Field Obs3: Social Behavior and Phenology

Date: 13-March-2019
Time: 4:00-6:00PM
Location: Puerto Villamil, Isabela Island, Galapagos, Ecuador
Coordinates: -0.9533, -90.9864
Weather: Sunny, partly cloudy, 80°F (27°C)
Habitat: Mixed (see first paragraph below)

I was extremely fortunate to be taking a spring break course in the Galapagos Islands studying conservation and the natural history. Beforehand I ensure I purchased a nice camera so I would be able to take pictures of the marvelous and diverse birds that reside in these unique islands. The islands are notorious for their rapid changes in scenery, in a single 30-minute drive I was able to see beach, desert, tropical rainforest, and high-altitude volcano ecosystems. The hostel I was staying at was right on the beach and was a short 2.5-mile walk to a dry, dusty, tortoise breeding center which followed a boardwalk through a light forest and a lagoon back to the hostel. This unique setting allowed me to see a wide variety of birds from extremely different environments all within 90 minutes of each other.

I started the walk at my hostel, where there was a local, friendly Yellow Warbler that joined us for breakfast every morning. I was happy to see my little friend right before embarking on my excursion. Along the beach, I observed shorebirds, primarily Whimbrels and Sanderlings. These birds are generally solitary foragers, although Sanderlings could be observed in small foraging groups, although little interaction occurred. These birds were primarily observed foraging along the shoreline at dawn and dusk in order to escape the heat. Frigate birds and a Brown Pelican were also observed flying by, but it was not uncommon to see these birds flying solitary in the sky at any time of the day. Many Frigate birds observed during the trip had a large, red sack underneath their neck which they are able to inflate to attract a mate, indicating a fully mature male. This inflation is a major communication method male use to try and attract a female in, the larger the air sac, the more likely they are to obtain a mate. Other Frigates had a white, feathered neck, indicating that they were either juvenile males or females.

Once at the tortoise breeding center, a Galapagos Mockingbird was immediately spotted in a nearby low-lying tree. There are two other Mockingbirds found in the Galapagos, but these birds are able to differentiate each other due to their variety in plumages, although not an issue as many of these species are separated by islands. Although they have wings, they prefer to hop and walk around, limiting their dispersal and hybridizing abilities. A Smooth-billed Ani was seen drinking water out of one of the tortoise’s baths. These birds are generally found in groups of 10-40 birds and communicate with a variety of calls, although this bird was seen alone. While leaving the breeding center, I walked through a low-density forest of smaller trees where various finches were observed. A Sharp-beak Ground-finch and a Medium Ground-finch were seen in close proximity of one another, and although descendants of the same finch and very similar in physical attributes, these birds are not the same species. The thirteen finches that reside in the Galapagos actually all developed their own unique calls and will not respond to that of another finch. So, although these two birds were heard chirping similar notes in close proximity of one another, they were not communicating.

After exiting the forest, a boardwalk led me through saltwater lagoon where a flock of Greater Flamingos was observed communally foraging. Flamingos of all sub species on a global scale can be found in flocks ranging from 10 individuals to upwards of 200, the flock I observed had approximately 20 individuals. One several birds were observed foraging, perhaps suggesting this was not a peak foraging time, or perhaps could mean they all forage at different times. Most notable about the Flamingos is their bright pink coloration, which is not used for communication but is a side effect of the keratin found in the prawn and shrimp their diets primarily consist of. It is not entirely known how and why their bodies process the pigmentation the way that it does, but it is truly beautiful to see. Younger Flamingos had more grey-white coloration, but after eating more keratin-rich shrimp, their plumage will mature to the gorgeous pink color seen in the adults. Other lagoon birds were observed as well, including the White-cheeked Pintail which was seen in close proximity to other individuals, but no verbal communication was noted. Two Yellow-crowned Night Heron were observed independently of each other, these birds generally forage alone so I was not surprised to not see it within a group. Additionally, it is a nocturnal bird, so observing is at almost at dusk time was appropriate with its feeding and circadian schedule.

Although the Galapagos is extremely diverse, there are not many foraging flocks of smaller birds that would respond to pishing. Fortunately, I do this often when in Vermont forests to try and attract smaller, flocking birds like Black-capped Chickadees and Tufted Titmouses. By either making a “pssh” noise or a whistle, it indicates to smaller birds that the area is safe enough from predators that another organism (me) feels safe making noise. The birds aren’t confusing my vocalizations as another of their species trying to communicate, merely using it as an environmental cue that the region is safe for foraging. Larger birds generally don’t respond to this kind of noise because they primarily use vocalizations for intraspecific communication and not as environmental cues for safety.

Posted on March 19, 2019 11:09 PM by kylermose