The Red-crested Cardinal is a misnamed Brazilian beauty with a surprising high parental intelligence that helps it evade parasites, pests and predators.
By Rex Graham
This species, which is found in southeastern Brazil, eastern Bolivia, northern Argentina and Uruguay (and introduced to Hawaii), looks like a close relative of the Northern Cardinal. It’s not.
Instead, the Red-crested Cardinal belongs in the Tanager family, based on analysis of its genome. (Some taxonomists put it in the Emberizidae family with buntings and New World Sparrows.) Its melodious song also is Tanager-like, and it eats what tanagers eat – berries, insects and fallen fruit, in addition to seeds.
Red-crested Cardinal parasite defense
An Argentine biologist with a long-term interest in the Red-crested Cardinal has documented its preference for habitats that have been shown to be sub-optimal for other birds. He was mystified. How had this species become so abundant in territories with hordes of parasites, deadly insect pests and predators?
Its skills become apparent in late-August or September, the beginning of its breeding season. Its first challenge is the Shiny Cowbird, a brood parasite that lays its eggs in other birds’ nests. Cowbirds closely watch every move of their would-be victims. The cowbirds is a brood parasite of 250 bird species, and their strategy is to lay one spotted eggs in other birds’ nests without being spotted.
Lurking cowbirds? No worries
Surprisingly, Red-crested Cardinals are tolerant of cowbirds perched near their nests. They aren’t aggressive toward a foe that could drastically reduce their own reproductive success. They have a smarter defense. When a spotted cowbird egg appears in their nest, they reject 67 out of 68 of them.
That was the finding of Juan C. Reboreda, a scientist at Universidad de Buenos Aires in Argentina, and a colleague. They reported in the journal Behavior that rather than expending energy chasing away cowbirds, the Cardinals have perfected a counterfeit-recognition system. It’s nearly flawless.
Red-crested Cardinals have another threat during nesting season – biting flies, especially botflies. The cardinals usually initiate nesting before the botflies become most prevalent in December. By that time, any chicks remaining in the nest have feathers that tended to shield them from biting flies. That’s according to another Reboreda study published in The Wilson Journal of Ornithology. The cardinals also nest farther away from streams and waterways, which results in fewer flies to cope with.
There is one more potent threat to Cardinal chicks – predators. Since Cardinals nest in semi-open areas with scattered trees, you might assume that predators would easily spot nests and nestlings. The parents use a two-tactic deterrent: they become increasingly vigilant as their chicks grow, and more vigorously attack avian predators.
The best placement of Cardinal nests is another surprise. The most successful parents build nests in small, fragmented groups of trees surrounded by grassland. They tend not to nest in lines of trees at the edge of forests, such as along rivers that are favored by avian predators.
“For such predators, the open areas of grassland that separate the isolated patches of forests from the rows of forests parallel to the river could be a barrier to predator movements,” wrote Reboreda in yet another paper in the Journal of Field Ornithology.