I have about two days’ worth of photos left before this feature goes kaput, so please send in your photos! Thanks.
Today we have the second installment of photos from the Galápagos from reader Ephraim Heller (the first part, the “non-birds,” is here). There will be one more installment of bird photos. Ephraim’s captions are indented, and you can enlarge the photos by clicking on them.
Following up on my non-bird Galapagos photos, below are the Galapagos bird photos.A flightless cormorant (Nannopterum harrisi) playing with a tiger snake eel (Myrichthys maculosus) before eating it. The Galapagos cormorants have lost their ability to fly but use their small wings for agile swimming. Per Wikipedia:
The flightless cormorant is the largest extant member of its family, 89–100 cm (35–39.5 in) in length and weighing 2.5–5.0 kg (5.5
This unique cormorant is endemic to the Galapagos Islands, where it has a very restricted range. It is found on just two islands; Fernandina, and the northern and western coasts of Isabela. Distribution associates with the seasonal upwelling of the eastward flowing Equatorial Undercurrent (or Cromwell Current) which provides cold nutrient rich water to these western islands of the archipelago. The population has undergone severe fluctuations; in 1983 an El Niño-Southern Oscillation (ENSO) event resulted in a 50% reduction of the population to just 400 individuals. The population recovered quickly, however, and was estimated to number 900 individuals by 1999:
American oystercatcher (Haematopus palliatus). I have often seen these in California:
Galapagos mockingbird (Mimus parvulus). The Galápagos mockingbird is one of four mockingbird species endemic to the Galápagos Islands. These four are all closely related, and DNA evidence shows they likely all descended from an ancestor species which reached the islands in a single colonization event. There are six subspecies, each endemic to a particular island or islands:
Galapagos dove (Zenaida galapagoensis). A common endemic bird:
Blue-footed booby (Sula nebouxii). It turns out that blue feet are sexy (per Wikipedia):
The blue color of the blue-footed booby’s webbed feet comes from structures of aligned collagens in the skin modified by carotenoid pigments obtained from its diet of fresh fish. The collagens are arranged in a manner that makes the skin appear blue. The underlying color is a “flat, purplish blue”. That color is modified by carotenoids to aquamarine in healthy birds. Carotenoids also act as antioxidants and stimulants for the blue-footed booby’s immune function, suggesting that carotenoid pigmentation is an indicator of an individual’s immunological state. Blue feet also indicate the current health condition of a booby. Boobies that were experimentally food-deprived for 48 hours experienced a decrease in foot brightness due to a reduction in the amount of lipids and lipoproteins that are used to absorb and transport carotenoids. Thus, the feet are rapid and honest indicators of a booby’s current level of nourishment. As blue feet are signals that reliably indicate the immunological and health condition of a booby, coloration is favored through sexual selection.
The brightness of the feet decreases with age, so females tend to mate with younger males with brighter feet, which have higher fertility and greater ability to provide paternal care than older males. In a cross-fostering experiment, foot color reflects paternal contribution to raising chicks; chicks raised by foster fathers with brighter feet grew faster than chicks raised by foster males with duller feet. Females continuously evaluate their partners’ condition based on foot color. In one experiment, males whose partners had laid a first egg in the nest had their feet dulled by makeup. The female partners laid smaller second eggs a few days later. As duller feet usually indicate a decrease in health and possibly genetic quality, it is adaptive for these females to decrease their investment in the second egg. The smaller second eggs contained less yolk concentration, which could influence embryo development, hatching success, and subsequent chick growth and survival. In addition, they contained less yolk androgens. As androgen plays an important role in chick survival, the experiment suggested female blue-footed boobies use the attractiveness and perceived genetic quality of their mates to determine how much resources they should allocate to their eggs. This supports the differential allocation theory, which predicts that parents care more for their offspring when paired with attractive mates.
