from Nilsen, T., Pedersen, O. & Edqvist, L. E. 1995. nificant role influencing ungulate population parameters. This may be because the effects of weather on ungulate pop- the First International Reindeer/Caribou Symposium, Plasma concentrations of progesterone, oestradiol, LH ulation dynamics and life history traits are scale dependent and it is difficult to isolate climatic effects from density dependent factors. This confirms the complexity of the relationship between environment and ecosystem. We point Fairbanks, Alaska, 1972. Biological Papers of the and 15-ketodihydro-PGF-2alpha in Norwegian semi- out limits of comparability between systems and the difficulty of generalizing about the effect of climate change University of Alaska. Spec. Report No. 1, pp. 194-198. domestic reindeer (Rangifer tarandus tarandus) during the broadly across northern systems, across species and even within species. Furthermore, insect harassment appears to be Jacobsen, E., Hove, K., Bjarghov, R.S. & Skjenneberg, first reproductive season. - J. Repr. Fert. 105: 307-314. a key climate-related factor for the ecology of reindeer/caribou that has been overlooked in the literature of climatic S. 1981. Supplementary feeding of female reindeer on Skjenneberg, S. & Slagsvold, L. 1968. Reindriften og dens effects on large herbivores. In light of this, there is a need for further studies of long time series in assessing effects of lichen diet during the last part of pregnancy. – Acta naturgrunnlag. Universitetsforlaget, Oslo. 332 pp. climate variability on reindeer/caribou. Agriculturae Scand. 31: 81-86. Skogland, T. 1984. The effects of food and maternal con- Krog, J., Wika, M. & Savalov, P. 1980. The development ditions on fetal growth and size in wild reindeer. – Key words: body mass, caribou, climate change, fecundity, insect harassment, moose, NAO, North of the foetus of the Norwegian reindeer. – In: E. Rangifer 4 (2): 39-46. Atlantic Oscillation, red deer, reindeer, sex ratio, survival, weather. Reimers, E. Gaare & S. Skjenneberg. (eds.). Proceedings White, R. G. 1991. Nutrition in relation to season, lacta- from the 2nd International Reindeer/Caribou Symposium, tion and growth of north temperate deer. – In: R. D. Rangifer, 22 (1), 2002 Røros, Norway, 1979. Direktoratet for vilt og ferskvanns- Brown (ed.). The biology of deer. Springer-Verlag, New fisk, Trondheim, pp. 306-310. York, pp. 407-417. Langvatn, R. (ed.), Leth Sørensen, P., Nygren, K., White, R. G. & Luick, J. R. 1984. Plasticity and con- Reimers, E. & Stålfelt, F. 1977. Criteria of physical con- straints in the lactational strategy of reindeer and Introduction well as identification of the important factors influ- dition, growth and development in Cervidae, - suitable for rou caribou. – Symp. Zool. Soc. Lond. 51: 215-232. Determining the causes of spatio-temporal varia- encing the traits (Loison et al., 1999a). Most of the tion in life history traits among individuals is one life history traits are influenced by a great number Manuscript received 27 July, 1998 of the main goals of ecology (Begon et al., 1996). of intrinsic and extrinsic interactions that deter- accepted 22 November, 2000 This requires long-term studies, accurate estimates mine the developmental process of populations of population sizes and demographic parameters, as (Cappuccino & Price, 1995). In efforts to under- 28 Rangifer, 22 (1), 2002 Rangifer, 22 (1), 2002 29 stand the importance of factors influencing life his- Stenseth (1999). Furthermore, we discuss the indi- influences timing of emergence of forage plants such as reindeer more in contrast to browser, which tory traits and population dynamics of northern rect effect of climate through insect harassment on (Klein, 1985; Langvatn et al., 1996; Post & Klein, could be more flexible. ungulates, attention is increasingly being given to reindeer/caribou, an aspect that has been largely 1999). Most importantly, in years of deep snow the importance of environmental stochasticity overlooked by reviews in this field. Indeed, climate there is a prolonged period of access to newly emer- Global climatic change (Murdoch, 1994; Turchin, 1995; Putman et al., also acts indirectly on some ungulates, as in the gent forage due to a variable time of snow melt. and plant quality and quantity 1996; Sæther, 1997). Density-independent varia- case of reindeer and caribou, through interaction Finstad et al. (2000a) found that annual variations Models of climate change predict that global tem- tion in phenotypic traits can, if persistent, con- with insects that affect their population parameters in summer weather influenced forage availability perature and precipitation will increase within the tribute substantially to population fluctuations in (Anderson et al., 1994; Gunn & Skogland, 1997; and digestibility through, for example the varia- next century, the changes being more pronounced ungulates (Sæther, 1997). Some general patterns Mörschel & Klein, 1997; Mörschel, 1999; Colman, tion in the Growing Degree Days in May and June. in northern latitudes and during winter have emerged showing, for example, that recruit- 2000). A more thorough understanding of these Sand et al. (1996) reported that high crude protein (Dickinson, 1986; Maxwell, 1997). Warming ment is affected more than adult survival (Grubb, mechanisms is made more urgent by global climate levels in birch (Betula sp.) were associated with trends and increased precipitation have been 1974; Sæther, 1997; Gaillard et al., 1998). changes that are affecting most northern areas years having low temperatures and high amounts of recorded in many regions of the Arctic during the However the effects of weather on population (Hughes, 2000). precipitation in early summer, and high tempera- past century, consistent with these climate models dynamics in herbivores still remain only superfi- tures in late summer. High environmental temper- (Chapman & Walsh, 1993; Serreze et al., 1995). cially understood (Sæther, 1997). atures, however, often lead to increased lignifica- Brotton & Wall (1997) also mentioned increased Climate may act directly on animal behaviour at Climatic variability and plant responses tion of plant cell walls, lowering digestibility. winter snowfall in the Northwest Territories of different scales (Helle, 1984; Skogland, 1989; Plant adaptation Amino acids and protein require sugar for their Canada. Both these past and projected climate Kojola, 1991). For example, the direct effect of Because of stochastic variation in climate, plants synthesis, therefore an increased nitrogen supply changes may have affected or may affect the quali- severe cold or chilling due to rainfall may lead to may develop different survival strategies to cope can reduce the sugar content of plant tissues, and ty and quantity of plant material available as forage increased costs of thermoregulation (Parker & with unfavourable environmental conditions. Taiz this effect is promoted at high temperatures and for ungulates through changes they bring about in Robbins, 1985; Putman et al., 1996), and increas- & Zeiger (1999) called this «stress tolerance». At high light intensity (Deinum, 1984). Cloud cover heat, moisture and available soil nutrients during ing snow depth to increased