Saturday, April 30, 2016

[Ornithology • 2016] Reproductive Biology of the Sapayoa Sapayoa aenigma, the “Old World suboscine” of the New World

A Sapayoa Sapayoa aenigma emerges from its nest in the Panamanian rainforest.  

photos: J.M. Hite
  DOI: 10.1642/AUK-16-5.1 

The Sapayoa (Sapayoa aenigma), a low-density resident of Chocó rainforests from Panama to Ecuador, has long perplexed ornithologists. It was originally described as a manakin (Pipridae), but molecular work has revealed its closest living relatives to be Old World suboscines (Eurylaimides) and supported its placement in the monotypic family of Sapayoidae. Despite such phylogenetic intrigue, little is known about the Sapayoa's general life history or reproductive biology; only one nest has been described. We present information on 2 actively attended and 13 inactive Sapayoa nests in Darién National Park, Panama. We provide the first detailed description of individual effort at an active nest, family group dynamics during the nesting period, the plumage of immature birds, and the range of vocalizations produced. We also present the first documentation of cooperative breeding and compile several recent nesting observations, extending the published Sapayoa breeding period by several months. Furthermore, we describe unusual behaviors among provisioning birds, including mounting between individuals of the same sex and mounting of a female by immature male helpers during chick provisioning. The receiving individual gave a conspicuous solicitation display before each mounting. Finally, we highlight elements of the Sapayoa's natural history that echo its Old World relatives and contrast with members of the New World Tyranni. For example, the Sapayoa resembles the eurylaimid broadbills—and differs starkly from the manakins—in diet, nest structure, breeding system, and mode of parental care.

Keywords: cooperative breeding, helpers, mounting, Old World suboscines, Sapayoa aenigma, Sapayoidae

Sapayoa aenigma, Nusagandi, Panama 
photo: Jan Axel 

Sarah A. Dzielski, Benjamin M. Van Doren, Jack P. Hruska, and Justin M. Hite. 2016. Reproductive Biology of the Sapayoa (Sapayoa aenigma), the “Old World suboscine” of the New World [Biología reproductiva de Sapayoa aenigma, el “suboscín del Viejo Mundo” que habita el Nuevo Mundo]. The Auk. 133(3); 347-363. DOI: 10.1642/AUK-16-5.1

Field Study Helps Confirm The Sapayoa Is Like No Other Bird In The New World
An Old World bird in a New World rainforest via @physorg_com

The Sapayoa, a rainforest bird from Central and South America, is an evolutionary enigma—genetic analysis shows that its closest relatives are bird species living across the ocean in Asia and Africa. Now, new research in The Auk: Ornithological Advances demonstrates for the first time that its natural history links it to its evolutionary relatives thousands of miles away.

How the Sapayoa ended up so far from other members of its lineage remains a mystery, and little is known about its reproductive biology or social behavior. However, new field work in Panama by Sarah Dzielski and Benjamin Van Doren of Cornell University and their colleagues reveals that Sapayoas consistently build nests that hang over the water along ravine-bottom streams. One of the active nests they observed was attended by a family group comprised of an adult male and female and two immature males, all four of which brought food to the two chicks. The researchers were surprised by the social behavior they observed, which included mounting between individuals of the same sex, possibly to establish dominance and maintain social cohesion.
These are the first extended observations of Sapayoa breeding behavior, and they provide hints at how this unusual bird is connected with its roots. Many of the Sapayoa's Old World relatives are cooperative breeders, getting help from family groups, and the pear-shaped hanging nest also is consistent with Old World "suboscines," the group of birds to which Sapayoas belong.
Dzielski, Van Doren, and their colleagues Jack Hruska and Justin Hite searched for Sapayoa nests as part of an expedition to Panama's Darién National Park in summer 2014, observing the family group at their focal nest for more than 70 hours over ten days. "Nest searching was always an adventure," says Dzielski. "We found countless abandoned nests, and while checking inside for eggs or evidence that the nest was active, we found all sorts of surprises. In a few instances, a large grasshopper the size of a mouse hopped out from under the flap and scared the daylights out of us!"
"The Sapayoa is so different from other passerine birds that it is currently placed in its own family, Sapayoidae, but relatively little is known about its natural history," adds Van Doren. "This gap in scientific knowledge was the reason we traveled to eastern Panama to learn about this enigmatic species. We hoped that more information about the Sapayoa's natural history would cast its surprising evolutionary relationships in a new and clearer light."
"The Sapayoa has long been a mystery bird. When my colleagues and I identified it as the only Old World suboscine in the New World in 2003, it only became more mysterious," says Jon Fjeldså of the University of Copenhagen, who led the research team that first identified the Sapayoa's unusual origins. "How did it arrive in South America? Why does it resemble a manakin? And does it still behave like an Old World suboscine? I am excited to learn that it indeed does!"

Sapayoa aenigma, un ave residente en bajas densidades en los bosques húmedos del Chocó desde Panamá hasta Ecuador, ha confundido a los ornitólogos por bastante tiempo. Aunque la especie originalmente fue descrita como un saltarín (Pipridae), estudios moleculares recientes revelaron que sus parientes más cercanos son los suboscinos del viejo mundo (Eurylaimides) y sustentan su ubicación en la familia monotípica Sapayoidae. A pesar de esta intriga filogenética se sabe muy poco sobre la historia de vida o la biología reproductiva de Sapayoa; sólo se ha descrito un nido. En este trabajo presentamos información de 2 nidos activos y 13 nidos inactivos de Sapayoa encontrados en el Parque Nacional Darién, Panamá. Presentamos la primera descripción detallada del esfuerzo individual en un nido activo, la dinámica del grupo familiar durante el periodo de anidación, el plumaje de las aves inmaduras y el repertorio de vocalizaciones. También presentamos la primera evidencia de cría cooperativa y recopilamos varias observaciones recientes de anidación que extienden el periodo reproductivo conocido de Sapayoa en varios meses. Además describimos comportamientos inusuales entre las aves que proveen alimento a sus crías, incluyendo la monta entre individuos del mismo sexo y entre un individuo joven y una hembra adulta durante la alimentación de los polluelos. El individuo que recibía la monta ejecutaba antes un despliegue para solicitarla. Finalmente, resaltamos elementos de la historia natural de Sapayoa que se asemejan a las de sus parientes del Viejo Mundo y contrastan con las de miembros de Tyranni en el Nuevo Mundo. Por ejemplo, Sapayoa se asemeja a los Eurylaimidae (y difiere drásticamente de los Pipridae) en dieta, estructura de los nidos, sistema reproductivo y modo de cuidado parental.

Palabras clave: ayudantes del nido, cría cooperativa, monta, Sapayoa aenigma, Sapayoidae, suboscines del viejo mundo