By Bob Groos
Killdeer. What an odd name for a bird. Apparently, “killdeer” is a phonetic translation of the vocalization that 18th century naturalists thought they heard when the bird was in flight.
This past April, killdeer began appearing on the mudflats around Blue Heron Lake. I had high hopes of photographing their nesting activity. Following is my account of three mating pairs, five nests, twelve eggs, and seven chicks. It’s complicated, so grab your favorite beverage, sit down, relax, and read on.
You will probably hear killdeer before you spot them. Their alarm calls are shrill, repetitive, and ear piercing. The sound travels for at least 1/4 mile, from one side of the lake to the other. No wonder the Latin name for this member of the Plover family is “charadrius vociferus.”
You are not likely to casually find a killdeer nest, as it may be not much more than a shallow depression in gravelly soil surrounded by low vegetation. It was in mid-May, however, that I discovered one while watching geese near the clubhouse. I might have stepped on it while walking down to the water’s edge had one adult not been shrieking wildly, and performing broken wing display to lure me away.
“Broken wing” is a type of distraction that some birds exhibit to lead a predator away from a nest or its young. Feigning injury, the bird hobbles a short distance, then pauses while making a shrill, trilling sound. When the predator approaches, the bird quickly moves further from the nest, over and over. Once far from the nest, the adult flies off, leaving the predator behind to look for something else to eat. I can attest from personal experience that this behavior is quite effective in dealing with camera-toting predators.
The egg laying had just begun, as evidenced by the single egg I quickly photographed before retreating. You can imagine how pleased I was at my good fortune in discovering this nest: I would have a good vantage point from which to observe nesting activity, and perhaps photograph a brood of 4-6 chicks in about 30 days.
Sadly, that vision was not to be realized. Two days later, I returned to discover the nest had been inadvertently destroyed by human activity. So much for my dream of taking photos of newly hatched killdeer chicks.
The following week, I found a second nest. This one was off the lakeshore path, in a more secluded area. I felt more confident about the success of this clutch. There was even a natural blind behind which I could quietly observe the birds.
During the last week of May, a heat wave moved in. Could the developing embryos survive the unusually warm weather? Not to worry. During the last days of incubation, the adults stood over the eggs to shade them and keep them cool. The result: two chicks hatched on June 2.
While Killdeer are classified as shorebirds, they are commonly found far from the shore. Grazed fields are a good place to find them. With horses or cattle afoot, however, nests risk being trampled. Remarkably, killdeer have developed a distraction behavior called “ungulate display.” The robin-sized adult rushes the far larger interloper and takes an aggressive posture. I don’t know how a cow might react, but I was startled when it happened to me as I came out from behind my blind.
A day later, I returned to photograph the egg shells, but there were none to be found; nor could I find any evidence of the nest. Apparently, as a precaution against predators noticing vulnerable, newly-hatched chicks, killdeer immediately remove the egg shells from the nesting area.
Continuing my walk around the lake, I came upon a third killdeer pair on the side of the lake behind the swimming pool. With them were two chicks, perhaps a few weeks old, foraging the mudflats. So now we have a tally of four chicks on the lakeshore.
Since the precocial chicks won’t fly for about 30 days, survival depends upon their ability put distance between themselves and danger. You would be hard pressed to keep up with them if they didn’t stop frequently to catch an insect or other invertebrate to consume. It’s a joy to watch them scurry across the ground, moving in fits and starts, bobbing their heads up and down as if they have a bad case of the hiccups.
When two killdeer are in close proximity, they will often approach each other and pause, then pass side by side, only to stop, face each again, and repeat the process.
Mid-June delivered another surprise: a fourth killdeer nest. And this one was filled with four eggs. It was located on one of the large, partially submerged boulders by the boat launch ramp.
Imagine the serendipity of the situation: The nest is on a mini island, only forty feet from the lakeshore; the chicks will be safe from land predators, and they won’t be able to run away. Perfect.
Killdeer may have from one to three broods per season. Since this location was just opposite the shore where the very first nest had been, I want to believe that this killdeer pair was trying again. I can’t prove it, but that is what intuition tells me. Isn’t that a wonderful thought?
Coincidently, June / July is also molting season for our resident geese and ducks. They can’t fly until their flight feathers are replaced, so during this period they spend much of their time grooming themselves on shore.
The killdeer boulder seemed to have a special attraction to them. You know from my Canada goose article what that means: up to 3 lbs. of soggy calling cards each day. So much so that I named this new nesting site “Bird Poop Rock.” With all the activity on the boulder (geese, ducks, turtles, and grackles coming and going), I feared this combination could not end well.
Indeed, four days later that nest, too, was gone. All that remained was bird poop. Research has determined that 53% of killdeer eggs are lost to predators.
After the catastrophe at Bird Poop Rock, my photographic attention drifted towards the juvenile green herons now residing along the lakeshore (that will be a future article). But wait! You know from my introduction, one nest, three eggs, and three chicks have yet to be accounted for. It is a happy accounting, as follows:
On August 2, at the very location of the first nest I wrote about at the beginning of this story, I observed three killdeer chicks foraging on the mudflat. A lone adult was blaring alarm calls, and performing broken wing displays like there was no tomorrow. It had to be one of the original nesting adults, but this time with a third, successful brood.
I’ve watched them for the past ten days. They have moved from that shore to a small, boomerang-shaped island in the lake. Killdeer chicks can swim early on, and they will be flying soon.
As we go to publication, I observed beginning flight behavior by the chicks. They stretch and flap their wings while standing still. One chick flapped its wings and jumped off a large stone. The largest chick flapped while running, and went airborne for a second or two, like the Wright Brothers at Kitty Hawk.
And that concludes my account of seven killdeer chicks, twelve eggs, five nests, and the three adult mating pairs that started it all on Blue Heron Lake.
Robert Groos is a published photographer and keen observer of nature who lives in Yosemite Lakes Park. He shares some of his outstanding images of our local feathered friends along with some tidbits of interesting facts about each. We hope you enjoy them as much as we do.
What’s good for the goose
It’s nesting time
Wild turkeys on parade
The Pied-Billed Grebe
Hunchback of YLP: The black-crowned night heron
The secret world of the phainopepla
The turkey vulture