Faces

I took the grandkids to Como Zoo, and they watched the orangutans with fascination, maybe because the orangutans were awake and watching the crowd gathered around their enclosure with some fixed stares.

orangutan at como zoo-

Males seem to have excessive amounts of flesh, although I’m sure their diet is tightly regulated. The brow ridge is so accentuated, the eyes seem to disappear into deep hollows.

orangutan at como zoo-

Moving slowly, looking around…

orangutan at como zoo-8982

A closer look at that fascinating face of this mature male …

orangutan at como zoo

The gorillas were interesting too.

a tale of two Swallowtails

During the last week, I’ve seen several Eastern Tiger Swallowtail butterflies in the backyard.  They seem to be especially attracted to the Cup Plant (the same plant the Goldfinches have been tearing apart).

eastern tiger swallowtail butterfly

The easily recognized yellow and black striped color morph of the eastern tiger swallowtail. Bright blue almost iridescent scales at the tip of the hind wings indicate this is a female.

eastern tiger swallowtail butterfly

Nearby, the other color morph of the female eastern tiger swallowtail — all black with the same iridescent blue scales on the hind wing — nectars on the same plant.  There are no traces of the black or yellow stripes; the wings are entirely melanistic.

eastern tiger swallowtail butterfly

There were actually several of these butterflies on the Cup Plants, two of which sort of cooperated for a group shot. Can you see a Goldfinch between the two butterflies?

The male color pattern is entirely yellow and black, but without the iridescent blue highlights), so why are there two color morphs for the female?

As I have described in an earlier post, several species of Swallowtail butterflies, and in particular, the female Eastern Tiger Swallowtail, imitate the color pattern of the distasteful Pipevine Swallowtail (a different species entirely).

pipevineswallowtail-female-bob-moul

Pipevine Swallowtail, the model species for the mimicry complex, and dark color morph of the Eastern Tiger Swallowtail.  (Photo by Bob Moul)  Larvae of these butterflies are specialists on Pipevine plant species, which produce organic compounds that are toxic carcinogens and urologic poisons.

Predators usually remember what tastes bad or makes them sick, so mimicking something that predators avoid is a good survival strategy.  However, that requires that the predators actually have experience with the model (the one being copied), and so far, Pipevine Swallowtails are rare strays in Minnesota because the Pipevine food plants on which their larvae develop are absent here.

We now know that the melanistic (dark form) Eastern Tiger Swallowtail females produce almost all melanistic daughters, and the yellow color morph females produce almost all yellow daughters.  So perhaps our melanistic females are offpspring of Tiger Swallowtail butterflies that hatched in nearby Iowa or Wisconsin, where Pipevine Swallowtails have been sighted along with their required food plants.

eastern tiger swallowtail butterfly

Joe Pye weed offers lots of nectar to the butterflies in the garden as well.  The fact that these butteflies have beautifully intact wings (including the swallow “tails”) and scales probably means they have only recently emerged from their pupal cocoons.

It’s interesting to note that there is no melanistic female color morph in the Eastern Tiger Swallowtail’s very similar sister species — Canadian Tiger Swallowtails, although the Pipevine Swallowtail has been found in several places in Ontario.

Curiousity

Like many young animals, fledgling Pileated Woodpeckers need to explore what’s good to eat and where to find it.  A pair of youngsters completely ignored the suet and seed at the bird feeders, and instead explored a rotten stump.

young pileated woodpeckers-

Let’s see what’s here…

Without parents to follow around, they must have some innate instinct to look for larvae in rotting wood.  I don’t think they found much though.

 pileated woodpeckers-

pileated woodpeckers-

But who knows, their curiosity might yield a tasty meal.

