DIURNAL DEFECATION RATE OF MOOSE IN SOUTHWEST FINLAND Juho Matala1 and Antti Uotila2 1Finnish Forest Research Institute Metla, P.O. Box 68, FI-80101 Joensuu, Finland; 2University of Helsinki Hyytiälä Forest Station, Hyytiäläntie 124, FI-35500 Korkeakoski, Finland. ABSTRACT: An accurate measure of defecation rate is essential for application of pellet group counts in moose (Alces alces) population estimates. We measured the wintertime, diurnal defecation rate of moose by tracking 7 GPS-collared and 22 uncollared moose in southwest Finland. The mean defeca- tion rate was 23.5 ± 4.2 pellet groups/d, one of the highest values reported. The mean defecation rate did not differ between the tracking methods (GPS vs. uncollared moose); limited sample size pre- cluded conclusions about sex and age differences. The defecation rate was not correlated with calendar week, length of accumulation period, or number of diurnal beds. Our results are appropriate for use in southwest Finland when using the pellet group method to assess moose population density. ALCES VOL. 49: 155–161 (2013) Key words: Alces alces, Finland, defecation rate, moose, pellet group, tracking. Counting fecal pellet groups of moose (Alces alces) has been widely used to esti- mate habitat utilization, feeding behavior, and population trends and density (see Franzmann et al. 1976b, Forbes and The- berge 1993, Härkönen and Heikkilä 1999, Rönnegård et al. 2008, Månsson 2009, Mån- sson et al. 2011a, b). Reliable moose popula- tion estimates are not always realized from pellet group counts (Rönnegård et al. 2008), but the method's usefulness has been noted (Neff 1968, Lautenschlager and Jordan 1993, Månsson et al. 2011b), despite some uncertainty (Neff 1968). However, to suc- cessfully estimate moose population density using a pellet group count, it is critical to use an accurate defecation rate in the survey area and time period (Timmermann 1974). Earlier studies have used 2 main meth- ods to estimate the defecation rates of moose: 1) track moose in snow-covered ter- rain (Joyal and Ricard 1986, Andersen et al. 1992), and 2) estimate the number of pellet groups in a closed area or island where the number of moose is known (Jordan et al. 1993). Defecation rates have occasionally been estimated by comparing the aerial cen- suses and pellet group counts in specific areas (Rönnegård et al. 2008). Moose enclo- sures could also be utilized, but results from domestic moose can be affected by food quality and behaviour that are dissimilar to natural conditions. GPS radio-collars enable intensive and accurate tracking by identify- ing specific individuals and the beginning and end points of their specific tracks, pro- viding ideal conditions to measure defeca- tion rates of free-ranging moose. Moose defecation rates vary by age, sex, habitat, food quality, season, and year (Des- Meules 1968, Franzmann et al. 1976a, Olde- meyer and Franzmann 1981, Joyal and Ricard 1986, Andersen et al. 1992, Månsson et al. 2011b). Large variations in defecation rate have been reported in different areas; for example, in North America variation was 9.6–32.2 pellet groups/d (Timmermann 1974), and in northern Europe rates varied Corresponding author: Juho Matala, Finnish Forest Research Institute Metla, P.O.Box 68, FI-80101 Joensuu, Finland. +358 40 801 5275. juho.matala@metla.fi 155 from 14–26.9 pellet groups/d (Andersen et al. 1992, Remm and Luud 2003, Rönnegård et al. 2008). These data emphasize the importance of using area-specific rates when using the pellet group method to esti- mate moose population density. Our main objective was to formulate a general estimate of the wintertime, diurnal defecation rate of moose in southwest Fin- land by tracking both GPS-collared and uncollared moose in snowy terrain. We also compared these 2 tracking methods and looked for differences in defecation rates between sex and age. STUDY AREA Moose were tracked in 2 separate areas approximately 100 km apart in southwest Finland (Fig. 1). Uncollared moose were tracked in the Orivesi-Kangasala area (∼WGS84 61°36′ N, 24°22′ E) and GPS- collared moose in the Loppi-Hyvinkää area (∼WGS84 60°38′ N, 24°35′ E). Both areas are located in the southern boreal vegetation zone with Scots pine (Pinus sylvestris) and Norway spruce (Picea abies) as the domi- nant tree species. Forest cover was 78% of the total land area in Orivesi-Kangasala and 71% in Loppi-Hyvinkää (Metla 2012). METHODS Tracking of Uncollared Moose We actively searched for uncollared moose in their known habitats during fresh snow conditions between December and April, 1999–2003. The accumulation period for pellet counts began when moose were seen or flushed, enabling data collectors to accurately time their count by locating fresh resting places, pellet groups, or tracks in Fig. 1. Study area locations and starting points of moose tracking periods in southern Finland. In the Orivesi-Kangasala area some of the starting point coordinates of uncollared moose are rough estimates and overlap because they could not be separated at the map scale. 