Apr 14 2009
Why Easter Egg Hunts are Less Popular in the Tropics
Easter Egg hunts are one of those activities engineered to give participants a better than average chance of success. The eggs are hidden, but they’re not too hidden–just tucked away behind a few obvious obstacles dotting a nice expanse of perfect green lawn. Now, I know, some of you probably had an especially mischievous parent or other relative who hid the eggs in impossibly obscure places once you’d gotten a little older, but my point remains. Easter Egg hunts are supposed to be easy and rewarding.
Even finding real bird nests in temperate regions tends to be pretty easy, especially in April and May. Again, there are some species whose nests are well hidden, but for every Grasshopper Sparrow there are a thousand Mourning Doves and American Robins, whose efforts at nest concealment are so minimal that one could easily imagine eggs being a regular menu item for our hunter-gatherer ancestors.
In tropical forests, finding bird eggs is generally so challenging that it would destroy the carefully nurtured self-esteem of nearly any temperate egg hunter. For starters, the habitat is impossibly thick and dark. The shot below is a long exposure (1/3 second) taken on a tripod in a fairly bright spot along the Cock-of-the-Rock Trail at Cabanas San Isidro.
I walked this trail a couple of times the first few days I was in Ecuador. I noticed that on two occasions, a medium-sized bird flushed off into the undergrowth from the same general area of trailside trees. I suspected a nest and made a few mental notes about exactly where the tree was. I still had no clear idea about what bird species was involved–the fleeing parent was little more than a shadow winging away into the green darkness. I returned to the site with Forrest and we spent several minutes staring into the dim light, trying to visually separate feathers from foliage–a surprisingly difficult process, given that we already knew exactly where the nest was located.
Finally, Forrest found a spot where he could actually see the incubating mother. “Glossy-black Thrush,” he announced. It was a relief to have the nest owner identified, but also a tiny bit of a letdown, I must confess. Though I knew the odds favored my having found something relatively common, in the tropics, there is always a very real chance of finding a nest that may never have been described before. Of course, few such nests would likely be placed right next to a trail, but hope springs eternal, you know.
Amazingly, this area has seen the discovery and description of the nests of several dozen species of birds. Why? Because people are looking here. Not only Mitch and the staff at Cabanas San Isidro, but also the researchers at the adjacent Yanayacu Biological Station, especially its director, Harold Greeney, whose nest-finding skills are legendary. Take a look here to see a bunch of photos of recent student projects, many of them involving the breeding biology of local birds.
Wanting to check the nest contents, we quickly approached and retreated, moving as swiftly and efficiently as we could manage in the dense conditions. Below is an exterior view of the nest. It’s nearly dead center. Look for a baseball-sized bare area of trunk just above a baseball-sized patch of especially thick green moss. Basically, the bird formed a deep cylindrical cup by walling in a fold in the trunk.
Here’s a peek inside the nest, a view I never actually saw myself. To get this shot, I had to hold the camera and external flash above my head and direct them down into the hollow. Two eggs, one more pigmented than the other, safe for the moment inside a lovely cradle of mosses, ferns and roots.
I’d like to be able to report on a happy conclusion for this nest. But unfortunately, it met the same fate as the vast, vast majority of tropical forest nests. When we returned to the area a week and a half later, there was nothing left but eggshells.*
Tropical nesting birds have some advantages over their temperate and polar counterparts. The food supply tends to be more constant and there are certainly a lot of nooks and crannies in which one can place a nest. But the terrible downside is that there are hundreds of adept egg predators. Snakes. Monkeys. Toucans. The list seems endless. As a result, tropical birds tend not to invest too much in each nesting attempt. Small clutches are the rule.
By contrast, “our” birds have it easy, whether they live with us year round, or migrate here for nesting. Space is abundant, prey (in summer) easy to find, and perhaps most of all, there are fewer nest predators. Not none, of course, but many fewer. One can understand why many of our birds have huge clutches, even why they aren’t always stealthy about where their nests are situated. And how people might get the idea that searching for eggs could be child’s play.
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For a nice photo of a male Glossy-black Thrush by Scott Olmstead on Flickr, click here.
*I realize that our looking at this nest may have been partly responsible for its discovery and destruction by a predator. I’m not happy about this possibility, of course, but I am prepared to argue that the incremental danger to the nest from our examination of it was small enough to be justifiable. But I’m aware it’s far from an open and shut case either way. I’ll discuss these issues in the comments, if anyone wants to.
Jeff,
I know the guilty feeling of maybe being responsible for the loss of eggs from a nest. After years of monitoring bluebird nests safely, when I found a Red-winged Blackbird nest at my pond one year I felt the overwhelming compulsion to make daily observations. After about a week, the eggs were gone. I realize after the fact that I was laying a scent trail through the weeds, and probably led a predator to the nest. I felt pretty bad about it.
Whether one look would have the same disastrous effect or not is debatable, but I understand your concerns. Still, all God’s critters gotta eat, and when a bird puts its nest within reach of egg-eaters, bad things happen. I don’t think you are to blame here.
~Kathi