Into the Nest: Defending the Nest

  This series highlights the fascinating and marvelous ecology of grassland bird nesting, written by Madison Audubon education director Carolyn Byers.    Click here    for all of the Into the Nest posts.

This series highlights the fascinating and marvelous ecology of grassland bird nesting, written by Madison Audubon education director Carolyn Byers. Click here for all of the Into the Nest posts.

Our last post shared some pretty intense videos of predation events at nests. In both videos all of the chicks got eaten, and the parents either fled or did not approach the nest while the predator was there. The badger and the 13 lined ground squirrel weren’t challenged as they made off with nestlings. It’s not always like this, though. It turns out that bird parents respond differently depending on who is trying to eat their chicks.

Mammals are extremely strong in comparison to birds. Whenever a mammal stops by a nest, the adults generally steer clear. Sometimes they will shout alarm calls from a safe distance, or swoop down close to the predator and pull up at the last second. But generally they don’t make physical contact with the predators.

A red-winged blackbird chases an American crow away from its nest. This crow is looking for a quick meal, but the red-winged blackbird make him work hard for it. Video by Martin Nicolaus

Snakes are a different story. Another study that my advisor conducted also used video cameras to observe grassland bird nests (Ellison & Ribic, 2012). In this study, of the nests where adult birds happened to be with their chicks when a snake came a-calling, 76% of the parents defended their nest. This means they used the non-aggressive tactics I described earlier (alarm calling and feinting swoops) or they attacked aggressively and make contact with the snakes. 47% of these parents physically attacked the snakes.

I’ll let that sink in for a moment.

Imagine it: attacking an opponent that weighs more than you do, and is significantly stronger than you -- all in hopes of driving them away from your kids. Sure, you can fly… but you have no real weapons, you’re a songbird!


  This Warrior Sparrow is fierce and ferocious when it needs to be!    Artwork by NATAnatfan

This Warrior Sparrow is fierce and ferocious when it needs to be! Artwork by NATAnatfan

Most of the birds who chose to defend their nests aggressively pecked at the snakes. These were usually eastern meadowlarks and bobolinks -- our bigger, stronger grassland birds. Two meadowlarks also ran around the snake with their wings outstretched, as though trying to appear larger to intimidate the snake. Three bobolinks used aerial assaults and struck at the snakes while on the wing.

Birds take on some pretty serious risks when defending their nest. Adult birds may become injured, which could impact their ability to feed themselves or their young. Injury may also make them more vulnerable to predators in the future if they are slower or less agile. Adults could be killed by the predator themselves. Even if they successfully drive the predator away, chicks could be injured or killed by the scuffle. Many birds may choose to use non-aggressive defense (much safer for them), and then renest if their clutch is lost. They’re trading the short-term genetic gain of their current clutch for long-term success of future nests.

  This is a still frame from the video we shared below. A fox snake has grabbed an eastern meadowlark’s foot while she was defending her nest. You’ll have to watch the footage to see what happens next! Photo Credit: Ribic research lab

This is a still frame from the video we shared below. A fox snake has grabbed an eastern meadowlark’s foot while she was defending her nest. You’ll have to watch the footage to see what happens next! Photo Credit: Ribic research lab

So if nest defense can be so risky, why do birds attempt it? Remember, most nest defense is non-aggressive. Adults mostly stay out of the way of the predators. They try to lure them away from nestlings, especially if their chicks are old enough to scramble out of the nest and hide. They dive at the predator and peel away at the last second. Unless adults are making contact with the offender, they’re likely pretty safe. Noisy, angry parents may also attract other birds to the scene creating a mob. While a snake or skunk may put up with one bird harassing it, they may flee if a flock of birds start dive-bombing!

Birds are more likely to attack snakes than mammals for a few reasons. Snakes take a lot longer to eat an egg or nestling than most mammals do- so there is a greater chance of an adult bird witnessing the meal. Snakes have fewer weapons than mammals: they use their mouth to grab or bite, and possibly wrap their bodies around birds. Mammals have feet and claws that birds must avoid too.

  This milk snake is slowly swallowing a clay-colored sparrow chick. Photo credit: Ribic research lab

This milk snake is slowly swallowing a clay-colored sparrow chick. Photo credit: Ribic research lab

I think nest defense behavior is fascinating. Having had the experience of walking by a red-winged blackbird nest, I knew that birds attempted to drive predators away from their chicks. But I didn’t realize they would stick around to fight a predator that could be dangerous to them too! After seeing the intense footage below, I have a new appreciation for just how far birds will go to protect their offspring.

This video can only be described as an epic battle. The eastern meadowlark in the video is defending her nest against a fox snake. During this 15 minute rumble, the snake bites the meadowlark’s leg and wraps its body around the bird. The bird escapes, and goes on to strike the snake 198 times before driving it away. Despite the adult’s efforts, the chicks did not survive the ordeal. Researchers did discover the injured snake the following day, and it was in rough shape!