Frigatebird (Fregatidae). These birds are fascinating and first introduced me to the wonderfully descriptive term kleptoparasite (which I now use in political discussions). Per Wikipedia:
Able to soar for weeks on wind currents, frigatebirds spend most of the day in flight hunting for food, and roost on trees or cliffs at night. Their main prey are fish and squid, caught when chased to the water surface by large predators such as tuna. Frigatebirds are referred to as kleptoparasites as they occasionally rob other seabirds for food, and are known to snatch seabird chicks from the nest. Seasonally monogamous, frigatebirds nest colonially. A rough nest is constructed in low trees or on the ground on remote islands. A single egg is laid each breeding season. The duration of parental care is among the longest of any bird species; frigatebirds are only able to breed every other year.
Galapgagos hawk (Buteo galapagoensis). Sadly, there are believed to be only around 150 mating pairs in existence today:
Swallow-tailed gull (Creagrus furcatus) harrassing a galapagos hawk who dared enter its territory:
Red-billed tropicbird (Phaethon aethereus). The males’ tails are about twice its body length. I think these are beautifully elegant birds in flight. They cannot stand and is not proficient at walking, and require an unobstructed takeoff to fly from land:
Never ceases to surprise me, these entries/series from the Galápagos – the tiger eel especially!… also learning finally which “a” gets the accent aigue (or whatever it is called here)…
Wonderful!
Interesting discussion of the Blue-footed booby!
Interesting that oystercatchers are on the US W coast, too. I saw them in Bergen, too – also a W coast, but AFAIK there are no E coast oystercatchers.
Dungeness crabs also seem to be W coast critters. They’re on Swedish W coast as well as CA, but not on the US E coast.
Are these only two of plenty of other such examples?
Sorry to be a picky naturalist, but:
There are American Oystercatchers all along the east coast of N. America. A range map can be seen here:
https://amoywg.org/american-oystercatcher/distribution/
Wikipedia lists 12 species of oystercatchers, many pied (black and white) and remarkably similar in appearance but with distinct ranges, so the Eurasian and American Oystercatchers are separate species.
There are also a few solid black species, such as the Black Oystercatcher of the west coast of N. America. You often see Black Oystercatchers in groups of 3 or 4 during the summer. After fledging, the chicks stay with their parents for months learning to forage and though they look very similar to adults you can pick out the chicks by the fact that the tip of their bill is not solid orange-red but dusky.
There is even a variable oystercatcher in New Zealand which can be pied, mottled or solid black, varying with latitude and is sympatric with the slightly smaller South Island Pied Oystercatcher. How to make ID confusing!
The crabs of Sweden are a different species from the Dungeness crabs of the US west coast. The US east coast has its own crab species (blue crabs, stone crabs, etc.). The east coast of the US also has horseshoe crabs but they are actually more closely related to arachnids than to crabs.
There are similarities between west coasts in the temperate northern hemisphere as they have cool currents coming down them from the north while east coasts have warm currents coming up from the south (mirror image in the Southern hemisphere). These currents are driven by predominant winds and the Coriolis effect from earth’s rotation, but there is lots of variation attributable to local topography as well and oceanic circulation rapidly becomes quite complex. None the less, this can lead to climatic similarities and thus similarities in biological communities though generally with distinct species unless we intervene (think of Giant Sequoias thriving in Britain).
Sorry I’ve gone on too long…
Nope, not at all. Thx very much for the detailed info. (I’m an East Coast kinda guy and know the blue & stone crabs much better than any of the others.)
Thank you for the fantastic action shots and interesting information about these Galapagos birds.
It’s fascinating how the Blue-footed booby’s feet are subject to sexual selection, and it’s equally fascinating that people have actually done experiments to study them!
Fantastic series. The interplay captured in the cormorant shots are perfect. I’m fascinated by all that the blueness of the blue-footed booby’s feet entail for that bird, its mate, AND its offspring. It blows my mind. Thanks!
Fabulous cormorant vs. eel sequence!