on the edge

Tromping around Weaver Dunes, south of Wabasha MN, for 8 hours trying to identify every bird we could find was exhausting but rewarding, and what an absolutely beautiful day to participate in The Nature Conservancy’s bird blitz on May 12.

Cape May Warbler-

First bird of the day — Cape May Warbler, high in a leafy tree (bane of photographers — the tree, not the bird)

The spring migration was running a little behind schedule, but we managed to find (and identify) 58 species (which admittedly doesn’t sound like a lot for 8 hours of work).  We explored a variety of habitats, but the best places to look were edges between shrub and forest, or prairie and forest.

Yellowrump Warbler-

Yellow-rumped Warblers outnumbered other warbler species, and thankfully posed at much lower elevations in the trees.

Rose-breasted Grosbeak-

We only saw one Rose-breasted Grosbeak, and he was quite shy about coming out in the open to show off his raspberry bib.

Lark Sparrow

Lark Sparrows were more common than the warblers, flashing their white outer tail feathers as they flew. True to their name, their song is much more of a warble than a buzz — i.e., lark-like.

Lark Sparrow

Lark Sparrows typically nest in shrubs and forage in grassy areas removed from the nest. They have the unusual habit of walking, instead of hopping.

Northern Waterthrush-

Down at the edge of a small pond, a Northern Waterthrush hunted for insects.

Northern Waterthrush-

A distinctive eyestripe and wagging tail made this large warbler easy to identify.

Brown Thrasher-

A Brown Thasher was very uncooperative about posing, and remained hidden in the dense foliage of trees in the grassy savannah.

Baltimore Oriole-

Orioles foraged high in leafy treetops, but were easy to find by listening for their characteristic song.

Gray-cheeked Thrush-

Another edge-lover found skulking among the low vegetation in the woods surrounding a pond was the Gray-cheeked Thrush, with its characteristic white eyering.

Our efforts were added to those of the birders walking other TNC properties throughout the tri-state region of MN, North Dakota, and South Dakota.  Together all observers on May 12 found over 200 different bird species, or approximately 50% of those known to reside or pass through MN on migration in May.  Not bad…it’s a nationwide competition, so we’ll see how MN bird numbers stack up with those elsewhere in the U.S.

Considering that our American birds have to navigate and survive stormy weather and drastic climate changes, glass windows and glass-covered buildings, marked habitat alterations, and depleted food supplies from all the pesticide and herbicide applications, it’s a wonder that we see the diversity that we do.

Why is Fall the best of the four seasons?

Number 1 (for me) has to be the colors of Fall — they’re bright, warm, and make us (well, me, especially) want to be outside communing with Nature.

Beaver River Falls, Beaver Bay, MN

How could you resist a walk along this river admiring the fall foliage?  I think this is the last waterfall before the Beaver River empties into Lake Superior (near Beaver Bay).

Number 2 might be the temperature — warm days, cool nights, always changing, something for everyone…

mississippi-river-fall-color-

Perfect temperature for canoeing down the Mississippi River

mississippi-river-fall-color-

Or for studying outdoors in a warm, sunny space. If you get too warm, you can just move into more shade.

Number 3 is a little more abstract:  the effect of short daylength on our brains makes us a little lazy and lethargic (or is it the warm sunshine?); long nights give us the perfect excuse to get more sack time.  The end result is we might feel more rested and less stressed (or is it the warm, bright colors of fall that do that?).

human-hiberanation

Beginning in the Fall and continuing through the winter, extended periods of sleep are common in some human cultures. Drawing from the British Medical Journal article on Human Hibernation

Number 4 is the fact that Fall is harvest season — it’s a time of plenty, for both humans and animals.

Sometimes the "harvest" is almost too big to carry...

Sometimes the “harvest” is almost too big to carry…

Scads of berries, nuts, seeds, and fruits are available for primary consumers, along with a large supply of young, naive prey animals for the predators.

yellow-rumped-warbler-eating-cedar-berries

With their high sugar content (30%) these berries are a great resource for migratory birds like this Yellow-rumped (Myrtle) Warbler. Even the waxy coating on the berry can be utilized by the birds, whose digestive systems have been primed to secrete an enzyme to break down the wax esters.

At other times of year, consumers most likely face food shortages, with scanty plant and animal productivity during winter and spring, and limited food supplies during much of the summer as plants and animals are growing the next generation.

I’m sure there are many more reasons why Fall is the best time of year — or do you disagree?

mississippi-river-fall-color

Fall color along the Mississippi River. Click on the image for a larger view.

Berry pickers

Eastern Red Cedars are loaded with plump, blue berries that look ripe for the picking.  To be completely correct here, Red Cedars aren’t really cedars — they are junipers, and the berries aren’t really berries — they are cones with a fleshy covering.

