Things have been going very well so far. First off, we are in such a beautiful area – the Santa Catalina Mountains, near Tucson, AZ. These mountains are part of the sky islands (mentioned in a previous post) that are located throughout south-eastern Arizona. Essentially, the sky islands are a series of isolated mountain ranges that are surrounded by desert or grassland. This is one of the more northern chains, and is a smaller range than others. Due to its proximity to Tucson, it is one of the more popular ones, and Mt. Lemmon, the highest point in the range, is very famous. There is even a ski resort and tiny town called Summerhaven contained within these mountains. The Santa Catalina mountains are full of trails and campsites, which made things logistically much easier for us to find good filming locations.
The film crew has found several nests that they are watching and getting some excellent shots. These females are apparently super tolerant and allowing the cameras to get very close to them. I’ve been able to get some good pictures of females on their nests and some rare shots of fledglings and feeding behaviors. Hummingbirds make their nests out of lichen and spider webs. The spider webs not only help hold the nest together, but it also makes the nests flexible and spongy so that as the chicks grow, the nest can expand. Though, by the time the chicks are about the fledge, the nest is so full that mom can’t really sit on it anymore. These nests are also usually very hard to find, not only because they are small, but because they are well concealed within a plant.
Most hummingbirds seem to lay two eggs, that are very tiny to us, but actually quite large compared to the female. Females will incubate the eggs for 2-3 weeks, and then will feed the fledglings mostly insects. Nectar doesn’t contain the necessary proteins for development, which is why females will switch to a more insect heavy while feeding young. Hummingbirds always incorporate insects into their diet though, as this is their source of essential proteins. Males do not help with nesting or raising young at all. Depending on the length of the breeding season, females can have multiple clutches, as several of the females did at our site. Also, an interesting fact: because hummingbird legs are so small and not good for walking, when a female is perched at the edge of her nest, she can’t really hop into it; instead she has to hover into it. Here are a few pictures illustrating the nesting and raising of young in hummingbirds.
I’ve been focusing on finding male territories and trapping females so that we can elicit and film some male courtship displays. The place we are filming is quite full of broad-tailed hummingbirds. I’ve also seen several other species here including broad-billed, black-chinned, and magnificent hummingbirds. I’m pretty sure I heard an Anna’s hummingbird at one point too. We are up about 8,000 feet, which is typically too high for Anna’s.
At this point, I’ve found several male territories, all throughout the area, and identified several males that would be good to film, such as this one:
I’ve also set up feeders so that I can trap some females and use them to get males displaying. Sometimes setting up feeders has the added bonus of creating new male territories, as males will come and claim feeders for their own. It is unclear whether males of this species select territories based on resources or form what are called leks – a spot with a single or multiple males, where females go to mate, but receive no other resources, typically. Based on my observations with this species, I would say they lek, as most males do not have any flowers on their territories and have to leave their territories to feed. However, males will guard valuable resources like feeders, as these are permanent and consistent sources of food. Overtime as the feeders attract more and more hummingbirds, these males will actually end up spending most of their time chasing away rivals, which might interrupt their ability to court females.
In my next post, I’ll have details on how the filming went and hopefully have some videos of my own to show. For now, I’ll end with a surprise I met while scouting for territories. I nearly stepped on it, and it gave me quite a fight!