Seed-eater’s Paradise

There is quite a banquet of tasty choices for seed-eaters in the backyard these days, with all the wildflowers trying to set seed.  Goldfinches have been attacking the seed heads of the cup plant, tugging forcefully to loosen the seeds that are packed into a dense head.  More than a dozen male Goldfinches chirped and chittered as they tore into the plants.

goldfinch feeding on seeds

Apparently it takes quite a bit of tugging force to dislodge the seeds packed tightly into cup plant seed heads.

goldfinch feeding on seeds

The technique is simply to tear off the outer leafy material exposing the seeds within.

goldfinch feeding on seeds

Got it out, now what?

goldfinch feeding on cup plant seeds

The bird turned the seed around and around in its mouth, like it was tasting it, and then dropped it and went on to another seed head. Maybe this one wasn’t ripe enough?

goldfinch feeding on bee balm seeds

Other male Goldfinches explored the seed heads of the bee balm (Monarda).

goldfinch feeding on bee balm seeds-

There is a good crop of these in the backyard as well, and each seed head produces a lot of seed.

goldfinch feeding on seeds

And of course there is coneflower seed for dessert.

it’s all in the tongue

Have you ever wondered how hummingbirds manage to slurp up the nectar in a flower so quickly?  Rarely do they pause at one flower for longer than a second or two before moving on.

ruby-throated-hummingbird-on-cardinal-flower

Female Ruby-throated Hummingbird feeding on Cardinal Flower in my wildflower garden

Occasionally we get a glimpse of a long tongue protruding from their bill when they exit the fake flower on a feeder.

hummingbird-sticky-her-tongue-out-tj-baccari

Female or juvenile Ruby-throated Hummingbird (Photo by TJ Baccari)

But how does that tongue work to enable them to sip so quickly?  Initially, it was thought that the tongue was merely a long capillary tube that drew the nectar up through cohesive action of fluid droplets.  But that is much too slow a process.

High-speed videography by researchers at the University of Connecticut has revealed that a hummingbird’s tongue expands rapidly from a flattened ribbon inside the bill to a forked pair of open tubes as the tongue is protruded into a feeding tube or flower nectary.  The tongue moves in and out of the bill 15 times a second, expanding and compressing as it moves in and out of the bill, and that pumping action is what delivers the nectar to the mouth so rapidly.

hummingbird tongue-1

You can see the expanded tongue segments immersed in the nectar in this screen capture from a high-speed video taken by the University of Connecticut researchers who made this discovery.  Science Daily, August 19,, 2015.

A short video illustrates this much better than I can explain it.

https://static01.nyt.com/video/players/offsite/index.html?videoId=100000003892113

ruby-throated-hummingbird-approaching-cardinal-flower

I never tire of learning about the wonders of nature.

lazy summer days

What do you do on a hot, summer day when soft, grassy lawns and the sweet aroma of wildflower blooms beckon?  It calls for a short nap in the grass, I guess, even for wildlife, and the backyard was the perfect place yesterday.

whitetail fawns-

A pair of fawns wandered by, one of whom decided on a short rest while munching on fallen leaves.

whitetail fawns-

Still spotted, although they’re now half the size of their mom.  The left ear of the fawn standing has a torn notch — perhaps it had an encounter with a predator early in life.

whitetail doe-

Mom watched me warily from the woods, as I snuck up on her darlings.

red fox kit-

A little later a red fox kit wandered by, checking out the squirrels at the bird feeder.

red fox kit-

And then settled down for a little rest near the wildflower garden while still watching those squirrels.

red fox kit-

Resting in the shade on a hot summer day…that’s the life.

Division of labor

In many bird species, males set up and defend breeding territories, and females build the nest, lay the eggs and incubate them — a division of labor that ensures the best possible outcome for their offspring.  In other species, both parents feed their chicks; in still others, just the female, or just the male takes responsibility for providing food to the incubating female as well as the chicks.  The latter is the case for the ospreys I have been observing at a local marsh.

osprey-at-the-nest-

Male osprey bringing a delicious fish to his mate who is incubating her eggs.  The fish are always headless — I wonder if he eats the head?  Does it have some particular nutritional value for him?

Males bring the sticks to the nest, the females arrange them, forming a large nest cup surrounded by a foot or two of sticks and even leafy material around the outside.  Female osprey perform almost all of the incubation, sitting on those 2-3 precious eggs for more than a month! (32-42 days), rarely getting a chance to fly off and spread their wings.  The male brings her food, but she might also get some of her daily energy requirement by metabolizing some of the protein in her inactive flight muscles.  (More about the implications of this in the next post.)

osprey and chicks-

While the chicks are young, they must still be brooded in the cold, shaded in the heat, and need their food diced up for them.

