Readers’ wildlife photos (and videos)

Professor Bruce Lyon continues to regale us with stories, pictures, and his own videos about his group’s research on the fascinating American Coot (Fulica americana). There’s a lot of good science in these, so don’t skip the text! I especially like the “tousling” behavior described below. One lesson is that if you watch an animal very carefully (and quantitatively), you discover complexities that are both fascinating and overlooked by the casual observer.

Bruce’s words are indented, and he’ll be looking at the comments in case there are questions.

Coot Soap Opera, Part III

This is my third post on the soap opera that is family life in American coots (here, here). Work with my former student, Dai Shizuka, now a professor at the University of Nebraska, revealed that coot family life is somewhat more nuanced than the death-and-destruction picture I previously painted. What I described was the first phase in the life of a coot family, but there is a very different second phase that warms the heart (well at least for some of the chicks). In first ten days after hatch, the chicks seem to control who gets fed—without any clear parental interference—but this free-for all ends when the parents suddenly begin to exert control and determine which chicks are fed.

Below: The first ten days after hatch comprise a ‘first-come-first-served stage’: the chicks follow the parents around the territory and when a parent finds food, it typically offers the food to the nearest chick. Or, if there is a group of chicks, the parent holds the food out and one of the chicks grabs the food.

Most of the chick mortality occurs during the first ten days when parents do not exert control. We believe that size gives the older chicks an advantage—being larger, they can swim faster and are more likely to be able to get to a proffered prey item. We have never seen evidence for direct aggression among chicks: unlike some birds like raptors and egrets, the bigger chick never beat up their smaller chicks. Instead, if food is limiting, the younger, smaller chicks simply do not get fed enough and eventually get too weak to follow the family and perish.

Below. The video clip shows how chick size affects which chicks are fed. A parent offers a food item to three chicks that are following it and the largest chick, which is farther away than the others, rushes in and grabs the food.

Around day ten (roughly), things change dramatically. Parents take control and start to show aggression towards chicks. Parents ‘tousle’ the chicks by grabbing them by the back of the neck and shaking them. This behavior is common and screams of chicks getting spanked often ring through the wetlands. We are not the first to study this tousling behavior: it has been previously studied in two other rails: moorhens (Gallinula chloropus) and Eurasian coots (Fulica atra). However, the family life in these other two species differs a bit from that of the American coot.

Below: This parent is not eating its chick, it is tousling it (AKA spanking).

Below: Another photo of a parent tousling one of its chicks that nicely shows the shaking motion.

Below: Still photos do not do justice to the parental aggression so here is a video of a parent tousling one of its chicks. Although the chicks scream blue murder during the tousling they are not seriously hurt by their spankings. They do, however, give the parent a wide berth for a while after getting spanked.

We initially thought that tousling might be used to cull the brood during brood reduction, as has been suggested for European coots, but our observations do not support this idea—most of the chick mortality occurs early in the free-for-all stage, before parents use aggression to take control of food allocation.

Why, then, do coots beat up their kids? It turns out that they are intervening to help the smallest remaining chicks in the brood survive. Parents use aggression to make sure the smallest chicks get enough food. Larger chicks are tousled more than small chicks and, as a result, they spend less time near the parents and are fed less. Given the extreme hatching asynchrony, we suspect that without parental intervention and control of food allocation, brood reduction would continue until only one or two very fat chicks remained.

Below: Sometimes larger chicks dash in and take food that is clearly intended for a smaller chick. These thefts are often punished by a spanking, as shown in the video below. Note the sequence of events: the parent offers the food to the smaller chick, a larger chick rushes in and grabs the food but is then chased and tousled. Kind of like watching human families at the supermarket! And hard not to chuckle sometimes.

There is an additional layer of complexity to the parental control—the parents divide the brood so that mom has her chicks that only she feeds, and dad has his chicks. Once this ‘brood division’ occurs, each parent continues to feed the same subset of chicks until the chicks are independent. Interestingly, both parents often forage in the same general area so brood division is not the result of the parents dividing up the territory spatially and keeping the two subsets of the brood separate. It seems clear that the parents recognize the individual chicks in their brood.

Below: Video showing brood division, where the male is foraging while ‘his’ chicks follow him around, and the female is attended by ‘her’ chicks. The yapping adult is the male—it is easy to tell the sexes apart by their calls. The larger male has a higher pitched call, which is a reversal from animals generally where larger animals have deeper vocalizations.

