Demographic risk to eagles from anthropogenic causes of death

Demographic risk to eagles from anthropogenic causes of death TODD KATZNER, U.S. GEOLOGICAL SURVEY David Nelson, University of Maryland, MD, USA Melissa Braham, West Virginia University, WV, USA Adam Duerr, Bloom Biological, PA, USA Tricia Miller, Conservation Science Global, NJ, USA Renee Culver, NextEra Energy, CA, USA Andrew DeWoody, Purdue University, IN, USA U.S. Department of the Interior U.S. Geological Survey

Anthropogenic causes of death

Assess how birds die

Can’t simply study birds people find – non-random and biased towards certain processes.

Published study of 400 telemetered eagles (FWS 2017)

Cause of death known for 97

Bayesian model predicts rates

Anthropogenic causes of death

Natural causes of death

Starvation/disease = 22%

Fighting with other eagles = 11%

Natural Injury = 7%

Drowning = 2%

Predation (eaten) = 1%

Anthropogenic causes of death

Anthropogenic causes of death

Poisoning (non-lead) = 17% Shot = 15% Collision (wind, vehicles) = 9% Electrocution = 8% Trap = 4% Lead toxicosis = 3%

Anthropogenic causes of death

63% of fatalities of adults caused by humans

34% fatalities of first year birds caused by humans

Annual eagle survival rates would be 10% higher without humancaused fatalities

Example: Altamont Pass Wind Resource Area

Altamont is one of oldest facilities in the world

Very large

Kills many birds of prey each year, including many golden eagles

once up to 7,000 turbines currently <5,000 operational

Golden Eagles 101

Demography 101

Nt = N(t-1) + Bt â&#x20AC;&#x201C; Dt + It â&#x20AC;&#x201C; Et N = population size at time t B = # births at time t D = # deaths at time t I = # of immigrants at time t E = # of emigrants at time t

GOEA = k selected, B & D low

GOEA = mobile, I & E may be high

Research Question

What is the origin of eagles killed at Altamont?

What does that mean for eagle demography?

If eagles killed are locals, implies high Bt If eagles killed are from elsewhere, implies high It

Methods

Answer three key questions about Altamont killed golden eagles: 1. What is their age?

2. How many genetic populations do they represent?

3. Where did they grow their feathers?

Data collected through study of dead golden eagles 1. Individuals photographed and aged (molt patterns).

2. Genetic analysis (microsatellites, SNPs).

3. Feather samples for stable isotope analysis (δ2H, etc.).

Methods - Genetics

Collected feather and organ tissue samples from turbinekilled eagles

Genotyped eagles

9 microsatellite loci established sexing primers 159 nuclear SNPs 1 sexing SNP 2 mtDNA SNPs

Methods - Stable Isotopes Light water:1H1HO δ2H : more negative

Heavy water: 1H2HO δ2H: more positive

Methods - Stable Isotopes

Turbine-killed & known-origin refs δ2H : 3 body feathers

Convert feather- δ2H to precip.- δ2H (Lott & Smith 2006)

Geospatial model to calculate likelihood-of-geographic origin map based on δ2H (Bowen et al. 2014) Monte Carlo simulation to estimate if bird local or non-local

Results

Age: n = 49 DNA: n = 62 (52 SNP) Isotopes: n = 66 44 known origin references

Of the 49 aged

HY = 1 2Y = 15 3Y = 16 4Y = 2 A4Y = 15

Results - genetics

STRUCTURE

K = 1 thru 5 suggests that K = 1 (one population)

microsats & SNPs = same message

Results – stable isotopes

δ2H of May – Aug precipitation

location of 44 reference eagles

Results â&#x20AC;&#x201C; stable isotopes

comparison of known-location and isotope-inferred summering grounds isotope models were reasonable predictors of origin

Results â&#x20AC;&#x201C; stable isotopes

some birds clearly grew feathers locally

others clearly grew feathers non-locally

Example – golden eagles at APWRA 17 of 66 birds = “nonlocal”

minimum distance up to 837km

Probability of being non-local not linked to: age month sex

Results - demography

Models predict that ~11% of GOEA should be 2Y In fact, 30% of birds killed are 2Y

Nearly impossible to model a population whose age structure replicates killed birds

Together with isotope data, suggests that population sustained by immigration of 2Y-4Y birds

Origins of birds at APWRA

Eagles at APWRA are one genetic population

~25% of the birds killed at APWRA are â&#x20AC;&#x153;non-localâ&#x20AC;?

Turbine-associated mortality at APWRA is additive

Anthropogenic causes of death

APWRA influences continental-scale demographic processes

Illustrates important considerations for of anthropogenic sources of death

Can have far-reaching consequences

• Acknowledgments • Funding: BLM, USDoE, DFG/DFW, FWS, etc.