costs of locomotion in northern latitudes, unfavourable and harsh envi- and shade have been thought to decrease produc- the plant growth season (Klein, 1999). In areas of snow (Parker et al., 1984). Climate also acts indi- ronmental conditions can be persistent (Heide, tion of the aboveground plant biomass and the the high Arctic that may experience warmer and rectly on ungulate population parameters through 1985), and plant responses to these conditions nutritive value of forage by affecting the amount of longer plant growth periods with sufficient avail- its effect on plants. Indeed, climatic conditions are include acclimation, as well as adaptation. Because light received by plants (Van Soest, 1994). This able moisture, there will be an increase in plant known to have major impact on abundance and of the short growing season and generally low tem- may be valid where plants require high light inten- biomass (Klein, 1999). Post & Stenseth (1999) nutritional quality of plant tissues available to her- perature and variation in photoperiod in the north, sity and temperature for optimal growth under found that the North Atlantic Oscillation (a meas- bivores (Deinum, 1984; Van Soest, 1994). For some light and temperature are suggested to be the most short day length at lower latitudes. Restricted light ure of large-scale climatic variability; see below) northern ungulates, much of the variation in popu- important factors influencing plant growth and due to cloud cover and, in the case of forest floor was significantly related to plant phenology, as lation parameters has been related to the availabili- development (Van Soest, 1994). Because moisture vegetation, to shade from the crowns of trees, how- most plant species bloomed earlier following ty of resources in either winter (Skogland, 1985) or stress is an important factor during winter for trees, ever, may improve quality of leaf tissue as forage by increasingly warm, wet winters with herbaceous summer (Reimers et al., 1983; Reimers, 1997; leaf shedding and winter bud formation are impor- extending early stages of phenology. This results in species being more sensitive to climatic variation. Hjeljord & Histøl, 1999; Finstad et al., 2000a). tant adaptations (Levitt, 1980). Early leaf develop- a low ratio of structural to photosynthesising tis- This could have an effect on length of the growing There have been recent reviews on the effects of ment enables perennial and herbaceous plants to sues and limits accumulation of digestion-inhibit- season which, when extended, has the converse climate on large herbivores (Sæther, 1997) and the utilize short and cool growing seasons, and plants ing secondary chemicals derived from carbon that effect of shortening the winter period of plant dor- effects of climate in specific geographic areas with adapt to water stress by a limitation in leaf expan- may otherwise be produced in excess of growth mancy (Klein, 1999). This would further lead to either fairly mild (U.K.; Putman et al., 1996) or sion (Taiz & Zeiger, 1999) needs of plants (Bryant et al., 1983). Bø & Hjeljord increase in winter forage, but with variable quality extreme climates (Gunn & Skogland, 1997; Klein, (1991) found that continental moose ranges (Chapin & Shaver, 1996). The projected increase in 1999). However, there has not been a synthesis of Local climatic variation improve during cloudy, wet summers. They report- cloud cover during summer could result in an the recent new advances in assessing climatic and forage quality and quantity ed, after investigation on the most important extension of the period when forage is highly effects on northern ungulates with an emphasis on Although nutrients, water, light and heat are nec- browse species (Betula sp.), that with a decrease in digestible and has relatively low levels of secondary mechanisms, and reindeer in particular. Sæther essary for growth of plants, they have to participate solar radiation, there is an increase in the crude pro- chemicals (Ball et al., 1999; Klein, 1999). This (1997) stressed the need for a better understanding in appropriate proportions for optimal plant tein:dry matter ratio and a decrease in the tannin could be of great ecological importance at higher of the mechanistic basis behind climatic effects on growth (Jurïsson & Raave, 1984). Yearly variation content of forage plants. At high latitudes in sum- latitudes where the plant growth season is short. large herbivores. In this paper, we review and dis- in forage quality is strongly influenced by weather mer, the short and cool nights have a positive effect cuss central aspects of the current knowledge con- (Bø & Hjeljord, 1991; Finstad et al., 2000b). on forage quality because there is little respiratory cerning the effect of climate (local and global) on Because of the difference in radiation received at loss by plants at night (Klein, 1970a) and slow Local climate regime and population dynamics and life history traits of the soil surface, Bennett & Mathias (1984) found a build up of fibrous tissues. As winter weather varies large herbivore populations northern ungulates, with emphasis on reindeer and more than two fold difference in above ground annually, snow condition might also vary. Body weight caribou (both Rangifer tarandus). We also consider growth in some plant species as a consequence of Therefore, the availability of forage to ungulates Body weight is one of the most important life his- recent advances regarding possible mechanisms, slope exposure and associated differences in radia- during winter will be affected. Indeed, cold weath- tory traits (Calder, 1984). Several aspects of the life but restrict our focus to indirect effects of climate tion received at the soil surface. Snow cover and er following wet snow or rain, may lead to ice lay- history of deer are associated with body weight; mainly on plant quantity and quality, and their depth affect length of the growing season and ers in the snow or «icing» on the ground surface those factors that affect body weight may also have nutritional importance in the population dynamics hence forage quality (Hjeljord & Histøl, 1999; Van limiting access of herbivores to vegetation. This an important influence on population dynamics of northern ungulates as suggested by Post & der Wal et al., 2000). Timing of snowmelt also will affect species feeding mainly in the field layers (Klein, 1970b; Sæther, 1985). 