recent trends in dall’s sheep populations in alaska’s ......feb 20, 2016 · recent trends in...
TRANSCRIPT
Recent trends in Dall’s sheep populations in Alaska’s
National Parks and Preserves
Kumi Rattenbury, Joshua Schmidt, Laura Phillips, Steve Arthur, Bridget Borg, John Burch, Kyle Joly, Jim Lawler, Buck Mangipane, Judy Putera
Alaska Dall Sheep Working Group Meeting, February 20-21, 2016, Anchorage, Alaska
Ovis dalli dalli
Alaska Dall Sheep Working Group Meeting February 20-21, 2016, Anchorage, Alaska
Ovis dalli dalli
Sheep Monitoring Objectives 1. Trends in abundance
and distribution 2. Changes in age
composition
Alaska Dall Sheep Working Group Meeting February 20-21, 2016, Anchorage, Alaska
Basic form – Traverse a transect line
– Identify individuals or
groups of interest
– Record perpendicular distance from line
– Detection probability decreases with distance
Burnham et al. 1980, Buckland et al. 2001, 2004 Alaska Dall Sheep Working Group Meeting February 20-21, 2016, Anchorage, Alaska
Distance Sampling
In mountains – transects follow contours
Alaska Dall Sheep Working Group Meeting February 20-21, 2016, Anchorage, Alaska
2010 Gates of the Arctic Survey
In mountains – transects follow contours
Distance Sampling Surveys
Dete
ctio
n Pr
obab
ility
Perpendicular distance of sheep groups from line (m)
Bars = observed distances of sheep groups from the transect
Estimate total sheep using Bayesian modeling
Alaska Dall Sheep Working Group Meeting February 20-21, 2016, Anchorage, Alaska
Disadvantages • More restrictive • More gear in the plane • Additional prep/training • Analysis more complex • Difficult to estimate full-curl rams
Advantages • Direct estimates of detection • Time per transect low • Weather less influential • Movement ok • Park-wide estimates • Directly comparable estimates • Estimates of sightability
Distance Sampling Surveys
Alaska Dall Sheep Working Group Meeting February 20-21, 2016, Anchorage, Alaska
Noatak (2011) ~2,800 sheep
Denali (2011) ~2,200 sheep
Lake Clark (2012) ~1,000 sheep
Yukon-Charley (2009) 333 sheep - minimum count
Wrangell-St. Elias (2010-2011) ~12,400 sheep
Gates of the Arctic (2010) ~10,000 sheep
~29,000 total sheep estimated on NPS
lands in Alaska
Schmidt et al. 2012 Schmidt and Rattenbury 2013
Joly 2015
2009-2012 Distance Sampling Survey Results
Alaska Dall Sheep Working Group Meeting February 20-21, 2016, Anchorage, Alaska
2009-2012 Survey Results
WRST Unit 14 (8:100)
Lake Clark (29:100)
Denali (3:100)
Wiseman area (9:100)
Itkillik (no lambs observed; 50% decline total sheep)
Minto (34:100) Dawson Range (34:100) Nisling (10:100)
Caribou/Nares (14:100) Gray Ridge (28:100)
Granger/Fish Lake (10:100) WRST Unit 4W (22:100)
Mackenzie Mountains Front Range (23:100)
White Mountains (16:100) Black Rapids (22:100)
(ratio of lambs per 100 ewe-like)
Alaska Dall Sheep Working Group Meeting February 20-21, 2016, Anchorage, Alaska
2013 – Low lamb numbers across range
• 1974-1996 and 2008-2015
• Average lamb:ewe ratio 43:100
• Lamb productivity low in 1993 (6:100), 2012-2014
Borg 2014 Alaska Dall Sheep Working Group Meeting February 20-21, 2016, Anchorage, Alaska
Denali Road Surveys
Itkillik subarea
Gates of the Arctic National Park and
Preserve
Minimum count Distance sampling
Error bars are 95% Credible Intervals Alaska Dall Sheep Working Group Meeting February 20-21, 2016, Anchorage, Alaska
0
500
1000
1500
2000
2500
1983 1996 2005 2009 2010 2011 2012 2013 2014 2015
Adults Lambs Ewe-like Rams
Itkillik Sheep Surveys 1983-2015
Alaska Dall Sheep Working Group Meeting February 20-21, 2016, Anchorage, Alaska
0
200
400
600
800
1000Adult sheep Lambs 3 per. Mov. Avg. (Adult sheep)
0
100
200
300
400
500
600EwelikeRams3 per. Mov. Avg. (Ewelike)3 per. Mov. Avg. (Rams)
1986-2015
1986-2009 Minimum count 2011-2015 Distance sampling
Partial surveys in 1986, 1987, 2005-2007 Error bars are 95% Credible Intervals
Shults 2004, Schmidt and Rattenbury 2013
Western Baird Mountains Sheep Surveys
2009-2012 Distance Sampling Survey Results
Alaska Dall Sheep Working Group Meeting February 20-21, 2016, Anchorage, Alaska
2013 Delayed spring
Alaska Climate Dispatch, June 2013. https://accap.uaf.edu/sites/default/files/Alaska_Climate
_Dispatch_june%202013.pdf
Anaktuvuk Pass
Wiseman
Kotzebue
Gates of the Arctic NP&Pres
Noatak NPres
Itkillik W Baird
2013 - Delayed spring, snow melt
Swanson 2014
April 18, 2012
April 17, 2013
2012
2013
Deviation from median
