DOI: 10.5061/dryad.tht76hf19
title: Avian botulism is a primary, year-round threat to adult survival in the endangered Hawaiian Duck (Anas wyvilliana) on Kaua‘i, Hawai‘i, USA

description: Adult survival is the most important demographic parameter influencing
 population dynamics for many bird taxa. Thus, understanding how survival
 probabilities and causes of mortality vary throughout the annual cycle is
 critical for developing informed and effective management strategies. In
 this study, we used radio-telemetry data to evaluate the effects of biotic
 (e.g., sex, peak [September–April] vs. off-peak [May–August] nesting
 seasons) and abiotic factors (e.g., rainfall, year, bi-monthly interval)
 on adult survival, estimate annual survival probabilities, and identify
 primary sources of mortality for Hawaiian Ducks (Anas wyvilliana), an
 endangered, non-migratory dabbling duck, on the island of Kaua‘i, Hawai‘i,
 USA over 2013 and 2014. Additionally, we used contemporaneous Hawaiian
 Duck carcass recovery and surveillance data to examine temporal and
 climatic associations with avian botulism outbreaks. Our results suggested
 bi-monthly survival decreased with total rainfall during the preceding
 two-month interval. Survival did not vary with sex, between peak and
 off-peak nesting seasons, or between the two years of this study. Annual
 survival probabilities (62–80%) were relatively low compared to the
 closely related Laysan Duck (Anas laysanensis) on Laysan Island. Primary
 causes of mortality included avian botulism and presumed predation by cats
 (Felis catus). The botulism surveillance dataset revealed support for the
 effect of rainfall on the number of sick and dead birds recovered (n =
 216), with generally a greater number of recoveries during months with
 middle-range total rainfall during the concurrent and preceding months.
 Our study provides critical baseline demographic data for population
 monitoring and highlights the importance of managing botulism risk and
 non-native mammalian predators for the recovery of the endangered Hawaiian
 Duck.
description: We attached 18-g radio-transmitters (Model AI-2M, Holohil
 Systems, Carp, Ontario, Canada) to adult Hawaiian Ducks
 (<em>n</em><sub>female</sub> =
 50, <em>n</em><sub>male</sub> = 67) at Hanalei
 National Wildlife Refuge on the north shore of Kaua‘i, Hawai‘i, USA. We
 monitored the location and status (i.e., alive, dead) of tagged birds from
 December 2012 through December 2014. When carcasses or remains were
 recovered, we classified the suspected cause of mortality as predation by
 mammal or bird, avian botulism, other pathogen, anthropogenic, or unknown
 using a combination of evidence at the mortality site, external
 examination of the carcass, necropsy, and testing for botulinum toxin type
 C.  During our study, USFWS personnel conducted
 botulism surveillance at least once weekly and up to three times daily to
 recover sick birds and carcasses at Hanalei NWR. During botulism
 outbreaks, observers walked transects within affected impoundments and
 lo‘i. Sick birds and carcasses were also recovered incidentally while
 performing other tasks on the refuge. We obtained
 rainfall and temperature data from USGS climate station USC00518165 at
 Princeville Ranch, ~1 km north of the refuge (National Climate Data
 Center, https://www.ncdc.noaa.gov). Missing data (4% for rainfall, 8% for
 temperature) were supplemented with data from nearby climate stations
 (USC00513386, US1HIKI0007, USC00514561).
description: Please review the associated article for detailed descriptions of
 response variables, covariates, and analyses. We provided file and data
 descriptions in a README.txt file. Known-fate Survival
 Analysis Required software: Program MARK
 (available at: http://www.phidot.org/software/mark/) Required files: inp and csv files Cause-specific Mortality Estimates Required software: The R Project for Statistical Computing (available at: https://www.r-project.org/) Required files: R and csv files Botulism Analysis Required software: The R Project for Statistical Computing (available at: https://www.r-project.org/) Required files: R and csv files