Cues for migratory species and implications for adaptability to changing seasons

1. Cues for migratory species and implications for adaptability to changing seasons Ken Tape Institute of Arctic Biology Alaska Cooperative Fish & Wildlife Research Unit EPSCoR All-Hands Meeting May 24, 2012

2. EPSCoR-2008

3. Apr07

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

5. 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.

6. Manipulated vs. unmanipulated shrubs

8. Legacies of ptarmigan browsing intensity and snow depth can be inferred from the architecture of shrub branches… Unbrowsed Repeatedly browsed

9. …and shrub architecture partial hedge hedge

10. snow-ptarmigan-shrub interactions

11. 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.

12. Cues for migratory species and implications for adaptability to changing seasons Ken Tape1, David Ward2, David Gustine2 1Institute of Arctic Biology, ACFWRU 2USGS Alaska Science Center EPSCoR All-Hands Meeting May 24, 2012

13. Post-Doctoral USGS Projects:Changing Herbivore Habitat • Accelerated permafrost degradation facilitates vegetation change along the Arctic Coast of Alaska: Paul Flint, Brandt Meixell • Dynamics of the thaw lake system and succession of emergent vegetation: Tom Fondell • Advances in the date of snowmelt impact the timing of bird arrival: David Ward • Observed and Predicted Herbivore Responses to Earlier Snowmelt and Advanced Vegetation Phenology: Dave Gustine, Roger Ruess

14. Outline • Background for studying snowmelt • Some initial results

15. 8/1/1948 2004 Lake 3 Lake 3 7/27/2002 8/11/1948

16. 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 after April 1st

17. Discharge does indeed reflect the decreasing snow fraction on the landscape

20. Acknowledgements • Ptarmigan work: Alaska EPSCoR NSF award #EPS-0701898 and the state of Alaska • Recent work: USGS Alaska Science Center

21. Thank You

23. 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