A flight, a gulp, a rookery, a stunning, a swim…of Cormorants

Neotropical Cormorants by the hundreds congregated on barren islands in the middle of the lagoons at Los Pantanos de Villa reserve, south of Lima, Peru.  The various terms for groups of cormorants really don’t do this mass of breeding birds justice.  Instead of a “swim” of cormorants, it should be something like a “swarm”.

Neotropical Cormorants at Los Pantanos de Villa reserve, Lima, Peru

Neotropical Cormorants at Los Pantanos de Villa reserve, Lima, Peru.  This view shows how close the reserve is to the surrounding part of the city.

Neotropical Cormorants at Los Pantanos de Villa reserve, Lima, Peru

Neotropical Cormorant carrying nesting material to the overcrowded conglomeration of nest sites.

Neotropical Cormorants at Los Pantanos de Villa reserve, Lima, Peru

A few cormorants avoided the congestion on the islands by sunning on a nearby dead tree.

Neotropical Cormorants at Los Pantanos de Villa reserve, Lima, Peru

Cormorant  drying its wings and body feathers

Neotropical Cormorants at Los Pantanos de Villa reserve, Lima, Peru

Not the most handsome of birds…

Neotropical Cormorants at Los Pantanos de Villa reserve, Lima, Peru

Crowded conditions for nesting, but safety in numbers perhaps…

A wealth of bird life

Who would have thought you could see so many birds just 7 miles from our hotel in Miraflores and adjoining the industrial district of Chorrillos, south of Lima?

Los Pantanos de Villa ecological reserve, Lima, Peru

Franklin’s Gulls and Black Skimmers were found in huge numbers at Los Pantanos de Villa ecological reserve, on the outskirts of Lima, Peru.

Los Pantanos de Villa is a protected series of brackish marshes and lagoons designated as a RAMSAR site since 1997, meaning it is a wetlands of world-wide importance.  Both migratory and resident bird species frequent the complex of wetlands, along with a myriad of invertebrate, fish, amphibian, and mammal species.

Views of some of the wetland bird species were truly spectacular.

Black Skimmers

Black Skimmers congregated in huge numbers, but were easily flushed into flight.

Black Skimmers and Franklins Gulls, Los Pantanos de Villa reserve, Lima, Peru

Black Skimmers and Franklin’s Gulls take flight together

Black Skimmers and Franklins Gulls, Los Pantanos de Villa reserve, Lima, Peru

Unfortunately, the Skimmers weren’t interested in feeding, but glided effortlessly over the water to a different part of the beach.  When feeding they dip the longer, lower mandible into the water to scare up fish, grabbing them as they attempt to dart away.

Franklin’s Gulls and Elegant Terns, Los Pantanos de Villa

A mob of Franklin’s Gulls and Elegant Terns congregated far out in the water.  Willets foraged in shallow water in the foreground.

Black Skimmer and Elegant Tern

A Black Skimmer and Elegant Tern take off together.

An amazing, if hot and sweaty morning, of birding in the big city.

Shrike, the impaler

My brother-in-law wondered why there were bumblebees stuck on the barbed wire surrounding a portion of the San Jose NASA Ames facility where he works, so he sent me a couple of photos of them.

bumblebee impaled on barbed wire by shrikes

That’s not a random clump of fur stuck on the barbed wire six feet up in the air.

bumblebees impaled on barbed wire by shrikes

It’s a large bumblebee purposefully impaled on the barbed wire.

I knew immediately what had caused the bee to get stuck there — it was an appetizer snack put there by one of the local Loggerhead Shrikes, a feisty little gray and black bird sometimes known as the Butcher Bird.

loggerhead-shrike-

A bad photo I took of a Loggerhead Shrike posing while surveying the landscape for his next meal.  Their definitive black mask and dark gray head and back make them easy to ID.

Shrikes could be thought of as tiny raptors, except for the fact that they have delicate perching toes instead of grasping talons.  Strong beaks enable them to snare their prey and powerful wing muscles help them carry it aloft where they then nimbly attach it to a sharp projection, like a thorn, or a broken stub of a twig, or in this case, the barbs of a barbed-wire fence.  The sharp projection holds the prey in place while it is consumed, making up for the lack of talons and strong, grasping toes.  Sometimes they are so successful in hunting, they leave a string of carcasses hanging, to be consumed later.