30 Rangifer, 22 (1), 2002 Rangifer, 22 (1), 2002 31 Several studies have shown a relationship body mass of calves and yearling moose with caribou (2, 3, 4 and 6 year olds) was affected by 1991). Annual variation in population growth rate between body weight and conditions on the sum- increasing snow depth during the preceding winter winter snowfall with natality declining with in Svalbard reindeer was strongly negatively relat- mer range (Aarak & Lenvik, 1980; Reimers, 1983; and spring. Furthermore, condition of calves may increasing late winter snow fall during the winter ed to winter precipitation. High growth rate Langvatn et al., 1996; Sæther et al., 1996; Hjeljord be poor following winters with low temperature prior to the autumn breeding season (Adams & occurred when winters were dry, and the effect of & Histøl, 1999). Langvatn et al. (1996) suggest and high snow depth (Sæther & Gravem, 1988; Dale, 1998). In Southern Norway Sæther et al. climate was stronger at high densities (Aanes et al., that weight gain of red deer (Cervus elaphus) during Cederlund et al., 1991). Additionally, Cederlund et (1996) found that female moose also matured earli- 2000). Survival rates of red deer calves of both sexes the early summer growth spurt should be rapid al. (1991) found a negative correlation between er after two winters with almost no snow cover. were positively correlated with temperature and during cool May-June weather. They associated body mass loss and snow depth. Snow depth has Similarly, delayed maturity was found on mountain negatively with snowfall, while only a slight nega- this with retarded phenological development of been reported to be the only local climatic variable goats (Oreamnos americanus) in a population living tive effect of day-degrees on yearling survival rate forage plants during periods of cooler weather, that has a significant effect on red deer body mass under harsh winter conditions (Jorgenson et al., was detected in males and a slight positive effect of causing leaf:stem ratios and digestibility of plants in Sør-Trøndelag, Norway (Loison & Langvatn, 1993). Kruuk et al. (1999) found that fecundity of day-degree was detected on adult male survival parts to decline more slowly, thus enhancing qual- 1998; Loison et al., 1999b). Similar negative influ- female red deer decreased with rainfall in the pre- rates (Loison & Langvatn, 1998). A negative effect ity of the available diet. Climate variables ence was found on black-tailed deer Odocoileus ceding winter. of winter harshness was found for red deer on Rum, expressed through local weather conditions, there- hemionus (Parker et al., 1993), and white-tailed deer Recently, climate variables have been demon- Scotland (Clutton-Brock & Albon, 1982), with a fore, can be expected to have a major effect on for- O. virginianus (Moen & Severinghaus, 1981). This strated to affect population sex ratios in red deer lower male than female survival rate (Table 1). age quality and quantity in summer, with associat- differs, however, from results of studies by Ouellet (Kruuk et al., 1999; Post et al., 1999b; Mysterud et Juvenile mortality was observed to increase during ed affects on ungulate body size or body weight. et al. (1997) on caribou, as they did not find any al., 2000). The proportion of male red deer born winter with both high population density and high Climatic variables, both through their direct effects relationship between winter severity and body con- yearly on the island of Rum, Scotland, declined November-January rainfall (Kruuk et al., 1999). on forage quality and its quantitative availability, dition. with winter rainfall, associated with increased Studies by Jorgenson et al. (1997) in bighorn sheep can be expected to play a major role in population nutritional stress in females (Kruuk et al., 1999). In (Ovis canadensis), and Loison & Langvatn (1998) did dynamics of northern ungulates (Table 1). Reproductive performance and sex ratios Norway, the proportion of male red deer harvested not detect a relationship between winter severity Sæther (1985) found that a combination of Age at maturity and fecundity are strongly related during autumn each year declined with increasing and adult survival. These observations show that many climatic variables explained a significant por- to body weight and condition (Lenvik et al., 1988; snow depth in March (Mysterud et al., 2000). The there are differences in mortality by sex and age tion of annual variation in mean carcass weight of Gaillard et al., 1992; Jorgenson et al., 1993; Festa- annual sex-ratio was not related to e.g. sex-depend- class within a population in response to weather moose (Alces alces) in autumn. Mean summer tem- Bianchet et al., 1994; Langvatn et al., 1996; Sæther ent mortality during the summer season. Female variables. In wapiti (Cervus canadensis), calf survival perature and summer precipitation were the most et al., 1996; Reimers, 1997). Therefore, climatic red deer thus reared fewer sons as nutritional stress rate correlated positively with July temperature important variables. Sand et al. (1996) reported variation is expected to affect these life history increased with increasing severity of climate both and negatively with November precipitation while that years with relatively high body mass of moose parameters (Table 1), but this relationship may, on Rum, Scotland and in Norway. The extrinsic cow survival was positively correlated with January in Sweden were generally associated with low tem- however, differ regionally due to different selective modification of ungulate sex ratios by climate temperature, but negatively correlated with May perature and high amounts of precipitation in early regimes (Sæther et al., 1996). occurs at a population scale and is probably not temperature and total July precipitation (Sauer & summer, and with high temperatures and low pre- Finstad et al. (2000b) reported that the propor- adaptive (Kruuk et al., 1999; Post et al., 1999b; Boyce, 1983). It is noteworthy that, the effect of cipitation in late summer and early fall. They also tion of reindeer yearlings lactating in June was pos- Mysterud et al., 2000). However, the physiological climate interacts with population density. Indeed, found a positive correlation, although significant itively related to Growing Degree Days the previ- mechanism by which sex ratio is determined the effect of winter weather on survival of wapiti only for adult females, between previous winter ous May and June and negatively related to both remains unknown (Hewison & Gaillard, 1999). cows and calves seemed stronger at high population snow and body mass, suggesting a delayed effect of Growing Degree Days the previous July and snow Possible mechanisms include a higher in utero mor- density (Sauer & Boyce, 1983). weather variables on body mass. depth the winter prior to birth. Cameron et al. tality of males under harsh conditions, and modifi- Mortality is sometimes also attributed to sum- The effects of winter climate appear also to be (1993), reported that the probability of a successful cation of the sex ratio at conception and/or implan- mer conditions. Comparing latitudinal gradient important, through, for example, the indirect effect pregnancy of female caribou may be largely prede- tation (Reimers, 1999; Mysterud et al., 2000). both in summer and winter range condition in dif- of late snow melt on forage quality or snow condi- termined during the previous breeding season, ferent Norwegian moose populations, Sæther et al. tion on forage availability, but direct effects may based on autumn condition, whereas maternal con- Survival, abundance and population growth (1996) found that mortality was highest in the also be important. In years with high snowfall, dition during late pregnancy has greatest influence A close relationship has been reported between northernmost study area, where most death caribou calves were lighter at 10 months of age and on calving date and early calf survival. Sand et al. winter weather and both annual mortality rate in occurred during summer and very few calves died presumably unable to gain sufficient mass by (1996) found in Sweden that high fecundity and several species of ungulates (Martinka, 1967; during winter. They found no relationship between autumn to breed successfully as yearlings (Adams recruitment rate of moose were associated with Clutton-Brock & Albon, 1982; Sauer & Boyce, winter food supply and calf mortality. Stubsjøen et & Dale, 1998). Negative correlations between body years having relatively warm September weather. 