Steph is studying North Island brown kiwis on a private island in New Zealand’s Hauraki Gulf. Read her previous post, Listening for a Kiwi.
Sarah and I sure were surprised by our most recent visit to the kiwi island! We had a few weeks off and came back with the expectation of having maybe one nest by the end of our stay. Instead, we’ve seen an explosion of nests and activity here on the island!
We stay on our feet practically all day when we’re collecting data on the island. Our 40 study kiwis, with names ranging from Taco and Bel to James, nest in 3 main gullies. Sarah and I each search a gully and a half: she searches Kauri Bush, I search Pipe, and we split Red Stony. We use the kiwis’ radio signals to track them to
burrows and nests.
In Sarah’s experience from last year, she had expected the birds to start breeding and laying eggs in another month or so. Instead, some birds appear to be about 1.5 months earlier in the cycle! I’m learning that it’s difficult to say anything is “for sure” in the kiwi world, which keeps life interesting.
We typically can tell that a burrow may actually be a nest when a lone male demonstrates lower activity levels overnight, which indicates he is probably incubating an egg. This year two nests were discovered before the males were incubating! With the unexpected breeding activity, our conversations in the cabin at night were full of questions. As a “newbie” to the kiwi world, it was entertaining for me to hear and see the shocked reactions of Sarah, her supervisor, Isabel, and new masters student Alex Wilson.
Since part of understanding the breeding season means we need to know the ages of eggs, Sarah and I headed out for our first night excursion to check on a couple of nests. Kiwis forage and socialize during the night, meaning they leave their burrows and nests to run around the gullies. We settled in a little ways away from one known nest to wait for the male to leave. Unfortunately, we never can know exactly how long it will be until the birds wake up and decide to venture out. Luckily, we just needed to wait an hour for Genesis to leave his nest and take a stroll.
Some nests are easier to reach than others. Lit by my headlamp, Sarah reached into the base of the tree in an attempt to feel any eggs. Genesis appeared to have nested pretty deeply in the tree, and Sarah wasn’t able to reach anything. Martin, on the other hand, is nesting at his same site as in previous years. The terrain is really steep, but his two eggs were accessible. I watched with wonder as Sarah shone a light directly on the eggs to gauge development.
I knew that kiwi eggs were large, but seeing them in person made me realize just how huge they are! I can appreciate the amount of energy it must take the females to lay them. Reading about kiwi eggs in a textbook is one thing; seeing them for myself is pretty awesome!
Now that breeding has begun, we’ll be busy monitoring incubation times and making evening checks on the eggs. I’m excited to see how this season goes!
Steph Walden is a volunteer for the San Diego Zoo Institute for Conservation Research.