Thursday, December 30, 2010

26 Miles Across The Sea...


Santa Catalina is a-waitin for me…or at least this is how the song from The Four Preps written back in the 50’s goes. Catalina Island is one of the Channel islands and is located just about 26 miles off shore of Los Angeles. This is the place I spent three springs in a row working for the Smithsonian Migratory Bird Center studying the endemic Orange-crowned Warbler. This is a little yellowish-greenish bird with a bright orange flash of feathers on the top of it’s head..hence it’s name. The little orange crown is not always prominently displayed, but can be quite obvious on males either showing off for a female or fighting off a rival male in his territory.
The island consists of the “city” of Avalon, although I lived in the interior of the island in an area called “Middle Ranch” which mostly consists of employees and/or biologists that work for the Catalina Conservancy (whom owns most of the island) or the Institute for Wildlife Studies. There are no cars allowed on the island except by special permit. Only golf carts are allowed in the city of Avalon, but not anywhere outside the city limits. We however had the special permits to drive cars on the island and had access to the city AND the entire rest of the island. This allowed us to drive to our study sites, and make trips into the city at least weekly for groceries and supplies. It also allowed us to visit many beaches that most people could not gain access to except by boat. We would spend time on beautiful beaches that were empty of other visitors.
While I was there, we were not the only researchers on the island. There was also a group of biologists studying the island fox, the Bald Eagle, plants, a woman studying shrews, another studying feral cats, and a biologist studying herptiles, as well as a handful of pig hunters. We all identified each other by what type of animal or thing we studied. It was sort of like being a member of a tribe. We were known as ”the bird people“, while others were “the fox people“, “the eagle people“, and the “shrew girl”.
The little birds we studied were unique in that they nested both on and off the ground. Their mainland counterparts (a separate sub-species) nested strictly on the ground. The study was to see why they nested where they did and to figure out other basic behaviors.
We captured all the birds by mist net and banded each with a unique color code. Each bird was given 3 color bands and one numbered aluminum Fish and Wildlife band (2 on each leg). We always placed the aluminum band on the right leg along with another color, and 2 color bands on the left leg. We would read the colors like so: top right, bottom right, top left, bottom left. We would use letters to represent each color (usually the first letter of the color) so that we could “name” the bird by it’s color band. For example a bird with green band above an aluminum on it’s right leg, and an orange band above a white band on it’s left leg would be called “GAOW” (Green, Aluminum, Orange, White). Many of the combos we used made funny words that became the birds “name”. We had an “AROO” (Aluminum, Red, Orange, Orange), WARY (White Aluminum, Red, Yellow), etc. etc. Some of my other favorite names were “RAYY” or “Ray Y” as I called him, and “WABuBu” (White, Aluminum, Blue, Blue). We cheated a little to make other names more interesting, like “ABuGY” who became known as “A bogey”. Whenever we referred to these birds we would use their given “names” and often thought if anyone overheard us talking they would think we were speaking in code or some secret made up language especially since we talked about the birds as if they were people or friends .
We did different experiments to see if we could influence where the birds built their nests. We placed different decoys in their territory while they were nest building. We placed a stuffed Scrub Jay (an aerial nest predator), a weasel (a terrestrial nest predator), a snake (also terrestrial nest predator), and a Hutton’s Vireo (non-nest predator) as our control. The idea was that the birds should build a nest on the ground if an aerial predator was present, and that they would built off the ground if a terrestrial predator was present. The results showed ALL but one bird doing exactly as predicted. “WARY” built her nest on the ground right NEXT to the snake! Either WARY was a very stupid bird, or a very smart one recognizing that the snake was not real. Maybe she was a genius, thinking that this would be the safest place to built a nest as the fake snake would scare off other predators
They also had different reactions to the predators. They were much more cautious going to the nest when the aerial (Scrub Jay) predator was “watching”. They were not as cautious when the snake or weasel was out. It was also interesting that the Jay was recognized as a predator since Jays do not naturally occur on the island.
By the end of the season we had observed some very interesting behaviors that had not been seen in this species before. We found many of the males were paired up with more than one female and would go from nest to nest feeding all their babies. We also found a young male helping feed chicks in a nest that he did not “father”. Usually a rival male in another males territory is attacked or chased out, but this male was allowed to stay and help raise the territorial males chicks. We thought maybe the male was trying to “woo” the female to mate with him since he had no mate of his own. We also found out that the males were extremely aggressive with each other and would often witness violent attacks and fights between them. Even the females were seen fighting sometimes. When we took blood samples from them, we found that their testosterone levels were extremely high compared to other birds their size. We also found that year after year, the same birds occupied the same territories. Most males paired up with the same female they mated with the previous years. Occasionally a bird would go missing, and a new male or female would replace them. It was always a little depressing when we would get back to the island and not have our favorite bird(s) show up that year, knowing that they had not survived the winter.