Sexual conflict over parental care in Penduline Tits Remiz pendulinus: the process of clutch desertion

Abstract

Do the two parents at a nest make simultaneous decisions whether to care for their offspring or to desert? If a single parent is sufficient for rearing young, one parent (typically, the male) may desert and reproduce with a new mate within the same breeding season, leaving the other parent with the brunt of care. As each parent is expected to maximize its own reproductive success, the interests of the two parents do not necessarily coincide, and a sexual conflict over care may emerge. Here we investigate the process of clutch desertion in a small passerine bird, the Penduline Tit Remiz pendulinus. Among birds, this species has a remarkably variable breeding system, because a single parent (either the male or the female) may provide the full care of the young, whereas about 30% of clutches are abandoned by both parents. First, we show that biparental desertion occurs within a single day in 73.7% of the clutches (n = 14), whereas desertion decisions are sequential in 26.3% of the clutches (n = 5) (male first: 10.5% (n = 2); female first: 15.8% (n = 3); n = 19 clutches in total). Secondly, we observed the behaviour of both parents before desertion, and investigated whether desertion can be predicted from their behaviour. However, neither singing nor nest‐building behaviour predicted whether the male or the female would desert. We therefore suggest that biparental desertion may be simultaneous by male and female in our population of Penduline Tits. Furthermore, the parents do not appear to signal their intention to desert their mate. We argue that the parents’ interest may be actually to disguise their intention to desert.

Sexual selection and the function of a melanin-based plumage ornament in polygamous penduline tits Remiz pendulinus

“…Desertion by a parent was recognized if the parent was not observed at the nest for at least two consecutive checks . Predation is an unlikely explanation for the 'disappearance' of penduline tit parents because (1) in most cases, deserting individuals (58 out of 89 males and 66 out of 78 females) were resighted later in the same season or in subsequent years, (2) the 'disappearance' of parents is not scattered through incubation and brood rearing, but characteristically concentrated during a short (2-3 days) interval during egg laying (van Dijk et al 2007), and (3) frequencies of 'disappearance' are highly consistent between different populations of penduline tits (see Persson and Öhrström 1989), whereas one may expect local variations if predation of adults cause the disappearance.…”

Individual variation and the resolution of conflict over parental care in penduline tits

“…Males were usually trapped before incubation using mist nets, whereas females were usually trapped at the nest during incubation. We searched for nest-building penduline tits and then visited each nest roughly every 2 days [40] to determine the date of nest initiation, date of pair formation, number of eggs (between the sixth and the ninth day after the start of incubation; median, eighth day), date of desertion, identity of the parent attending the nest and the number of nestlings (10 days after hatching of the first egg; the number of nestlings on the tenth day after hatching is highly correlated with the number of fledglings [39,40]). Adults were trapped and ringed with one metal ring and a unique combination of three colour rings (A. C. Hughes, Middlesex, UK).…”

Offspring sex ratio in the sequentially polygamous Penduline Tit Remiz pendulinus

“…Of all nests, 52% was abandoned either before pair formation had taken place [i.e., the male was unsuccessful in attracting a female (37%), or the nest was abandoned due to disturbance by humans, heavy winds or predation (12%), or a new owner overtook the nest (4%)]. We searched the study site to identify unpaired, nest-building males, and then visited the males every other day to monitor their status by observing them for at least 15 min (see details in Bleeker et al 2005;Van Dijk et al 2007).…”