From a beach on east March Point across from Anacortes, Sue Ehler scanned the shallow waters of an ebbing Padilla Bay, tallying the number of great blue herons standing in the eelgrass beds.
About 9:30 a.m., Ehler reported to Matt Kerschbaum that she saw 182 of the region’s iconic birds foraging in the ecologically sensitive estuary.
Ehler, Kerschbaum and Bonnie Kerschbaum are part of a 19-member team of volunteer citizen scientists working on a survey of herons in Skagit County.
The survey was initiated in 2014 by regional heron expert Ann Eissinger, who is using the data to create maps highlighting areas where the herons tend to congregate when looking for food.
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Matt Kerschbaum said during nesting season the volunteers survey area bays from nine different stations once every two weeks from mid-April to September.
During a recent count, the March Point team tallied 75 to 280 herons during each of its four counts, or sweeps, of the bay between Hat Island and the Twin Bridges.
After the initial sweep, the volunteers identified how many birds were grouped in different parts of the bay.
“The reason we’re doing the grouping is to see if there’s some areas of habitat they’re using more than others,” Ehler said.
Padilla Bay is known to have one of the largest eelgrass beds in the U.S., according to the National Oceanic and Atmospheric Administration.
The eelgrass is essential to supporting many marine, bird and mammal species. The great blue herons are among those species, and in west Skagit County are found in some of the largest numbers along the West Coast.
According to a 2007 report “Great blue herons in Puget Sound,” the Padilla Bay colony — which includes birds from March Point and Samish Island — is the largest in the Salish Sea.
Based on Skagit Land Trust data collected in 2015, about 1,700 adult herons nest in colonies on March Point and Samish Island.
Based on that data, Eissinger estimates about 2,550 young herons may occupy the nesting sites and feed in area bays this year.
“These are the most significant, largest heronries in the Pacific Northwest … and they’re indicators of environmental health,” Matt Kerschbaum said.
The birds that nest on March Point and Samish Island rely on the area bays for their primary food source, which is small fish, according to the Audubon Society.
“They’re an iconic species and they’re making their living off of these bays,” Matt Kerschbaum said.
That’s why it’s important to monitor the population and its nesting and feeding habits, according to Eissinger.
In addition to supporting two large heron colonies, the area is an industrial hub with two oil refineries on March Point.
Ehler said the potential for an oil spill is a concern because the birds are sensitive to disturbances at their nesting sites and rely heavily on the marine environment for their survival.
“If something happens to these colonies, it can take out a large part of the population. While it’s great that they’re here, a disaster would be a real disaster,” she said.
Another threat surfaced this nesting season after a major protest occurred at March Point.
“Because it’s May the chicks are about to hatch. The birds are particularly sensitive,” Skagit Land Trust Executive Director Molly Doran said.
The land trust owns property on March Point where the herons nest.
According to Google Maps, the heronry is within about 1,000 feet of the nearest refinery.
The refineries were the focal point of the protest, which was aimed at promoting a transition from fossil fuels to clean energy sources.
Eissinger, the land trust and others who want to see the herons protected were concerned about traffic and protesters using loudspeakers. Both could interfere with the nesting birds.
Eissinger said the activity “has potential for disturbing wildlife in a sensitive area at a critical time in their breeding cycle.”
She provided protest organizers and some media outlets with maps of areas she recommends avoiding, particularly with aircraft, and hoped for the best, she said.
Volunteers will continue to count the birds from a distance this summer and hope they don’t see negative effects of the event on the population later in the season, Ehler said.
For Ehler, whose background is in ornithology, which is the study of birds, it’s hard to put into words why the herons fascinate her.
“They’re absolutely beautiful birds,” she said. “They have a prehistoric look to them.”
Matt Kerschbaum said in some ways, the survey work is similar to his past duties managing wildlife refuges for the U.S. Fish & Wildlife Service in the Midwest. He enjoys seeing the birds nest, fly and forage.
“You know why the little fish didn’t want to go to the restaurant with the heron? He was afraid he would get stuck with the bill,” he said.