News and events

National Park Service and CCB continue to assess exposure of eagle nestlings to contaminants

July 14, 2017

By Bryan Watts, Center for Conservation Biology

The National Park Service (NPS) is the keeper of our most precious crowned jewels.  It manages the places that hold the essence of our history, culture, and natural wonders, the spectacles that we describe with pride to visitors that travel from other nations, and the inspirational vistas that we all run to for solitude and contemplation.  In addition to their cultural importance, this portfolio of lands is also the infrastructure that supports our most imperiled wildlife. We, as a people, entrust all of these most valuable possessions to the staff of the National Park Service - a charge that they accept with pride and commitment.

National parks have been instrumental in the recovery and maintenance of many threatened species and often support the best remaining examples of intact ecosystems.  They have played a critical role in the recovery of bald eagles.  Within the Chesapeake Bay, colonization rates and subsequent breeding densities of eagles on park lands have far outpaced those on private lands.  Parks now support a significant number of breeding pairs.  Although these parks are managed with a mandate to provide habitat for existing territories, breeding pairs should not be considered secure due to the continuing risk of exposure to environmental contaminants emanating from external sources. Park Service biologists understand that managing wildlife populations often requires mitigating risks coming from outside park boundaries, and that park properties often represent some of the best opportunities to monitor the health of larger systems that contain them.

For a second breeding season, CCB and NPS biologists collected blood samples from nestling bald eagles from park lands within the Chesapeake Bay to monitor for contaminant exposure.  The 2017 effort focused on park lands along the Potomac River, including The National Capital Region.  Blood and other tissues were collected from 11 eagle broods.  The ongoing study is a collaborative effort with eagle biologists from the Great Lakes and will compare contaminant exposure experienced by eagle broods in the Chesapeake Bay to those reared on NPS lands within the Great Lakes Region.

James River eagle recovery enters final chapter

July 12, 2017

By Bryan Watts, Center for Conservation Biology

One of the enduring questions in population ecology is: what determines the size of a population?  Stated another way:  what are the factors that regulate population size?  One of the classic approaches of investigating regulatory mechanisms is to study a population over time that has either recently colonized a new habitat or is rebounding from a catastrophic event.  Investigating a population that is growing within an effective “vacuum” allows us to observe its behavior as it increases and approaches capacity. 

During the height of the DDT crisis, the James River supported no breeding bald eagles for a period of five years during the 1970s.  The once-thriving population was diminished as productivity sank to levels below that needed to offset adult mortality.  Over an 11-year period during the 1960s and early 1970s, eagles on the river produced only three young.  After DDT was outlawed in the United States, the James River was recolonized by breeding eagles and productivity rose through the 1980s, leading to dramatic population growth.  Annual surveys have documented the phenomenal recovery that continues through the 2017 breeding season.  The breeding population has experienced tremendous momentum over recent decades, increasing from 18 pairs in 1990 to 57 pairs in 2000 to 272 pairs in 2017. 

As we have witnessed the population advance every year since the late 1970s, the central questions remain:  How high will the population rise and what are the underlying regulatory mechanisms that will constrain it?  Although the population continues to increase, the long-term trend in productivity gives the first real signal that we have entered the last chapter of the recovery.  The average number of young produced per breeding pair reached a peak during the late 1990s and has shown a gradual decline since this time.  The rate has now contracted back to levels not seen since the 1980s.  The continued decline of productivity back down to or near maintenance levels is the demographic response that will ultimately constrain the population and bring it to some form of equilibrium.

Why is productivity declining?  The recovery in productivity throughout the 1980s and 1990s drove exponential growth in the breeding population.  Beginning in the late 1990s, actual growth of the population began to diverge from that expected based on the number of young produced.  This divergence created an increasingly large population of floaters (breeding-age birds that do not hold territories) setting up a class war between the haves and the have-nots.  We believe that the disruption of breeders by floaters represents the negative behavioral feedback that is pulling down productivity and will ultimately bring the population into equilibrium with available breeding space.

Late arrival and breeding in juvenile-plumaged night herons

July 11, 2017

By Bryan Watts, Center for Conservation Biology 

Age to first breeding is a relatively consistent trait across heron species and typically coincides with the attainment of adult plumage.  For most migratory herons, juvenile-plumaged birds oversummer on the winter grounds and are infrequently observed around breeding colonies.  Yellow-crowned night herons transition into adult plumage in the summer of their third year (fourth calendar year) and presumably migrate to breeding grounds the following spring to breed for the first time.  Past surveys of yellow-crown colonies have documented that juvenile-plumaged birds account for less than 3% of breeding individuals.  However, very little is known about the circumstances of breeding in younger age classes.  As part of the ongoing investigation of yellow-crown breeding phenology, particular attention has been given to birds in juvenile plumage, their arrival times, and gender, in order to increase what we know about the rare young birds that breed.

