Tag Archives: Target taxa

Nest Searching Tales

The following are several accounts of nest finding by team member Eric Gulson.  We named the nests after the species (RBGR=Rose Breasted Grosbeak, SCTA=Scarlet Tanager) and the order in which the nests were found.

RBGR 4

Earlier in the season, we were working with several Scarlet Tanager nests and one Grosbeak nest. However, one day Cat monitored that Grosbeak nest (RBGR 1) and found that it was abandoned: no adult came during those two hours or ever again.  Because of this, finding a Grosbeak nest became a more pressing matter, and we began looking for more adults. Two days later, Jack and I were heading into the woods on the trail we take every day and I was lingering behind. As I passed a group of shagbark hickories to my right, I heard the Grosbeak call, similar to a sneaker squeaking on a basketball court. Around five meters up a pair was perched, but they immediately left and flew across the corner of a small field, a total of around 20 meters. I followed them and it seemed as though the female was collecting nesting material. She was near the ground, but disappeared momentarily behind a tree. Soon though, to my surprise, they flew back to the group of trees they came from, where the female headed straight up and towards what proved to be a nest under construction. The nest, as if to humiliate us, was over halfway done and directly above the trail. We had passed by it several days straight without taking notice. We immediately began monitoring it and by the end of the field day, it looked considerably less like a platform and had a clear bowl shape. The pair also copulated in a nearby sapling that day, and the flashing of the male’s white rump and wing patches along with its pink underwing coverts was a striking sight.

SCTA 4

One afternoon in late May I decided to stay after everybody had left, because I had my bicycle and did not depend on anybody else for a ride. It was the day after RBGR 1 had abandoned their nest, so I checked on that site before heading headed further south. Here, I heard the chck-brrr of a Scarlet Tanager, followed by two more. Four individuals, two pairs, appeared and I was clearly at their territorial boundary, since one pair stayed around in an oak tree while the other flew south. I lost track of the pair in the oak, but after a while was able to hear the other pair calling and decided to follow them. Here, I found the male in a small tree, while the female was moving around quite near the ground. She was looking around and dropped to the ground, where she hopped around several times and began pulling at something between a leaf and the floor: spider silk. She was collecting the fibers for a nest, but I quickly lost track of her when she left the floor. However, the male was always to be found in a group of small trees and I resolved to visit the next day. I did, and once again found the male in a group of trees and the female on the ground. I lost track of her until I noticed her flying into a group of basswoods, high above the ground. After watching her enter the area and loosing her four times, I finally saw the nest, twelve meters up, on the fork of a major branch. It immediately struck me how obvious its position seemed, with twelve meters of open space between it and the ground, but it still took me two days to find. I was particularly attached to this pair because the male often came quite close to us when we monitored its nest, and both individuals had distinctive patches of yellow on the head, especially the female. Unfortunately, we lost track of them once their chicks fledged.

SCTA 5

We found the nest of Scarlet Tanager 5 quite by accident. Hilary, Justin, and I had just spent hours searching for a new Rose-breasted Grosbeak nest in early June and were returning from a swamp through a different route when Justin heard a Scarlet Tanager to our north. We decided to follow it for a moment because it was near SCTA 4, although further to the east. The male was distinctive, because he had a couple of white spots on his wing, so Hilary decided to try to photograph it, and I began recording a description of its foraging movements in a microphone, trying to keep track of the bird’s every movement. As he approached a beech tree, he suddenly attacked a woodpecker that had been in its branches. Because I had seen grosbeaks and woodpeckers forage side by side, it seemed odd that the tanager would ever chase it off, so I decided that its nest might be nearby. Sure enough, a little to above and to the right of the incident there was a group of twigs and grasses, so I called Justin and kept monitoring the birds foraging behavior. As it turned out, where I was standing was the only one of four places where the nest is visible from the ground, I had been extremely lucky. It also became clear that this one and SCTA 4 were neighbors, because we would hear the males counter-singing in the mornings and were able to walk in a nearly straight line from one nest to the other.

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Spotlight on: Scarlet Tanager

The Scarlet Tanager (Piranga olivacea) is arguably the bird that led to the conception of this entire project. The story begins with the Piranga tanagers, a genus that also contains familiar North American birds like the Summer (P. rubra) and Western Tanagers (P. ludoviciana) as well as more southerly species like the Flame-colored (P. bidentata) and Rose-throated Tanagers (P. roseogularis). These tanagers were originally classified with…well…the other tanagers, a wide radiation of American birds in the family Thraupidae. Recently, advances in molecular studies have indicated that this is not, in fact, the case. Piranga tanagers are not tanagers at all. According to their molecular make-up and DNA, these birds are actually Cardinalids. The American Ornithologists’ Union has since updated its taxonomy to reflect this change, placing the Scarlet Tanager and its kin alongside the cardinals, buntings, and grosbeaks of the family Cardinalidae. This discovery prompted the realization that, if these birds are so similar at their most basic building-block level, perhaps there are biological and behavioral similarities that had previously gone unnoticed. Thus, the Tompkins County branch of CEFO was born, with the goal of observing and recording the breeding biology of our own local Cardinalids.

Credit: Justin Hite

Tricky taxonomy aside, the Scarlet Tanager is a very impressive bird. They can be found in a wide range of wooded habitats across eastern North America, being replaced by the similar and appropriately-named Western Tanager in the west. They winter in northern South America, but their breeding habitat is the deciduous and mixed forests in the United States and southern Canada. The birds are about 7 inches long, with a greyish bill and feet in all plumages. Adult males have a striking pattern: brilliant red plumage with contrasting black wings and tailfeathers. The female is a dull, inconspicuous olive-green with some yellow and grey mixed in. Immatures and nonbreeding males are similar to females, though nonbreeders possess the black feathers of the breeding season. In their first spring, male tanagers may retain some yellow feathering in patches, while other males have an orange coloration overall. Fledglings often have streaking on their breast and flanks for some time after leaving the nest. The tanager is readily identified by its song, which resembles that of a robin, but with a hoarse, “burry” quality to the phrases. The bird’s “chck-brr” call is a common sound, and a distinctive identifier, in these woods.

Scarlets are birds of the canopy. Even the flashy males can be challenging to pick out as they move about the foliage in the treetops, though they can be spotted when they come into the opening or move closer to the ground. They forage as they go, gleaning insects and spiders from the leaves or snagging aerial arthropods such as dragonflies. They are also known to eat some plant matter. They usually place their nest towards the end of a branch with a clear view of the surrounding area, building a loose-looking cup of twigs and other plant materials. They seem to prefer deciduous trees, but one of our most productive nests was located in a conifer along the trail! Clutch size ranges from 1-6 greenish blue eggs with brownish speckling. Incubation lasts around 2 weeks, and the chicks themselves fledge within 9-11 days after hatching.

At our study site, we found a surprising number of Scarlet Tanager territories spread across the woods. We were able to locate and monitor 7 individual nests over the course of our field season. The birds’ distinctive vocalizations made them easy to locate, and they proved to be very cooperative subjects. The tanagers seemed to adjust readily to our presence, carrying on with their daily activities at the nest with us watching intently. Some individuals even seemed interested in us, with the pairs at nests 3 and 4 often coming down out of the canopy to watch the nest-watchers from nearby branches. We were able to observe a wide range of behaviors related to site selection, nest building, raising the eggs and chicks, and territory defense from rivals and predators. They were also much more successful than our observed grosbeak pairs at making successful nesting attempts where the chicks survived to fledge, but more on that later!

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