Florida Scrub-jay: One Step Forward, A Big Step Back

Scrub-jays disappear from southern Palm Beach County; disease is likely culprit of higher-than-average scrub-jay deaths at Archbold Biological Station sites in Lake Wales Ridge.

ALTAMONTE SPRINGS, FLORIDA — January 14, 2009 — “One step forward, a big step back” describes the mixed results of The Nature Conservancy’s 2008 Jay Watch report.

The seventh annual Jay Watch report reveals that while about 40 percent of the sites monitored by Jay Watch volunteers in 2008 saw scrub-jay numbers increase, about half of sites surveyed saw the bird’s numbers decline. This is compared with survey data of 42 scrub-jay sites also monitored by Archbold Biological Station scientists during a 1992-93 survey. In addition, scrub-jay faced their most dramatic decline in southern Palm Beach County and a possible epidemic reduced the number of scrub-jays at sites in the Lake Wales Ridge.

The Nature Conservancy began its Jay Watch monitoring program in 2002, working closely with scrub-jay experts at the world renowned Archbold Biological Station. Based out of the Conservancy’s Tiger Creek Preserve on the Lake Wales Ridge, Jay Watch is a citizen-science approach to large-scale monitoring of Florida scrub-jay populations. The Florida scrub-jay is the only bird species that lives only in Florida. The species is listed by the federal government as “threatened” because only a few thousand of the birds are left and its oak scrub habitat has been depleted and degraded through fire suppression.

“The best way to help the Florida scrub-jay survive is for people to support prescribed fire,” said Cheryl Millett, a Nature Conservancy biologist and the coordinator of the Jay Watch Program. “Where conservationists have restored scrub habitat, using controlled burns and other means, we’ve typically seen scrub-jays survive and thrive.” Learn more about saving the Florida scrub-jay.

In 2007, Jay Watch conducted biennial vegetation monitoring of conditions related to scrub-jay persistence. The results showed that fire management is needed. One-third of points surveyed had habitat too tall, and more than half were too dense, to be ideal for scrub-jays. This information helps land managers decide where controlled burning is needed.

“One of the good stories is from the former Cordell Ranch in Manatee County owned by the Southwest Florida Water Management District, where the land managers reduced vegetation and used fire to restore scrub in 2005,” she said. “Before those efforts, the site had two groups of scrub-jays. Now they have four.”

The Florida scrub-jay is an unusual bird. The species is one of a handful of cooperative breeders in North America. As cooperative breeders, offspring stay with their parents to help raise other younger siblings for at least one breeding season, sometimes longer. The birds also are homebodies—living in a territory of about 25 acres, and usually traveling no more than three territories from their original nest.

The 2008 Jay Watch survey showed that the decline in the population was most dramatic in Palm Beach County, where the species has disappeared altogether from the southern part of the county.

The Florida scrub-jay thrives in rare oak scrub habitat—one of the oldest ecosystems in Florida. Scrub is generally high and dry making it well-suited for agriculture and development. Those characteristics also make it one of the most threatened habitats in the state with nearly two-thirds of original scrub destroyed.

“It’s all about habitat,” Millett said. “There just isn’t a lot of scrub habitat protected in Palm Beach County and there aren’t large pieces of scrub habitat until you reach Jonathan Dickinson State Park. The development pressures in Palm Beach County are a warning sign for the Lakes Wales Ridge.”

In the Lakes Wales Ridge region—which contains one of the three largest populations of the birds—the number of groups of scrub-jays at the 16 Jay Watch survey sites are at especially vulnerable levels. Scientists consider fewer than 10 groups of birds at one site to be more vulnerable to extinction. All of the sites surveyed by Jay Watch on the Lakes Wales Ridge had fewer than 10 groups, though several Ridge sites with larger populations are intensively monitored by Archbold Biological Station scientists.

At Archbold Biological Station, scientists witnessed higher than average mortality during the late summer and fall in the local population of scrub-jays, which they believe may be caused by mosquito-born encephalitis. The total number of birds dropped significantly, but since scrub-jays live in family groups that may include many members, this resulted in a small decrease in the number of groups, but smaller group sizes. Researchers are still analyzing blood samples from mosquitoes and scrub-jays to determine the exact cause of the high mortality in this local population.

At Archbold, researchers have monitored scrub-jays populations at the site since 1969. Dr. Reed Bowman, head of Archbold Biological Station’s avian ecology lab, said over the last 40 years there have been four instances of very high mortality rates among scrub-jays with the most serious occurring in 1979. That year, 50 percent of adult birds died and 100 percent of the young-of-the-year birds died. The death rate for birds this year started out higher than 1979 in the months of July through October, but then returned to normal rates, Bowman said. The difference between 1979 and 2008 is that the weather became dry and cool this past October reducing the abundance of mosquitoes.

“Disease is natural, but there are changes to the landscape that are human induced that may affect the severity of disease,” explained Bowman, who is also a member of The Nature Conservancy’s Florida Chapter board of trustees. “As landscapes change, so might the abundance of mosquitoes. For example, if we replace natural wetlands, which tend to have water flow, with stagnant retention ponds that are more favorable to mosquitoes we might change the frequency and distribution of mosquitoes.”

Millett added that while many conservation land managers have worked hard to bring natural cycles of fire back to scrub habitat, there also remains a significant backlog of properties needing to be burned for conservation. The Nature Conservancy is helping to address this backlog by using fire strike teams across the state to assist its conservation partners with prescribed burning and other land management activities.

During the summer 2008 survey, 232 volunteers contributed more than 2,000 hours surveying 67 sites across more than a dozen counties. The number of sites monitored by Jay Watch grew in 2008 thanks to a cadre of dedicated volunteers and supporters. In 2009, The Nature Conservancy hopes to continue to expand the number of sites, volunteers and agencies monitoring Florida scrub-jays and to provide information to improve scrub habitat condition to help scrub-jays thrive.

Download the entire Jay Watch report.

The Nature Conservancy is a leading conservation organization working around the world to protect ecologically important lands and waters for nature and people. To date, the Conservancy and its more than one million members have been responsible for the protection of more than 18 million acres in the United States and have helped preserve more than 117 million acres in Latin America, the Caribbean, Asia and the Pacific. Visit The Nature Conservancy on the Web at www.nature.org.