Table 2.
Mortality from lead poisoning in common loons in North America. Unless specified otherwise, “Total Mortalities Collected” include all age classes
| State/country/region | % Lead mortalities | Total mortalities collected | Population size (in most recent year of study) | Years of study | Source |
|---|---|---|---|---|---|
| New Hampshirea | 48.6 | 253 (NH AD population only) | 638 | 1989–2012 | Grade et al. (2018) |
| Maine | 25.2 | 480 (AD only) | 4100 (in 2010) | 1990–2017 | B. MacDonald, pers. com.; Evers et al. (2010) |
| New Yorkb | 20 | 261 | 1900–2300 | 1972–2017 | Stone and Okoniewski (2001); J. Okoniewski, pers. com. |
| New England | 44 | 254 (Breeding AD only) | 1987–2000 | Sidor et al. (2003) | |
| Canada | 15.0 | 433 (AD only) | ~ 500,000 | 1992–2018 | E.J. Parmley, pers. com.; CLLS (2019) |
| Michiganc | 14.1 | 340 (AD only) | 700–800 breeding pairs | 1987–2017 | J. Melotti, pers. com. |
| Wisconsin | ~ 20 | ~ 100 | 4350 | 2006–2017 | Strom et al. (2009); S. Strom, pers. com. |
| Minnesota | 11.4 | 132 | 12,000 | 1976–1991, 2009–2015 | C. Henderson, pers. com. |
| Washington | 38% from 1996 to 2010; 0% post-2010 | 21 (AD only) 1996–2010; 5 AD post-2010 | 50 | 1996–2018 | D. Poleschook and V. Gumm, pers. com. |
AD adult
aCommon loon mortality from lead poisoning is underrepresented in New Hampshire because the Grade et al. (2018) study included only loons that were clearly from the New Hampshire loon population and for which multiple lines of evidence indicated that birds died from lead fishing tackle ingestion. Thus, cases of lead-poisoned loons were excluded from this study that would have been included in studies and reporting from other regions
bTwenty-one additional loons that died from ingested lead fishing tackle were collected during type E botulism outbreaks on the Great Lakes in New York. Because the total number of dead loons collected during these outbreaks in New York is unknown, these lead mortalities are not included in the numbers reported in this table
cNote that “% Lead mortalities” and “Total mortalities collected” in Michigan include loons collected from type E botulism events on the Great Lakes