Male crickets court females in unison -- unless rivals get too close

University of Exeter scientists watched more than 100 male field crickets, and measured how often they chirped at the same time (called "singing overlap").

Singing by males one to five metres away from a listening male had a "stimulatory effect," leading to a chorus of crickets singing together.

However, males were less likely to sing if another cricket chirped within one metre -- possibly because the territorial insects instead chose to fight these space-invading rivals.

"Courtship displays are common in nature, but we know surprisingly little about how animals tactically adjust these in response to their environment," said Joe Wilde, a PhD student at Exeter's Centre for Research in Animal Behaviour.

"For crickets, singing is an energy-intensive activity, and males have to decide when to chirp and when to stay silent.

"Our results reveal show that singing by other males has an impact on this decision-making process."

Wilde added: "We can't say for certain why the males tend to sing together, but a likely explanation is that females are drawn to areas with multiple males calling.

"By 'chorusing' in this way, the males all benefit.

"We also can't be sure why males sing less when others chirp within one metre, but it's likely that they choose to fight rivals that get too close to their burrow."

The researchers used data from the WildCrickets project, which continuously monitors field crickets (Gryllus campestris) in a meadow in northern Spain via CCTV cameras.

The study used over a million scan samples of 129 males over 51 days to explore how the singing and proximity of other males influenced male singing behaviour.

The study was funded by the Natural Environment Research Council (NERC).