The female remains on the nest to protect them for at least another month, although the male might share some of this time with her.  Meanwhile, he is the chief food provider, bringing as much as 6 pounds of fish to his brood and his mate on a daily basis.

osprey with fish-

This fish still has its head…

Once the chicks are feathered out, grown almost to the size of the adults, and able to stand up and move around in the nest, the female takes some time off, and leaves their care to the male. Now he has to not only feed them, but guard them from potential marauding eagles or owls that might like a tasty osprey chick for dinner.  (An account of this predatory behavior is described here.)

osprey-

Dad is on duty, watching over the nest from a tree nearby.

At about two months of age, having exercised their wing muscles, and practiced “helicoptering” (hovering over the nest), osprey chicks may try a test flight to a nearby tree, where they hang out, still insisting that dad come feed them.

osprey nest and fledglings

The scene at the osprey nest currently — one chick still on the nest, and one in a nearby tree (highlighted brown and white spot). Dad was busy looking for fish, mom was never seen — this is when the chicks are vulnerable to predation.

osprey chick-

This chick was making some incessant begging calls, as the male flew by the nest in search of a fish.

The male flew right in, dropped and the fish, and the chick immediately started picking at it.  Notice the way it stretches out its wings to hide its food from view -- typical raptor feeding behavior.

The male flew right in, dropped the fish, and the chick immediately started picking at it.  So, now they are apparently able to feed themselves. Notice the way the youngster stretches out its wings to hide its food from view — typical raptor feeding behavior.

osprey nest, adult and fledgling-

Now the other chick is making begging calls — dad has to go and get a fish for that chick.

osprey-

Osprey are busy parents during June and July in Minnesota.  This female has finished molting, replacing worn and broken feathers, damaged during her long stint on the nest. Now she must exercise those atrophied wing muscles to get ready for migration.

“here’s looking at you”

With huge, globular eyes that make up about 50% of their head, dragonflies are amazing visual predators.

dragonfly eyes

A sampling of beautiful dragonfly eyes from a Google search

And those eyes are key to their success as highly visual predators.

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Halloween Pennant dragonflies search from the tips of the highest plants in grassy fields, with their orange-banded wings fluttering in the breeze.

In fact, they are probably the most efficient predators in the animal kingdom, with an astounding 95% success rate per attempt.  In comparison, lions are lucky to succeed once every four to five tries and great white sharks only manage to catch what they are after half the time.  How do dragonflies do it?

Here's looking at you...

Here’s looking at you… the facial disk of the Horned Clubtail.  Depending on the angle of incoming light (and observer position), the eyes might look turquoise blue.

Enough clues? The eyes and more particularly, the wiring of retinal cells to the brain is key to their hunting success.

The eyes and more particularly, the wiring of retinal cells to the brain, is key to their hunting success.

Those giant optical domes on the top of their heads give them a 360 degree view, and contain as many as 30,000 optical units (ommatidia), each with a complement of photopigments that can process images separately.  Thus, instead of one retinal focusing area, they have thousands.

The eye of a dragonfly, showing the individual facets or ommatidia that contain visual pigments. Each facet can detect and send an image to the insect's brain. Imagine having 30,000 eyes!

The eye of a dragonfly, showing the individual facets or ommatidia that contain visual pigments. Each facet can detect and send an image to the insect’s brain. Imagine having 30,000 eyes! From Science Blogs, July 8, 2009.

In addition, where human eyes have three photo pigments, dragonflies have 15-30 pigments that can detect light in ranges beyond human capability, including detection of polarized light.  What if we could see images in UV or infra-red, or whatever other spectral wavelengths dragonflies can resolve?

A newly emerged male Common Whitetail has the wing markings of a male and the abdominal coloration of the female. Over the course of the next week, he will gradually transform to the powder-white abdomen typical of males.

A newly emerged male Common Whitetail has the wing markings of a male and the abdominal coloration of the female. Over the course of the next week, he will gradually transform to the powder-white abdomen typical of males.

Photopigments sensitive to blue and UV light are concentrated in the upper part of the compound eye, so that prey (or predators) above them stand out against a perceived white background.  Pigments sensitive to longer wavelengths (green, yellow, red) are concentrated in the lower part of the compound eye and allow prey flitting below the dragonfly in dense vegetation to be detected.