1983; Skogland, 1985; Gaillard et al., 1993;) and al. (2000) found seasonal variation in survival mass and severity of the preceding winter have The proportion of 2-year-old red deer calving in abundance of calves (Lee et al., 2000). Direct effects among calves but very little among adults, in three been reported for wild reindeer (Skogland, 1983). Norway, and cohort differences in the proportion of winter climatic conditions on survival are com- populations of moose in northern Norway. The Gerhart et al. (1996) associated winter undernutri- calving as 3-year-old red deer on Rum, Scotland, monly reported, but there may also be effects of highest mortality was found among neonates dur- tion with declines in body fat and protein in adult were negatively related to variation in May-June summer weather. ing summer in two populations. The natural mor- female caribou. This was not the case on degree days 12 months earlier (Langvatn et al., Skogland (1985), comparing different wild rein- tality of calves was different among regions during Southampton Island, Canada, where caribou condi- 1996). They also revealed that the proportion of deer herds, revealed a relationship between calf sur- both summer and winter. Stubsjøen et al. (2000) tion (measured as bone, muscle and empty body hinds calving on Rum had a tendency to decline vival rate and the amount of forage available during attributed part of the natural mortality to severe mass) did not appear to be related to the winter with increasing number of days with snow in win- late winter. Caribou in northwestern Alaska also climatic conditions in both winter and summer. severity index (Ouellet et al., 1997). Hjeljord & ter. Winter conditions, thus also influence repro- experienced highest calf mortality in years when Early survival in roe deer (Capreolus capreolus) fawns Histøl (1999) also reported a decrease in autumn duction. The reproductive performance of female snowmelt was relatively late (Fancy & Whitten, tended to increase with increasing rainfall in May 32 Rangifer, 22 (1), 2002 Rangifer, 22 (1), 2002 33 , 1991 , 1993 , 2000 , 1996 ., 1997 , 2000b ., 1997 , 1999a , 1999b ., 1999 ., 1999 , 2000 ., 1993 et al. et al. et al. , 1996 et al. et al , 2000 et al et al. et al et al et al et al. et al. et al. et al. et al. Canada Previous July GDD and snow depth prior to birth - Wetter winter prior to rutWetter autumn prior to birthWarmer + ! - ! temperature preceding spring performance Growing Degree Days (GDD) phenotypic parameters Natality at 2,3,4 and 6 years old female Late snow fallBody conditionCalf mortality severity index Winter Body mass - * of snow melt Time Reproductive None USA Alaska, Population growth rate Southampton Island, Previous May and June Severity previous winter - precipitation Winter Ouellet + - & Dale, 1998 Adams USA & Canada Alaska, Fecundity - *Age at maturity Fancy & Whitten, 1991 Seward Peninsula, USAFecundity Norway Svalbard, Norway(Proportion of male) Finstad Autumn sex ratio May and June degree days Cool May June weather Aanes Male survival rate - * Preceding winter rain fall Snow depth in March + Skogland, 1983 Norway - * harshness Winter - and Rum Norway Scotland Rum, Norway - * Langvatn Kruuk Rum Mysterud Clutton-Brock & Albon, 1982 Calf survival rateCalf survival rateAdult male survival rate male survival rateYearling May to June day – degrees May to June day – degrees Temperature Snow fall + - Birth sex ratio + * Rainfall November-January - * Norway Sør Trøndelag, - * Loison & Langvatn, 1998 Age at maturity Number of day with snow(Proportion of male) Juvenile winter mortality - ! rainfall High November-January - Rum Rum, Scotland Kruuk Body massBody massAdult female massFecundity and recruitment rate First previous winter May-June temperature September weather Warm September Warm + + * - + Cow survival July precipitation Total Calf body massBody mass loss body weightYearling - * Calf and yearling mass Snow depth severity Winter Snow depth Snow depth - * - * - * - * Sweden Grimsö, Norway Southern Norway Cederlund Hjeljord & Histøl, 1999 1985 Sæther, Calf survival rateCow survivalCow survival November precipitation January temperature May temperature - * + ! - ! Survival Low degree-day spring - The Pyrenees, France < 0.10. < 0.05. P P Moose and adult mass Yearling May-June rainfall ! + Sweden Grimsö, Sand Wapiti Calf survival rate July temperature + !Roe deer Wyoming Fawn early survivaldeer White-tailed Body massdeer May June rainfallChamois survival Cohort Mountain Sauer & Boyce, 1983 goat Snow depth Age at maturity+Positive correlation. +- High precipitation and low correlation. Negative ! * harshness Winter + * France Alps, France The - - USA New York, Loison Canada Alberta, Gaillard & Severinghaus, 1981 Moen Jorgenson Table 1. Northern ungulate population responses to annual local climatic variability. Table Species Demographic and variables Climatic Trend Locality Red deer Body mass References Snow depth - * Norway Sør Trøndelag, Loison Caribou Calf body massReindeer Snow fall Live calve recorded winter prior to rut Warm - * - Finland Northern USA Alaska, Lee & Dale, 1998 Adams Black-tailed Body mass Snow depth - Alaska, USA Parker

34 Rangifer, 22 (1), 2002 Rangifer, 22 (1), 2002 35 and June (Gaillard et al., 1997). The cohort survival malian herbivores, including phenotypic variation, which they were in utero. They also reported a neg- temperature and low precipitation in winter) of the chamois (Rupicapra rupicapra) has been fecundity, sex ratios, demographic trends and pop- ative relationship of both reindeer calf mass and exhibited low winter survival in the Pyrenees, reported to increase when precipitation was high ulation dynamic processes (Post et al., 1997, female fecundity with NAO in Finland and while in the Alps, survival decreased following pos- and temperatures were low during the preceding 1999a,b,c; Forchhammer et al., 1998; Post & Norway respectively (Table 2). On the contrary, itive NAO. Accordingly, they suggested that com- spring in the Pyrenees, while no cohort effect was Stenseth, 1998, 1999; Loison et al., 1999a; Loison et al. (1999b) found that body mass of red mon ideas about effect of winter harshness and detected in the Alps, but decreased survival Mysterud et al., 2000). Global climate change will deer was positively correlated to NAO, but lagged snow on survival of herbivores are more complicat- occurred following a low degree-day spring (Loison likely increase both the extent and seasonal dura- one year. Also, while yearling moose in Norway ed than assumed previously. et al., 1999a). In an investigation of the regional tion of open water in the arctic seas, and the fre- were heavier if born following positive NAO win- On the western side