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Humberto has more impact on some birds

Watchful eye: formerly abundant in Bermuda, the North American Eastern bluebird Sialia sialis feeds primarily on insects, but they will dine on fruits and berries, in the wake of a hurricane like Humberto (Photograph by Blaire Simmons)

Bermuda quickly bounced back from the impact of Hurricane Humberto, but some of the island’s bird species may take longer to recover.

David Wingate, a veteran conservationist, wrote in the Bermuda Audubon Society’s autumn newsletter that some bird species handle the after effects of a hurricane better than others.

Dr Wingate said Hurricane Humberto was particularly bad for birds, because of the mini tornadoes that downed trees and tore off roofs and the lack of rain.

He said: “It was a dry hurricane, meaning that there was no heavy rain to wash the wind-carried salt spray off the foliage.

“Assuming most birds survived the hurricane itself, and amazingly most seem to, even when the hurricane hits at night, the real problems begin to occur in the aftermath.”

The availability of food is a problem for some species, but Bermuda’s native birds have had time to adapt.

Dr Wingate said: “The birds that suffer most are the tree foraging insect eaters like most of the warblers and our local “chick of the village” — an endemic race of White-eyed vireo.

“Nevertheless, the latter does surprisingly well, having adapted over hundreds of thousands of years to just such periodic events.

“While mostly an insect feeder, I have seen the local vireo switch readily to berries and even predate on anolis lizards close to its own size after hurricanes.”

Dr Wingate added that Miguel Mejias, a Bermudian researcher, is carrying out a study of the White-eyed vireo.

He said: “His follow-up surveys next year should provide a very accurate measurement of their hurricane and post-hurricane mortality.”

Dr Wingate said other species thrive after a hurricane, particularly seed-eating birds.

He said: “Seed-eating species can reap a bonanza, especially in casuarina groves, where uprooting and broken branches induce the seed cones to open en masse and release their seed.

“I noted that house sparrows took immediate advantage of this. Likewise, the food supply of ground-feeding seed-eaters, like mourning and ground doves, and soil-probing species like starlings and bluebirds, are relatively unaffected.”

Dr Wingate said some migratory birds might skip over Bermuda in the wake of a storm if food is not available.

Species that are blown to the island may be forced to stay and cope with the conditions.

He said: “These are hit doubly hard in the aftermath of a hurricane because they are often already starving when they find the island.

“Ironically, it is this latter group which make up the bulk of our migrant fallout because they are so desperate to find land that they converge to high density on it as soon as they come within sight of it.”