Gang-brooding in Northern Bobwhites in West Texas.

Northern Bobwhites (Colinus virginianus) have several reproductive strategies to enhance recruitment including large clutch size, multiple clutches, and male incubation (Burger et al. 1995). Faircloth et al. (2005) described four possible post-hatch brood amalgamations in bobwhites: adoption, creaching, gang-brooding, and kidnapping. Here we define gang-brooding as two or more broods combining with pairs or single adults. This differs from other post-hatching brood amalgamations involving only the adoption or mixing of offspring. Gang-brooding has been observed in other species of quail, including California Quail (Callipepla californica) (Lott and Mastrup 1999) and Gambel's Quail (C. gambelii) (Brown et al. 1998). Gang- brooding conferred survival and was adaptive in California quail; adult quail involved in communal brooding lived longer than adults not involved in communal brooding (Lott and Mastrup 1999). Gang-brooding has not been documented in Northern Bobwhites across the more arid parts of their range, e.g., Texas and Oklahoma, despite numerous studies dealing with radio-marked birds and nesting records (e.g., Burger et al 1995, DeMaso et al. 1997, Hernandez et al. 2003).

METHODS

We followed adult radio-marked bobwhites to monitor reproduction in southwestern Fisher County in the Rolling Plains Ecoregion of Texas during the 2003 and 2004 breeding seasons. The radio-marked individuals were located twice weekly by triangulation and once by walking in on the bird until a visual sighting was obtained (Brooks 2005). All reports of gang-broods were from visual observations of radio-marked birds. These observations commonly resulted in flushing of the adults and possibly the broods.

OBSERVATIONS

The first occurrence of gang-brooding involved two apparently unmated hens (only one of which was radio-marked) combining broods. The radio-marked hen hatched eight of nine eggs on 3 June 2003. Seven days post-hatch (10 Jun 2003) the hen was observed with another mature hen and >15 chicks. A similar observation occurred at 14 days post-hatch (17 Jun 2003). However, at 4 weeks post-hatch the radio-marked hen abandoned the brood, or left it in the care of the other hen. On 15 July the radio-marked hen was found incubating a second nest.

Two radio-marked males were responsible for the care of the second gang-brood. They were first observed on 7 July 2003 and the brood remained intact until radio failure prohibited further monitoring of the adult males on 1 August 2003.

The final gang-brood was reared by two (presumably) mated pairs, of which both females and one male were radiomarked. Both clutches were incubated by the radio-marked females and hatched on the same day (4 Jun 2003). The first observation of all birds together occurred on 1 July. This group of four adults and surviving chicks stayed intact until 15 August when the still-functioning radio transmitters were removed.