Almost nothing escapes their attention as potential prey: from crickets and bumblebees, to frogs, lizards, small mice, even other birds.  If they can carry it, they can stash it on something sharp.  The video below by Angie Li captures some of this behavior and illustrates the wide variety of food choices shrikes make. (The narration is interesting but is somewhat redundant and sounds like it is computer generated.)

sharing the space

Sharing the space:  something we often see in nature, where species or individuals divide up the resources in a way that maximizes their gain while reducing competition from closely related individuals.  Some sparrow species seem to be flexible in where they forage, adjusting their resource use based on the presence of other birds.  For example, at the Alviso marina park in the southern San Francisco bay, we saw Song Sparrows, Field Sparrows, and White-crowned Sparrows in the same area of the park, but in quite different micro-habitats.

song sparrow in swamp grass-

This particular Song Sparrow was practicing his song, but only half-heartedly. Just a warm-up before the breeding season gets going.

Song Sparrows were found in brushy areas and dried grasses of the wetland in the park, although they can often be found on the edge of more open, grassy areas in other habitats.

white-crowned sparrow-

Juvenile and adult White-crowned Sparrows foraged in small flocks together. First-year birds have brown and white crowns; adults are a more striking black and white.

White-crowned Sparrows are migrants, overwintering in the lower 48 states but flying as far north as northern Canada and Alaska to breed in the spring.  Some birds may be permanent residents along the California coast, but these particular individuals were not acting territorial.  In the park, the White-crowned sparrows foraged at the base of shrubs and along rocks and logs on the shoreline, picking at the seeds in the litter that accumulates in crevices.  In their higher latitude or altitude breeding sites, they prefer open grassy meadows dotted with small shrubs in which they place their nests.

adult white-crowned sparrow on anise seed-

An adult White-crowned Sparrow perched on a dried wild anise plant gets a better view of where to forage next.

The third species we saw in the park, Field Sparrows, were found in the field (as their name implies), i.e., in grassy meadows dotted with occasional tall annual plants and shrubs.  These birds are typical of “old fields”, areas that are undergoing successional change from cultivation back to shrub and forest.

field sparrow-

Field Sparrows aren’t particularly colorful (except for their pale pink beak), but they sing a song that sounds like a bouncing ball, and are usually easy to spot once you’ve heard them.

These are just a few of the ground-feeding seed-eaters that most likely can be found in the park area:  Golden-crowned Sparrows and Towhees are also seen on occasion.  The variation in habitat throughout the park makes it attractive to a wide diversity of wildlife that can share the rich resources.

“get out of my territory”

This is the time of year in California when male Anna’s hummingbirds are staking out their territory and advertising it with their scratchy song.  I heard a male singing while we were walking along the dike at Alviso marina county park, and played a short song on my phone to lure him out into the open.

Male Anna’s hummingbird

From the side view, it doesn’t look like he’s particularly threatened.  The iridescent feathers in the neck look black in the absence of light directed straight at them.

The bird was definitely annoyed by the sound of an intruder, which he would happily have chased away, but he couldn’t find another hummer to chase. So he hovered about 2 feet from us, much too close to capture with my telephoto lens.  After a minute or so, he landed on a nearby shrub to try to intimidate the interloper, with increasing levels of threat display.

Male Anna’s hummingbird threat display

Level 1 of the threat display, gorget and head feathers turned to the light to reflect their magenta iridescence.

Male Anna’s hummingbird threat display

We haven’t vacated his territory, so he escalates to a level 2 threat by flaring the gorget feathers out to the side to create an even bigger display.

Male Anna’s hummingbird threat display

He means business with this level 3 display of gorget feathers erected straight out from his neck, making him seem even bigger and pinker!

It’s time to leave this guy alone, so he can get on with the dating game.

the sally

I always wondered why we call what flycatching birds do to snare their food “sallying”.  So I looked it up:  to sally, from the French verb saillir, means to leap forth.  And that’s exactly what I saw a Black Phoebe do today from its favorite perch in a blue spruce tree.

Black Phoebe

Black Phoebe waiting for some insect to fly by…

The leaping forth was almost faster than I could catch on camera, but I could hear the snap of their beak as they tried to close on their prey.

Black Phoebe flycatching (sallying)

It’s easy to miss the launch from their perch — it happens fast!

Black Phoebe flycatching (sallying)

Black Phoebe flycatching (sallying), beak open, aiming to catch something…

Black Phoebe flycatching (sallying)

Another attempt

The typical “sally” for most flycatchers is a quick dart out from a perch, perhaps followed by a swoop, and then a u-turn back to their perch.

Black Phoebe flycatching (sallying)

And back to the perch…

Black Phoebe

and now we wait for another juicy insect to fly by…

the benefits of black feathers

Adding to the white, gray, and brown monotone colors of the winter landscape now, the resident birds also seem to be mostly shades of black, white, and gray or tan.  In fact, many of them use black as a primary “color” of their plumage.  Is black somehow advantageous to birds in the winter?

american crow-

Of course, crows are black all year, so their plumage color can’t be an advantage just for winter time.

I usually feel warmer with a dark colored sweater or jacket on a cold day, and we know that black absorbs and holds radiant heat energy much better than other colors.  So, do birds utilize their dark brown/black feathers to stay warm?

turkey vulture basking

Turkey Vulture basking in early morning on a northern California riverside.