This Dot-tailed Whiteface continually moved its head up and down as it scanned for prey. Each time I tried to get in front of it to photograph its white face, it flew away.

This Dot-tailed Whiteface continually moved its head up and down as it scanned for prey. Each time I tried to get in front of it to photograph its white face, it flew away.

In addition to their heightened visual sensitivity and acuity, dragonflies exhibit single-object tracking, which means they keep a particular prey item exactly on a collision course with themselves. (Kind of sounds like a drone, doesn’t it?)

And that’s where the fancy flying comes in handy. To keep the image of the prey in exactly the same place in their visual field, a dragonfly might fly up, down, sideways, backwards, even upside down, if needed. Four wings that can move independently facilitate this maneuverability, and in fact, they don’t even need all four.

This female 12-spotted Skimmer has lost half of its hind wing, but it's doubtful that it comprises hunting success.

This female 12-spotted Skimmer has lost half of its left hind wing, but it’s doubtful that it comprises hunting success.

These amazing little machines have been around for several hundred million years, feasting on slower flying, less visually talented prey.  Such a visual formula for hunting success ensures that they will be around for a while, keeping those pesky mosquitoes in check.

[This is an edited version of a previous post from Backyard Biology]

baby, it’s hot out there

This week’s extreme heat (high 90s) and high humidity (felt like 90%) are what makes us grateful for MN winters…I guess.  There wasn’t much activity in the backyard today, with a only a few birds visiting the feeders and a few bumblebees buzzing in the garden.  Dissipating heat is hard for endotherms that generate heat through their metabolism, so it makes sense to find shade, or increase evaporative cooling with a nice bath.

catbird-

Ah, a little soak to cool off a hot Catbird.

catbird-

Getting wet all over is even better.

catbird-

Feeling much cooler, now to find a perch in the shade and wait out the daytime heat wave.

But even the low metabolic ectotherms were fighting the solar load, like this female Blue Dasher dragonfly that tipped her abdomen toward the sky to block the heat radiating down on her sensitive head.

female blue dasher dragonfly

This little dragonfly can reduce its heat load by positioning the slender abdomen up into the “obelisk position”.

female blue dasher dragonfly

What pretty eyes they have — red on top, pale blue on the bottom.

Garden beauties

The wildflowers are at almost peak color and diversity in the backyard, and happily this year, quite a few butterflies have made an appearance there for the first time in several years.

monarch butterfly-

It’s always great to see Monarch butterflies flitting about — this beautiful female spent far more time sipping nectar from the coneflowers than she did laying eggs on the milkweed. Numbers of Monarchs have dipped precipitously in the last few years, due to a number of stressors along their migratory route.  Hopefully this will be a good year for Monarch production.

red admiral-

A well-worn Red Admiral with a rather large bite out of one of his wings is one of several of these butterflies that frequent the coneflowers in the backyard.  This is one species that does not seem to have suffered population declines in recent years.

american lady

An American Lady (sometimes erroneously called Painted Lady which is a different and related species), with its bright black and blue spots on its hind wing, is closely related to the Red Admiral.  This is another very common species across the U.S.

american lady

Part of its forewing looks just like that of the Red Admiral, but those two big eyespots are unique to the American Lady.  The butterflies we see in MN (and other parts of the northern U.S.) are most likely offspring of more southerly distributed butterflies that migrated north in the spring.

great spangled fritillary-

Great Spangled Fritillary butterflies are another widespread species across North America.  It’s one of the larger butterflies (> 2 inches), a little larger than a Monarch.  Larvae feed on native violets — plenty of those in the backyard.

great spangled fritillary-

With its combination of black slashes on the top of its orange wings and large white ovals on the other side, it can be difficult to tell this species from other fritillaries, but the wide buff band between the two rows of white spots differentiate this species from Aphrodite and Atlantis Fritillaries, with which the Great Spangled overlaps in range.

backyard garden-

Where the excitement takes place in the backyard…

What else is in the garden today?  A small Gray Tree Frog matches the leaves on which it is resting.

gray tree frog-