Brown Jay Psilorhinus morio

  • Order: Passeriformes
  • Family: Corvidae
  • Polytypic: 4 subspecies
  • Authors: Matthew F. Jones
Sections

Breeding

Nest

Nests are relatively large structures composed of bulky, coarse sticks on the botton and outside of the nest and finer sticks toward the center (Skutch 1960). Nest materials are generally taken from live trees rather than the ground. An exception is the fibrous roots that are pulled from bare soil and line the outside of the nest. One nest measured 14 cm in diameter and was 7.6 cm deep (Skutch 1960). Building can begin as early as February but generally occurs in March or April with pairs taking roughly equal share of nest building responsibilities (Skutch 1960). Nests usually are placed 10-15 m above the groundh on a thin branch or crotch of a branch (Skutch 1960, Lawton and Lawton 1980). Nests built atop crown of banana plants are found 3-6 m high (dos Anjos 2009). Reducing exposure to wind and predation are important factors in nest site selection for Brown Jays (Lawton and Lawton 1980). Nest failure is most often attributed to predation (Williams and Hale 2006). As a result, Brown Jays prefer isolated trees (Ficus tuerckheimii, Croton gossypifolius, Inga tonduzii) to decrease predation risk; however, Monteverde Brown Jays balance nest placement between isolation from predators and wind-protected sites. Nesting in isolated trees has a large effect on successful nestling production (Williams and Hale 2006, dos Anjos 2009). Females on average create two nests per breeding season (range 1-5) but generally do not attempt nesting again after successfully fledging a brood (Williams and Hale 2006).

Eggs

Eggs have pale bluish gray ground color and are covered in fine reddish brown spots. Density of reddish brown spots increases on the thick end (Skutch 1960, Hubbard and Niles 1975). Mean egg measurements are 33.9 mm x 23.6 mm (Hubbard and Niles 1975).

Clutch size

Observations of nests suggest an individual female can lay a clutch of 2-3 eggs (Skutch 1960). Large clutches of up to 8 eggs consist of eggs from multiple females (dos Anjos 2009).

Incubation

Eggs are laid between February and June with a peak in egg production in April (Lawton and Lawton 1985, dos Anjos 2009). Incubation is undertaken solely by females and generally begins in April (Skutch 1960). Females are particularly noisy during incubation, uttering their hunger call to signal their mate and helpers for food (Skutch 1960). While the female is incubating the nest, male mates and helpers gaurd nests and deliver food to the female (Skutch 1960). Incubation period of one pair of Brown Jays was observed between 18-20 days (Skutch 1960).

Parental care

Nestling period is 18-22 days and fledgling period lasts 22-31 days (Lawton and Lawton 1985). First-year birds generally remain with parents to assist as nest helpers and are protected by older members of the group (dos Anjos 2009).

Cooperative breeding

Brown Jays have never been observed to breed without the aid of helpers (Skutch 1960, Williams and Hale 2006). In Monteverde, Costa Rica, helpers provide 70% of nestling feedings, the highest reported in New World jays (Williams and Hale 2006). Helper birds are both male and female, mostly in natal territory; however, some helpers are immigrant birds (Selander 1959, Williams and Hale 2006). Helpers in their natal territory are frequently related to offspring they help raise and thus gain indirect benefits from helping (Williams and Hale 2006). Immigrant helper males may primarily benefit by increasing their opportunity to mate with the breeding female in subsequent years (Williams and Hale 2006). True communal breeding is observed in 29% of groups, which consists of 2-3 breeding females with separate nests aided by helper. Generally, only one female in such a group is reproductively successful (dos Anjos 2009). The number of old flock members predicts breeding success of a group better than the number of flock members (Lawton and Guindon 1981).

Recommended Citation

Jones, M. F. (2012). Brown Jay (Psilorhinus morio), version 1.0. In Neotropical Birds Online (T. S. Schulenberg, Editor). Cornell Lab of Ornithology, Ithaca, NY, USA. https://doi.org/10.2173/nb.brnjay.01