A new study into sparrow behaviour has found that unfaithful females lead to the father of their offspring caring less for their young.
Who will love a little sparrow? So asked Simon & Garfunkel many moons ago, perhaps not realising the promiscuity of the species.
Tracking hundreds of sparrows on Lundy island in the UK, a new 12-year study found that ‘cheating’ female sparrows result in male fathers providing less food in the nest for their young.
Of course, it isn’t all ‘boo’ against the females, with monogamous relationships under threat from both sides at all times.
While males mate often to ensure a decent return of offspring, females do so to find sparrows with better ‘genetic quality’. However, it’s quite the morale killer when it happens.
According to Imperial College London’s Dr Julia Schroeder, male behaviour notably changed depending on the female partner.
Essentially if she was “prone to infidelity”, he provides less. However, the social cues are not obvious, nor universal. They don’t know how males know of the infidelity.
Jilted, but not too observant
Better still, there is little evidence that males knew which chicks were even their own.
“If chicks were switched into a nest where the female was faithful, then the father at that nest kept up his hard work providing for the chicks, suggesting they have no mechanism, such as smell, to determine which chicks are theirs,” said Schroeder, who led the research.
One odd finding, amid admittedly odd findings, is that males who benefitted from additional paternal care provided less care themselves.
Also, while males contributed less food to nests when jilted, females provided the same average brood size regardless of whether or not it was through monogamous mating.
The wonderfully titled Predictably philandering females prompt poor paternal provisioning was published in The American Naturalist this month.
A separate study in the same issue looked at inbreeding among sparrows, finding that the more inbred the bird, the more likely it was to inbreed.
Sparrow image via Shutterstock