Young night herons arrive late, lay eggs late, and are predominantly females.  In recent years, weekly monitoring of yellow-crowned night herons has focused on 10 colonies supporting 95 pairs.  During the 2017 breeding season, seven pairs contained juvenile-plumaged birds and all juveniles were mated with adult-plumaged individuals (<5% of breeders were juveniles).  Two individuals (both females) were in first-year plumage and the remaining birds were in second-year plumage.  Pairs containing young individuals were the last to arrive and the last to complete clutches.  Seven of the nine juveniles observed to breed were females, based on behavior. 

Little is known about the ecology and distribution of juvenile yellow-crowned night herons between the time of independence and the time they return to the breeding grounds in adult plumage.  Unlike many species where early breeding has been reported, juvenile yellow-crowns are not associated with breeding areas as nonbreeders.  Because of this, it seems unlikely that conditions on the breeding grounds would trigger the migration and breeding of young birds.  No definitive information is available on the formation and maintenance of pair bonds.  The arrival of paired juvenile and adult birds on the breeding grounds suggest that pair bonds likely form on the winter grounds and that demographic conditions during winter may induce juvenile migration and breeding.

Virginia Oyster Shell Recycling Program featured on Virginia's River Realm

July 10, 2017

The Virginia Oyster Shell Recycling Program is featured on the Virginia's River Realm website blog.

You can read blog post here

Cliff swallow population explosion continues in coastal Virginia

July 6, 2017

By Bryan Watts, Center for Conservation Biology 

Cliff swallows are a wonder to see up close.  Adults are richly colored in a combination of deep chestnut, cream, blue, and salmon that is reminiscent of the earthy colors of their winter grounds in the lowlands of Argentina, Paraguay, and southern Brazil.  Following spring arrival on the breeding grounds, pairs gather mud by the mouthfuls and craft unmistakable gourd-like nest structures.  Historically, these structures were built on exposed cliff faces under overhangs.  With the expansion of artificial structures throughout the continent the swallows rapidly adapted, attaching their nests to barns, dams, culverts and bridges, and expanding their range beyond the western mountains.  Over the past 150 years cliff swallows have marched across the continent, disappeared from some regions, and more recently mounted a selected resurgence.

The Coastal Plain of southeastern North America is experiencing a swallow boom.  The most recent colonization of this physiographic region began 50 years ago when birds moved across the Piedmont and began to establish footholds on bridges of the inner Coastal Plain.  In Virginia, Fred Scott of Richmond recorded the first breeding record within the Coastal Plain in 1979, when he documented 12 nests on the Benjamin Harrison Bridge along the James River near Hopewell.  In 1995, The Center for Conservation Biology conducted a systematic survey of breeding areas throughout the Coastal Plain of Virginia to establish a population benchmark and to document geographic expansion.  During the breeding seasons of 2016 and 2017, this effort was repeated in order to establish a second benchmark.

Since 1995, the cliff swallow population has increased nearly seven-fold in coastal Virginia from 454 to 3,052 pairs within 11 colony sites.  The largest colony site, supporting more than 1,000 pairs, continues to be on the Benjamin Harrison Bridge.  Since their discovery in 1979, the population has grown exponentially with an average doubling time of just 4.8 years and has continued to expand geographically. 

Breeding cliff swallows require surfaces protected from the weather and predators, a source of mud to construct their nests, and swarms of flying insects to raise broods.  Bridges are ideal places for nesting because they provide both protected surfaces and access to mud along their banks.  However, only 10% of the bridges surveyed currently support swallow colonies.  One of the most interesting aspects of the current breeding distribution is that all occupied bridges occur within tidal-fresh reaches of rivers where salinity is low, presumably facilitating high insect production.  Work is needed to clarify the link between salinity and insect production that may help to clarify constraints on distribution as the ongoing colonization plays out.

Rice Rivers Center part of Ellwood Thompson's Wooden Nickel Program

June 30, 2017

VCU Rice Rivers Center is excited to be one of two nonprofits to benefit from Ellwood Thompson's Wooden Nickel Program during the months of July, August and September. 

