Cerulean Warbler: To List or Not to List!

Buzz Williams

The Cerulean Warbler (Dendroica cerulea) is a beautiful little migratory songbird that spends the winter in the Andes Mountains, from Venezuela and Columbia to eastern Peru and northern Bolivia, before returning in mid-April to its breeding grounds in North America in the mature, deciduous hardwood forest, usually along floodplains from southeastern Minnesota and western New England south to the northern Gulf Coast states. The Cerulean was once one of the most abundant warblers in the lower Mississippi valley where rich bottomland forest provided ideal habitat during the breading season. But heavy logging at the turn of the century in North America, and later land-clearing for coffee plantations in South America soon caused the significant decline of the species. The Cerulean made somewhat of a comeback in its North American range with the recovery of the Eastern forest after the logging boom of the early 1900s. There are indications that the species even expanded its range east of the Allegheny Mountains as well as in the Southern Appalachians, only to begin an even more precipitous decline with the return of clear cutting, human population growth and development in recent years.

Consequently, on 30 October 2000 the Chattooga Conservancy joined 27 national, regional and local conservation organizations in the United States to petition the U.S. Fish and Wildlife Service (FWS) to list the Cerulean Warbler as a “threatened” species and designation of critical habitat under the Endangered Species Act. In November 2000 and again in April 2001, our attorneys received letters from the FWS stating that they did not have funds to meet the requirements of the Endangered Species Act (ESA) to formally respond to our petition. However, the agency explained that they would use funds from their “candidate conservation program” to evaluate the status of the species and to “continue our internal discussions on elevating the Cerulean to candidate status.” Then on December 21, 2001 the FWS said that our petition to list the Cerulean Warbler as threatened had been denied, based on insufficient information about the species. As a result of our disagreement with the FWS in this regard, all parties involved in the original petition filed a 60 day notice of intent to file a lawsuit to force the FWS to formally respond to our petition, and to conduct a more extensive and conclusive status review of the Cerulean to make a final determination concerning its listing.

The heart of the dispute between the conservation community and the FWS is related to varying interpretations of the ESA, in regard to the delegated responsibility of the FWS to determine which species are threatened or endangered, and to determine what actions might result in recovery of the species. The Act is clear about the definition of threatened and endangered. An endangered species is one that is in danger of extinction throughout all or a significant portion of its range. Similarly, a threatened species is one that is likely to become in danger of extinction within the foreseeable future throughout all or a significant portion of its range. The dispute is over how the FWS makes these determinations. In so doing, the FWS looks for two types of data: 1) Data showing a continuous reduction in range and/or a decline in population abundance or density that puts the species on the brink of extinction now, or the likelihood that it will be in the foreseeable future, and 2) Documentation of current or imminent threats to the species or its habitat or range that are reasonably likely to result in the range reduction or population decline as above.

The preponderance of data upon which the FWS relied to determine not to list the Cerulean as a threatened species is known as Breeding Bird Survey (BBS) data. BBS data is a collaborative process between various academic institutions, most prominently Cornell Laboratory of Ornithology, and trained volunteers who conduct annual bird surveys at designated locations. The FWS oversees this program. The data collection for a particular species in question is conducted range-wide. The FWS typically relies on this information to estimate the size of the population of a species for its range.

In the case of our petition to list the Cerulean Warbler as threatened, the FWS denied the request because they said that BBS data was not reliable for making listing determinations. The agency now claims that BBS data is inaccurate because the sampling points were near roadsides as opposed to interior forests, where the Cerulean is more likely to exist. They argue that often, Cerulean habitat has been lost to development along roadsides and therefore overstates the actual decline of the species. In addition, the FWS claims that state and federal management agencies have shown great interest in investigating and implementing ways to conserve and improve Cerulean Warbler habitat. One example given is of a switch by the Forest Service to two-aged shelter wood timber harvesting on the Chattahoochee National Forest.

Our side counters with the argument that BBS data has been in the past the primary source for listing determinations by the FWS. While it is true that the more we look the more we find, many credible organizations such as the Audubon Society rank the Cerulean Warbler as a high priority for conservation, citing threats from forest fragmentation and logging as well as nest parasitism by Brown-headed Cowbirds, as major factors in the continuing decline of the species. The Audubon Society ranks the Cerulean at 25 of 30 points on its priority conservation priority list. The fact is that credible data (i.e. BBS data) widely recognized by multiple independent sources indicates that the Cerulean Warbler has declined an average of 4% a year for the last three decades, for a total loss of 70% of its population. Other real threats that the FWS is certainly aware of are mountain top removal mining, chip mill proliferation and extensive private land development in the East, as well as continued extensive habitat destruction in South America. Altogether by any evaluation these threats spell big trouble for the dwindling population of Cerulean Warblers.

The argument that state and federal agencies are effectively working to protect the Cerulean is absurd. The example the FWS offers showcasing efforts by the Chattahoochee National Forest and their shift to “Cerulean-friendly” timber harvesting is not supported by any significant actions. The Chattahoochee National Forest has conducted some shelter wood and seed tree timber harvests, but the fact is the Forest Service has been halted from almost any form of timber harvesting (with the exception of fuel wood and salvage logging) since Sierra Club vs. Martin in 1999. This was the lawsuit were the judge ruled that the Forest Service was woefully negligent in conducting monitoring for species in peril on the national forests. Thus, the FWS argument that better timber harvesting methods on the Chattahoochee National Forest have led to improving the Cerulean’s chances of survival is not even speculation built on a grain of truth, but are pure fantasy.

We can only conclude that the failure of the FWS to execute its charge to seriously consider our petition to list the Cerulean Warbler as a threatened species is the result of a greatly under-funded agency, under siege by an overwhelming work load because so many species are in serious decline. The fact is, the law is the law. The FWS is required to conduct a formal process of an in-depth status review, and then make a final determination concerning a credible petition to list a species as threatened within 12 months of petition. They have done none of these things. No amount of additional research will ever tell us exactly how many Ceruleans are left in the wild. There is no doubt, however, that a valuable and beautiful songbird is in swift decline in a dwindling forest habitat. The FWS should list the Cerulean Warbler as threatened before it’s too late. This is the best bet to get support for funding and more research.

Cerulean Warbler

PHYSICAL CHARACTERISTICS:

Male

Size: 4-4.5 inches long with a 7.5-8 inch wingspan. Color: Sky blue back with white belly, distinctive dark blue or black line across the throat, dark streaks on sides and back, and two white wing bars.

Female

Size: Slightly smaller than males. Color: Dull gray-blue above, yellowish below and two white wing bars.

Juveniles

Color: Brownish-gray above, with pale central crown stripe and white beneath. Molting occurs into adult plumage following hatchling year, prior to breeding.

CALL:

Buzzing call rising in pitch.

HABITAT:

Mature hardwood forest usually in floodplains.

RANGE:

South America: eastern Andes, Venezuela, Columbia, Peru, and Bolivia. North America: Midwest across to New England, south to Gulf States throughout Appalachian chain to north Georgia.

LIFE HISTORY:

Migratory insectivores. Ceruleans build compact nests from shredded bark, lichens and moss, 3-3.5 inches in length, from 15 to 90 feet from the ground. Egg clutches: 3-5, hatching in 12-13 days. One brood per season.