4 and 20 Blackbirds

Well, not only blackbirds, but grackles, descended in a large flock (maybe 100 birds), some concentrating on spilled seed on the ground, others attacking the feeders to displace even more seed onto the ground.

Males jockeyed for position on the feeders.

There was a noticeable pecking order: male grackles over male red-winged blackbirds, over lowly females of either species, who fed almost exclusively on the ground and in the wildflower garden. Grackles aggressively dominated the suet feeders and tried to fit their big wide bodies on the seed feeders desiged for chickadees.

Blackbirds have lost their glossy black exterior and are brown instead, resembling the female plumage, but still have their bright red and yellow wing patches, which they flare out when trying to displace another bird.

Grackles haven't lost any of their brilliant breeding colors, because they have iridescent feathers. There is quite a range of color on the males, from the brilliant light blue on their heads, to the deep purple on their backs, and brown on the sides. Getting pecked by that long saber of a bill must really hurt.

Male grackles were quite aggressive toward one another at the feeders, as well as the blackbirds, as illustrated below. It's clear who the top dog is.

Does this look like a scene from "the Birds"? It doesn't really capture the moment accurately because there were probably five times that many birds, and they were all squawking continuously.

Forming a huge flock like this in the fall is typical in migratory birds. They get the advantage of many eyes to find food and to detect and ward off predators, but with such a feeding hierarchy you wonder if the bottom of the pecking order really gets enough food to make the migration.

Cold Goldfinch

This has been the longest and nicest fall weather I can remember since we moved to Minnesota. But we now have reminders every morning of the cold weather on its way as the temperatures dip into the 30s overnight. I was surprised to find lethargic Goldfinches in the garden on two of these nippy mornings this week; they sat quietlly allowing me to approach within a few feet. Their plumage was so fluffed out they looked like little round puffballs.

I found this one sitting on the ground near the bird bath I was filling. Of course I didn't have a camera with me, but he/she was still there when I went back with the camera in hand.

Could those feathers get any more fluffy?

The bird appeared healthy enough, with its alert eyes following me as I walked around it. It moved into the sun a few minutes later, and then flew off into the weeds near the bird feeder.

Fall weather is hard on all us homeotherms, as we try to rev up the metabolism that keeps us warm. Acclimation to cold typically takes a few weeks as increased thyroid hormone helps us increase heat production and changes in blood flow to the skin reduce heat loss. Decreased hours of daylight here in the far north means less time for animals to fatten up during the day to fuel the metabolic furnace overnight. Maybe these little guys (they only weigh 12-15 grams, about the same as a fast food ketchup package) just run out of energy on those colder nights and need more time to rewarm during the morning. I know mortality is much higher in the fall than in the middle of winter for these small birds. Once they get fully acclimated to cold they can withstand temperatures as low as -70 F for a few hours, and -40 F for 8-12 hours (based on studies done by a colleague in Michigan many years ago).

How different these drab winter plumaged birds are from their golden summer color. Here are two Goldfinches sitting in the same part of the garden, on the stems of Purple Coneflower. (click on any of the photos to enlarge to full size)

Woodpeckers are eating my house!

I like birds and enjoy watching them flit around in my yard, but the woodpeckers I once tried to attract to my yard with suet feeders, I now want to exterminate. Here's what they have been doing to the house this summer and fall. These holes are in the west wall of the 3-season porch, and there are similar drilled sites in the north wall of the new garage. Both are cedar siding; there are no holes in the harder, older redwood siding. So that's my first clue to what they like -- soft, hollow wood.

The damage isn't just in one spot near the eave; there are myriads of tiny holes they have drilled as "experiments" up and down the wall. Many people must have this problem because there are many links to "how to control woodpecker damage" on the web.

This hole is big enough to be a nest cavity. It might have served that purpose, but I wasn't paying attention back in the early summer. That's some pretty impressive drilling.

Why are they doing this? Theories abound on the web:

• Looking for insects in old, rotten wood (nope, the holes are in the newest wood on the house)


• Drumming to attract mates (maybe early in the summer, but that doesn't explain why they are still doing it now)


• Creating holes to store food (I don't see anything in the holes, but this is something that western Acorn Woodpeckers do)


• Because it's soft wood, that sounds good when you peck at it, and they're bored (my favorite theory because so far I've only observed them pecking at the walls on warm, sunny days).

I tried to take some pictures of the offenders. They don't sit still and their little heads are constantly in motion when they're pecking.

Their head vibrates like a jack hammer against the wood 100 times a minute, which makes me wonder why they don't get a headache. And the deceleration of the head when it actuallly strikes the wood has been measured at 100X the force of gravity. Obviously woodpeckers have some astounding adaptations that permit this lifestyle.

