The Tiger River “string” is composed of six bird exhibits that line the Tiger Trail above and below the Malayan tiger exhibit at the San Diego Zoo. In these 6 exhibits there are around 120 birds. Normally, the birds are fairly predictable and easy to keep track of. The blue-winged pittas Pitta moluccensis come out of hiding for their tossed megaworms. The Malay great argus male Argusianus argus greets me at the door but expects his peanuts to be tossed deeper into the exhibit. His friendlier mate comes directly up to my shoe for the same thing.
Our nice-and-quiet routine is dramatically altered once their hormones kick into high gear. Starting around March and typically lasting through August or September, the breeding birds behave differently. They find new hiding places to make nests, they need more fruit or bugs added to their daily diet, and they become more territorial. The easy-to-predict birds suddenly become much more unpredictable!
I have my own calendar at my workstation that helps me visualize what is going on in these six exhibits. When I find eggs that I expect to hatch (fertile eggs that are being incubated), I look up the incubation duration for that species and figure out when those eggs should hatch. The earliest date when an egg should hatch is labeled and highlighted in pink. Any approaching pink-highlighted date lets me know I have to get ready for a potential new chick! The actual hatch is highlighted in yellow. Having hatches easily visible and clearly marked comes in handy many times. Expected fledges are noted in blue. These dates are important, because keepers need to know when a chick is expected to leave the nest, as we frequently add low perching or empty a deep pool for the young and inexperienced fliers.
For example, I noticed a pair of black-throated laughingthrushes Garrulax chinensis sitting on a nest earlier in the month and had figured out that April 12 was the earliest hatch date for the egg. Just before expected hatch, I ordered more bugs to go into their exhibit, as laughingthrush chicks eat a lot of insects. But there was a gap of two days before the chick did hatch. I did not go up to the nest and disturb the parents but knew there was a hatch based on the parents’ behavior—they were stacking bugs in their beaks and bringing a mouthful of mealworms, crickets, and waxworms up to their nest!
Usually 12 days after a black-throated laughingthrush hatches, the chick leaves the nest or fledges. A few days before the chick fledged, I put out some shallow water pans and emptied the pool in their exhibit. If the chick left the nest early, I wanted to make sure that it didn’t get trapped in the cold water. But that is not all! In May, I wrote down the date when the chick would be big enough to have an ID band put on its leg.
One last thought. As crowded and as colorful as this calendar can get, the six exhibits on the Tiger River string are not even the busiest breeding exhibits in the Bird Department. There are eleven other strings in the department, and many of them have more going on during this dynamic time of the year! I am humbled by the amount of knowledge my coworkers have and the amount of work they and our supervisors—who have to organize and manage all 12 strings!—put into their jobs. My hat’s off to all of them!
Mike Grue is a senior keeper at the San Diego Zoo. Read his previous post, Food Time!