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

EPSCoR-2008

Apr 07

• Elucidate relationships between ptarmigan herbivory, snow, and shrubs.

Objective

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.

Manipulated vs. unmanipulated shrubs

Legacies of ptarmigan browsing intensity and snow depth can be inferred from the architecture of shrub branches…

Unbrowsed Repeatedly browsed

…and shrub architecture

hedge partial hedge

snow-ptarmigan-shrub interactions

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

Outline• Background for studying snowmelt• Some initial results

Lake 3 Lake 3

8/1/1948 2004

8/11/1948 7/27/2002

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

Series1Linear (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

Days

afte

r Apr

il 1s

t

Discharge does indeed reflect the decreasing snow fraction on the landscape

King Eider

Northern

Pintail

Red-neck

ed 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

Thank You

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