Great blue herons nesting in CVNP
|The Bath Road heronry, located on Bath Road between Akron-Peninsula and Riverview roads, is experiencing change due to loss of trees and limbs. Occupancy peaked in 2003 with 176 nests. In 2013, it had 110 nests, some of which are shown above, that produced an estimated 251 young.|
|Photo: Ken Crisafi|
|Shown are great blue herons in the Cuyahoga Valley National park.|
|Photo: Tom Jones; courtesy of Cuyahoga Valley National Park|
Wildlife in parks is unlike animals in zoos. It is neither caged nor fed. Instead, the National Park Service protects habitat and allows natural processes to occur with as little human interference as possible. Animals seek their own survival.
Great blue herons provide one of the wildlife viewing experiences in CVNP. They are relatively easy to observe with distinctive physical traits and behaviors. It is also feasible to track how their populations change from year to year.
Great blue herons are the largest and most common wading bird in North America. They stalk food in shallow water, aided by their long legs, neck and bill. Look for them in wetlands and along the Cuyahoga River, where they feed on small fish, amphibians and aquatic invertebrates. Their markings — a gray-blue body, yellowish bill and black stripe above the eye — are distinguishing. So is their size: they stand 4 feet tall and have a wingspan of nearly 7 feet.
Their migration patterns in Ohio are extremely variable. Some birds travel to the Gulf States. Others fly just one or two states south. A few stay all year. Depending on the severity of the winter, some begin to return in February; others linger further south for a while longer.
When they return, herons gather in nesting colonies, known as heronries. Nests are typically 30 to 70 feet high in trees, sometimes surrounded by water. Males and females share nest building and caring for the young. Males return first to claim their nests. Two to three weeks later the females arrive, and birds pair up for the season. From early March to early April is the best time to observe nest building. A male will gather a stick and present it to the female, who takes the stick and adds it to the nest, strengthening their pair bond.
After courtship and mating, the female lays three to seven eggs. Both parents share in incubating the eggs for approximately 28 days. They roll the eggs every few hours to evenly distribute the heat to the developing embryo. Hatching typically occurs in late April or early May. May and June are busy with feeding the nestlings. The young usually fledge by early July.
The heronries in the Cuyahoga Valley have changed quite a bit in recent years. The first record of nesting great blue herons occurred in 1985. A pair was discovered in the Pinery Narrows along the Cuyahoga River north of Station Road Bridge Trailhead in Brecksville. This site became a sizable heronry until a pair of bald eagles moved in in 2006.
The eagles claimed a heron nest, expanding it for their own. Since then, eagles have returned each winter, including this year. Bald eagles are known to eat heron eggs, so herons did not react to them as welcome neighbors. Each year, fewer herons returned until the heronry became abandoned. By now, most of the nests have fallen and it is hard to see traces of the heronry.
However, herons did not abandon Pinery Narrows. A new heronry emerged across the river, high on the valley rim. In 2011, there were 60-70 active nests in this heronry; in 2012, around 100.
The new heronry is tucked away and harder to see. However, the Bath Road heronry is easily visible. It is located on Bath Road between Akron-Peninsula and Riverview roads. A pullout provides an observation location. This heronry is also experiencing change, mostly due to loss of trees and limbs used for nesting. Occupancy peaked in 2003 with 176 nests. In 2013, it had 110 nests that produced an estimated 251 young.
This was only part of the activity near Bath Road. For the second year, herons also had at least 24 nests along both banks of the Cuyahoga River north of the road. Other herons nested a few miles away at a small heronry tucked away near Wetmore Road. It has been used since 2006.
As the stories of the heronries show, nature is dynamic. When we allow natural processes to occur unimpeded, change occurs in cycles of birth and death. Populations move, expand and contract. Of course, nature is not untouched by the influence of people. Part of the story of natural change in CVNP is the story of recovery from human impact. Nesting great blue herons were gone from the valley; they came back. Nesting bald eagles were gone from the valley; they came back and added a new dynamic between species. The return and survival of herons is in part a reflection of the human efforts to restore and protect habitat.
Jennie Vasarhelyi is chief of interpretation, education and visitor services for Cuyahoga Valley National Park. Park Ranger Paul Motts and volunteer Peg Bobel contributed to this story.
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