Warblers in Boxes

When I think of southern swamps, there are a few bird species that come to mind – Pileated Woodpecker, Red-shouldered Hawk, Barred Owl, Northern Parula. But none is more closely associated in my mind with southern wetlands than the Prothonotary Warbler. The ringing songs of these bright yellow birds are a prominent feature of spring and summer mornings in wetlands from Maryland southward.

Prothonotary Warblers are one of only two North American wood warbler species to nest in cavities. (The other is Lucy's Warbler.) This imposes a natural restriction on nesting opportunities. Even where the habitat is right, the warblers must compete for nest sites not only against members of their own species but also against other cavity nesters like Tree Swallows and House Wrens, as well as introduced species like European Starlings. While it presents a challenge for nesting warblers, it also makes it possible for people to help the species directly by providing additional nesting boxes that meet their needs.

Volunteers in Virginia have been doing just that over the past few decades. Virginia is one of the few places where the Prothonotary Warbler's breeding population has been increasing, thanks to an active program of installing and maintaining nestboxes, coupled with the protection of appropriate habitat. There are currently about 500 artificial nest sites in eastern Virginia, and volunteers continue to add more.

This year, the attempt to add an additional 60 nest boxes to the Northwest River State Natural Area in Chesapeake ran into protests from a nearby landowner.

But Luton also made it clear he wanted no part of a scientific project next door at the Northwest River State Natural Area, where volunteers want to help revive populations of a small, yellow songbird - the prothonotary warbler - struggling against a tide of predators and vanishing habitat.

Speaking before the Virginia Marine Resources Commission, a state agency debating whether to allow construction of 60 bird boxes on the Chesapeake preserve, Luton said he feared the little bird might some day be declared an endangered species.

Citing its decline across most of the United States - except in Virginia, where numbers are increasing - Luton reasoned that the warblers could jump across Smith Creek and take up residence on his land, where federal endangered-species protections "could be a catastrophe."

"I'm fighting for my property," he told the commission.

Eventually the Virginia Marine Resources Commission decided to install 60 boxes on the preserve anyway, but not along the border of Luton's property. This course of action was probably the easiest way of continuing the important conservation program while minimizing conflict. However, the case raises some important questions. There are a lot of issues to unravel in this story, and I doubt that I will do any one of them justice in this short post. But here are a few problems that I see.

First, there is a certain incoherence in fearing that Prothonotary Warblers might be listed as a federally endangered species but obstructing actions that would prevent further decline. The best way to avoid any hardships that an endangered species listing might impose is to avoid having to list a species in the first place. In the case of the Prothonotary Warbler that means preserving southern wetland habitat and maintaining adequate nesting sites for a sustainable breeding population. One of the commissioners noted this when he issued the decision.

"I hear what you're saying, Mr. Luton," said commission Director Steve Bowman. "But it seems the more you have of them, the less likely they will be on the endangered list."

Second, I have to wonder just how likely the Prothonotary Warbler is to be listed, or at least to be listed any time soon. This species has experienced a substantial decline in recent decades, as much as 30-40% since 1966. This decline, while startling, is only enough to place the species with a yellow flag on the Audubon Watchlist and as a species of Least Concern on the IUCN Red List. There are many bird species that have suffered far worse declines over the same period.

As far as I can tell, Prothonotary Warbler is not currently a candidate for federal listing. This places it in line behind other candidates (such as the rufa subspecies of the Red Knot) that have suffered even more dramatic declines yet have languished on the candidate list for years without being given the full protections that come with listing under the Endangered Species Act. In part, this was a result of the Bush administration dragging its heels on species protections, but so far the Obama administration has not shown much interest in wildlife conservation, either. This makes me skeptical that the Prothonotary Warbler would suddenly be rushed through the system, especially since the organizations that might push their cause seem more concerned with species threatened by climate change right now.

In other words, Luton probably has little to fear in terms of the Prothonotary Warbler becoming an officially endangered species anytime soon. And even if it did, this would not necessarily mean restrictions on his property. Much would depend on whether they were breeding there, how much of his property was occupied, and other factors – all of which are hypothetical at the present time. In addition, one of the warbler's biggest problems is that its wintering range in Central America and the West Indies is under pressure because of the destruction of mangrove forests to make way for other uses. Any conservation strategy for these warblers needs to deal as much with that threat as with preservation of potential breeding grounds in the United States.

Third, there is the problem of the intrusion of private interests onto public property. Luton wanted to block a conservation program on state property on the basis of a hypothetical future presence of a hypothetically endangered species on his own private property. The species is not on his property now, and we cannot be certain that any future presence of the species there would be caused by the nestbox program. The implication in all this is that the concerns of private landowners should trump the legitimate management decisions made by public officials, even when the harm claimed by the landowner only involves some possible future land use, not current conditions. In my opinion this sets a bad precedent for future wildlife management on public land.

Fourth, even on private land, property rights are not absolute. Landowners are not free to develop their properties as they see fit. Instead they must comply with a variety of laws from zoning regulations to fire codes to noise and nuisance ordinances. If a property is needed for a project that benefits the public, it can be seized (with compensation) through eminent domain. Endangered species protections are simply one set of regulations among many and not inherently more onerous than restrictions on building height or requirements for off-street parking. Compliance with such regulations costs money and limits how a property might be used, yet they are subject to far less opposition and paranoia than endangered species (and other environmental) protections.

The good news is that the nestbox project will continue, at least for this year, despite Luton's opposition. It has been very successful; this year alone 108 nestlings were banded in the 38 boxes at Northwest River Park, near the preserve in question. The program's success makes me think that other states within the Prothonotary Warbler's range would do well to follow Virginia's example and implement nestbox programs if they have not done so already.

(Top photo by Birdfreak.com; second photo by Robert Mussey. Thanks to long-time reader Peter Doherty for alerting me to this article.)