TY - JOUR

T1 - Hatching asynchrony decreases the magnitude of parental care in domesticated Zebra Finches

T2 - empirical support for the peak load reduction hypothesis

AU - Mainwaring, Mark C.

AU - Lucy, David

AU - Hartley, Ian R.

PY - 2014/6

Y1 - 2014/6

N2 - Parent-offspring conflict over the supply of parental care results in offspring attempting to exert control using begging behaviours and parents attempting to exert control by manipulating brood sizes and hatching patterns. The peak load reduction hypothesis proposes that parents can exert control via hatching asynchrony, as the level of competition amongst siblings is determined by their age differences and not by their growth rates. Theoretically, this benefits the parents by reducing both the peak load of the offspring's demand and their overall demand for food and benefits the offspring by reducing the amplification of their competition. However, the peak load reduction hypothesis has only received mixed support. Here, we describe an experiment where we manipulated the hatching patterns of domesticated zebra finch Taeniopygia guttata broods and quantified patterns of nestling begging and parental feeding effort. There was no difference in the begging intensity of nestlings raised in asynchronous or experimentally synchronous broods, yet parental feeding effort was lower when provisioning asynchronous broods and particularly so when levels of nestling begging were low. Further, both parents acted in unison, as there was no evidence of parentally biased favouritism in relation to hatching pattern. Therefore, our study provided empirical support for the prediction that hatching asynchrony reduces the feeding effort of parents, thereby providing empirical support for the peak load reduction hypothesis.

AB - Parent-offspring conflict over the supply of parental care results in offspring attempting to exert control using begging behaviours and parents attempting to exert control by manipulating brood sizes and hatching patterns. The peak load reduction hypothesis proposes that parents can exert control via hatching asynchrony, as the level of competition amongst siblings is determined by their age differences and not by their growth rates. Theoretically, this benefits the parents by reducing both the peak load of the offspring's demand and their overall demand for food and benefits the offspring by reducing the amplification of their competition. However, the peak load reduction hypothesis has only received mixed support. Here, we describe an experiment where we manipulated the hatching patterns of domesticated zebra finch Taeniopygia guttata broods and quantified patterns of nestling begging and parental feeding effort. There was no difference in the begging intensity of nestlings raised in asynchronous or experimentally synchronous broods, yet parental feeding effort was lower when provisioning asynchronous broods and particularly so when levels of nestling begging were low. Further, both parents acted in unison, as there was no evidence of parentally biased favouritism in relation to hatching pattern. Therefore, our study provided empirical support for the prediction that hatching asynchrony reduces the feeding effort of parents, thereby providing empirical support for the peak load reduction hypothesis.

KW - hatching asynchrony

KW - parental care

KW - offspring begging

KW - FOOD ALLOCATION

KW - TAENIOPYGIA-GUTTATA

KW - PROVISIONING RULES

KW - OFFSPRING CONFLICT

KW - BIASED FAVOURITISM

KW - BROOD REDUCTION

KW - SEXUAL CONFLICT

KW - TREE SWALLOWS

KW - WILD

KW - BEHAVIOR

U2 - 10.1111/eth.12229

DO - 10.1111/eth.12229

M3 - Journal article

VL - 120

SP - 577

EP - 585

JO - Ethology

JF - Ethology

SN - 0179-1613

IS - 6

ER -