The brood is not divided randomly by the two parents, nor is the pattern of feeding by each parent. Each parent typically takes one of the two youngest remaining chicks in the brood, which then becomes its favored chick. These chicks are fed more than the other chicks, often dramatically so, and they are tousled far less. Even though these chicks start out smaller than their sibs, they are so pampered and stuffed with food that they catch up and even surpass their older sibs in size. We believe that parent coots use this parental favoritism to level the playing field and undo the negative effects of hatching asynchrony.

Sometimes it is hard not to think of these little favorites as spoiled brats. They show a behavior called ‘pestering’, first documented in Eurasian coots by John Horsfall, who coincidentally did the work while at the Edward Grey Institute of Ornithology, David Lack’s old stomping grounds. It is mainly the favorites that pester their parents: this involves making a rapid twittering noise and clambering around the neck and lower back of the parent. This pestering is annoying and therefore causes the parent to lash out and tousle a chick. Surprisingly it is not the pestering chick that receives the parent’s wrath, but rather the victim is a sibling that has come too close and threatens the dear little precious small chick’s monopoly on food. It sure looks to us like the favorites use pestering to cause the parents to chase off the favorite chick’s competition. This is a bizarre form of indirect dominance—the pesterers use a parental enforcer to exert dominance over their larger sibs. The non-favored chicks even learn their station in life and begin to defer to the pesterer by moving away as soon as the pestering starts. The closest similar behavior I can think of is inherited dominance in primates: based on inherited rank, a small baby of a dominant female can be socially dominant over other adults that could beat the crap out of the baby.

Below: A photo showing pestering in action. The chick riding the parents back is the pesterer. Note that the parent is not spanking the annoying pesterer but a second chick that is nearby. “Mommy, Bobby threatened to steal my food!”

Below: Video of pestering. The video starts with a pesterer bugging its parent (note the twittering calls), the parent takes a couple of swipes at a second chick, who hightails it for safety to avoid getting tousled.

That’s it for the coot soap opera for now. In a few weeks I will prepare a couple of posts on the bizarre chick coloration and the brood parasitism, where female coots lay eggs in each others’ nests.

29 Comments

  1. Randy schenck
    Posted July 18, 2017 at 8:03 am | Permalink

    Photography and education at the same time. Really great wildlife.

  2. TJR
    Posted July 18, 2017 at 8:38 am | Permalink

    It seems that baby coots understand the benefits of passive-aggressive behaviour just as well as humans do.

    Excellent stuff, thanks.

  3. rickflick
    Posted July 18, 2017 at 8:50 am | Permalink

    Fascinating. Coots have a very complicated way of life. Thanks for presenting this.

  4. Heather Hastie
    Posted July 18, 2017 at 8:58 am | Permalink

    More fascinating stuff! And the coot chicks are so cute – until they turn into pesterers.

  5. Simon Hayward
    Posted July 18, 2017 at 9:05 am | Permalink

    Very cool, now off to moderate a lab meeting, not sure one can apply the coot approach to grad students and postdocs, but it might be worth a try 🙂

    • Diane G.
      Posted July 19, 2017 at 1:55 am | Permalink

      I’ll bet your favorites are not the pesterers. 😉

  6. Lee Beringsmith
    Posted July 18, 2017 at 9:14 am | Permalink

    Living in the Central Valley of California I see a lot of coots, and have strangely been drawn to these goofy birds. What a delight to get a basic understanding of their complex social lives. Thank you for this wonderful series.

  7. another fred
    Posted July 18, 2017 at 9:18 am | Permalink

    Fascinating. Is there any correlation to “tousling” and number of chicks lost. For example, if food is abundant and fewer small chicks starve does tousling decrease. I would think “anxiety” would be lower in the parents in that situation and conversely higher the more chicks are lost.

    • Kevin
      Posted July 18, 2017 at 10:46 am | Permalink

      I think anxiety is greater when resources are less and/or there are more chicks than can possibly be supported.

      Reminds me of large American (mostly Christian) families where four children means more anxiety for families sending kids to college. If the same families had one or two kids, there would not issue with paying for college.

      Limited resources + lots of kids = anxiety for kids and parents.