Yellow-rumped Warblers and Cedar Waxwings were swarming “fruit”-laden branches at the St. Paul Reservoir the other day.  The warblers, in particular, were comical to watch as they attacked the “fruits” which were almost too big for them to get into their mouths.

yellow rumped warbler eating red cedar (juniper) berries-

The new growth where most of the berries were found weren’t strong enough to support even a 15 gram warbler, so the birds hung upside down to get them.

yellow rumped warbler eating red cedar (juniper) berries-

Dense foliage of the red cedar provides great protection from predators, too.

yellow rumped warbler eating red cedar (juniper) berries-

The top of the tree provided a little better support for berry picking.

yellow rumped warbler eating red cedar (juniper) berries-

Sometimes, berries were snatched on the fly.

With their high sugar content (30%) these berries are a great resource for migratory birds.  Even their waxy coating can be utilized by the birds, whose digestive systems have been primed to secrete an enzyme to break down the wax esters.

Junipers (and in particular the Eastern Red Cedar) leaves and “fruits” contain other useful compounds, one of which is a fairly potent antiviral against common flu and herpes viruses. Florida’s Seminole Indians used juniper extracts to treat colds, swollen joints, stiff neck and back, eye diseases, fever, headache, diarrhea, etc.   In addition to teas brewed to relieve these ailments, juniper berries have been used as flavorings in gin and French Chartreuse liqueur, as well as several wild game recipes.

red squirrel eating red cedar berries

Even the Red Squirrels enjoyed feasting on the prolific crop of juniper berries.

Just the beginning

As nighttime temperatures dip toward freezing, the trees are starting to show a little color.  It’s just the beginning of the most colorful season of the year —

beginning fall color-

Warm days and cold nights signal plants to cease photosynthesis and begin breaking down the chorophyll pigment in their leaves to unmask other, colorful light-gathering pigments.

Fall weather and decreasing day length signal animals to begin making preparations for winter — either storing food (like the squirrels have been doing) or eating like crazy to get fat enough to migrate south.  Waves of warblers and other small songbirds have been moving through the Twin Cities recently, and some wind up in the backyard, looking for insects on late-blooming plants.

female or juvenile yellow-rumped warbler-

Large flocks of Yellow-rumped Warblers move quickly through the vegetation, but occasionally stop to pose for a photo.

showy goldenrod-

Only a few species of perennial plants are still flowering here, like this Showy Goldenrod that is buzzing with several species of insects.

showy goldenrod pollinators-

Pollinators looking for a late autumn meal of nectar and/or pollen crowd onto a Showy Goldenrod plant that stands out in a field of Little Bluestem grass.  In addition to the bumblebees, two species of hoverfly, a beetle, and a small wasp were foraging here.

sulfur butterfly on new england aster-

New England Aster was buzzing with Pink-edged Sulfur butterflies, bumblebees, and hoverflies.

Seed-eating migrants might find a banquet waiting for them too, as perennial plants put forth their seed crops.

canada goldenrod seed head

Canada Goldenrod seeds are buried in the wispy tendrils that help disperse the seed around the prairie.

indian grass-

Perennial grass seeds are ripe for the taking as well.

With all the rain late this summer, I hope this will be one of the most colorful fall seasons in recent years.  But that depends on the day-night temperature differences in the next few weeks.  So, stay tuned for more posts on fall color later.

Warbler bonanza

What a morning!  Here in the Twin Cities we went from a few migratory birds to a lot, from one warbler species (Yellow-rumped) to many in the space of just a couple of days between storm fronts.  I was getting whiplash from spinning around shooting photos at Veteran’s Park south of Minneapolis. Rather than tell stories about each of these bird species now, I’ll just present the array for your spectator pleasure, and save the biology for later.  I saw a total of 11 warbler species, but only got decent photos of 7 of them.

black and white warbler

Black-and-white Warblers are well named and easy to recognize. They specialize in gleaning insects from bark and spiral upward (or downward) around the trunk of the tree. They remind me of a nuthatch in the way that they forage.

chestnut-sided warbler

Chestnut-sided warblers are also insect gleaners, preferring to work the foliage of the smaller branches on trees and shrubs. They have a golden cap, which you can’t see very well in this photo, in addition to their rust-brown sides.

common yellowthroat

The Common Yellowthroat Warbler is easy to spot in dry cattails or the low grass along the shore, but this bird is constantly on the move, and almost impossible to catch in a momentary pause.

nashville warbler

Nashville Warblers are supposed to concentrate their foraging efforts in the lower branches of the trees, but the only ones I’ve seen are way up in the top. Bright yellow bellies contrasted with gray head and back is typical of several warbler species, but this one has a white eyering!

palm warbler

Palm Warblers forage more on the ground than other warbler species do, digging through the leaf litter to find insects. This bright yellow fellow is, of course, much more colorful than his drab mate, but both of them have the signature chestnut cap and yellow eyestripe.

yellow-rumped warbler

The most common of the warblers that migrate through this area — the Yellow-rumped Warbler. Affectionately known as “butterbutts” for their characteristic flag of yellow rump feathers, they also sport a very handsome vest of black chest feathers beneath their black mask and slate-blue caps.

