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”.
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 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.
An amazing, if hot and sweaty morning, of birding in the big city.
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 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 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.
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.
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.
Some birds have names that aptly describe their physical appearance or a sound they make, or perhaps a name that derives from a descriptor in a language other than English. The name for these distinctive black and white, long-legged wading birds in the Alviso slough make them easy to identify and remember: Black-necked Stilt.
Large numbers of Black-necked Stilts congregated in the Alviso slough, probing in the mud for worms or other small invertebrates.
Bird lovers are keen to give large groups of one species special names, like a banditry of Chickadees, a swirl of Phalaropes, a college of cardinals, or a convocation of eagles. What do they call a huge group of Black-necked Stilts? Nothing quite as novel as those listed above, and in fact, disappointing that this large group of stilts is merely referred to as a “flock”. Boring!
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.
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.
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.
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?
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.
Watching ducks and swans take off from the mostly unfrozen lakes the other day, I was impressed with how important those big, webbed feet are in keeping the birds’ bodies up near the surface of the water. For example, a light-bodied, male Hooded Merganser “ran” on the water less than 50 feet before it was air-borne.
These small diving ducks weigh only 1-2 lb, so getting air-borne from the water surface is less of an impressive achievement. However, Trumpeter Swans, the heaviest bird in North America, weigh 20-30 lb, and lifting those big bodies into the air requires the combined effort of both feet and wings.
And those are some really big feet aiding the launching effort. Swans rarely show off those big appendages that are so useful in water take-offs, as well as digging up the bottom sediment while they forage.
The birds with probably the longest required take-off pathway from water are the loons. With relatively short wings and legs placed far to the rear, loons need two to three times the distance for take-off that ducks do, and as they take-off, they too appear to be skipping along the water surface — or even hydroplaning.
The true masters of “running on water”, however, have to be the Western Grebes, whose courtship dance is a synchronized ballet of movement across the water, all performed without a single wingbeat, paddling with just their feet in completely upright posture. A clip from David Attenborough’s Life of Birds shows this incredible feat the best.
“getting to know all about you” — that’s what we often see in the synchronized displays of paired birds that mate for life. It’s more commonly seen in the spring resurgence of pre-breeding behaviors, but often, mated pairs renew their bond in the fall before migrating to warmer climates with open water.
Trumpeter Swans pairs exhibited their neck bowing and chest-to-chest-wing flap and trumpet greetings with each other on Lake Vadnais yesterday with gusto.
Because these birds often don’t breed until they are 4-6 years old, cementing their partnership early is integral to their eventual breeding success, in defending their nest territory as well as protecting their offspring, which single individuals cannot do alone. Their synchronized neck bowing behaviors occasionally escalated to more vigorous displays of wing flapping and chest bumping (kind of remniscent of football players in the end zone after a touchdown).
But then, one swan seemed to be trying out a couple of different partners as it first performed the neck bowing sequence with one individual and then took-off flying and pursued another individual, bowing and wing-flapping with it, and then eventually settling down to feed side by side. I wonder if this is the equivalent of swan dating?
I might have thought this was one male chasing another, except for the behavior that followed.
Just another day in the lives of the Trumpeter Swans, even if confusing to us human observers.
As I look back at previous years’ blog posts around this time of the year, I always find a few posts about duck migration. And once again, right on schedule, huge rafts of Common Goldeneye and Ring-necked Ducks have taken up residence on Lake Vadnais in St. Paul, to fatten up before completing the rest of their migration south.
This particular reservoir seems to be a favorite stop-over for these ducks, and they usually stay until the freezing weather causes the lake to ice up.
A scene from across Lake Vadnais in St. Paul called to me to get closer and try to photograph the group of Trumpeter Swans.
So I hiked around the lake trying to figure out where on the trail they might be. However, it was bow season for deer that day, and so I couldn’t stray too far off the path into the woods.
By the time I found them, this is what I saw: seven swans a-sleeping (well, one was alert).
However, road noise woke a couple of them up, just for a few moments.
I guess when you’re as big as an adult Trumpeter Swan, you don’t worry too much about photographers creeping up near by. Even the Mallards were unperturbed.
Well, not so much the color of the river per se, but it was the color along the river last week in Wisconsin and Michigan during the peak of the fall color show that was impressive. Some examples, seen between rain showers:
We know that warm days and cool nights of fall stimulate plants to break down their chlorophyll, unmasking all the xanthophyll and carotene photo pigments in the leaves, and those changes in leaf metabolism produce the yellow, orange, and red colors. I have written more about the chemistry of leaf color change earlier — (“you know it’s fall when…”). But what accounts for the synchronous color changes of rural northern hardwood forests, compared to the more prolonged sequential color changes we see in urban landscapes?
Lots of factors might be responsible: urban areas are generally warmer with a less homogeneous climate than surrounding open countryside; plants in a natural forest most likely respond to climatic changes in similar ways, whereas planted urban trees, often non-native, adapt to a mixture of environmental cues with different schedules for leaf fall. Leaves might change color more slowly and stay on trees longer in the urban environment simply because temperature and moisture conditions there are so different from the surrounding countryside.