of the Atlantic, caribou, effect of climate on reindeer, Lee et al. (2000) found quency of oceanic cyclonic storms at high latitudes ters, body mass of moose in Sweden, where winter moose, muskox (Ovibos moschatus) and white-tailed that the number of live calves recorded in northern (Serreze et al., 1995). Icing events can, therefore, be weather was more continental, declined following deer abundance increased following high NAO Finland was negatively related to both warmer and expected to increase, limiting access to forage by warm, wet winters (Post & Stenseth, 1999). This (Table 2) in West Greenland, Isle Royale, East wetter winter weather prior to the rut, and posi- caribou (Klein, 1999). Such broad patterns of glob- suggests that the effect of NAO on population Greenland and Minnesota respectively (Post & tively to warmer autumn weather prior to birth al change will affect most herbivore population parameters varies regionally. Post et al. (1999c) Stenseth, 1999). The rates of increase of both (Table 1). This study did not specify when live calf parameters (See Gunn & Skogland, 1997; Table 2). documented recently that the state of the NAO moose and white-tailed deer in North America numbers were recorded and did not include snow during fetal development of hinds in red deer influ- were influenced by global climatic fluctuation at 2 characteristics in their models. Body mass, fecundity and sex ratios enced the mass of their sons, but not daughters. and 3 years lags, as well as delayed density-depend- There is a correlation between the NAO and red Winters with a high NAO index also led to ence feedback and wolf predation (Post & Stenseth, deer cohort-specific mean body weight and skeletal increasingly male biased sex ratios of offspring, 1998). Global climatic regime ratios of adults when cohorts were in utero (Post et independent of changes in the mean age of hinds and large herbivore populations al., 1997). Recently, however, opposite correlations (Post et al., 1999b; Mysterud et al., 2000; Table 2; In the North Atlantic region, winter climatic vari- between the NAO and red deer body weight were see also discussion above). There was, however, no Climate, insect activity and harassment ability is, to a large extent, explained by a large- reported from the same area in Norway; both high residual effect of the NAO once the effect of snow Studies discussing effects of climatic variability on scale alternation of atmospheric pressure called the body weights of red deer calves (Loison et al., depth (at low elevation) was controlled for male- ungulate populations have generally not related it North Atlantic Oscillation (NAO) (Rogers, 1984; 1999b) and low body weights of adult red deer biased harvest with increasing snow depth to the effects of insects. However, this mechanism Hurrell, 1995). The NAO refers to a meridional (Post et al., 1997) followed years with positive (Mysterud et al., 2000). may potentially be very important. Klein (1991) oscillation in atmospheric mass with centres of NAO. Mysterud et al. (2000) found that the con- suggested that harassment by the skin warble action near Iceland and over the subtropical trasting result was because Post et al. (1997) did Abundance and survival (Hypoderma tarandi, Oestridae) and nasal bot flies Atlantic from the Azores across the Iberian not control for the stronger and negative effect of In red deer, Forchhammer et al. (1998) observed (Cephenemyia trompe, Oestridae), introduced to Peninsula (Hurrell, 1995). Because the signature of local density, as both density and the NAO that, warm, moist winters (high NAO) were asso- Greenland in the 1950s, and infestation by their the NAO is strongly regional, its state is quantified increased during the span of the study. A high ciated with decreased abundance (through over- larvae may have been a major factor influencing annually by a simple index based on the mean devi- NAO index was indicative of higher precipitation. winter mortality the following year), whereas the decline in body condition and suppression of the ation from the average sea-surface pressure between As winter temperatures at the west coast of Norway delayed two-year effect of warm, moist winters had population of West Greenland caribou. the Azores and Iceland, from December through is commonly around 0 ºC, the warmer tempera- a positive effect on abundance (through increased Syroechkovskii (1995) estimated that caribou or March for the winter. Positive values of the NAO- tures, however, at higher NAO (Hurrell 1995; Post fecundity of the cohort born following high NAO), reindeer could lose up to 2 kg of blood to mosqui- index characterize unusually warm, wet winters in et al., 1997) result in a negative correlation with the positive effects being relatively larger. toes during one season in the Taimyr Peninsula, northern Europe (and unusually cold, dry winters between snow depth and the NAO at low eleva- They suggested that the NAO effect was sex-spe- Russia. Colman (2000) reported lower body mass in North America), while negative values charac- tion, whereas this relationship is reversed above cific, operating primarily through the female seg- in the southernmost population of reindeer in terize unusually cold, dry winters in northern approximately 400 m a.s.l. (Mysterud et al., 2000). ment of populations. It also has been shown that Norway after a summer with severe insect harass- Europe (and warm, wet winters in North America) Forage in the field layer is thus probably more eas- male and female calves responded differently to cli- ment than after a cool summer (Table 3). It has (Hurrell, 1995). Because the NAO accounts for ily available to red deer in these coastal and low- matic variability (Post et al., 1999c). Post et al. appeared in the same area and during the same most of the year to year fluctuations in winter pre- land areas during winters with a high NAO index (1999a) reported that in both Sør-Trøndelag period that free ranging sheep weight was higher in cipitation in northern latitudes (Hurrell, 1995, (Loison et al., 1999b), and a high NAO index thus (Norway) and Rum (Scotland), total abundance of the year with warmer summer (unpubl. data), sug- 1996; Hurrell & Van Loon, 1997) as well as varia- probably indicates favourable conditions for red red deer increased two years after increasingly gesting that the pasture was not of bad quality, and tions in wintertime temperatures on the scale pre- deer. Indeed, body weights of red deer in Norway warm winters (Table 2). Whereas in Norway, this that insect harassment may affect reindeer/caribou dicted by theoretical models of climate change in general were positively correlated with the NAO increase was attributed to the enhancement of body condition independently of range quality. (Hurrell, 1996), the NAO has a clear potential to when taking population substructure into account cohort specific fecundity of 2 year-old hinds, on Considerable behavioural evidence supports harass- affect the ecology of plants and animals in the and using an index for local density, although this Rum it was attributable to increases in annual ment by insects as the most important causal link Northern Hemisphere (Post et al., 1999a). relationship was reversed