Female Costa's Hummingbird Building Nest

It's been a busy week here in my Sonoran Desert yard. Some of you may already know that I live on the border of Tucson Mountain Park in Tucson Az. not far from Saguaro National Park West. It's been above 100 degrees here all week so I get outside around 6 A.M. to do my yard work and make sure that water is available for all my daily visitors. First I make sure that the bird bath which is placed on the ground is clean and filled. If it's starting to grow things I use bleach and a tooth brush to scrub it and then I rinse it exceptionally well before filling. Because we get so little rain this time of year I have a varied and a sometimes unusual parade of visitors hoping for a drink. As you can clearly see I live in a residential area that was carved out of the desert many years before I arrived here in Tucson. Nearness to the park puts us in a locale that has close proximity to wildlife so visitors like these Mule Deer while not the norm pay us an occasional visit. Today promises to be 106 degrees maybe more so it will be important to keep the water filled. I usually change it 3 or 4 times a day as needed.

It has been an unusual season for Diamondback Rattlesnakes having encountered two here in the yard and one at the Desert Museum. The two in the yard were very young perhaps from the same hatch so I suspect that their might be a den somewhere nearby. Young rattlesnakes can travel up to a mile from their den and adults up to three miles in search of food.
Gambel Quails have been visiting the watering hole for a couple of months in pairs and family groups and only rarely solitary individuals. This week they have started showing up with the tiniest of chicks in tow. I have seen 2, 3 and 7 chicks in different family coveys.
We have the usual assortment of Mourning and White Winged Doves, House Finches, English Sparrows, Lesser Goldfinches, Goldfinches, Verdins, Northern Cardinals, Mockingbirds, Gila Woodpeckers with occasional visits from Phyrraloxia, Phainopepla, Hooded Oriole, Bullocks Orioles, Cottontail Rabbits, assorted Lizards and a very disruptive Coopers Hawk. My favorite visitors are however the hummingbirds.

At this very moment a female Costa's is building a nest outside my workroom window. Females are really hard to identify and I have spent the last couple of days trying to decide if she was a Costa's or a Black-chinned. I finally concluded she was a Costa's for two reasons. She has faint spotting on her breast and there is a male Costa's hanging around who is not being aggressive towards her. Males are very aggressive toward any other hummingbird that is in their territory. There is a daily battle raging as other hummers try to get a drink at the feeders.
 Here in Arizona there are 17 different hummingbirds. Some are rare and localized and some are common depending on the time of year. So far I have managed to see 8 different varieties including a Blue-throated Hummingbird in Patagonia. There are at least five different hummers who frequent my three feeders here at the house and I have seen two other attempts to nest in the yard but both were unsuccessful due to high winds. Hopefully this time i will get to watch the entire process from nest building to egg laying and hatching and finally fledging. I'm keeping my fingers crossed.

Note: Sadly the hummingbird nest was abandoned with two tiny eggs after several days of temps above 105 degrees. Mama spent all day each day sitting in the sun keeping the eggs shaded but I suspect that it was too much for her as she just disappeared. It's possible that some other harm befell her but I will never really know for sure. Of the three attempts that I have witnessed of hummers nesting in the Oleanders all three have failed. I am beginning to wonder if Oleanders are unsuitable nesting sites perhaps because as they bloom they sag under the weight of the blossoms exposing the the nests to the elements.