156 DIURNAL DEFECATION RATE OF MOOSE – MATALA AND UOTILA ALCES VOL. 49, 2013 the snow. The pellet groups were counted the following day, until moose fled from the counter. The end of the accumulation period was determined in a similar manner as the starting point. The accumulation periods varied from 8–31 h. Moose were classified as either adults or calves by visually observing them and their pellets, bedding places, and behavior. Their sex could be determined without visual con- tact by analyzing their urination methods, as bulls urinate in front of the hind hooves. We measured the diurnal defecation rate of 5 bulls, 3 cows, and 3 calves. Additionally we measured 3 cows with twin calves and 1 cow with a single calf, without separating the pellet groups of the cows and calves. In total, we were able to record the diurnal defe- cation rates of 22 uncollared moose and count the number of beds of 7 individuals. Tracking of GPS-Collared Moose The Finnish Game and Fisheries Research Institute (FGFRI) provided loca- tion data for the GPS-collared moose. The FGFRI implemented GPS-collaring proce- dures in accordance with Finnish legislation, with permission from the National Animal Experiment Board of Finland. An individual GPS-collared cow was tracked once and another on 5 separate occasions, while 1 cow with twin calves was tracked once, and one cow with a single calf twice; altogether, 7 individuals were tracked. The GPS-collared moose were tracked a few days after fresh snowfall in December– March 2010. The counter went to the most recent location of moose tracks which were usually ∼12 h old. The pellet groups were counted along the moose track by following it against the original course of the moose; the coordinates of the pellet groups, beds, and urination sites were located with hand- held GPS devices. The accumulation period finished when an individual track became mixed with others or sunset precluded tracking. The duration of the accumulation period was determined by identifying the time associated with the closest location of the tracks with GPS collar data. The accumu- lation periods ranged from 6–47 h. Data Analysis At least 20 pellets were required to make a pellet group. We processed the pellet group data of 29 moose (7 GPS-collared, 22 uncol- lared) to calculate the diurnal defecation rate (number of pellet groups produced per indi- vidual in 24 h) from the accumulation peri- ods of individual bulls, cows, and calves. Mean values were calculated for the group of cows and calves when it was impossible to identify calf from cow pellet groups; ana- lyses of 25 separate cases were used to calcu- late the diurnal defecation rate. For comparison, we sampled the mean values of diurnal defecation rates of 3 sex and age classes: 1) bulls, 2) cows, and 3) calves and cow-calves. The last class was required because we were only able to track 3 individual calves, which was insufficient for any reasonable analysis. We also com- pared the mean defecation rates of the uncol- lared and GPS-collared moose. Due to limitations in the linearity and homogeneity of variances in the data, we used the Kruskal-Wallis test for multiple samples and the Mann-Whitney test for paired sam- ple comparisons. Furthermore, we searched for possible correlations between the diurnal defecation rate and 1) the calendar week of the accumulation period, 2) the duration of the accumulation period, and 3) the number of diurnal beds for part of the samples. All statistical calculations were performed using the Statistical Package for the Social Sciences (SPSS) 17.0 software. Data relating to home range of moose during the accumulation period (calculated using the Home Range Tools for ArcGIS® version 1.1 with the Minimum Convex Polygon method), length of the moose track ALCES VOL. 49, 2013 MATALA AND UOTILA – DIURNAL DEFECATION RATE OF MOOSE 157 during the accumulation period, and the number of diurnal urinations were also col- lected from the GPS-collared moose, but insufficient sample sizes precluded their uti- lization in the analysis. RESULTS The diurnal defecation rate ranged from 12.2–32 pellet groups with an overall mean of 23.5 ± 4.2 (SD; Table 1, Fig. 2). The mean values of bull, cow, and calf/cow-calf groups were different (Kruskal-Wallis test: χ2 = 9.9, df = 2, P = 0.007; Table 1). The calf and cow-calf group had the highest mean rate, but was statistically different only from the cow group (Table 1). The bull group had the lowest mean rate, but also the lowest and highest absolute values (i.e., the widest range; Table 1). The cow and bull group rates and the rates of the uncollared and GPS-collared moose were not different (Table 1). The diurnal defecation rate was not related to the calendar week of the accumula- tion period (Fig. 2, Table 2). The GPS- collared individual which was tracked 5 times between 17 January and 23 February 2010 showed no trends during this period. The defecation rate did not correlate to the duration of the accumulation period or to the number of diurnal beds (Table 2). The mean values for the other variables were: diurnal number of beds = 8.0 ± 4.2 (SD, n = 15), the diurnal urination rate = 1.0 ± 1.0 (SD, n = 9), the area of home range