at very low NAO values fecundity of 3 year-old hinds. Indeed, adult male between warm summer temperatures and low body However, as the effect of this large-scale climatic (A. Mysterud, N.G. Yoccoz, N.C. Stenseth & R. abundance was negatively correlated to the previ- condition of reindeer. Indeed, dense aggregations index may result in different local weather patterns Langvatn, unpublished results). ous NAO on Rum (Post & Stenseth, 1999). Both and associated movement of reindeer and caribou in different areas (Mysterud et al., 2000), these On Rum, Scotland, Post & Stenseth, (1999) abundance (Post & Stenseth, 1999) and lamb sur- during warm summer weather are associated with interactions are inherently complex. observed that birth mass and adult mass of red deer vival (Milner et al., 1999) of Soay sheep (Ovis aries) insect harassment (Anderson & Nilssen, 1996; The NAO, through its effects on vegetation and increased following positive (warm, wet) NAO have also been reported to decrease following high Noel et al., 1998), which results in increased time climatic conditions, influences several aspects of winters while fecundity of female red deer correlat- NAO. Loison et al. (1999a) found that adult cham- spent moving and/or standing, and reduced time life history and ecology of terrestrial large mam- ed negatively with the NAO index of the winter in ois born after positive NAO (indicative of high spent feeding, with detrimental nutritional conse- 36 Rangifer, 22 (1), 2002 Rangifer, 22 (1), 2002 37 quences (Helle et al., 1992; Toupin et al., 1996; Mörschel & Klein, 1997; Colman, 2000). Using activity change per minute as an indicator of harassment, Mörschel & Klein , 1996 , 1998 ., 1996 (1997) reported higher rate of activ- , 1992 , 1992 ity changes among caribou in central , 1998 , 2000 , 2000 et al et al. et al. et al. et al. et al. , 1999 , 1999 Alaska when insects were present. , 1999b , 1999a , 1999a et al. et al. , 1999b , 1997 , 1999a Temperature and wind speed had a et al. et al. et al. et al. et al. significant effect on the rate of activ- et al. et al. et al. ity changes of caribou (Table 3), reflecting the regulation of insect activity by these abiotic factors. Behavioural responses to avoid insects are commonly observed. Indeed, as reported by Pollard et al. (1996), caribou movements, distri- bution, and behaviour were significantly influenced by harassment

from parasitic insects such as mos- Alaska, USA Noel Alaska, USA & Klein, 1997 Mörschel quitoes and oestrids, during the post-calving period. Espmark & Langvatn (1979) reported that lying down was a strategy to cope with head fly harassment in red deer in Norway. This indicates a possible detrimental effect of insect harass- + * Norway+ * Scotland Rum, & Stenseth, 1998 Post & Stenseth, 1999 Post - Finland & Stenseth, 1999 Post ment also on other species of deer. Three major parasitic insects are of primary concern for reindeer: mosquitoes (especially Aedes sp., Culicidae), warbles flies and nasal bot flies (Gunn & Skogland, 1997; Mörschel & Klein, 1997). But, caribou responses Anderson & Nilssen (1998) reported and/or standing and decreasing time spent feeding Norway Canada Colman, 2000 Toupin in utero in utero in utero evidence for potential contribution to the harassment on reindeer by black flies (Simuliidae) and horse and deer flies (Tabanidae) as well. NAO 2 years lags + Norway NAO 1 year lag None Norway Mysterud NAO 2 years lags + * Scotland Rum, Roby (1978) observed a higher percentage of standing and running and a lower percentage of lying under oestrid fly harassment than under similar levels of mosquito harassment. Mörschel & Klein (1997) found that the presence of oestrid flies had a larger influence on activity budgets of caribou than did mosquitoes by substantially increasing (Proportion of male) NAO + * Norway Mysterud Autumn sex ratio NAO + * Norway Hordaland, Post Yearling massYearling NAO 3 years previousCohort fecundity (3 years olds + milk hinds) - *Cohort fecundity (2 years olds) Adult female mass Sweden Post & Stenseth, 1999 - * + * Scotland Rum, + Norway Scotland Rum, phenotypic parameters Adult female fecundity NAO 1 year previousCalf body mass - * NAO 3 years previousAdult male abundanceCalf birth mass Norway previous NAO - * NAO when Adult male mass SwedenAdult female mass - *Adult male mass & Stenseth, 1999 Post Body mass Scotland Rum, Adult survival Post & Stenseth, 1999 NAO 1 year lagAdult female survival NAO year of birth NAO + * + - * - ! - * Norway Sør Trøndelag, Norway Scotland Rum, Pyrenees, France The Loison - ! Loison St Kilda, Scotland Post Milner Lamb survival NAO - * St Kilda, Scotland Milner Total abundanceTotal 2 years previous NAO + * Norway Sør Trøndelag, Post the amount of time spent standing and decreasing the amount of time spent feeding. It is during summer, which is the < 0.10. < 0.05. < 0.05. P P

peak period in energy and nutrient P Moose mass Yearling Red deer Abundance NAO when previous NAO - Norway Forchhammer Temperature Increase mosquito abundance Higher disturbance Alaska, USA Pollard Warm summerWarm IncreaseTemperature speedWind Cloud cover Increased*Relative humidity Aggregation and movement Increase Decreased* Decrease Norway Increase rate of activity change Anderson & Nilssen, 1996 Alaska, USA & Klein, 1997 Mörschel * Table 2. Northern ungulate population responses to the North Atlantic Oscillation (NAO) index. Table Species Demographic and CaribouReindeer Abundance Climatic variable Calf body mass NAO when Previous NAO Trend Locality + * Greenland Sissimiut, West Reference Post & Stenseth, 1999 MuskoxSoay sheep Abundance Abundancedeer+ Positive correlation. - correlation. Negative 1 year previous NAO ! Previous NAO Population rates of increase NAO 2 years lags + * + * - * Greenland East Isle Royale, USA UK Bay, Village Post & Stenseth, 1999 & Stenseth, 1998 Post Post & Stenseth, 1999 3. Insect responses to climatic variability and related consequences on reindeer/caribou. Table Climatic variables Insect harassmentCloud cover reindeer/ Resulting summerWarm Increase Decrease* Locality speedWind Relative humidity Decrease Lower body weight * mosquito abundance Decrease Increase time spent moving Lower disturbance Reference Finland Lower disturbance Helle Alaska, USA Walsh White tailed Population rates of increase NAO 3 years lags + * USA Minnesota, & Stenseth, 1998 Post Wind velocityWind Decrease mosquito abundance Lower disturbance Warm summerWarm Temperature Increase Increase* Lower body weight Lower body weight Southern Norway Colman, 2000 Chamois Survival NAO 1 year lag - *intake and Alps, France The requirement Loison for northern 38 Rangifer, 22 (1), 2002 Rangifer, 22 (1), 2002 39 ungulates that harassment by insects occurs. plant quantity might be driven by low levels of by species and population status (sex, age and size of the adult phase of these Dipteran species, their Russell (1993) reported that the warble and nasal available plant biomass and high forage quality for example). This suggests that we should ques- life span and their activity and flight capacities bot fly season lasted from the end of June until during the growing season in the high arctic, tion the factors guiding choices of some specific under different