Skip to content

Nature

Brood parasites: The South American cuckoo mimics its parents

by Dave Armstrong 30 May 2012
Brood parasites: The South American cuckoo mimics its parents

Baywing image; Credit: © Shutterstock

A parasite and its host evolve so closely that often the parasite is tied for ever to its specific partner, while even the host can become dependent on the nuisance species!

Brood parasites have apparently not been much studied beyond the egg stage. Now listen closely. I will explain this only once! The screaming cowbird mimics the baywing while the related shiny cowbird is also parasitic but doesn't mimic the baywing.

Maria C. de Marsico, with her co-researchers, Mariela G. Gantchoff and Juan C. Reboreda from the Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, took this useful natural situation and performed the ultimate experiment to prove that parasites mimic host offspring (after the egg stage). The Latin names could help, so the baywing is known as Agelaioides badius, while the two cowbirds are screaming cowbird with Molothrus rufoaxillaris and shiny cowbird with Molothrus bonariensis. To ease the situation, we'll call these two SCR and SH and the baywing, BW.

Baywing, screaming cowbird and shiny cowbird fledglings (from left to right); illustrating juvenile plumage coloration

Baywing, screaming cowbird and shiny cowbird fledglings (from left to right); illustrating juvenile plumage coloration; Credit: © Proceedings of the Royal Society B: Biological Sciences

Brood composition at fledging of eight breeding groups of baywings observed over a week after fledging

Brood composition at fledging of eight breeding groups of baywings observed over a week after fledging. Figures indicate number of fledglings of each species; bw, baywing; scr, screaming cowbird; sh, shiny cowbird. The last column summarizes the observations of non-mimetic shiny cowbird fledglings. All baywing and screaming cowbird fledglings were found alive by the end of the observation period.

With the common cuckoo, no Latin names are necessary (it sounds like its English name if you want to know), but the egg parasitism involves disposal of host eggs and nestlings by the parasite chick and the monster chick flying away looking nothing like its would-be nest-mates.

The screaming cowbird has obviously managed it better, along with parasitic finches and, possibly, bronze cuckoos,by mimicking the nestling to some extent. After the nestling stage, the SCR nestling begins to resemble the host fledgling more and more until they look identical. Five weeks later, the cowbird juveniles moult into their black adult plumage, but until then, mimicry seems to rule for the SCR.

Maria de Marsico and her co-workers agree in ascribing two possible explanations for the rejection on non-mimic fledglings. Parasites could adapt to host sensory systems and prefer the visual and vocal signals of their adopted species in order to encourage adequate parental care in competition with their brood-mates. Strangely, Maria has recorded in unpublished data, "pilot observations showed that screaming cowbird fledglings experimentally cross-fostered to chalk-browed mockingbird nests displayed similar begging calls than those raised by baywings .and were able to attract the attention of adult baywings from nearby territories."

Alternatively, it is possible that, having paid the cost of parasitism before fledging their brood, parents might find it selectively advantageous to reject the alien chicks late They would then regain some improved prospects for future survival or reproduction. Our screaming friend, the SCR becomes the latest weapon in an evolutionary arms race, which the SH is losing, because it's adapted to many more species as its host.

href="https://earthtimes.org/index.html">Nature News

Trending Eco-Friendly Clothing

Love My Planet Women's Relaxed Fit Hoodie
Earth
Quick Add
Close
Notify me
Notify me
Love My Planet Women's Relaxed Fit Hoodie
Love My Planet women's eco-friendly relaxed fit hoodieSize Guide Centimeters 8 10 12 14 16 18 Bust 84 88 92 97 103 108 Waist 66 70 75 80 85 91 Hips 91 95 99 104 109 116 Bust: Measure around the fullest part of...
£38.00
£38.00
Close
Notify me
Notify me
Penguins Hate Push-Ups Men's Pullover Hoodie
Earth
Quick Add
Close
Notify me
Notify me
Penguins Hate Push-Ups Men's Pullover Hoodie
Penguins Hate Push-Ups men's eco-friendly pullover HoodieSize Guide Centimeters XS S M L XL XXL Height 171 175 179 183 189 195 Chest 86 93 99 104 116 129 Waist 71 76 81 89 99 112 Chest: Measure all round your chest just below...
£38.00
£38.00
Close
Notify me
Notify me
Lightning Bolt Kids Long Sleeve T-Shirt
Earth
Quick Add
Close
Notify me
Notify me
Notify me
Lightning Bolt Kids Long Sleeve T-Shirt
Lightning Bolt kids eco-friendly long sleeve t-shirtSize Guide Centimeters 3-4yrs 5-6yrs 7-8yrs 9-10yrs 11-12yrs Height 98 112 125 136 147 Chest 60 66 70 75 84 Chest: Measure all around your chest just below your armpits. Height: Your natural height If you fall between...
£18.00
£18.00
Close
Notify me
Notify me
Notify me
Union Jack Tote Bag
Earth
Quick Add
Close
Notify me
Notify me
Union Jack Tote Bag
Union Jack eco-friendly colour tote bagProduct Specification Organic Cotton Tote Bag. Twill Weave (170gsm). 37 x 42 cm (7cm gusset.) Made in India / Designed on the Isle of Wight. Wash Cool, Hang Dry.
£16.00
£16.00
Close
Notify me
Notify me
Prev Post
Next Post

Eco-Friendly Shop

Women's Clothing

Eco-Friendly Clothing for Women Our online shop offers a wide range of sustainable women’s clothing products, including t-shirts, hoodies, vests, sweaters, shorts, and...
Shop Now

Men's Clothing

Eco-Friendly Clothing for Men Our online shop offers a wide range of sustainable men’s clothing products, including t-shirts, hoodies, vests, sweaters, shorts, and...
Shop Now

Kids Clothing

Eco-Friendly Clothes for Kids Our online shop offers a wide range of sustainable kids clothing products, including t-shirts, hoodies and jumpers. Our garments...
Shop Now
Someone recently bought a
[time] ago, from [location]

Thanks for subscribing!

This email has been registered!

Shop the look

Choose Options

Earth Times
Sign up for exclusive updates, new arrivals & insider only discounts

Recently Viewed

Edit Option
Back In Stock Notification
this is just a warning
Login
Shopping Cart
0 items

Before you leave...

Take 20% off your first order

20% off

Enter the code below at checkout to get 20% off your first order

CODESALE20

Continue Shopping