A: Scarlet Tanagers and other migratory songbirds moving north from South America into Canada face far greater ecological threats from deer than hurricanes.
By Rex Graham
Scarlet Tanagers spend the winter in South America and pass through Central America to the U.S. and Mexican Gulf Coast in April. They and other colorful warblers, tanagers, thrushes and other songbirds delight of tens of millions of North American birdwatchers every spring.
Scarlet Tanager thrills
Songbirds like the Scarlet Tanager create so much birding excitement that spring birding festivals across the region have sold out field trips.The Point Pelee National Park in southern Ontario, Canada, is one of North America’s premiere spring birding hotspots where deer and hurricanes are hot topics of discussion.
Birding enthusiasts and tour guides consider Point Pelee, a 7-km-long V-shaped spit of forest and marsh jutting into Lake Erie, a must-see place for North American birds. Spring migrants transform Point Pelee into a noisy paradise. The Festival of Birds at Point Pelee is one of the birding world’s signature events. In 2017, the festival is May 1-22.
Spring birding tours
Birding tour companies offer concurrent 12-day all-inclusive tours that stop at the park and at lesser-known birding hot spots across southern Ontario. “May is very comfortable and a lovely time to visit the province,” said Cam Gillies, a guide with Canada-based Eagle-Eye Tours.
Overpopulated herds of White-tailed deer can denude Point Pelee or any other North American forest if left unchecked. The deer eat anything edible, including plants, fruit, and crops such as corn. They particularly like acorns in the fall. They even eat poison ivy, prickly pear cactus and millions of songbird nestlings annually.
Herds of deer strip the lowest 8 feet of a forest, leaving a strange leafless zone of bare ground and tree trunks. Migrating Scarlet Tanagers don’t bother to stop. There are no insects or fruit for them here.
Nibbling forests to nothing
Researchers at the College of William and Mary in Virginia and Louisiana State University said in the journal Landscape and Urban Planning that Black-and-White Warblers, Hooded Warblers and Prairie Warblers also are significantly less common in deer- browsed forests. They conducted their study in Virginia.
The deer story is becoming depressingly familiar to wildlife biologists. Deer are benefiting from milder winters and a lack of natural predators. The population explosion of deer is why wildlife management workers at Point Pelee National Park “cull” them to sustainable numbers during the winter. (The venison is donated to Caldwell First Nation “for personal, community and ceremonial purposes,” according to Parks Canada.)
The mixed conifer and hardwood forests of the Great Lakes region of the U.S. and Canada have been devastated by an overabundance of deer.
During the 1980s, the deer herds in a group of 10 parks in central Ohio exploded and the parks’ ecosystems suffered. In one 308-hectare (761-acre) park near Columbus, Ohio, more than 150 species of vascular plants disappeared. “Populations of many species of small mammals, birds, reptiles and invertebrates had been reduced, and the estimate 350 deer showed evidence of nutritional distress,” researchers with the Columbus and Franklin County Metropolitan Park District reported in the Wildlife Society Bulletin.
Post-hurricane songbird surprise
Any birder who has seen hurricane-devastated Gulf Coast coastal forests might guess that they are just as inhospitable to songbirds. Ornithologists assumed the same thing.
For example, Hurricanes Rita (2006) and Ike (2009) demolished most of the trees in Louisiana’s biodiverse chenier forests. Ornithologists were deeply concerned about the negative consequences for birds. Yet, when they conducted routine spring surveys they were amazed by the high numbers of songbirds captured in their mist nets.
Despite the “dramatic” hurricane damage to the forests, scientists with the U.S. Geological Survey and the University of Southern Mississippi discovered that migratory songbird numbers were virtually the same as pre-hurricane years. They said in the Journal of Avian Biology that whether in prime condition or severely hurricane-damaged, chenier forests are equally beneficial to migratory songbirds.
Oak- and cypress-dominated cheniere forests grow on sandy soil that is only a few feet above sea level. Groups of trees are interlaced with marshes, mud flats and dense underbrush. The forests function as both wildlife sanctuary and a physical buffer of high tides during storms and hurricanes