• The force of the bill strike somehow passes underneath the brain through the bill and neck muscles, which are thick and reinforced to absorb the shock.


• Reinforced bone in the skull, especially around the eye sockets.


• Cervical vertebrae with ribs for attachment of these big neck muscles.


• Incredibly long tongues with barbs on the end for spearing prey deep inside those holes they are drilling. The tongue support actually wraps around the back of the skull under the skin, when the tongue is retracted.


• Two toes point forward and two point backward to help brace the bird in a vertical posture on the tree. The stiff feathers in the tail are also used as vertical braces, allowing the bird to lean far away from the tree and accelerate its head rapidly forward to strike with maximum force, like this.

Pretty cool, huh?
Almost cool enough for me to forgive their destructive habits.

Some videos that demonstrate the incredible rate of tat-a-tatting in woodpeckers:
http://www.youtube.com/watch?v=fSGK2MTsTv8 AND
http://www.youtube.com/watch?v=fOG-fgx4QrY&feature=related

Decorative Duck

Nature went overboard in selecting colors for male Wood Ducks. You might expect such a brightly colored species to be tropical, but in fact Wood Ducks are entirely North American, breeding in the Eastern US and southern Canada, and overwintering in the southeastern US and Mexico to Central America.

In contrast to her ornamented male partner, female Wood Ducks are rather plain brown with bright blue under the wing.

Wood Ducks are dabblers, meaning they feed on suspended matter in the water, but they also eat a variety of food on land (e.g., acorns and insects), so they really are omnivores. However, what they were feasting on this particular morning was duckweed. I always wondered if duckweed was actually eaten by ducks or they just swam around in it. But Wood Ducks seem to love it.

This is one of the rare ducks that can perch on limbs (they have sharp nails at the end of their webbed toes) and nests in tree cavities, preferably above water. After incubating their large brood of up to 16 eggs for 30 days, they encourage their hatchlings to launch themselves out of the nest. Of course they can't fly at this stage, which is why a water landing is preferable. I found three females sunning themselves on a tree branch in the early morning before setting out to feed.

There was only a single male on this particular lake, but at least six females (or perhaps the young of the year) accompanying him to feed.

Like the Great Egret, Wood Duck feathers were heavily utilized in the hat industry in the early 1900s, causing a significant dip in the population. Introduction of nest boxes in prime wetland habitat, as well as protection through the Migratory Bird Treaty allowed their population to rebuild.

Even in the shade the coloration of the male is a bold pattern.

Bluebird morning

I went out this morning to look for the Trumpeter Swan family that I saw yesterday (when I didn't have my camera along...). I couldn't find them but I did stumble across a flock of bluebirds cavorting in the weeds next to the "swanless" lake. Bluebirds make good subjects for bird photography because they pause once in a while to look around and see what they want to chase next. Some of their chosen perches were well within the range of my zoom lens in some very photogenic scenery.

How's this for a little fall color matching?

Males still sport the bright blue color on their heads, wings, and tails, which contrasts sharply with the ruddy brown color of the breast feathers. You might not realize that there is no blue color pigment. Instead blue is a "structural color", meaning that it is produced by the feather structure itself. Tiny particles in the feather (smaller than the wavelength of red light) scatter only the shorter light wavelengths in all directions. Thus blue color is reflected from the feather at almost all angles from which it is observed.

Bluebirds like to hunt from a perch, diving into the weeds to chase insects, or hovering above them like a flycatcher. Knotholes on the pines made excellent perches for these hover hunters this morning.

Eastern bluebirds like these seem to be quite common here in the upper Midwest, thanks to the efforts of landowners and park managers who have installed "bluebird boxes" near their ponds and lakes. These artificial nesting holes boosted the bluebird breeding population, which was unable to compete successfully with introduced House Sparrows for natural nest cavities. Typically two "bluebird boxes" are installed about 30-40 feet apart in fields or woods near a source of water. Why two boxes? To insure that there is at least one box for the bluebirds, while the other may be taken by Tree Swallows, Chickadees, House Wrens, or House Sparrows. These species are more likely to tolerate close presence of a different species than one of their own kind.

Heron Cafeteria

I discovered a hot feeding spot for the Great Egret (also known as the Common Egret, but really a heron) while waiting for Alison to start her photo shoot at the Roseville "arboretum" the other day. There were 20 or 30 birds wading in the shallows vigorously attacking whatever swam near them. Fortunately they were amazingly tolerant of walkers on the trail right next to their marsh, so I could stand there without scaring them away.

Wait a minute, who is the ugly duckling is this group of all white herons?

