Veery on migration, early May 2008 (photo by Chuck Tague)

18 August 2025

This news from 2018 is worth repeating.

Back in May 2025 NOAA predicted a strong hurricane season this year so it was a little surprising how quiet the ocean was this summer … until now. Last Friday Tropical Storm Erin was upgraded to a hurricane and quickly grew to Categories 4 and 5. Is this the start of the strong season we expected? Veerys could tell us the answer if we knew this spring’s nesting status and whether they’ve already left on migration.

Veerys (Catharus fuscescens) breed in cool climates in North America and spend the winter in Brazil. Banding and tracking studies found that southbound veerys never travel overland through Mexico. Instead they always cross the Caribbean to get to the Yucatan, Central and South America. Even northwestern breeders begin by traveling east to later fly across the Gulf. (Their path is actually a great circle route.)

I’ve marked up the veery range map to show some of their southbound routes across the Gulf.

Veery range map. Cross-Caribbean migration routes added (map from Wikimedia Commons)

Veerys have been studied in Delaware since 1998. In 2017 with decades of data on nesting outcomes and fall departure times, ornithologist Christopher Heckscher discovered an amazing correlation. In bad hurricane years, Delaware’s veerys abbreviate the breeding season and leave in midsummer on migration. This timing gets them safely across the Caribbean before the hurricanes hit.

By midsummer 2017, Heckscher knew the veerys had shortened their breeding season so he boldly predicted a bad hurricane season even though meteorologists had already said otherwise. When the season was over it was true. The veerys were right. Heckscher published a paper on this in Scientific Reports in 2018.

Heckscher has a theory on why veeries know this:

 Heckscher hypothesizes that, on their wintering grounds, they may notice precipitation patterns linked to the El Niño and La Niña cycles that influence hurricane activity. “Whatever it is, they know by mid-May,” he says, explaining that the average date of all nesting attempts in years with low ACE(*) was after May 23. 

So have the veerys abbreviated their nesting season and left for Brazil? I’d really like to know.

For more information, see this August 2019 Audubon Magazine article and Heckscher’s paper A Nearctic-Neotropical Migratory Songbird’s Nesting Phenology and Clutch Size are Predictors of Accumulated Cyclone Energy.

(*) ACE is Accumulated Cyclone Energy, a numeric measure of hurricane season intensity.