Feeding bluebirds helps fend off parasites

FEBRUARY 4, 2020

by University of Connecticut

If you feed the birds in your backyard, you may be doing more than just making sure they have a source of food: you may be helping baby birds give parasites the boot.

New research published in the Journal of Applied Ecology from UConn assistant professor of ecology and evolutionary biology Sarah Knutie shows that feeding bluebirds can have a significant impact on parasitic nest flies feeding on baby bluebirds.

Parasitic flies can be found in the nests of many bird species, and some can have significant impacts on nestling survival.

The flies lay eggs in the nests, and once the eggs hatch, the larvae feed on the blood of nestlings by drilling holes through the young birds' skin.

In the case of bluebirds, Knutie says it appears nestlings are generally tolerant of the flies, meaning they can sustain high loads of parasites but not suffer significant negative impacts on survival and growth. However, the parasite removes a lot of blood from the nestling, which could have lasting impacts.

"Bluebirds do not have a detectable immune response to the parasitic flies," says Knutie. "Since backyard bird feeding by humans is so popular, I was interested in how giving these birds food could influence their immune response against the parasite, and whether there is a particular time during the breeding season when supplemental feeding is most effective."

To perform the study, Knutie and her father set up 200 nest boxes in northern Minnesota. She followed each nest for the presence of bird eggs, and then, when the eggs hatched, fed some of the birds live mealworms.

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DNA analysis of bluebird feces reveals benefits for vineyards

Date: November 23, 2016

Source: Central Ornithology Publication Office

Do bluebirds nesting in California's vineyards help grape growers by eating agricultural pests, or hurt them by eating insects that are beneficial? The researchers behind a new study in The Auk: Ornithological Advances found that bluebirds' presence is likely a net positive -- and they did it by analyzing DNA in bird poop.

Bluebirds are one of several groups of birds that catch insects on the wing, but because they're constantly on the move and the animals they eat are tiny, it's difficult to determine exactly what species make up their diet. Julie Jedlicka of Missouri Western State University and her colleagues tackled this question using a new approach called "molecular scatology," analyzing DNA fragments in the birds' feces to determine insect species the bluebirds were eating. They found that Western Bluebirds in Napa Valley vineyards mostly ate mosquitos and herbivorous insects, likely having only negligible effects on the predaceous insects that benefit vineyard production by eating pests. Jedlicka hopes that these results encourage more vineyard owners to install bluebird boxes, helping replace natural tree cavities lost when land is cleared.

Jedlicka and her colleagues collected 237 fecal samples from adult and nestling bluebirds living on three vineyards in Napa County, California. "Many people I talk to get a very romantic vision in their minds when they think about how beautiful it must be to do fieldwork in California vineyards, especially in the Napa Valley," says Jedlicka. "Honestly, the landscape was beautiful, but the fieldwork is very demanding. Temperatures during the summer often rose into the 90s and 100s, and I was lucky to have wonderful help from vineyard farm workers and undergraduate field assistants."

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Persist and shout: Male bluebirds alter songs to be heard over increased acoustic noise

Research shows birds 'shout' to be heard over noise produced by human-made activity

Date: August 21, 2015

Source: University of Exeter

Summary: Birds 'shout' to be heard over the noise produced by human-made activity, new research has shown. Researchers recorded songs produced by 32 male bluebirds, and analysed two from each male -- those produced during the quietest and loudest period of ambient noise -- to investigate whether males changes their songs between these two conditions

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Research trio finds bluebird mothers give sons extra dose of androgen when antagonized

(Phys.org)—A trio of researchers has found that western bluebird mothers add a little extra androgen to clutches of eggs during times when there is competition for nest cavities. In their paper published in the journal Science, University of Arizona biologists Renée Duckworth, Virginia Belloni and Samantha Anderson describe how they conducted a ten year field study of the bird species and also carried out some experiments to learn more about induced maternal effects on the cycle of species replacement. Ben Dantzer, with the University of Michigan, offers a Perspectives piece on the work by the team in the same journal edition.

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Bluebirds struggle to find happiness on island paradise

Date:

January 27, 2014

Source:

University of Chicago Press Journals

Summary:

A recent study shows that Eastern bluebirds in Ohio differ in a variety of ways from their relatives in Bermuda.

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