Manuela Panzacchi, Bram Van Moorter, Roy Andersen, Olav …...Manuela Panzacchi, Bram Van Moorter,...
Transcript of Manuela Panzacchi, Bram Van Moorter, Roy Andersen, Olav …...Manuela Panzacchi, Bram Van Moorter,...
EXECUTIVE SUMMARYThe 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
RESULTSMIGRATIONS: on average start on Sept
20th & Mar 15th, last 49 & 69 days, respectively, and cover 56 Km
ROAD CROSSINGS: occur on average on Apr 23rd & Oct 9th, before daylight in spring, at any time in autumn
CALVING: occurs on average on May 13th (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
METHODSData: 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 (1st sigmoid) & the return to calving ground (2nd; Bunnefeld et al. 2011). Start & end of migration were defined as 5% and 95% of the sigmoid
Net
Squ
are
Dis
plac
emen
t
Year day - from calving date0 100 200 300
0.0e
+00
1.
0e+0
9
2.0e
+09
3.
0e+0
9
START
END spring
migration
END
START autumn
migrationResi
denc
e tim
e (1
50m
radi
us)
Date
CALVING
20 Apr 20 May 20 Jun 14 Jul
0 2
0 4
0 6
0 8
0 1
00
120
140
N locations 45 days before/after crossing
0
1
0
2
0
3
0
-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
DIS
PLAC
EMEN
T FR
OM
TH
E RO
AD
(km
)
SPRING MIGRATION
AUTUMN MIGRATION
ROAD CROSSING
-300 -200 -100 0 100 200 300
N locations 45 days before/after crossing
STEP
LEN
GTH
(km
/3
hrs)
0
1
2
3
4
ROAD CROSSING
M I G R A T I O N
Average calving
date
Manuela Panzacchi, Bram Van Moorter, Roy Andersen, Olav StrandNorwegian Institute for Nature Research, Tungasletta-2, N-7485 Trondheim, Norway