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Sources of Mortality in Bald Eagles in Michigan, 1986–2017
Author(s) -
Simon Kendall L.,
Best David A.,
Sikarskie James G.,
Pittman H. Tyler,
Bowerman William W.,
Cooley Thomas M.,
Stolz Scott
Publication year - 2020
Publication title -
the journal of wildlife management
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.94
H-Index - 111
eISSN - 1937-2817
pISSN - 0022-541X
DOI - 10.1002/jwmg.21822
Subject(s) - bald eagle , wildlife , fishery , geography , biology , ecology
As bald eagle populations recover, defining major sources of mortality provides managers important information to develop management plans and mitigation efforts. We obtained data from necropsies on 1,490 dead bald eagles ( Haliaeetus leucocephalus ) collected in Michigan, USA, conducted from 1986 to 2017 to determine causes of death (COD). Trauma and poisoning were the most common primary COD categories, followed by disease. Within trauma and poisoning, vehicular trauma ( n = 532) and lead poisoning ( n = 176) were the leading COD subcategories, respectively. Females comprised a greater number of carcasses for most COD diagnoses. The proportion of trauma and poisoning CODs significantly increased in the last few years of the study in comparison to a select few years at the beginning. Trauma CODs were greater in autumn months during whitetail deer ( Odocoileus virginianus ) breeding and hunting seasons and in February, when aquatic foraging is unavailable and eagles are likely forced to scavenge along roadsides. Poisoning CODs were greatest in late winter and early spring months, when deer carcasses containing lead ammunition, which are preserved by the cold weather, also become a supplemental food source. The major infectious disease CODs, West Nile virus and botulism ( Clostridium botulinum type E), were more prevalent during summer months. We recommend moving road‐killed carcasses, especially white‐tailed deer, from the main thoroughfare to the back of the right‐of‐way, and the transition from lead ammunition and fishing tackle to non‐toxic alternatives to decrease these main anthropogenic sources of mortality for bald eagles, and other scavenger species. © 2020 The Wildlife Society.