dur- ing the accumulation period = 95,267 m2 ± 122,399 (SD, n = 9), and length of track dur- ing the accumulation period = 955 m ± 832 (SD, n = 6). DISCUSSION The mean defecation rate was considered high (23.5 ± 4.2 pellet groups/d) but similar to the average rate measured in relatively good moose habitat in southern Norway (22.9 pel- let groups/d; Andersen et al. 1992). Lower defecation rates were measured in southern Sweden (14 pellet groups/d; Rönneberg et al. 2008) and on Isle Royale, North America (20.9; Jordan et al. 1993). Many studies have reported lower defecation rates in Alaska and Canada (see DesMeules 1968, Franzmann et al. 1976a, Oldemeyer and Franzmann 1981, Joyal and Ricard 1986). The high values reported in our study area are not unreasonable when comparing the status of the moose population in Finland to other Nordic countries. The Finnish moose population is lower and of a higher productive state compared to those in Table 1. Mean values of the wintertime, diurnal defecation rate and comparisons between moose groups in southern Finland. Pellet groups (#/ind/24 h) Mann-Whitney Test Mean Min Max n SD Test against U-value P Grouping by moose type: Bulls 20.1 12.2 32.0 5 7.3 Cow 12 0.152 Cows 22.3 18.9 24.0 9 2.2 Calf + groups 10 0.002 Calf and Cow-calf groups 25.9 23.0 31.3 11 2.2 Bull 11 0.061 Grouping by tracking method: GPS-collared 23.5 20 26.7 9 1.8 Uncollared 64 0.647 Uncollared 23.4 12.2 32.0 16 5.2 All moose 23.5 12.2 32.0 25 4.2 158 DIURNAL DEFECATION RATE OF MOOSE – MATALA AND UOTILA ALCES VOL. 49, 2013 Sweden and Norway (Lavsund et al. 2003, Tiilikainen et al. 2012). These differences presumably imply better foraging habitat, higher nutritional condition, and a resultant higher defecation rate in Finland. Because defecation rates are influenced by food qual- ity and availability and show large variation (Andersen et al. 1992), it follows that area- specific defecation rates should be measured when using pellet group counts to estimate population density. The extremes in defecation rate varied largely in our study, but most observations, especially of the GPS-collared individuals, were similar to the mean indicating the gen- eral reliability of these data and their applica- tion to estimate population density. The extreme values could result from local fora- ging conditions or from longer movements associated with unintended disturbances while tracking the uncollared moose. Because the defecation rate can correlate with age and sex, these relationships should be taken into account if a change in popula- tion structure occurs (Franzmann et al. 1976a). Our data indicate that the calf and cow-calf group had slightly higher defeca- tion rates than individual cows as also reported by DesMeules (1968), but opposite that of Joyal and Ricard (1986). Bulls and cows were not different in our analyses; however, general conclusions about sex and age differences cannot be made due to the limited sample size. Using an accurate defecation rate is criti- cal when applying pellet group counts in moose population density estimates. Defeca- tion rates have not been published previously in Finland, and given the considerable varia- tion in similar data from northern Europe, we consider our results the best available for local use. Furthermore, similar defecation rates were obtained for both regions in our study, making the mean values applicable to all of southern Finland. The lack of corre- lation between calendar week and defecation rate indicates a stable accumulation rate throughout winter, suggesting that these rates might be applicable for springtime pel- let group counts. Variations in the absolute data and means should be taken into account when calculating confidence limits for the final moose density estimate. ACKNOWLEDGEMENTS We thank Mr. J. Sillanpää for tracking the GPS-collared moose and Mr. H. Mattila 50 Fig. 2. The diurnal defecation rate of moose in southern Finland relative to the time of the tracking period (calendar weeks). Moose types are classified as: 1) individual bulls, calves, and cows, and 2) cow-calf groups (when individuals could not be separated during tracking); cow1 = cow with single calf, cow2 = cow with 2 calves. Table 2. Pearson correlations between the diurnal defecation rate (pellet groups/moose/24 h) and temporal variables in southern Finland; no differences were found. Calendar week Accumulation period (h) Beds/ moose/ 24 h Coefficient −0.144 −0.086 −0.403 P-value 0.492 0.682 0.136 n 25 25 15 ALCES VOL. 49, 2013 MATALA AND UOTILA – DIURNAL DEFECATION RATE OF MOOSE 159 for tracking in the Kangasala area. Dr. J. Pusenius from the Finnish Game and Fish- eries Research Institute is greatly acknowl- edged for organizing the GPS-collaring and thus enabling data availability on exact moose locations for our study. 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ALCES VOL. 49, 2013 MATALA AND UOTILA – DIURNAL DEFECATION RATE OF MOOSE 161 DIURNAL DEFECATION RATE OF MOOSE IN SOUTHWEST FINLAND STUDY AREA METHODS Tracking of Uncollared Moose Tracking of GPS-ollared Moose Data Analysis RESULTS DISCUSSION ACKNOWLEDGEMENTS REFERENCES