Common Name: Passerini's Tanager

chris's_pic_tanager.jpg

Latin Name: Ramphocelus passerinii
Family: Thaupidae

Range:

The Passerini’s Tanager is found on the Carribean side of Central America ranging from southern Mexico all the way down to northeastern Panama. It is not typically found on the Pacific side of Central America, where its sister species Cherrie’s Tanager lives.

Abundance:

It is very commonly found in countries such as Belize, Costa Rica and Panama. Paserini’s Tanager is endemic to the Americas and they can be found from sea level up to 1670 m high. It has a large enough range and abundance that it has a conservation status of “least concern”.

Coloration:

They considered part of the “dull-colored” group of tanagers. R. passerinii is sexually dimorphic; the males are all black with a patch of red covering their lower back, tail and rump (they formally were called scarlet-rumped tanagers). The females however, are a brownish and olive green color sometimes with a small patch of yellow on their chest. The juveniles resemble the female in color but with a greyer head. Young males may have scattered black feathers and when they begin to reach adult age (approximately six months old) the males shed their olive feathers and become black with the red patch [1].
female
female in tree
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male in tree

Morphology:

It is a small-sized bird, with both male and female adults approximately equal size and weight of 30-31 grams [1].

Reproductive cycle:

The breeding season begins in March and continues until July and sometimes into early August. The males sing to attract females and the females typically build the nests. It is not clear whether these birds are monogamous or polygynous. Females almost
both_tanagers_together
Male (left) and female (right) perching together
always lay exactly two eggs that are blue and spotted in color and they hatch after twelve days [2]. The female is also exclusively responsible for taking care of the babies. Sometimes the father will bring pieces of food to the nest to give to the babies [1].



Habitat:

The habitat of R. passerinii is secondary growth areas that are relatively low in growth. They prefer cleared areas with small trees such as forest edges [1]. In La Selva, I saw these birds in the trees around the area with the cabins and various buildings. Multiple times I saw them in a small tree outside the cafeteria or in another small tree next to our cabin. Because they like cleared areas, it was not surprising they were found commonly among places that people inhabited. They build their nests in bushes, low trees, or at the edges of plantations or forests. They are not found very high up in trees.

Ecology:

Just two predators of R. passerinii are humans and bigger birds. There are probably more, but it is unknown. Their prey include insects, spiders and harvestmen. They compete with other birds who feed off of the same food as them, but this is probably low due to the generalization these birds have. They are not known to have any symbiotic relationships.

Behavior:

Typically a gregarious bird, they flock and forage in small groups of 3-5 birds [3]. They are also known to forage in mixed groups with other species and this is believed to help increase their foraging success due to additional protection, less competition and ease in finding food. There is no rigid social structure since the flocks are not permanent and the only birds that come to the nest are mother father and nestlings [2,3]. R. passerinii does not defend territories and nests can be found close to other nests [1]. They commonly sing in the forest; their vocalization is used to attract females as well as alert others of predators. Males sing to attract females during the mating season on low perches and expose their bright red feathers[1]. The calls are moderate to low-pitched ik wak and wah sounds that are sung in small phrases and repeated many times. When calling due to predators, the calls are higher sharp-pitched sounds.

Diet:

they are a generalized bird, so they eat a wide range of food consisting mostly of hard and soft fruits, nectar, insects, spiders, and harvestmen. They are known to eat a less preferred food source depending on travel distance to save energy and time [4]. They forage on the ground or in the foliage during the day, usually in small flocks/assemblages. In La Selva they were most commonly seen eating miconia impertiorlaris.
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miconia impertiorlaris

Interactions with other Species:

R. passerinii interacts with many other species of birds during its foraging activites. Some of the birds most commonly seen with passerinis tanager include:Short-billed Pigeon, Red-caped Manakin, Masked Tityra, and White-shouldered Tanager [2]. These birds flock together to search for food while providing protection from predators and “safety in numbers”.

Personal Experience:

I was lucky enough to see my bird at least once every day while I was at La Selva. I saw it in three different places: in a small tree next to the cafeteria, in a small tree next to the cabin I stayed in, and in a bush near one of the classroom buildings on the other side of the bridge. Twice I saw both the male and female flying or perching together. My classmates saw the pair eating berries together next to the cafeteria. I saw the male bird more often than the female, and I saw him eating red berries (miconia impertiorlaris) which the literature I read stated was a common food source for them. I usually saw them eating or perching during the morning and early afternoon hours; I did not see them late afternoon or at night.

References:

[1] Pascal O. and Kevin J. Burns. Neotropical Birds: Ramphocelus passerinii, Cornell University April 2009.
[2] David J. Moriarty. Flocking and Foraging in the Scarlet-rumped Tanager. The Wilson Bulletin, Vol. 8 No. 1 March 1977
[3] Alexander F. Skutch, Outline for an Ecological life history of a bird, based upon the song tanager Ramphocelus passerinii costaricensis. Ecology Vol. 31, No. 3 July 1950.
[4] Douglas J. Levey, Timothy Moermond, Julie Denslow, Fruit choice in the Neotropical birds: the effect of Distance between fruits on preference patterns. Ecology, Vol. 65 No. 3 June 1984