While we were walking around Bluestem Prairie in northern Minnesota a couple of days ago, we encountered a busy pair of Kingbird parents who were feeding their fledgling chicks. The parents continually cruised out from the bush’s top branches and brought back tiny meals to the chicks every few minutes.
It’s prime time for summer flowers, and the bumblebees and honeybees are making the rounds carrying pollen from one flower to another and sipping nectar as their reward.
It’s a particularly busy time of year for prairie bird parents — all those open mouths to fill. And it doesn’t stop when they fledge and leave the nest because the youngsters just follow the parents around and continue begging for food.
Minnesota prairies are in full bloom, and the ones that were burned this spring (as part of the prairie maintenance) are especially colorful right now.
It’s not your usual Fourth of July today, so I looked at what the Backyard Biology blog posts for previous years showed. Here’s a post from 2014 that is appropriate for today’s world.
For those of you who might have wondered why red, white, and blue were chosen for the U.S. flag, here’s the description from USFlag.org:
The colors red, white, and blue did not have meanings for The Stars and Stripes when it was adopted in 1777. However, the colors in the Great Seal did have specific meanings. Charles Thompson, Secretary of the Continental Congress, reporting to Congress on the Seal, stated:
“The colors of the pales (the vertical stripes) are those used in the flag of the United States of America; White signifies purity and innocence, Red, hardiness & valour, and Blue, the color of the Chief (the broad band above the stripes) signifies vigilance, perseverance & justice.”
Perseverance in pursuing justice might be something to keep in mind from this holiday going forward in 2020…
Do the birds feel as hot as we do on a 90 degree day with 90% humidity?
Probably not, plus they can rise above the heated landscape, like these White Pelicans that ceased feeding in the shallow pools at Sherburne National Wildlife Refuge to ride the thermals above us.
There was plenty of action going on in those shallow pools, with Black Terns, a Loon, a few Cormorants, and a couple of herons competing for fish with one lone Pelican, while Trumpeter Swans and some dabbling ducks foraged on the vegetation.
Some of the Black Terns have begun their molt to winter plumage already. Eventually their trademark black head will be white with a black cap and ear flaps, and their sooty gray breast will be white after the molt is complete.
When I was looking up information on the Blue Grosbeak (previous post), I was surprised to discover it was a member of the Cardinal family, which turns out to be quite a large and diverse, but extremely colorful set of bird species. It also turns out that I have blogged about this before, when I have photographed some of the other North American species in this family (short memory!).
The Cardinalidae family consists of Buntings, Grosbeaks, Tanagers, Chats, Seedeaters, and Cardinals, 14 species of which can be found in North America at some time of the year — so far, I’ve managed to photograph 12 of the 14. Although the species look very different from one another and live in very different places, they are all medium-sized, stocky birds that use their somewhat overly large bill to consume seeds, fruits, and insects of all sizes. As a group, the males exhibit bright coloration and females are more muted in color.
the Buntings — make liberal use of blue structural coloration, in addition to several other bright pigments in their plumage.
the Tanagers (most of the Tanagers are in their own family — but ornithologists have decided several of them are more closely related to the Cardinalidae.)
the Grosbeaks (well-named for their overly large seed-crushing bill)
the Cardinals (only two members in North America)
lastly, the Dickcissel — not a member of any group
There are Bluebirds …
and then there are really blue birds.
Blue Grosbeaks are a rarity in this part of Minnesota, but they are another example of a species that is expanding its range northward in recent decades as forest land is cleared for housing development and agriculture. They favor patches of shrubs and deciduous trees and old farm fields to set up housekeeping and raise a family before flying back to their winter headquarters in Mexico and Central America.
Indigo Buntings and their relatives the Blue Grosbeaks are some of the bluest of blue-colored birds. Blue Jays and Bluebirds pale (literally) in comparison to the deep blue color of the two buntings (grosbeaks are technically a type of bunting).
As you may know, birds do not have blue pigments in their blue feathers — the color is achieved by structural elements in the feather (keratin deposits that surround small air pockets) that reflect the short wavelength blue color back to the viewer’s eye. Without this structural interference in the transmission of light through the feather, it would look brown — the color of the underlying melanin pigment.
So, why are some birds so much bluer than others, males bluer than females, Indigo Buntings and Blue Grosbeaks bluer than Blue Jays? Inquiring minds want to know…but there don’t seem to be answers, other than vague references to the importance of bright colors in males compared to females. And here’s another thought to ponder: are “blue birds” blue to other birds — or can they see patterns in the blue reflected light because they can see/process shorter wavelength light than humans can?
The youngster didn’t want to be photographed, but it just couldn’t resist the red serviceberries, and had to pluck a few.
In previous posts, I made the case that some bird species adapt well to the human urban/suburban landscape, increasing in numbers as they make use of the rich resources of our gardens and backyards. Other species, not fussy about where they live, what they eat, or how inclement the weather have also increased in numbers in our backyards because they are generalists whose survival strategy is simply to make use of whatever is available.
A third and more recent influence on the local abundance of particular birds is the changing climate in the last 100 years. Not only has the average winter temperature here in Minnesota increased 4-6 degrees F, but the winters are shorter, less snowy, and more unpredictable in severity.
Two species in particular have responded to that warming trend:
A monograph published in 1916 by Thomas S. Roberts MD for the Minnesota Geological and Natural History Survey listed Cardinals and Robins as “accidental” occurrences in Minnesota during the winter. Dr. Roberts even stated: “Records of the occurrence of this common cage bird [Cardinal] are always open to the suspicion that the individuals seen are escaped captives.” In 1916 there were just two dozen records of Robins having been seen in sheltered locations in southeastern Minnesota.
Two other common residents of our backyards most of the year, Crows and Goldfinches, were listed by Dr. Roberts as mere “visitors” to the Minnesota winter landscape, being rare occurrences 100 years ago. Of course it may not just be a response to changing winter climate that has caused increases in numbers of these birds. Goldfinches are attracted to backyard bird feeders, which makes it easier for them to find sufficient food in the winter. Crows are adept at avoiding cars while feasting on road-killed animals, and there certainly are more of those than 100 years ago.
The northward expansion of bird species includes migrants coming from tropical areas as well. For example, Blue-winged Warblers and Orchard Orioles migrate much farther north to breed than they did 100 years ago. In fact, because of their northward expansion Blue-winged Warblers now encroach on breeding areas of closely related Golden-winged Warblers and may be a cause of marked population decrease in Golden-winged Warblers.
Northward expansion includes birds moving their year-round residence from tropical areas that are heating up to cooler areas in northern North America. For example, there were no Great-tailed Grackles north of the Mexican border except in southern Texas in 1934. Steadily moving north, they reached southern Arizona, then Houston, Oklahoma, California, on to Missouri and Nebraska, and finally Iowa by 1983. The species has become a common sighting throughout a vast area where it was completely unknown a century ago.
The real problem with this northward expansion of breeding and winter ranges of birds is that birds use the changing photoperiod (daylength) to time their annual cycle and come into breeding condition, but the plants and insects on which they rely to sustain themselves and raise their chicks depend on the temperature cycle of the local area — which may not necessarily be synchronized with photoperiod. In a warmer year, insect and flower blooms may take place before birds arrive at far northern latitudes, and birds may not have the resources to produce young that year, or even sustain themselves for their southern migration.
Here’s an interesting read on the subject from Audubon.