temperature, humidity and wind early August, while mosquitoes were primarily a whereas in temperate regions with high forage bio- weather variables and not others by authors in this conditions (see Roby, 1978; Russel, 1993; problem in July. In Norway the oestrid season lasts mass, selection for plant quality may be of greater field, as statistically it is often possible to find cor- Mörschel & Klein, 1997 above). Summer weather, from 10 July and ends around 20 August (Nilssen importance for herbivores. In Svalbard reindeer, relations among variables after several trials (e.g. through its effects on insect activity may play a & Haugerud, 1994). Although there is consider- therefore, selection for high plant biomass is likely Lindström, 1996). detrimental role on reindeer/caribou condition dur- able range in how the combination of weather vari- to lead to a more favourable nitrogen and energy ing summer, temperature being a key factor. ables affect levels of insect harassment, it is clear return than selection for high plant quality (Van Indeed, various means have been used to investi- that temperature, wind and relative humidity are der Wal et al., 2000). A reindeer/caribou perspective gate and evaluate the effect of insects on reindeer the primary interacting factors for reindeer and Although the existence of effects of weather In view of their numbers and, their socio-cultural and caribou, and temperature has consistently caribou, the relative importance of each varying parameters (local and global) on ungulate popula- and economical importance, there is a need for appeared to play an important role in determining with terrain features, location (altitude and lati- tion dynamics is widely accepted, there is little studies of long time series in assessing effects of cli- the level and type of avoidance behaviour of rein- tude), vegetation and substrate type, and animal consensus on the direction (positive or negative) of matic variability on reindeer/caribou. Indeed, many deer and caribou, even in the immediate absence of group size and behaviour. Walsh et al. (1992) used its effects and on which variables are more impor- northern indigenous peoples, including the insects (Mörschel & Klein, 1997). The expected an ambient temperature «greater-than-or-equal- tant. Some of the contrasting results probably arise Gwich’in of Alaska and northwestern Canada, the increased temperature with ongoing global climate to» 13 ºC and winds «less-than» 6 m/s to predict from methodological differences, or failure to Inuit of Canada, Alaska and Greenland, the Sami change could, therefore, be more harmful for rein- insect harassment while Brotton & Wall (1997) account for other significant covariates, such as and Komi of Fennoscandia and western Russia, and deer than other northern ungulates. We thus point suggested a minimum temperature of 6 °C for density (see e.g. Mysterud et al., 2000 and discus- numerous other peoples of Siberia and the Russian out the limits of comparability between systems oestrid fly activity. But, although he hypothesized sion above). For example, Mech et al. (1987) docu- Far East have dependence on reindeer/caribou for and the difficulty of generalizing about the effect of that summer climate was responsible for differences mented the cumulative negative effects of previous their livelihood. Reindeer areas in Norway experi- climate change broadly across northern systems, observed among years in larval infestation levels, winters’ snow on rates of population increase in ence large annual climatic variations with severe across species and even within species. The project- Nilssen (1997) has shown that cold weather certain moose and white-tailed deer. Messier (1991) impacts on herd reproductive output, as both live ed increased temperature in Scandinavia and other years may affect oestrids populations very strongly. analysing a smoothed version of the same dataset and dressed weight for calves and adults vary year- parts of the Eurasian and American North could Pollard et al. (1996) found that mosquito abun- reported no effect of snow accumulation on popula- ly in connection with climatic variation therefore lead to increased detrimental effects on dance was positively correlated with temperature tion dynamics. Post & Stenseth (1998) reanalysed (Reindriftsforvaltningen, 1998; R.B. Weladji & Ø. reindeer and caribou through its effect on insect and negatively correlated with wind velocity and both original and smoothed data on dynamics of Holand, unpubl. results). Furthermore, probably to activity when temperature, wind velocity and rela- relative humidity in Alaska. Colman (2000) report- moose and white-tailed deer accounting for serial a much greater degree than other ungulates, insect tive humidity are appropriate. The complex role of ed insect harassment of wild reindeer in southern autocorrelation and using the NAO (which has a harassment and associated parasitism, which is insects in the ecology of reindeer and caribou, and Norway to be positively correlated to increasing correlation with snowfall) and found that rates of related to summer weather conditions, is of partic- the associated influence of weather parameters on temperature and negatively correlated with increas- increase of moose and white-tailed deer in both ular importance in their ecology (Mörschel & the ecology of these insects, renders assessment of ing cloud cover (Table 3). original and smoothed data were influenced by Klein, 1997; Klein, 1999; Colman, 2000). The climate variability on the population dynamics of global climatic fluctuation at 2- and 3-year lags. total foraging time is considered to be a main reindeer and caribou particularly difficult. Even However, Loison et al. (1999a) reported opposite determinant of fattening in Rangifer (Reimers, less is known regarding possible effects of other Discussion effects of increase in spring temperature on cham- 1980). It is apparent that insect harassment during parasitic groups. Halvorsen et al. (1999) reported Several studies have been carried out investigating ois in the Alps and Pyrenees, showing different warm summers can have a detrimental effect on evidence for transmission of parasitic nematodes in the influence of local and global weather variation local response to the same global climatic variabil- body condition and productivity of reindeer and Svalbard reindeer during the arctic winter. on plants, and how this in turn affects population ity at the intra-specific level using the same caribou through lost foraging time, increased ener- Accordingly, as global changes are predicted to parameters of northern ungulates (Table 1). The methodology. This suggests that contrasting gy expenditure and increased parasite burden. affect winter climate the most, parasitic survival indirect effect of climate through its impact on responses to climate cannot be all explained by Models investigating the effect of climate change and transmission may increase with increased win- vegetation is confirmed through field studies show- methodological problems. There is considerable on reindeer predict an increase in insect harassment ter temperature. The relationship between climate ing that increased solar radiation and temperature