Behavioral Ecology Vol. 12 No. 5: 524-533
© 2001 International Society for Behavioral Ecology
Complex sex allocation in the laughing kookaburra
a Botany and Zoology, Australian National University, Canberra, ACT 0200, Australia b DEEB, Graham Kerr Building, Glasgow University, Glasgow G12 8QQ, UK
Address correspondence to S.L. Legge. E-mail: sarah.legge{at}anu.edu.au .
In groups of the cooperatively breeding laughing kookaburra (Dacelo novaeguineae), offspring sex varied with the type of social group and with hatch rank. Groups with female helpers, especially if all helpers were female, had male-biased clutch and fledging sex ratios. Groups without female helpers (unassisted pairs or male-only helpers) had female-biased clutch and fledging sex ratios. Breeding females responded facultatively to increases in the number of female helpers in their group by producing more male eggs. These biases may occur if breeding females try to limit the number of daughters recruited into their group because unlike male helpers, female helpers depress the breeding success of their parents. Across all nests, two-thirds of first-hatched young were male, two-thirds of second-hatched young were female, and the sex ratio of third-hatched young was even. Hatch rank sex ratios also varied dramatically between different types of social groups, from 16.7% for second-hatched nestlings of unassisted pairs to 100% for first-hatched nestlings of groups with only female helpers. A corollary of the relationship between hatch rank and sex was that hatching sex sequences were distributed nonrandomly: all groups avoided hatching a daughter first followed by a son (FM). Sibling competition is aggressive and sometimes fatal. Since females grow to be 15% larger than males the hatching sequence of sexes could affect nestling growth and mortality. However, an exhaustive analysis found little evidence that growth or survival of males was compromised if hatched after a sister. The small number of FM sequences may only have occurred in nests that were able to ameliorate any negative consequences. Alternatively, when clutch size is small and fledging success unpredictable because of brood reduction, the preferred brood sex ratio may be contingent on the number of fledged young, making it advantageous to order the sexes in the brood.
Key words: cooperative breeding, kingfisher, reverse dimorphism, sex allocation, sex ratio, siblicide.
CiteULike 
Connotea 
Del.icio.us What's this?
This article has been cited by other articles:
|
|
 |
|
  J. Abe, Y. Kamimura, and M. Shimada Sex ratio schedules in a dynamic game: the effect of competitive asymmetry by male emergence order Behav. Ecol., November 1, 2007; 18(6): 1106 - 1115. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
P. Korsten, C. M. Lessells, A. C. Mateman, M. van der Velde, and J. Komdeur Primary sex ratio adjustment to experimentally reduced male UV attractiveness in blue tits Behav. Ecol., July 1, 2006; 17(4): 539 - 546. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 A. V Badyaev, H. Schwabl, R. L Young, R. A Duckworth, K. J Navara, and A.F Parlow Adaptive sex differences in growth of pre-ovulation oocytes in a passerine bird Proc R Soc B, October 22, 2005; 272(1577): 2165 - 2172. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
D. Allaine Sex ratio variation in the cooperatively breeding alpine marmot Marmota marmota Behav. Ecol., November 1, 2004; 15(6): 997 - 1002. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
T. L. F. Martins Sex-specific growth rates in zebra finch nestlings: a possible mechanism for sex ratio adjustment Behav. Ecol., January 1, 2004; 15(1): 174 - 180. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
J. G. Ewen, R. H. Crozier, P. Cassey, T. Ward-Smith, J. N. Painter, R. J. Robertson, D. A. Jones, and M. F. Clarke Facultative control of offspring sex in the cooperatively breeding bell miner, Manorina melanophrys Behav. Ecol., March 1, 2003; 14(2): 157 - 164. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
A. Nathan, S. Legge, and A. Cockburn Nestling aggression in broods of a siblicidal kingfisher, the laughing kookaburra Behav. Ecol., November 1, 2001; 12(6): 716 - 725. [Abstract] [Full Text] [PDF]
|
|