Corey at 10,000 birds has an interesting post weighting the value of gray squirrels as a visitor to your bird feeder, vs. the nuisance they cause as a visitor to your bird feeder. Last summer, I found a way to combine both perspectives. Continue reading The grey squirrel from a birder’s point of view
Tag Archives: Birds
Egyptian Goose
Alopochen aegyptiacus … note, this is Egyptian goose, not Egypt goose. But it is Canada goos goose, not Canadian goose. Continue reading Egyptian Goose
More evidence that golf is evil
The White Browed Sparrow Weaver
Plocepasser mahali (subspecies stentor?) and friends. Kalahari, South Africa.
What bird was that?
The answer is here.
What bird is this?
Can you name the bird?
Charles Darwin Bicentennial – Finches
Darwin’s finches are a classic and historically important example of a species radiation (sometimes called an “adaptive” radiation, but that implies a specific assertion about the cause of the radiation which may not be appropriate in all cases). During the five weeks that Darwin spent on the Galapagos in September, 1835, he made a number of observations of these birds, but they did not occupy his time or attention more than any other aspect of this remarkable archipelago of islands. It seems that Darwin did not recognize all of the finches as finches, thinking some were of an entirely different group of birds, and in some cases, the variety seen across some of 13 or so species was initially interpreted by Darwin to represent a notably large range of variation in a single species. Please remember, Darwin was a rock man more than he was a bird man, at the time.
John Gould was a bird man, the most famous of his time at least in England, and he is the one who re-identified specimens mistaken by Darwin to be three or four different kinds (blackbirds, grosbeaks, and finches) as representing about a dozen different finches that had diversified into distinctly different forms.
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| There is even a Vampire Finch. And, even more amazingly, there is a Vampire Finch Movie!(click here to find out more…) |
There are two separate dimensions to variation in these finches. The overarching pattern is that different species are found on different islands, owing to a combination of genetic drift and local adaptation, the other is that different finches living in overlapping geographical ranges had different adaptations for differing diets. One gets the impression that Darwin was struck more by this first aspect of variation than the second. This pattern of variation … island by island … also applied to other animals such as the tortoises.
The phrase “Darwin’s Finches” was first advanced, or at least popularized, by David Lack, the famous ornithologist who also advanced a version of group selection theory, in the 1940s.
Here is a list of the species cribbed from Wikipedia: Continue reading Charles Darwin Bicentennial – Finches
Parasitic Birds and The Red Queen Effect
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The Avian Brood Parasites |
Brood parasitic birds lay their eggs in the nests of other birds (the “hosts”) who then raise them as their own. Examples of parasitic birds includes the cuckoo, cow birds, widow (“whyda”) birds, honeyguides, and even the South American Black-headed Ducks. Brood parasitism is virtually a world wide phenomenon.
Many interspecific brood parasites are obligate for this strategy … this is the only way they raise their own young. There are many variants (beyond the scope of this post). Intraspecific parasitism is known in many colonially nesting birds.
The Red Queen effect is a concept now widely known by aficionados of biology. The phrase is from Alice Through the Looking Glass, but the biological concept was first developed by Leigh Van Valen, a biologist at the University of Chicago.
While the Red queen and Alice are discussing chess, the following dialog and events ensue: Continue reading Parasitic Birds and The Red Queen Effect
Let The Eagle Soar
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| Golden Eagle |
I hope I won’t disappoint you … this is not about John Ashcroft. It is about golden eagles (actually, maybe its about one golden eagle in particular).
The golden eagle (Aquila chrysaetos) has been in decline for a very long time, so you may not know it formerly bred in a much wider range of habitats, across the entire U.S. Today it is known as a mountain eagle because this is where it is generally found, at least in North America. Any experienced birder will tell you that in places like Minnesota nine out of ten, or maybe 99 out of 100 golden eagle sightings are immature bald eagles.
Last winter my wife, Amanda, and daughter, Julia and I attended a talk (on owls) at the Minnesota Raptor Center in Falcon Heights. While there we took a tour through the facility, where several captive birds are kept. Some of these birds are in rehab and will be released, others are permanent residents because of some major disability. As we were shown around, the gracious and knowledgeable volunteer told us “Golden Eagles are not native to Minnesota. You never see them here. We get a lot of people telling us they saw a golden eagle, but I guarantee you it is always an immature bald….” And at that moment we were directed around a corner to see, in all it’s glory, a majestic golden eagle in one of the enclosures. Now, this was just after the “all our birds are brought here by our people or game officers from locations all over Minnesota” speech, so I said … “Well, there’s one there … in that cage … a golden eagle. There must be some of them in Minnesota.” I was trying not to be snide, really. The volunteer made some sort of apologies for the eagle being there, admitted it was brought in from a site in Minnesota, but stuck Continue reading Let The Eagle Soar