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3,000 birds and counting for 'bluebird grandfather'
5/10/2018 Volume XLVIII, No. 19

Bluebirds have been a symbol of happiness for thousands of years and across many cultures. With their brilliant blue plumage and flash of red on the breast, these year-round New Jersey residents are breathtaking.

But the last century hasn’t been the happiest time for these small thrushes, which historically nested in hollow tree cavities.

The Eastern bluebird was once common up and down the East Coast, especially in open habitat with little understory and sparse ground cover. But its population plunged from the 1930s through the 1970s due to habitat loss, pesticides and competition from aggressive non-native birds like European starlings and house sparrows.

Luckily for bluebirds, dedicated citizen scientists like Nels Anderson of Indian Mills, Burlington County - dubbed the “Bluebird Whisperer” of the Pine Barrens – are aiding their comeback.

For more than 20 years, Nels has maintained a bluebird trail, or series of nesting boxes, on public open space. He started in 1999 in Wharton State Forest, and in 2007 expanded into the Franklin Parker Preserve in Chatsworth.

“I’ve just always liked bluebirds,” says Nels, a retired engineer who is a founder and board member of the New Jersey Bluebird Society.

Nels now watches over 150 boxes, and checks them weekly during the March to September nesting season. During his rounds – which take two days a week - he peeks inside each box and logs his observations.

Over the years, Nels has learned a lot about bluebirds: their habits, the hazards they face, and how to build and place nest boxes for optimal results … that is, many chicks. He keeps detailed records of his two decades of monitoring bluebird boxes.

Nels constructs his own wooden nest boxes, using a template he’s honed over the years. Bluebirds, it turns out, are very much like Goldilocks in that they need conditions that are just right.

The houses, Nels explains, must have an opening large enough to allow bluebirds to get in but small enough to exclude larger birds. The boxes must keep out rain yet have enough air circulation so the babies don’t overheat on scorching summer days. Boxes must be mounted on poles with predator guards to keep out snakes, raccoons and other critters. But the boxes can’t be too near trees, or flying squirrels will try to glide in.

Despite the custom design, other birds also like the boxes. Tree swallows and chickadees, especially, battle fiercely with bluebirds over the boxes. “Sometimes they’ll just build over each other’s nests,” Nels said.

During his weekly visits, Nels politely taps on each box and makes a “shh-shh” whispering sound to warn adult birds of his presence so they can leave. If a box contains a bluebird, tree swallow or chickadee nest, he’ll log the number of eggs or hatchlings. If snakes, mice, ants, wasps or other uninvited guests have taken up residence, he’ll evict them.

Like many species, bluebirds have good years and bad. Sometimes parasites or viruses keep the number of fledglings down. Or early hatchlings may fail because of unusually cold weather that reduces insect food sources.

But Nels’ efforts have been very successful: He has helped fledge more than 3,000 baby bluebirds!

“I’m a bluebird grandfather, and I’ve got 3,000 grandchildren. It’s tough at Christmas when they all get a dollar!” he jokes.

For example, 2008 and 2013 were banner years at Franklin Parker Preserve, with over 100 bluebird chicks fledged each year from the 60 boxes. Conversely, 2015 and 2016 were down years at the Preserve, with only 23 and 27 bluebird chicks fledged. The Franklin Parker Preserved is co-owned and managed by New Jersey Conservation Foundation.

Bluebird populations are now considered stable by NJ Division of Fish and Wildlife. Thanks to the efforts of volunteer citizen scientists like Nels, their decline has been halted and their population is on a slow but encouraging upswing. 

Nels is not the only foster bluebird grandparent in New Jersey. Bluebird trails are maintained and monitored in several other counties, and additional citizen scientists are always needed. So are volunteers for other nest box projects, like the one working to restore declining populations of the American kestrel, our smallest falcon, which is now threatened in New Jersey.

The online e-bird portal, where citizen scientists report sightings, shows that bluebirds have been spotted all over New Jersey. Concentrations appear to be higher in the western part of the state, where there are more open fields. To see where bluebirds have been sighted, go to and enter Eastern bluebird in the species search box.

Citizen scientists provide an invaluable service to the research world by collecting data that would otherwise go unreported. In addition to reporting bird sighting, various citizen scientists also keep track of weather, plant blooming times, rare animal species, migrations, light pollution, invasive species and many, many other things!

To learn more about bluebirds and how to assist their recovery in New Jersey, visit the New Jersey Bluebird Society website at  To learn about citizen science projects, go to

And for information about preserving New Jersey’s land and natural resources, visit the New Jersey Conservation Foundation website at or contact me at



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