Abstract
Theory predicts that individuals behave altruistically towards their relatives. Hence, some form of kin recognition is useful for individuals to optimize their behavior. In species that display bi-parental care and are subject to extra-pair matings, kin recognition theoretically can allow cuckolded fathers to reduce their parental investment, and thus optimize their fitness. Whether this is possible remains unclear in birds. This study investigates whether males provide differential parental care depending on relatedness, as a proxy to recognizing chicks in their nest as kin or not. We cross-fostered House sparrow (Passer domesticus) chicks after hatching, and then expected that fathers would show a decrease in their parental efforts when tending to a clutch of unrelated offspring. House sparrow males are able to adjust their parental care to the identity of their partner, making them an ideal study species. However, there was no significant effect of relatedness on provisioning rates. This suggests that sparrows may not be capable of kin recognition, or at least do not display kin discrimination despite its apparent evolutionary advantage.
Highlights
Kin recognition is the ability to recognize the degree of relatedness with other individuals [1] and evidence for it has been found to be widespread across many taxa [2, 3, 4, 5]
We found no support for the idea that male house sparrows adjust paternal care according to relatedness, which suggests there is no kin recognition
Little research has previously been done on kin recognition and paternal care in house sparrows [23]
Summary
Kin recognition is the ability to recognize the degree of relatedness with other individuals [1] and evidence for it has been found to be widespread across many taxa [2, 3, 4, 5]. Zebra Finches (Taeniopygia guttata) appear to behave differently towards related and unrelated offspring [20] Because of this limited knowledge on the mechanism of kin recognition in birds, we here test the hypothesis that males are capable of kin recognition and adjust parental care in a large, long-term dataset with information on genetic relatedness in House Sparrows (Passer domesticus). This social bird species has a relatively high extra-pair paternity rate [21, 22], a relatively stable social mating system, and we know that male house sparrows are able to adjust their parental care to social cues [23]. This requires the males to be able to recognize their own kin to adjust their level of care
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