The Summer Tanager ( Piranga rubra ) is a medium-sized American songbird, known for its distinctive dietary habits. Once classified within the tanager family (Thraupidae), it now belongs to the cardinal family (Cardinalidae). This neotropical migratory bird is a fascinating subject, especially when considering its unique food preferences.
Appearance and Identification
Adult male Summer Tanagers are a striking rose red, resembling the Hepatic Tanager, but distinguished by their light-colored bill. Females exhibit orangish underparts and olive upperparts, with olive-brown wings and tail. Some females may develop complete male pigmentation as they age. Young males can display a patchy mix of yellow and red plumage. Reaching lengths of 17 cm and weighing around 30 g, they possess light brown, pointed, and fairly stout bills.
Distribution and Habitat
Summer Tanagers breed across the southern United States, reaching as far north as Iowa, and migrate to Mexico, Central America, and northern South America for the winter. They arrive in their breeding grounds from mid-April to late May. During migration, the summer tanager is sometimes found in orchards, parks, and trees along roadsides. Their wintering range extends from central Mexico to Bolivia and Brazil. They migrate north and south on a broad front, with some crossing the Gulf of Mexico and others traveling overland.
These birds favor open wooded areas, particularly those with oaks, and riparian habitats. The Summer Tanager inhabits open deciduous woods in the eastern part of its range. In the west, it occupies riparian woodlands consisting primarily of cottonwoods and willows, and at higher elevations, habitats dominated by mesquite and salt cedar. They can be found in lowlands and up to middle elevations in mountains, both in solid forests and in edges and clearings with scattered trees.
General Behavior
Summer Tanagers are diurnal birds. Outside of the breeding season, they are usually solitary or may join mixed-species flocks of fruit-eating birds. They often remain hidden, foraging high in the trees, but will fly out to catch insects in flight.
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Song and Vocalizations
The Summer Tanager's song is a cheery, rich, and musical melody, reminiscent of an American Robin but softer and sweeter. It consists of melodic units repeated in a constant stream. A distinctive rattling "chick-tucky-tuck" call is also characteristic of the species. Male summer tanagers arrive on the breeding grounds in full song, usually a few days before females arrive. At the start of the breeding season the male sings vigorously all day to attract females and establish a territory. If a female Summer Tanager does sing, it is a brief, garbled version of the male's song.
Breeding and Nesting
Summer Tanagers are serially monogamous, forming pairs for only one breeding season, which occurs between April and August. During this time, males are territorial, actively defending their nests and feeding territories. Male birds are the primary songsters in most songbird species. Pairs are usually hidden in tall treetops, and thus are difficult to spot.
The nests of summer tanagers in the west are sturdy and well-constructed, while birds in the east usually build nests so flimsy and ragged, the eggs can be seen through the bottom. After the 4 to 5 days it takes to complete an open-cup nest, egg-laying begins. The nest is constructed out on a horizontal branch by the female, and consists of dried grasses, weeds, leaves, spider webs and strips of bark lined with fine grasses. After the nest is complete, the female lays 3 to 4 somewhat glossy eggs, spotted more heavily on the large end with browns, purples, and grays, creating a 'capped' look. She incubates them for 12-13 days. During incubation, the male spends a lot of time resting and caring for his feathers, and occasionally feeds the incubating female, who may beg him for food.
The chicks hatch helpless with their eyes closed and are fed by both parents. After 8 to 10 days, they leave the nest but remain dependent on their parents for about 2-4 weeks more. Because the nests of the Summer Tanager are built inaccessibly high in the treetops, there have been few studies of their basic breeding biology.
The Summer Tanager's Diet: A Closer Look
The Summer Tanager's diet is a fascinating aspect of its natural history. Its affinity for stinging insects has earned it the nickname "Bee Bird." This bird is known to be a well-known pest around apiaries and is persecuted by beekeepers.
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Primary Food Sources
The Summer Tanager's stout, pointed bill allows it to easily capture and neutralize its preferred prey, bees and wasps and their larvae. They are excellent flycatchers, able to seize adult bees and wasps in mid-flight. The Summer Tanager often stays out of sight, foraging high in trees, and sometimes flying out to catch insects in flight.
Hunting Techniques
The Summer Tanager darts out from a perch to snatch a bee or wasp in mid-air, then subdues the insect by beating it against a branch. It then wipes them on the branch to remove the stingers before eating them. Summer Tanagers also rip into wasp nests to eat the larvae inside. They harass or kill the adult wasps guarding the vespiaries.
Seasonal Variations
In addition to their diet of bees and wasps, Summer Tanagers also eat fruits and berries, especially during the late breeding season, while migrating and while on their wintering grounds. They may also visit backyard feeders for jam and suet.
Other Invertebrates
While Summer Tanagers specialize in hunting bees and wasps, they also consume a wide variety of other invertebrates. This includes beetles, dragonflies, cicadas, caterpillars, and spiders.
Conservation Status
Overall, the population is considered stable, though sharp declines in the west may be attributed to tremendous losses in their riparian forest habitat. A nearly total conversion of riparian forest to agricultural lands in the Colorado River valley may be the leading cause of an almost complete disappearance of this species from that area. Night migration casualties due to radio and TV tower collisions may also be a factor. The total breeding population size of the Summer tanager is 12 million individuals.
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Role in the Ecosystem
Summer tanagers play a very important role in the ecosystem they live in. Summer Tanagers seem to recognize the threat posed by brood parasites such as Brown-headed Cowbirds, chasing them away from their territories whenever possible. Nevertheless, their nests are often parasitized.
Threats and Conservation Efforts
Although Summer Tanager populations are currently considered stable, the species is still vulnerable to habitat loss, particularly the clearing of riparian habitat in the western United States. There, the Summer Tanager shares habitat with several threatened birds, including the Southwestern Willow Flycatcher and western race of the Yellow-billed Cuckoo. ABC works to preserve riparian habitat throughout the Southwest. They have advocated for the San Pedro River, one of the last major undammed rivers in the American Southwest.