And last, but not least, the glow-in-the-dark Yellow Warbler, who frequent wet places near the shoreline of lakes and streams.  This one is my favorite -- because he sits still for more than a nanosecond.

And last, but not least, the glow-in-the-dark Yellow Warbler, who frequents wet places near the shoreline of lakes and streams. This one is my favorite — because he sits still for more than a nanosecond.

Fruit lovers

Out in my mother-in-law’s California backyard, the persimmon tree is drooping with fruit. The tree is deciduous in the winter, leaving just the bright orange globes hanging from rather spindly stems.

persimmon fruits

Persimmon may be an acquired taste for some (humans), but the animals love these juicy orange fruits. I found a variety of birds feasting on the semi-rotting pulp, as well as a gray squirrel.

A female (or juvenile) House Finch inspects the fruit to determine which one to peck.

A female (or juvenile) House Finch inspects the fruit to determine which one to peck.

The sharp, chisel beak of a Scrub Jay can open up these fruits so other birds can feed on them.

The sharp chisel beak of a Scrub Jay can open up these fruits so other birds can feed on them.

scrub jay feeding on persimmon

A flock of Yellow-rumped Warblers swarmed the fruits, digging into the gaping cracks in the fruit left by  larger-beaked birds

A flock of Yellow-rumped Warblers swarmed the fruits, digging into the gaping cracks in the fruit left by larger-beaked birds.

yellow-rumped warbler eating persimmonMockingbirds, and even Anna Hummingbirds, made their rounds through the persimmon tree for a bite of fruit or a stray insect attracted to the rotting fruit.  But the major consumer (by volume and time spent snacking) was the Gray Squirrel, who grabbed the fruit with his front legs while stuffing his head deep into the fleshy interior.

Can't get enough of this good stuff.

Can’t get enough of this good stuff.

Persimmon is originally from China, but is grown all over the world.  I love them, but many people don’t because of their astringent skin that imparts an unpalatable “furry-ness” to the fruit if not peeled correctly.   However, the fruit has a high glucose content (a whopping 33.5 g sugar/100 g fruit), so it provides quick energy to hungry animals.  Like many fruits, it is low in protein content (only 0.8 g/100 g fruit), although perhaps birds supplement their protein by eating the insects that are also attracted to the fruit’s exposed fleshy interior.

Another spectacular fall day

At William O’Brien State Park, near Marine-on-St. Croix, MN for an enjoyable 2-hour hike through their restored prairie and woods.wmobrien state park

wm o'brien state park

wm o'brien state park

wm o'brien state park

wm o'brien state park

wm o'brien state park

A Yellow-rumped Warbler wonders where all of his friends have gone (they left before the last weather front moved in).  This bird was hanging out with the juncos instead.

A Yellow-rumped Warbler wonders where all of his friends have gone (they left before the last weather front moved in). This bird was hanging out with the juncos instead.

Just passing through…

The peak of warbler migration may already be past here in Minnesota, but there are still a few around.  I found a hotspot for warblers yesterday at Tamarack Nature Center in a drying marsh that had sprouted a carpet of nodding bur-marigold.

This flat space used to be a pond -- it has dried up entirely as a result of our rainless summer.

This flat space used to be a pond — it has dried up entirely as a result of our rainless summer. There is a monoculture of Nodding Bur-Marigold which has attracted hundreds (perhaps thousands) of bees of all sorts.

Honeybees, bumblebees, flies of all sizes generated a low hum of activity among the flowers.

Honeybees, bumblebees, flies of all sizes generated a low hum of activity among the flowers.

Syrphid flies (hoverflies), which mimic honeybees both in size and foraging habits, were as common as the bees were.

These syrphid flies (hoverflies), which mimic honeybees both in size and foraging habits, were as common as the bees were.

Sure enough, a variety of birds had homed in on this hotspot.  Yellow-rumped and Palm Warblers zipped around the marigold carpet, peering into it to to find a choice prey item, then diving into the flowers to retrieve it, and finally chasing each other around just to show off (?).