      • another fred
        Posted July 18, 2017 at 11:48 am | Permalink

        I said, “For example, if food is abundant and fewer small chicks starve does tousling decrease. I would think “anxiety” would be lower in the parents in that situation and conversely higher the more chicks are lost.”

        In the paragraph, “that situation” is the situation of abundant food, so we are saying the same thing.

    • Bruce Lyon
      Posted July 18, 2017 at 11:46 am | Permalink

      I have not yet specifically looked for this but given that tousling tends to happen mostly after the die off I would be surprised if this pattern exists. However, I do suspect that there are more total tousles per brood in large broods (i.e. when more chicks survive) simply because there are more chicks to tousle. Tousle rate per chick might be the same though.

      • another fred
        Posted July 18, 2017 at 11:51 am | Permalink

        Thank you.

  8. Debbie Coplan
    Posted July 18, 2017 at 9:42 am | Permalink

    Wow! Really fascinating –
    Thanks you !

  9. Posted July 18, 2017 at 9:42 am | Permalink

    Very nice photos, videos, and detailed explanation! Thanks very much! Really cool stuff! Thanks Bruce and Jerry!

  10. Michael Fisher
    Posted July 18, 2017 at 10:10 am | Permalink

    I don’t want to come back as a coot! Great post

    • Bruce Lyon
      Posted July 18, 2017 at 12:04 pm | Permalink

      It is too late for some people! I used the following riddle as part of a talk on coot chick coloration that I gave at a animal behavior meeting last year. In the talk I was able to use the ‘strip=tease’ aspects of Powerpoint—namely, show the riddle without giving the answer away. Several people in the audience got the joke before the images came up.

      https://photos.google.com/album/AF1QipPfdGtVqTNYoFZWfrrtSXW3w0GoSs8pi2BabkpR/photo/AF1QipNvYZv_SPFXUpqi-oOfHCd26QZkItG-vqE0sGwH

      • Bruce Lyon
        Posted July 18, 2017 at 12:05 pm | Permalink

        Oops. Looks like my attempt to embed a photo failed!

    • Bruce Lyon
      Posted July 18, 2017 at 12:37 pm | Permalink

      OK one last attempt to embed a photo

      trumpcoot

      • Michael Fisher
        Posted July 18, 2017 at 1:19 pm | Permalink

        @Bruce LOL

        Yes, he’s definitely a former coot

        • Diane G.
          Posted July 19, 2017 at 1:59 am | Permalink

          The coots hardly deserve such calumny!

      • Diane G.
        Posted July 19, 2017 at 2:03 am | Permalink

        Love it! 😀

        I guess academia being more liberal allows one to make such a (visual) statement at a meeting. 😉

        • Bruce Lyon
          Posted July 19, 2017 at 9:55 am | Permalink

          I typically avoid politics (right vs left) in seminars or teaching but since Trump goes beyond simply politics I feel he is fair game for his hideous traits.

          • Diane G.
            Posted July 20, 2017 at 4:22 am | Permalink

            Plus–call me a bigot, but I really don’t expect to find a lot of Trump’s base at an animal behavior meeting.

            (Unless they’e the study subjects, of course…)

            • rickflick
              Posted July 20, 2017 at 5:36 am | Permalink

              They may attend if kicking into submission is part of the curriculum(hard to believe but these people do exist).

  11. W.Benson
    Posted July 18, 2017 at 11:22 am | Permalink

    Bruce, How do momma and poppa select their favorite chicks? Does each chick imprint on one or the other parent? What happens to the chicks if one of the adults dies? It looks like Fretwell’s ideal free distribution from the chicks’ point of view (each chick goes where it can get the most food).
    It is a shame that birds don’t return to the marsh each year so you could measure the fitness effects of upbringing.

    • Bruce Lyon
      Posted July 18, 2017 at 12:09 pm | Permalink

      Beyond the fact that they are the smallest/youngest surviving chicks we have no idea how the parents choose. We can reject idea for brood division that has been reported for some species: offspring sex. Males and females are not choosing favorite chicks on the basis of offspring sex.

  12. Diane G.
    Posted July 19, 2017 at 2:05 am | Permalink

    How I love this fascinating story! Can’t wait for the next installment. It’s going to be so much more fun watching coots from now on.

  13. cruzrad
    Posted July 19, 2017 at 7:01 pm | Permalink

    Excellent series of coot posts. Thanks Bruce!


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