biological variation in response to climate between in summer, due to an increase in average monthly and parasites in general should therefore be further lead to increased levels of secondary compounds in regions, areas, and localities, between species and temperature (Gunn & Skogland, 1997; Brotton & evaluated. plant tissues, such as phenols and tannins, while even within species. Wall, 1997). This may vary locally, however, The affiliation between reindeer/caribou and lowering the crude protein:dry matter ratio of tem- Also, most studies using the NAO have not because the level of harassment may vary depend- lichen is very strong (Boertje, 1990; Crittenden, perate forage plants (Jonasson et al., 1986; Laine & clearly shown its relationship with local weather ing on wind velocity, as insect harassment is 2000). Precipitation is one of the major processes Henttonen, 1987; Bø & Hjeljord, 1991). The inte- variables of the sites actually studied. There is evi- reduced on windswept areas (Walsh et al., 1992). that deliver nutrients to lichens (Crittenden, grated effects on availability of food resources per dently little consensus among authors on the gen- Other factors influencing insect levels and their 2000). Thus, increased precipitation during win- capita, on environmental conditions and on previ- eralized relative importance of specific climatic harassment include cloud cover (Colman, 2000), ters as predicted by climate change models ous reproductive success determine productivity of variables in influencing ungulates population relative humidity and access to «insect relief» habi- (Dickinson, 1986; Maxwell, 1997), may lead to ungulates. Therefore, environmental conditions parameters. There is considerable regional and local tat (Pollard et al., 1996; Mörschel & Klein, 1997). improved reindeer/caribou ranges during winters. such as adverse weather can be a significant influ- variability in how ungulates respond to specific cli- The effects of mosquitoes, biting flies, warble flies But in the presence of other plant types and under ence even for highly productive ungulates occur- matic variables (Klein, 1999). This demonstrates and nasal bot flies on reindeer and caribou may vary improved winter conditions, the competition edge ring at low densities (Adams & Dale, 1998). Van the complexity of the environmental/ecosystem differentially in relation to weather conditions. of lichens may be reduced, leading to lichens der Wal et al. (2000) suggested that selection for relationships that also vary regionally, locally and This is related to the different timing of emergence shrinkage and to reduction of the mat-forming 40 Rangifer, 22 (1), 2002 Rangifer, 22 (1), 2002 41 lichens, which might be detrimental for reindeer Skjelvåg, A.O. (eds.). The impact of climate on grass pro- Espmark, Y. & Langvatn, R. 1979. Lying down as a and reindeer to global warming. – Ecological studies and caribou. duction and quality. Proceedings of the 10th General means of reducing fly harassment in red deer (Cervus 124: 189-200. Predictions about possible effects of the ongoing Meeting of the European Grassland Federation. Ås, elaphus). – Behavioral Ecology and Sociobiology 5: 51-54. Halvorsen, O., Stien, A., Irvine, J., Langvatn, R. & global warming cannot be made with certainty, but Norway, 26-30th June, pp. 90-94. Fancy, S. G. & Whitten, K. R. 1991. Selection of calv- Albon, S. 1999. Evidence for continued transmission they will most likely be detectable, although vari- Bø, S. & Hjeljord, O. 1991. Do continental moose ing ground by Porcupine herd caribou. – Can. J. Zool. of parasitic nematodes in reindeer during the Arctic able between different geographic areas. range improve during cloudy summers? – Can. J. 69: 1736-1743. winter. – International Journal for Parasitology 29: 567- Zool. 69: 1875-1879. Festa-Bianchet, M., Urquhart, M. & Smith, K. G. 579. Boertje, R. D. 1990. Diet quality and intake require- 1994. Mountain goat recruitment: kid production Heide, O. M. 1985. Physiological aspects of climatic Acknowledgment ments of adult female caribou of the Denali herd, and survival to breeding age. – Can. J. Zool. 72: 22- adaptation in plants with special reference to high- We gratefully acknowledge the financial support of the Alaska. – Journal of Applied Ecology 27: 420-434. 27. latitude environments. – In: Kaurin, Å., Junttila, O. Norwegian Reindeer Husbandry Development Fund to Brotton, J. & Wall, G. 1997. Climate change and the Finstad, G. L., Berger, M., Kielland, K. & Prichard, & Nilsen, J. (eds.). Plant production in the north. R.B. Weladji and Ø. Holand. The authors express grati- Bathurst Caribou herd in the Northwest Territories, A. K. 2000a. Climatic influence on forage quality, Proceedings from «Plant adaptation workshop». Tromsø, tude towards the Circumpolar PhD Network in Arctic Canada. – Climatic Change 35: 35-52. growth and reproduction of reindeer on the Seward Norway, September 4-9. 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Jouko Kumpula1, Alfred Colpaert2 & Mauri Nieminen1

1 Finnish Game and Fisheries Research Institute, Reindeer Research Station, FIN-99910 Kaamanen, Finland ([email protected]). 2 University of Oulu, Department of Geography, FIN-99870 Oulu, Finland.

Abstract: Intensive reindeer grazing and the increase of other land use forms have caused a decline in the amount of arboreal (Alectoria, Bryoria spp.) and reindeer (Cladina spp.) lichens in the Finnish reindeer management area during the last few decades. Supplementary feeding of reindeer has increasingly compensated for the lack of natural winter fodder. The amount of the supplementary feeding and the quantity and quality of summer pastures should therefore have an increasing effect on the productivity of reindeer stock. In order to outline better the present carrying capacity problems on pastures in the Finnish reindeer management area we focused some of the most important productivity factors of Finnish reindeer stock from 1993 to 1999. The results showed that the productivity of reindeer stock in Finland was dependent especially on two main elements: amount of reindeer feeding and reindeer densities on summer pastures. Winter pastures had no clear effect on productivity when analysing the entire management area. High productivity figures in reindeer stock (calf production, carcass mass and meat production per reindeer) were reached in the management districts where winter feeding was the most abundant, reindeer densities relatively low and summer pastures abundant. An increase in reindeer density on summer pastures raised meat production per total summer pasture area but decreased carcass mass of reindeer calves and meat production per reindeer. It seems that the funda- mental factor for keeping the reindeer stock productivity sustainable at a high enough level is to optimize the long- term reindeer densities on pastures. Summer pastures may gradually become a limiting factor for reindeer stock productivity in some areas if overgrazed and decreased winter pastures are only compensated for by winter feeding of reindeer.

Key words: carrying capacity, feeding, reindeer, stock productivity, summer pastures. Rangifer, 22 (1), 2002

46 Rangifer, 22 (1), 2002 Rangifer, 22 (1), 2002 47