When you shop at Ellwood's and use resuable shopping bags, you will be offered ten cents for every bag or two wooden nickels. The wooden nickels can be deposited in a glass jar designated for Rice Rivers Center.  At then end of the quarter, the wooden nickels donated will represent real nickels for Rice Rivers Center.   

Ellwood Thompson's is a local market with strong roots in the Richmond community. Learn more about their Wooden Nickel Program here.  

If you wish to donate to Rice Rivers Center directly, please click here

Rice Rivers Center overnight lodge helps scientists devote more time to research

June 29, 2017

The undergraduate and graduate students are led by Cathy Viverette, Ph.D., assistant professor in VCU’s Center for Environmental Studies, and Lesley Bulluck, Ph.D., assistant professor in ENVS and the Department of Biology in the College of Humanities and Sciences. They are collecting data to inform conservation efforts on the warbler, which is of conservation concern.

Read the full story here.

The resurgence of ospreys along the Lynnhaven River

June 26, 2017

The Associated Press recently published a story about the abudance of new osprey nests along the Lynnhaven River in Virginia Beach. Bryan Watts, director for the Center for Conservation Biology, is featured.

Read the article here

Woodpecker partnership records first success within the Great Dismal Swamp

June 26, 2017

By Bryan Watts, Center for Conservation Biology  

Conservation partners are celebrating the first successful breeding of the endangered red-cockaded woodpecker within the Great Dismal Swamp National Wildlife Refuge.  Two young woodpeckers were banded on the 20th of May and flew from the nest cavity during the second week of June.  This event represents a milestone in an ongoing effort to establish a breeding population within the refuge.  A total of 18 woodpeckers were moved into the site during the falls of 2015 and 2016 by a broad coalition including several units of the U.S. Fish and Wildlife Service, the Virginia Department of Game & Inland Fisheries, The Center for Conservation Biology, The Nature Conservancy, and many volunteers. 

Similar in appearance to downy and hairy woodpeckers that are widely recognized and common “backyard” birds, the red-cockaded woodpecker has a much more specialized ecology.  Red-cockadeds require old-growth pines and are primarily associated with fire-maintained pine savannahs of the Deep South.  The shift to shorter rotation forest management and fire suppression virtually eliminated their historic habitat and ultimately led to their federal listing as endangered in 1970.

Red-cockaded woodpeckers in southeastern Virginia currently represent the northernmost population known.  Throughout the latter half of the twentieth century this population experienced a catastrophic decline, reaching a low of only two breeding pairs by 2002 (read more about their population decline in Virginia, Watts and Bradshaw 2005).  Heroic efforts to save the species on the only remaining site (the Piney Grove Preserve owned by The Nature Conservancy) have stabilized and increased the population to 14 breeding groups.  However, there has been ongoing concern from the conservation community about the risks of relying on a single site that could be destroyed by a hurricane or other natural disaster.  Establishing a second breeding population within the state has been a stated priority for more than a decade (read more about Virginia recovery objectives, Watts and Harding 2007).

Early in the year the likelihood of breeding within the swamp seemed like a long shot for 2017.  During the run up to the breeding season only five of the eighteen birds that had been moved from other populations remained within the refuge, including two males and three females.  All of these birds were isolated from each other in scattered sites.  By early May birds had formed two breeding pairs and soon each had laid three-egg clutches.  All three of the eggs from the first clutch hatched on 13 May, but only two of these young survived to be banded on 20 May.  One of the two birds was grossly underweight, weighing just over half as much as the other bird.  A check on these birds when they were 20 days old revealed that they were both doing fine and both were females.  The young birds were observed with the adult pair flying tree to tree foraging when they were approximately ten days out of the cavity.  The three-egg clutch laid by the second pair disappeared just before hatching (likely taken by a predator).    

Successful breeding of red-cockaded woodpeckers within the Great Dismal Swamp during the 2017 season represents a small but significant step in the long recovery of the species along the northern fringe of its breeding range.  Having the two locally-produced females making their way in the habitat of the swamp increases the population and is a real win for the conservation partnership dedicated to recovering this unique species.  

Virginia Oyster Shell Recycling Program wins grant

June 23, 2017

Keep Virginia Beautiful has awarded our Virginia Oyster Shell Reycycling Program a $2,000 30 in Thirty grant.  We are honored by their continued support of our mission.

Learn more about the award and Keep Virginia Beautiful here.  

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