end date CSS, 2001-2013
Alaska Dall Sheep Working Group Meeting February 20-21, 2016, Anchorage, Alaska
Satellite data showing end date of continuous snow season (CSS) Median date 2001-2013
2009-2012 Distance Sampling Survey Results
Alaska Dall Sheep Working Group Meeting February 20-21, 2016, Anchorage, Alaska
Noatak 2011 to 2014
Error bars are 95% Credible Intervals
0500
100015002000250030003500
2011 2014
Noatak National Preserve Dall's sheep distance sampling surveys
Total Adults Lambs Ewelike Rams
2009-2012 Distance Sampling Survey Results Gates of the Arctic 2010 to 2015
02000400060008000
100001200014000
2010 2015
Gates of the Arctic National Park and Preserve Dall's sheep distance sampling surveys
Total Adults Lambs Ewelike Rams
Alaska Dall Sheep Working Group Meeting February 20-21, 2016, Anchorage, Alaska Error bars are 95% Credible Intervals
2009-2012 Distance Sampling Survey Results Yukon-Charley Rivers 1997-2015
309 282
329 294
330 333
173
40 54 44 36 52 48 45
22 22 30 32 20 29 14 35
66 47
72 43 44 42
18 24 24 27 18 12 14 0
50
100
150
200
250
300
350
1997 1998 1999 2001 2002 2009 2015
Num
ber
Total SheepLambs:100 ewesYearlings:100 ewesRams:100 ewes% Legal Rams
Yukon-Charley Rivers National Preserve – minimum count surveys
Joly 2015
Alaska Dall Sheep Working Group Meeting February 20-21, 2016, Anchorage, Alaska
2009-2012 Distance Sampling Survey Results
Alaska Dall Sheep Working Group Meeting February 20-21, 2016, Anchorage, Alaska
Denali 2011 to 2015
0
500
1000
1500
2000
2500
3000
2011 2015
Denali National Park and Preserve Dall’s Sheep Distance Sampling Surveys
Total Adults Lambs Ewelike Rams (total)
Error bars are 95% Credible Intervals
2009-2012 Distance Sampling Survey Results
Alaska Dall Sheep Working Group Meeting February 20-21, 2016, Anchorage, Alaska
Lake Clark 2012
0200400600800
100012001400
2012
Lake Clark National Park and Preserve 2012 Dall's sheep distance sampling surveys
Total Adults Lambs Ewelike Rams
0255075
100125150175200225
Total Sheep Rams: 100 Ewe-Like Lambs: 100 Ewe-Like
Southern Lake Clark Minimum Count Surveys
Jul 1978Jul-Aug 1985Jul 1987Jun 2003Aug 2003Jun 2004Jul 2013
Error bars are 95% Credible Intervals
2009-2012 Distance Sampling Survey Results Wrangell-St. Elias 2010/2011
02000400060008000
10000120001400016000
Total Adults Lambs Ewelike Rams
Wrangell-St. Elias National Park and Preserve Dall's sheep distance sampling surveys
Wrangell-St. Elias 2010/11North Wrangell-St. Elias 2010South Wrangell-St. Elias 2011
Alaska Dall Sheep Working Group Meeting February 20-21, 2016, Anchorage, Alaska Error bars are 95% Credible Intervals
020406080
100120
Lambs: 100 Ewelike Rams: 100 Ewelike
Noatak 2011Noatak 2014Gates 2010Gates 2015Denali 2011Denali 2015Lake Clark 2012Wrangell-St. Elias 2010/11
2009-2012 Distance Sampling Survey Results Lamb and ram ratios
Alaska Dall Sheep Working Group Meeting February 20-21, 2016, Anchorage, Alaska Error bars are 95% Credible Intervals
0
2000
4000
6000
8000
10000
12000
14000
16000
Noatak 2011 Noatak 2014 Gates 2010 Gates 2015 Denali 2011 Denali 2015 Lake Clark2012
Wrangell-St.Elias 2010/11
Total sheep
Adult sheep
Alaska Chapter of The Wildlife Society Meeting March 31-April 3, 2014
• Annual distance sampling surveys – Western Baird Mountains (Noatak), Itkillik (Gates of the Arctic)
• Park-wide distance sampling surveys – every 4-5 years - Noatak, Gates of the Arctic, Denali, Lake Clark
• Annual ground-based surveys - Denali
• Diet composition and quality – Itkillik (Gates of the Arctic)
Alaska Dall Sheep Working Group Meeting February 20-21, 2016, Anchorage, Alaska
NPS Long-term Dall’s Sheep Monitoring
• Collaborators: J. Dau, M. MacCluskie, J. McMillan, B. Saito, B. Shults, D. Swanson, E. Wald, C. Westing
• Pilots: L. Alsworth, K. Barnes, J. Cummings, J. Dau, A. Greenblatt, S. Hamilton,
J. Lee, C. Milone, R. Richotte, B. Shults, E. Sieh, R. Swisher, H. Twitchell, M. Webb, L. Williams
• Observers and technicians: S. Backensto, B. Dunker, M. Johnson, E. Julianus, C. Priest, J. Shearer, M. Snover, C. Splechter, L. Stutzman, T. Whitesell
• Data management assistance: D. Bush, S. Miller, K. Pearson, C. Priest, K. Riffey, K. Ravariere, R. Sarwas, C. Smith, W. Thompson
• Funding and survey logistics support provided by ADFG, BLM, FWS, NPS (Parks and Preserves, I&M Networks, PMIS grant #147107)
Alaska Dall Sheep Working Group Meeting February 20-21, 2016, Anchorage, Alaska
Acknowledgements