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  Dickcissels are a beautiful, migratory grassland bird that benefits from the Migratory Bird Treaty Act. Photo by Kelly Colgan Azar

Dickcissels are a beautiful, migratory grassland bird that benefits from the Migratory Bird Treaty Act. Photo by Kelly Colgan Azar

This summer, to celebrate Year of the Bird and 100 years of bird conservation under the Migratory Bird Treaty Act, we’ll be posting regular articles about grassland bird nesting ecology. My M.S. thesis focused on grassland bird nesting ecology, and I’m excited to share my knowledge—and stories from the field- with you!  We’ll go into the nest to learn about chick behavior, adult sleep habits, feeding and fledging. We’ll discuss predation and learn about how adult birds respond to different predators. You’ll get to see beautiful photos of nests, eggs, and chicks, as well as video footage straight from the nest! Best of all, the next time you’re out hiking in your favorite Wisconsin prairie, you’ll feel a bit closer to the birds you love.

If you’re interested in reading more and can’t wait for the next post, you can read more about my thesis work here.

Stay tuned for our next edition of Into the Nest, coming soon!

Written by Carolyn Byers, Madison Audubon education director

Reference

Ellison, Kevin and Ribic, Christine, "Nest Defense- Grassland Bird Responses To Snakes" (2012). USGS Northern Prairie Wildlife Research Center. Paper 252. http://digitalcommons.unl.edu/usgsnpwrc/252

Cover photo credit: Ribic research lab

September 2018 Keystone Volunteers: Levi Wood and Peter Fissel

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This dynamic duo has been responsible for organizing Madison Audubon’s expansive list of public, diverse, and fascinating field trips for years. Each fall, Levi and Peter sit down with a calendar, a grin, and a bag full of ideas for what types of trips we should host the following year, and who we might ask to lead them. Their large network of birding, butterflying, botanically minded cronies are persuaded into service, thanks to Levi and Peter!

In addition to planning out the types, locations, and dates of the 20-40 field trips we host each year, Peter and Levi often lead them too! They bring people to nature, and make birding, butterflies, and natural history things to explore openly and thoroughly.

Thank you to both Levi and Peter for the many hours you dedicate to Madison Audubon each year, in particular for this work, as well as all the other ways you contribute to our mission!

Interested in volunteering with Madison Audubon? Fill out our interest form here.

Written by Brenna Marsicek, communications director

Into the Nest: Badgers gotta eat too!

Into the Nest: Badgers gotta eat too!

While adult birds and eggs are vulnerable during incubation, they are at even greater risk after chicks hatch. Most of our grassland birds are altricial as chicks, and need to stay in the nest long enough to be reasonably mobile when they fledge. However, chicks are also very vulnerable in the nest: they stay in one place, and the noise and activity surrounding the nest can attract predators. These birds need to balance the benefits of staying in the nest until they are able to fly to forage and escape predators with the potential risks of being found by predators while still in the nest.

Madison Audubon earns national land trust accreditation!

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Announcing our new Land Trust Accreditation!

Madison Audubon is a non-profit that works to acquire, steward, and conserve land – in other words, a land trust organization. Back in 2012, we made a bold decision to seek national land trust accreditation, a mark of distinction awarded to organizations meeting the highest national standards for excellence and land conservation permanence. This was no easy undertaking. Indeed, of roughly 500 Audubon chapters in the U.S., there is only one other chapter that has received this distinction. We're proud to say that Madison Audubon is now the second nationally-accredited Audubon chapter and among an elite group of other land trust organizations around the country that have received this recognition!

WHAT IS ACCREDITATION?

The Land Trust Accreditation Commission, an independent program of the Land Trust Alliance, conducts an extensive review of an organization’s policies and programs. Think of it like an audit of how a land trust does business. It gets deep into the nitty gritty – policies, procedures, record-keeping, finances, governance, land stewardship, and so much more. So we’ve been working diligently to demonstrate that Madison Audubon meets rigorous standards for excellence, accountability, and permanence of our conservation efforts. If you'd like more information about land trust accreditation, you can find it here

Madison Audubon is honored to continue to protect the land we all cherish, and the species that rely on healthy ecosystems. Our heartfelt gratitude goes out to the many people who helped make national accreditation possible. And of course, we couldn't do any of this work at all without our generous, vibrant donor and membership base -- you are the heart of our work!

Into the Nest: Cowbirds, everybody’s favorite villain

Into the Nest: Cowbirds, everybody’s favorite villain

A lot of people really dislike - even hate - cowbirds. I get it. It can be hard to watch a small warbler trying to keep a huge cowbird chick fed, and it’s sad when host species eggs get destroyed. But objectively and unemotionally, cowbirds are amazing, smart, resilient, and cool. Their reproductive strategy allows them to produce many more offspring than the average bird. Hopefully by the end of this post, you’ll be thinking about cowbird behavior in a new light too.