Cues for migratory species and implications for adaptability to changing seasons
Ken Tape
EPSCoR All-Hands MeetingMay 24, 2012
Institute of Arctic BiologyAlaska Cooperative Fish & Wildlife Research Unit
Methods
• Manipulated Betula nana and Salix pulchra by staking them upright throughout winter.
• Compared browsing severity on manipulated and unmanipulated (laid down) shrubs.
• Made additional, more specific, measurements.
Legacies of ptarmigan browsing intensity and snow depth can be inferred from the architecture of shrub branches…
Unbrowsed Repeatedly browsed
Conclusions, Chapter 3
• Ptarmigan (and other herbivores) strongly shape shrub architecture during spring migrations when snow is moderate to deep.
• The few unbrowsed buds in the low horizon on exposed willows suggests that late-winter forage may be limiting, and that the expansion of tall shrubs would increase ptarmigan populations.
• Ptarmigan may be facilitating floodplain succession to alder by preferentially browsing willow, much as moose do in interior Alaska.
Cues for migratory species and implications for adaptability to changing seasons
Ken Tape1, David Ward2, David Gustine2
EPSCoR All-Hands MeetingMay 24, 2012
1Institute of Arctic Biology, ACFWRU2USGS Alaska Science Center
Post-Doctoral USGS Projects:Changing Herbivore Habitat
1. Accelerated permafrost degradation facilitates vegetation change along the Arctic Coast of Alaska: Paul Flint, Brandt Meixell
2. Dynamics of the thaw lake system and succession of emergent vegetation: Tom Fondell
3. Advances in the date of snowmelt impact the timing of bird arrival: David Ward
4. Observed and Predicted Herbivore Responses to Earlier Snowmelt and Advanced Vegetation Phenology: Dave Gustine, Roger Ruess
1965 1970 1975 1980 1985 1990 1995 2000 2005 2010 20150
10
20
30
40
50
60
f(x) = − 0.212007504690432 x + 458.500938086304R² = 0.174612594970982
Series1
Linear (Series1)
Lengthened Growing Season• Asymmetrical toward spring, May 10 to May 2• Earlier disappearance of snow, onset of growing season
Kuparuk River Peak Discharge Dates, 1971-2010
Day
s aft
er A
pril
1st
King Eider
Northern
Pintail
Red-nec
ked Phala
rope
Yello
w-billed Lo
on
Sabine G
ull
Semipalm
ated Sa
ndpiper
Ruddy Turnsto
ne
Long-t
ailed
Duck
Greater
White
-fronted
Goose
Black B
rant
Glauco
us Gull
Snow Bunting
Tundra
Swan
Red-th
roated Lo
on
Laplan
d Longsp
ur0
0.050.1
0.150.2
0.250.3
0.350.4
0.450.5
0.550.6
0.650.7
0.750.8
0.850.9
0.951
P-value between bird species arrival date at Colville Delta and peak discharge date at nearby Kuparuk River, 1974-2010
Acknowledgements
• Ptarmigan work: Alaska EPSCoR NSF award #EPS-0701898 and the state of Alaska
• Recent work: USGS Alaska Science Center
Approach: Caribou and Ptarmigan
• Deploy time-lapse cameras at numerous locations covering a gradient in snow cover, from snow-covered to snow-free, to record the number of caribou or ptarmigan in relation to snow fraction.
• If the number of individuals of a given species, such as caribou or ptarmigan, shows a preference for a certain snow cover fraction, then can we deduce that an earlier disappearance of snow would equate to an earlier migration?
• That ability to adapt by migrating sooner is likely an important factor in predicting which species populations will survive the shift toward earlier snowmelt and green-up