It's the slight larger but close relative, the Great Blue Heron, which also has a white morph in some areas of the world (e.g., Florida). Like the GBH, the Great Egret is found world-wide, and seems to tolerate urban life well because it can be found in lakes and marshes near residential areas.

They are so interesting to watch while they hunt, quickly stretching out their snake-like neck to stab with that long beak at fish, frogs, or whatever else is swimming around down there.

The sun was in just the right position for hunting on this morning, but in mid-day, I've seen them spread their wings like an umbrella around their head and neck to cast a shadow so they can see what is in the water below them better.



When they have exhausted this food supply, they will move on to other lake shallows, building up their fat reserves to leave Minnesota as the temperatures drop and the lakes freeze here.

Interesting note: This species was once hunted almost to extinction back in the 1800s and early 1900s, when fancy bird plumes on ladies hats were stylish.

Another relative seen less frequently in the shallows is the Green Heron. I was lucky to sneak up on this bird this summer and use the highest magnification of my telephoto to get this picture. Green Herons are really secretive and fly away at the slightest disturbance. In fact, they seem to be more nocturnal than diurnal, so this mid-day sighting is a rare one. Perhaps it was foraging for its chicks. Green Herons also have a trick to help them catch fish and frogs -- they drop small sticks or even parts of insects to attract fish to the surface and then grab them with their sharp beak.

That's not grass the bird is standing on. This lake was so shallow and still that the water was completely overgrown with green algae. You wouldn't think that would be a great place for fish to live.

It's not a hawk, it's not an eagle --

It's an osprey, and although it looks like a small bald eagle, it is not really closely related to them.  In fact, there is only one species of osprey, distributed world-wide, and it is so different from hawks, falcons, eagles, and owls, that it is classified in its own family.



It's becoming more common to find ospreys nesting in parks, and this pair took up residence in a ball/soccer park in Maple Grove.  Similarly, an osprey nest at the Roseville ballfields made the local newspaper because the birds were so cooperative in posing for photographers. The lights make a perfect nesting platform, once a few sticks have been added.  The female lays two to four eggs and incubates them for 40 days (a long boring stretch of sitting in the hot sun).  The number of young raised depends on how many fish the parents can catch.





Males take care of most of the feeding and make frequent deliveries of fish to the chicks for about 6 to 8 weeks.  Osprey chicks are especially vulnerable to predation from Great Horned Owls and Racoons, so the female usually stays close to the nestlings.



Sometimes, it only takes one foot to grab and immobilize the fish, like this bird is doing here.



Osprey have remarkable feet, as well as wonderful eyesight, to help them catch fish feeding near the lake surface.  Like owls they can rotate their outer toe backward to oppose the other two, giving them a two prong pincer to immobilize their prey.  In addition, they have rough, barbed scales on the bottoms of their feet that help grip and stabilize that wriggling, squirmy, slimy fish.



Six weeks after hatching, young osprey like this little guy above, look like miniatures of their parents, but are not yet ready to catch fish on their own.  They might leave the nest and undertake short flapping flights to the nearest tree, but are still probably fed largely by the adults.





Seeing free-flying birds like this in a semi-urban area is a thrill.  Like the Bald Eagle, osprey almost disappeared from North America in the 1960s due to contamination of the water and their fish prey with DDT and related pesticides as well as PCBs used in plastics manufacture.  Vigorous reintroduction programs begun in the 80s and 90s (in MN) helped re-establish breeding pairs in the state.  Since osprey mate for life and offspring return to the area where they were raised, the Minnesota osprey population seems to be a healthy one again.

Hawks We Have Seen

The other day I was out looking for dragonflies when I saw this beauty in the tree just above me.  She (I think it was a she because it was a BIG bird) was sitting at the edge of a grassy old field full of wildflowers, scanning for mice or snakes or frogs or whatever appealed to her at the moment.  And she was completely oblivious to my creeping up on her to take her picture. 



This is an adult Red-tailed Hawk (you can tell by the red tail -- duh).  This species is one of my favorites.  Years ago I published (an interesting, I thought) paper about them, comparing their daily energy budget with that of their temporal counterpart, the Great Horned Owl.  Both species are common and are year-round residents all over North America, meaning they stick around throughout the nasty winter as well.  Unlike the owls, however, Red-tailed Hawks will lower their body temperatures at night during the winter when they run short of food and have failed to eat for several days.  This mild hypothermia allows them to balance their energy budget.  Perhaps being a nocturnal hunter allows owls to have greater hunting success, because their body temperature is absolutely stable at very cold temperatures, even when they are food-deprived.  Like humans, the feet and the head are two key areas of heat loss in hawks.  Both areas are well insulated by feathers in owls -- that might make a difference in the cold.  Check out those sharp talons in this picture (click on it to enlarge).  Could anything escape these pinchers?

