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Posts Tagged ‘Bushtit’

On Saturday, I spent about an hour-and-a-half with my three-month-old daughter wandering around a giant shopping center in Roseville, CA.  My wife was spending some time with some friends, and so my daughter and I took the opportunity to have a look around.  As we walked between huge box stores and along expansive parking lots I was impressed, as I often am, at how much animal life was finding a way to live in and amongst all the human impacts that exist in very urban areas.  House Finches were in the bushes all over the place and White-throated Swifts and Lesser Goldfinches were frequently flying and calling over head.

During our rambling, my daughter and I made two particularly exciting discoveries.  The first was finding a bee hive!  The swarm had built their hive in the nooks and crannies of a potion of a wall that have been made to look like pile rocks.  The bees were industriously visiting the wisteria vines, blooming not far away, and also coming in from much greater distances as they foraged for food for the colony.  I was pretty thrilled to find this hive, but was careful not to make too much a big deal about it when people were passing by because I was worried that someone would freak out and that the property managers would find out and spray the colony.  This was weird for me because I usually like to share sightings like this with anyone who is willing to listen, but here I figured that the best thing for the bees would be secrecy.  The second exciting discovery was a Bushtits nest!  The pendulum nest of lichens and spiders web was hanging in a small ornamental tree only about 6 feet above the ground.  The tree was in a little ally way between two humongous stores.  The two adults were very busy searching through the landscaped plant and bringing caterpillars and other insects they found back to the nest to feed their chicks.

Even though this was not a bird walk through some wild place it yielded some wonderful nature experiences, and was a wonderful way to spend some time.  It served as a terrific reminder that there is wildlife to be seen everywhere, and I look forward to continuing to share similar experiences with my daughter.

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This past weekend a friend, my wife, our 7 week old daughter, and I went birding in the Sacramento Bypass Wildlife Area.  It was a beautiful day with bright sunshine and just a little coolness in the air.  The Cattails (Typha spp.) in the central portion of the bypass were letting go of their fluffy seeds and the Mugwort (Artemisia spp.) were just starting to send up their spring growth, resprouting from their roots.  As we walked along the northern channel among the willows and oaks and cottonwoods I heard a flock of Bushtits.  Wanting get a look at them, and not wanting to miss any other birds foraging with them, I found the little flock of about 6 birds and started to sift my way through the group.  But, I stopped in my tracks when I got the first bird in my binoculars.  It was a small bird with a bright yellow belly.  At first my mind jumped to male Lesser Goldfinch, but it just as quickly rejected that option.  The bird I was looking at had a long tail and no dark patch on the forehead.  It looked like a Bushtit, but it was really, really yellow!  Is it a Yellow Warbler?  No.  Is it an Oragne-crowned Warbler?  No.  American Goldfinch?  No.  And then I see another one, and another, and another.  They are acting like Bushtits.  They sound like Bushtits.  But the whole flock is comprised of birds that are bright yellow!  Finally, I realize what is going on.  They are indeed Bushtits and they are foraging in a willow tree that is in full bloom.  Every time one of the birds jumps to a new twig to search for insects it is dowsed by the bright yellow pollen from the willow.  Since Bushtits are very active foragers and often hang upside down to find the insects they eat, even the bellies of these birds were coated in pollen.  They looked amazing!  Bright yellow Bushtits!  The flock finished searching through the willow tree and moved on to a nearby oak where they stood out even more.  Just goes to show you that when you see something odd, there is often a perfectly sensible explanation, just not one that anyone would guess.

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I came across my first family group of Bushtits of the year, today.  The group was comprised of what looked like three adults, which were probably the mated pair and one nest helper, and four young birds.  Bushtits are one of a number of species that include nest helpers in their reproductive strategy.  These helpers are usually young from the previous year that return to aid their parents.  Young birds that fledge from a nest early in the year also sometimes stay to act as helpers as their parents raise a second brood of young.  Since this family group that I found is so early I would not be surprised if the adults attempted a second brood.

A number of ideas about why young birds help raise their siblings are floating around.  One is that the young birds are getting valuable experience in raising babies, so that they will have better success when they do eventually go off by themselves.  Another idea is that the baby birds grow faster, and so fledge earlier, when there are more helpers to feed them.  A related idea has to do with what is called inclusive fitness.  This hypothesis says that the more individuals that carry a copy of a particular gene, the better, so helping relatives survive is actually a good strategy for preserving your own genes.  This is especially true if the individuals in question are close relatives, such as siblings, because there is a lot of shared genetic information.  A further idea is that good nesting territories are few and far between, so the helpers return to their parents territory and stay around in the hope of inheriting that nesting territory if and when their parents die or breed elsewhere.  This seems particularly possible in cavity nesting birds for which cavities have been shown to be a limiting factor in reproduction.  All these hypotheses seem reasonable, and they are not necessarily mutually exclusive, but few have been really well examined!  This seems to be an area that is ripe for some observations and experiments that might yield really interesting results.

So, who wants to put up a bunch of bird boxes and see what happens?

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