How two hurricanes in one year affected Cozumel’s birds

7/8/2018 | 0

The Caribbean Dove population on Cozumel Island suffered after two hurricanes in 2005. Photo by Liz Miller/Shutterstock

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The final assessment of the impact that Hurricanes Harvey, Irma, and Maria had on birds in 2017 likely will not be known for many years, if a recently published report is any indication.

In July 2005, the Category 4 Hurricane Emily struck Cozumel Island, located about 11 miles off the coast of Mexico’s Yucatan Peninsula. Three months later, a Category 5 storm, Hurricane Wilma, battered the island. The storms caused extensive damage to the island’s forests, including total defoliation, uprooted trees, and forest flooding.

Twice in the year prior to the storms, scientists with the National Autonomous University of Mexico and an independent researcher from Cozumel caught understory forest birds in mist nets at six sites within an area of semi-deciduous tropical forest. After the hurricanes, they set up the nets four more times to sample the forest’s birds: in winter and summer 2006 and winter and summer 2007.

In total, they captured and banded more than 2,500 birds of 45 species — 29 residents and 16 long-distance migrants. In a paper published in November 2017 in the journal Tropical Conservation Science, Héctor Perdomo-Velázquez and his colleagues reported that in the first winter following the hurricanes, the numbers of individual birds and species and the percentages of migratory individuals and species were down significantly from pre-storm levels.

By the following summer, bird numbers had largely rebounded. “Eight months after the hurricanes, the summer bird assemblage showed statistically similar mean values” for numbers of individuals and species, the researchers wrote. However, individual species populations varied after the storms compared to the pre-hurricane totals. Yellow Warbler, Yucatan and Cozumel Vireos, and other species increased in numbers; Caribbean Dove, Cozumel Wren, and Cozumel Black Catbird declined in the post-storm period.

In anticipation of an increasing frequency of intense hurricanes in coming decades, the authors call for “permanent biodiversity monitoring programs, captive breeding and reintroduction of endemic native taxa, establishment of effective and strategic pro­tected areas, enhancement of natural habitat connectivity in fragmented landscapes,” and other steps to protect the biodiversity of islands.

A version of this article appeared in “Birding Briefs” in the February 2018 issue of BirdWatching.

Studying how severe weather affects birds

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