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EXECUTIVE SUMMARY The development of roads and associated infrastructures has interrupted most traditional migrations of Norwegian wild reindeer Rangifer trandus. The Austhei population still migrates from winter to calving grounds by crossing a road surrounded by cabins through a narrow corridor, in which further anthropogenic development is planned. To understand if and how the road affects reindeer movements we first characterized migration patterns, and then investigated whether they were affected by the road. All trajectory parameters were clearly altered in proximity of the road, which hampered In particular the migration towards the calving ground. Further development in the migration corridor might have serious conservation consequences RESULTS MIGRATIONS: on average start on Sept 20 th & Mar 15 th , last 49 & 69 days, respectively, and cover 56 Km ROAD CROSSINGS: occur on average on Apr 23 rd & Oct 9 th , before daylight in spring, at any time in autumn CALVING: occurs on average on May 13 th (n = 20), 9-32 days after crossing CONCLUSIONS The motivation to cross is high, as optimal calving and winter grounds (left – see poster on fundamental niche) are on the opposite sides of the road. However, the disturbance associated to the road, which is higher during spring, hampers and delays the arrival to the calving ground. Further human development in the migration corridor might severely affect the persistence of migration Reference: Bunnefeld N, Börger L, van Moorter B, Rolandsen C, Dettki H, Solberg E, Ericsson G. (2011) A model-driven approach to quantify migration patterns: individual, regional and yearly differences. J. Anim. Ecol. 80: 466-476 PATTERNS OF SPRING & AUTUMN MIGRATION: in spring reindeer move slowly (15km/25 days; see Net Displacement, left) towards the road; in proximity of the road, reindeer move parallel to it back and forth for ca. 5 days without approaching further, possibly searching for a quiet place to cross. After crossing, reindeer head quickly to calving grounds (15km/5 days). In autumn they approach slowly the road, cross it without much waiting, and move slowly towards winter areas SPATIAL BEHAVIOR DURING CROSSING: travel speed (Step Length, above) is much higher (4 km/3 hr) than during migration (0.5 km/3 hrs); highly directional movement Optimal habitat (fundamental niche) Density of locations & calving locations METHODS Data: 10 ♀ monitored from 2002 to 2010 (1 GPS location/3 hrs). First, we identified the migration period in 2 steps: (1) based on ♀ spatial behavior we identified calving dates (2) starting from each calving date we calculated the Net Square Displacement, NSD (squared distance between start location and current relocation), to identify start & end of migration After, we calculated and compared Step Length, Turning Angles and NSD during migration and in proximity of the road Calving events were identified by detecting peaks in Residence Time and Step Length (Van Moorter et al, in prep) We fitted to the NSD a double sigmoid (blue) representing spring migration (1 st sigmoid) & the return to calving ground (2 nd ; Bunnefeld et al. 2011). Start & end of migration were defined as 5% and 95% of the sigmoid Net Square Displacement Year day - from calving date 0 100 200 300 0.0e+00 1.0e+09 2.0e+09 3.0e+09 START END spring migration END START autumn migration Residence time (150m radius) Date CALVING 20 Apr 20 May 20 Jun 14 Jul 0 20 40 60 80 100 120 140 N locations 45 days before/after crossing 0 10 20 30 -300 -200 -100 0 100 200 300 -300 -200 -100 0 100 200 0 10 20 30 CALVING RANGE Average calving date ROAD CROSSING NET DISPLACEMENT FROM THE ROAD (km) SPRING MIGRATION AUTUMN MIGRATION ROAD CROSSING -300 -200 -100 0 100 200 300 N locations 45 days before/after crossing STEP LENGTH (km /3 hrs) 0 1 2 3 4 ROAD CROSSING MIGRATION Average calving date Manuela Panzacchi, Bram Van Moorter, Roy Andersen, Olav Strand Norwegian Institute for Nature Research, Tungasletta-2, N-7485 Trondheim, Norway [email protected]