Like many birds of prey, these hawks enjoy really superb binocular, color vision that enables them to pick out the tiniest moving objects in complex backgrounds.  In addition, they have two different fovea (focus spots) in their retinas, one in the back of the eye like us, and one near the top of the eye, which allows them to focus on objects below.  I finally got too close to this bird, and she began to focus on me, as you can see here.  She sort of looks cross-eyed.

The Gold in my Garden

The wildflowers in the backyard are stunningly colorful right now: red, yellows of various sorts, purple, pink, lavender, greens of all sorts. Even the weeds are pretty. The colors or the smells or both are attracting a wide variety of insects and birds, especially one. Do you see him peering out between the coneflowers? (Hint: he's bright yellow and black). Yup, it's the American Goldfinch, also known as the Eastern Goldfinch or Wild Canary.

This is the breeding plumage of the male. He will drop these colorful feathers to look much more like the drabber and far less yellow female during the winter, when Goldfinches get together in large flocks to scour the countryside for seeds. But you can still recognize them by their striking black and white wing patches. You can tell how small these little finches are by comparing him with the size of the coneflower. They only weigh about 12-15 grams (roughly the equivalent of a McDonald's ketchup package).



After feasting on the seeds just beginning to form in the Blazing Star outside my kitchen windows, the Goldfinches have moved on to the very tall Cup Plant on the border of the wildflower garden. They tug and pull at the innards of those flowers like they are trying to dismember them, and bend the flowers by hanging upside down on the ends of the stems to reach inside.

The camera is almost unable to distinguish their yellow color from that of the flowers.

Life is great for Goldfinches now, but in a couple of months when the temperatures dip below freezing and the daylight decreases to a bare 8 hr per day, Goldfinches will remain in MN, unlike many of our summer bird species. Even though they are quite small, Goldfinches are veritable furnaces of heat production. They can maintain a warm and constant body temperature, even at -40 F overnight! That's the advantage of eating seeds, which provide a fat and protein-rich diet. Even nuthatches and chickadees, which eat insects during the summer, switch to eating seeds at your bird feeders during the winter. By foraging in large flocks during the winter, Goldfinches take advantage of the "many eyes" strategy to find new food sources while watching out for potential predators.

They're baaaack....

Many of us have reported seeing turkey hens and babies in the backyard the past couple of weeks.  This is a welcome sight because turkeys became extinct in Minnesota in the 1880s, probably due to over-hunting and loss of habitat and food supply as more people settled in the midwest.

How did they make a comeback?  In the 1970s Minnesota DNR traded walleye, prairie chickens, ruffed grouse, and hungarian partridge (an introduced species) to Missouri and neighboring states for wild turkeys, allowing them to get re-established in woods and fields far from agriculture.  Apparently the climate agreed with them, or at least they tolerated the frigid, snowy winters and the tropical monsoon summers to thrive well enough to allow their population to increase markedly.  Now there is both a fall and spring hunting season on them in MN, and I know some Minnesotans brag about the great taste of a wild turkey at Thanksgiving.



In April this year, a handsome Tom and his three lady friends visited the bird feeders in my backyard, picking up the leftovers the birds and squirrels had missed.  We saw them a couple of times this spring, but it was a long time before we saw them again in early July when a herd of females marched across the backyard on their way to the woods.  Last week, two hens brought their new and not-so-new chicks through the backyard to feast on the insects in and around the wildflower garden.  They were too shy of me trying to take their picture to pose nicely and made a beeline for the deep woods at the back of the yard.



I could only see 6 or 7 chicks, of two different ages in this bunch, and since Turkeys lay about 8-10 eggs in their ground nest, a lot of the babies must have been gobbled up by foxes, raccoons, or possums.  Baby turkeys, like chicks, are precocial, which means that they can run almost immediately after hatching, quite unlike the baby robins which are like limp noodles for the first 4-5 days of their life.  They can also feed themselves, which makes the hen's job mostly protection.  This is probably also the reason that hen turkeys raise their young together, forming flocks of up to 30 birds of varying ages in the midsummer.



Turkeys eat  a variety of insects, seeds, and young, rapidly growing weedy plants through the spring and summer, so they are a help to your garden in getting rid of weeds and pests.  In the fall their diet switches to nut crops, like acorns, which allows them to put on a thick layer of fat to help them survive winter cold.

Turkeys CAN fly, even though Toms may weigh up to 20 pounds!  In fact, with those powerful breast muscles (that we like to eat) they can zoom over tree tops at 55 mph. They roost at night in trees, which keeps them safe from the nocturnal ground predators.