Some birds, like Turkey Vultures, Anhingas, Cormorants, and Roadrunners, do use their dark plumage to advantage to warm up on cold mornings, basking with their dark feathers spread widely apart so heat can reach the skin below.

anhinga basking

Anhingas dry their feathers by spreading their wings, but their dark brown back feathers also give them a boost of warmth on cool mornings.  Photo taken on the Anhinga Trail in the Everglades.

However, wind ruffling the feathers of a crow reveals a flaw in the idea that their black feathers are used to keep them warm.  Their feathers are only black right at their tips, and are white-gray underneath; in fact their skin is pale as well.

american crow-white feathers beneath black ones

A crow sitting high on a tree branch in a steadily blowing wind must feel the chill on a day when the temperature is below 0 F.

This seems more like an adaptation to avoid overheating in summer sun, than conserving heat in winter cold.  In summer heat, black feather surfaces would heat rapidly, becoming warmer than the surrounding air, and would enable the bird to actually unload heat produced internally, reflected through the whitish underlayer of feathers to their outer surface.  This helps explain how large-bodied, dark-feathered Ravens can survive in hot, arid environments as well.

raven-grand canyon

Soaring above the canyon keeps them cool, but down at the bottom of the canyon where the food might be found often gets well above 100 F.

Assistance in regulation of body temperature might be one explanation for why so many birds have black feathers or black-tipped feathers, but there are a host of other possible explanations, as well.  One likely possibility is that the melanin pigment that colors the feather dark brown to black (depending on its concentration) binds to the keratin protein in the feathers and strengthens them and helps them resist wear.

birds with black wingtips

Large-bodied, white birds with black wingtips.  White Ibis photo by Ronnie Maum; Snow Goose photo from Birds of North America online; Northern Harrier photo by Jerry Ligouri.

During feather development, granules of melanin are deposited in the helical strands of keratin protein that make up the filaments that are in turn packaged into the barbs and barbules that make up the feather.  Melanin-enriched keratin has been demonstrated to make feathers stiffer, more durable, and resistant to abrasion.  The outer (primary) flight feathers are the propellers in the generation of powered flight, making it essential for them to be stiffer and wear-resistant.

But what are the benefits of black plumage patterns in all the other birds we see in the winter landscape?  Is black important for thermoregulation, resistance to wear, cryptic camouflage, something else…?

black and white birds

Birds in the Minnesota backyard, clockwise from upper left: Downy Woodpecker, Black-capped Chickadee, Yellow-bellied Sapsucker, White-breasted Nuthatch, and Northern Flicker.

Your thoughts?  What about all those other mostly black birds:  Red-winged Blackbirds, Pileated Woodpeckers, Puffins, Anis, Petrels, Auks, Grackles and Cowbirds, Coots, Moorhens, Frigatebirds, Starlings, and more.  Why black?

Like water off a duck’s back

It’s obvious where that expression, “like water off a duck’s back” came from.  Duck feathers shed water amazingly well — their plumage seems almost impenetrable.

mallard drake - feathers shedding water

Droplets of water bead up and slough (or sluff) off the outer feathers of duck plumage.  This guy had just righted himself from tipping up to scrounge algae off the rocks at the bottom of the creek bed.

No doubt part of staying warm in the chill winter temperatures and winds is staying dry, and duck plumage is intended to do just that.  Not only are the feathers incredibly dense, laid down in overlapping layers in feather tracts, but they are coated with a waxy residue from a gland at the base of the ducks tail that waterproofs them.

mallard hen

Beads of water are shed from all surfaces from head to tail end on this hen Mallard.

But what about those bare feet, exposed to near freezing water temperatures and standing on cold rocks or ice or snow for hours on end?  Feet don’t shed water, just the feathers.

mallard drake standing on ice

Cold toes?

This drake has just climbed out of the water, and is standing on ice, not something we would be comfortable doing (barefoot).  What happens when we reach for ice cubes in the freezer with wet fingers? The ice sticks to our fingers and is difficult to remove without losing some skin in the process. So how do ducks keep their wet feet from sticking to the ice?

mallard ducks-on ice

Ducks slip and slide on ice, but their feet don’t stick to the surface.

The secret is to maintain very cold toes that are the same temperature as the surface on which the duck stands or walks.  This is achieved by having arterial blood going to the foot run in parallel with the vein that is bringing cold blood back from the foot — making a heat exchange unit that promotes cooling the extremities while preserving the warmth of the body core.  Engineers have used this principle in the design of heaters and air conditioners, among many other uses.

mallard hen on ice

And this makes it nice for ducks to stand around admiring their reflections in icy pools.

