Population Delineation and Sea Ducks presented to SDJV Continental Technical Team at November 2015 meeting John Pearce, USGS Alaska Science Center

Population Delineation This talk came about because: I questioned how the SDJV was defining “population delineation” at the last meeting I want the SDJV to more visible in how it is completing this work and be clear about what we are funding Population delineation is important, but often difficult to express and quantify

Population Delineation From the 2015 SDJV Implementation Plan: “Lack of understanding about delineation is one of the highest priorities for future work” AGREE The primary method for “tracking sea ducks is satellite telemetry” DISAGREE, on two counts Tracking sea ducks ≠ pop. delineation Primary methods for pop. delineation

No overlap of band recoveries from Alaska and Barrow’s Goldeneye No overlap of band recoveries from Alaska and Western North America Alaska Western North America > 400 winter recoveries

Sampling areas are significantly differentiated Barrow’s Goldeneye Quebec British Columbia, Idaho Iceland Alaska Sampling areas are significantly differentiated

Population Delineation From the 2015 SDJV Implementation Plan: Telemetry also yields data on “seasonal habitat use and site fidelity, thus informing conservation” ??? Highest priority for 2015-2017 is to “complete population delineation” for BLSC, SUSC, WWSC and LTDU NEED TO CLARIFY

Population Delineation Poorly studied but needed: Savard et al. (2015) mentioned delineation as a gap in 6 of 15 chapters: Harvest Conservation Population dynamics Status and trends Migration Conclusions and future directions

Dan Esler Presentation: Summary of 1,547 publications on sea ducks SDJV Era (1999 to 2011) Pre-SDJV (≤ 1998) Percent of papers Productivity Dispersal Survival Population Delineation Population Dynamics Population Models Demographic studies have seen large proportional increases during SDJV era.

Population Delineation Complicated with highly migratory species We need to define what type of delineation scenario exists for each species or region Will help to show how we have completed this task for different species and regions

Long-tailed duck Sea duck population delineation scenarios Breeding Area 1 Breeding Area 2 Winter Area 1 Winter Area 2 Breeding Area 1 Breeding Area 2 Winter Area 1 Winter Area 2 Long-tailed duck Breeding Area 1 Breeding Area 1 Breeding Area 2 Winter Area 1 Winter Area 2 Winter Area 1

Population Delineation I’m not proposing redefining “population delineation” But we need some way to “complete” the population delineation work and categorize each species or region What does a “complete” picture look like? Full coverages of N. America? Only priority species?

Population Delineation SDJV supported science should be testing hypotheses about delineation rather than portraying migratory routes This may involve multiple methods Ask ourselves: Are PTT studies funded by the SDJV “completing population delineation” for priority species and regions?

Are we after (a) or (b)?

Population Delineation Stop focusing on fidelity: It is a cool behavior, but misleading But not a measure of demographic independence unless we know where the bird originally came from Only a measure for delineation if fidelity = philopatry or if fidelity is 1.0 and migratory connectivity is high (one breeding area to one wintering area)

Estimating fidelity (F) Burnham models Marked Alive Survival (S) Recapture (p) Alive (recaptured) Alive (not recaptured) Fidelity (F) Alive (recaptured) Dead Recovery (r)

Dau et al. (2000) Hypothesized that because of high molt site fidelity of Steller’s Eiders to specific beaches, that birds molting in specific locations could be from unique breeding areas (molting populations would represent unique sub-populations). However, band recoveries suggest that eiders molting in a specific location likely represent birds from multiple breeding areas. Conclude no sub-population structuring for Steller’s eiders molting along the Alaska Peninsula.

Hooded Mergansers Capture (p = 0.62) Survival (S = 0.72) Site fidelity Capture (p = 0.62) Survival (S = 0.72) Fidelity (F = 0.92)

Genetic methods Hooded Merganser

Genetic methods Arrows indicate significant differentiation mtDNA (n = 134) ΦST = 0.05 6 nuclear loci (n = 213) Hooded Merganser FST = 0.01 = DNA samples Arrows indicate significant differentiation Site fidelity based on band recovery appears inconsistent with DNA information

Comparison between endemic cavity nesting species mtDNA (n = 134) ΦST = 0.05 Hooded Merganser Gene flow or recent divergence? mtDNA (n = 44) ΦST = 0.31 Wood Duck (Peters et al. 2005)

“Isolation with Migration” (IM) Gene flow or recent divergence? Time since divergence ( ≥ 10,000 y) Migration 1.4 Hooded Merganser 3.8 1.1 0.07 Wood Duck (Peters et al. 2005) “Isolation with Migration” (IM)

Hooded Mergansers Breeding site fidelity is not a universal proxy for population structure and in the case of this species, fidelity does not equal philopatry Juvenile dispersal Adult emigration

“Evidence for significant structuring” Population delineation via mtDNA Not different Very different “Evidence for significant structuring” (J. Avise 2000) 0.01 0.20 0.50 0.70 FST among populations

Site fidelity, dispersal, and impact of future change Hooded merganser Common Goldeneye Barrow’s Goldeneye Bufflehead Common merganser 0.01 0.20 0.70 Fidelity 68% 92% 91% 63%

Site fidelity, dispersal, and impact of future change Hooded merganser Common Goldeneye Barrow’s Goldeneye Bufflehead Common merganser 0.01 0.20 0.70 Fidelity 68% 92% 91% 63% Dispersal High High Intermediate Low Impacts? Low Low Intermediate High

Definitions of “fidelity” in the Atlantic and Great Lakes Sea Duck Migration Study 2014 Progress Report Species Sex Status Type of fidelity Number returns Percentage Distance between used sites (km) Surf Scoter   F Breeding “Strong” 2 of 23 8% 0.5 Black Scoter “Exhibits fidelity” 12 of 12 in consecutive years 100% 3.25 (but one at 63 not included) M Molt “High” 6 of 15 40% Not given Winter Not stated 84 White-winged Scoter “Quite high” 12 of 18 <50 Long-tailed Duck 5

Population Delineation Recommendations: Complete (?) the picture (?) Target populations that are of management concern? Declining breeding populations. How many wintering areas? Is the issue on the breeding or wintering area? Harvest of winter populations (one or several breeding populations?) Calculate fidelity with caution