A Yellow-rumped Warbler, showing off his signature yellow rump.

A Yellow-rumped Warbler, showing off his signature yellow rump.

But this is a far cry from the magnificent colors sported last spring.  Yellow patches under the wing and yellow rump are all that remain.

But this is a far cry from the magnificent colors sported last spring. Yellow patches under the wing and yellow rump are all that remain. (Of course, this might well be a juvenile bird, or a female.)

Last spring, he looked like this.

Last spring, he looked like this.

Palm Warblers were just as numerous as the Yellow-rumps, but far more suspicious of me, so they never ventured close to my lens.  Nevertheless, I caught one in the act of devouring a hoverfly.

Hidden behind some reeds, this little warbler snacks on its catch.

Hidden behind some reeds, this little warbler snacks on its catch.

I was much prettier last spring, but I blend into the woodland vegetation better now.

You can barely see the streaked, once yellow belly, but the pale yellowish eye stripe is still recognizable.  Spring plumage is much brighter; fall plumage makes it impossible to tell one warbler from another.

palm warbler

Both warbler species are on their way south, to warmer areas in Florida, Cuba, Mexico, and Central America. No doubt a few hearty meals of bees and flies will speed them on their journey.

Watching for warblers

Spring starts and stops here; it can’t seem to really get going.  As a result, leaves have been slow to develop and that makes it a little easier to spot the flighty little warblers as they migrate through.  In fact, the cold weather seems to have slowed their normal migratory rush down a little.

Our strange spring weather and the numbers of new warbler species arriving daily means that we often get multiple species flitting around in the backyard on any given day.  Watching the warblers go about their daily hunt for food is a great illustration of a classical ecological study I learned about many years ago — Robert MacArthur’s study of niche partitioning in warblers to reduce competition.  He found that several warbler species could co-exist if they harvested the resource in different ways or from different areas of the tree.

From Biocyclopedia - Animal Ecology

From Biocyclopedia – Animal Ecology

A few examples to illustrate how one basic body type of small insectivore has specialized to divide up the food resource:

Yellow-rumped Warblers pretend to be flycatchers, “hawking” insects from the air or gleaning them from the terminal ends of branches of shrubs or trees, often flitting from the bottom to the top of one tree, or the top of one to the bottom of another.

yellow rumped warbler-male-2

Orange-crowned Warblers poke around in the leaf litter on the forest floor or into the newly emerging clumps of leaves on the branches of shrubs.

female orange crowned warbler

Black and White Warblers are nuthatch-“wannabes”, foraging upside down along the trunk and large branches of big trees.  They are constantly on the move and really hard to get in focus.

black and white warbler

Yellow Warblers prefer to forage among the branches of shrubs and trees along streams or other wetland areas.  Their bright color really makes them stand out among the willow branches.

yellow warbler

Ovenbirds and Waterthrushes are the largest warblers and prefer to forage in damp, swampy marshes or moist forest floor.

northern waterthrush

Those are just the ones I have seen in my backyard so far.  There are still more species arriving to fatten up for the last push toward the breeding grounds in the Canadian coniferous forest. Hopefully, I will get some photos of them too.

A break for spring

I have been back in Minnesota for a few days now, with weather that fluctuates in 30 degree swings (from 72 to 42 degrees F), but the birds, especially the warblers, seem to think it’s time for spring here.

While in Cuba with the real bird photographers, I developed telephoto lens envy, and one of my fellow travelers kindly lent me her Canon 100-400 mm lens to try out on the Minnesota birds.  Oh my!  I was sold on this lens in 5 minutes, and I want one.  No, I need one!  Here’s what I saw today (or what the camera saw, through this magnificent lens).

Chickadees apparently get some nutrition from pecking at unopened buds of Buckeye.

Chickadees apparently get some nutrition from pecking at unopened buds of Buckeye.

Female warblers confuse me.  This is either a female Yellow-throat, Orange-crowned, or Nashville.  My bet is the latter because they are frequently one of the first warbler species seen here in the spring.

Female warblers confuse me. This is either a female Yellow-throat, Orange-crowned, or Nashville Warbler. My bet is the latter because they are frequently one of the first warbler species seen here in the spring.

Easy!  A male Yellow-rumped Warbler (used to be called Myrtle Warbler, back when I learned about birds).  The temperature was in the low 40s, and this guy was fluffed out as much as he could be.

Easy! A male Yellow-rumped Warbler (used to be called Myrtle Warbler, back when I learned about birds). The temperature was in the low 40s, and this guy was fluffed out as much as he could be.

Where's the yellow rump?  I have never been able to take photos like this before!

Where’s the yellow rump? I have never been able to take photos like this before!