Spike and the boys

“Spike and the boys” — it’s not a new band, but a herd of White-tailed deer bucks that roam the backyard and beyond.  There are three mature (big) bucks and three first-year bucks with tiny antler spikes protruding from their foreheads — hence “spikes”.  They are browsing for anything edible in the backyard on this cold, snowy day.

first year white-tailed buck (spikes)

Two of the three spikes were doing a little playful head butting in the wildflower garden.

first year white-tailed buck (spike)

Number 3 of the trio ambled over to see what all the fun was about, chewing something as he ambled.

white-tailed buck-

Meanwhile the big boys were serious about finding something nutritious to eat. They have been through this long winter drought of good forage before.

Males lose 20-30 % of their body weight during the fall rut, as they follow the does around waiting for their opportunities to mate with them.  That allows little time to eat, and consequently, they may enter the winter period of low food availability with less fat than they will eventually need to survive.  Their winter browse on evergreens, leaves, and shrubs may not sustain them completely either, and they may continue to lose weight throughout the winter, despite trying to reduce their metabolism by being less active and lowering their body temperature and heart rate: lessons that the “spikes” will need to learn quickly.

white-tailed buck-

One of the big boys has already lost a portion of his rack on the right side.  It must get tricky maneuvering those irregular curves on his head through the dense branches of the forest undergrowth.

white-tailed bucks

Spike and the boys suddenly come to full attention, looking intently at the wetland valley below the brim of the hill. There are dogs and people walking down there.

white-tailed buck running away

And off they go, bounding out of sight, raising that white tail flag to indicate to the others that it’s time to flee.

why are cardinals so red? — continued

The proximate (immediate) answer to the question of why cardinals are red is that they have a diet rich in carotenoid pigments (e.g., the pigment that makes carrots orange), and will incorporate those pigments into their feathers as they develop each year during feather molt.  To read more about this process, click here to read an article from Bird Watching Daily that explains where feather colors come from.

northern cardinal

Resident Cardinal male posing on a garden stake in the backyard.  He’s bright and he’s loud, and he makes sure his mate and all the other would-be holders of his territory know it.

But I’m interested in the evolutionary basis for why cardinals stand out among other species residing year-round in northern climates in retaining their bright red coloration instead of molting to more muted shades during the non-breeding season, like, for example American Goldfinches do.   Cardinals undergo a post-breeding feather molt, just like other species, so why risk attracting predators with bright red, when you might escape notice with a dull brown plumage instead?

summer vs winter American Goldfinch plumage

Summer (top) vs winter (bottom) American Goldfinch plumage

Does sexual selection (that is, female choice for the most beautiful male, as Richard Prum argues) play a role?  Please see the yesterday’s Back Yard Biology post for more information about the importance of beauty in female choice.)

Some additional facts regarding male-female relationships in Cardinals and their close relatives, the Pyrrhuloxias of the southwestern U.S., might help to answer the question.

Cardinal vs Pyrrhuloxia--DFW Urban Wildlife

A comparison of two closely related Cardinal species, the Pyrrhuloxia, Cardinalis sinuatus (1 and 2) and the Northern Cardinal, Cardinalis cardinalis (3 and 4). Illustration in Chris Jackson’s DFW Urban Wildlife blog.

The first thing you notice from the illustration above is that the Pyrrhuloxia male and female look more alike than Northern Cardinal male and his mate do.  Why might that difference have arisen in such closely related species? And does it have anything to do with female choice for brightly colored, beautiful males?

The second and interesting difference between the two species is that Pyrrhuloxia share a pair bond only during the breeding season, breaking up in the non-breeding season into loose, often mixed-species flocks of seed-eating birds that move around to find food in their dry, desert habitat.  Each year, males vie for available females by staking out and advertising their territories, often very aggressively.  In contrast, Northern Cardinals may maintain their pair bond year-round, often for multiple years, unless one of the pair dies, and the pair stays in the same general area in which they nested, year-round.

cardinal courtship feeding-rudiger merz

A year-round pair bond exists in Northern Cardinal mates, which renews its strength in the spring with courtship feeding.  (Photo by Rudiger Merz)

Female Cardinals are making a choice of more than just a breeding partner; they may be choosing a life partner and his residence (territory).  Richard Prum might argue: what’s a male to do, but be the most beautiful thing she has ever seen?  And if he is better looking than his neighbors, she stays with him through that year and the next.  They raise multiple broods of young Cardinals together, and he passes on his good looks to the next generations.


This is an amazing high definition video of male and female Cardinals feeding their chicks (by FrontYardVideo).

In other words, it’s possible that their long-term pair bond and high fidelity to a territory year-round makes it possible for choosy female Cardinals to drive the accentuation of  beauty (in this case, “redness”) in their male partners, to the extreme that male Cardinals never lose their red color during the year.