Male sparrows can judge if a life partner is prone to infidelity, providing less food for their brood if their partner is unfaithful, finds a new study.
Researchers from the UK, Germany, and Australia have now revealed that males make the decision of how much to provide for their chicks based on the tendency of their partner to cheat.
The study, published today in The American Naturalist, followed the entire sparrow population of the island of Lundy in the Bristol Channel for 12 years.
Sparrows form pair bonds that are normally monogamous, but many females are unfaithful to their partner and have offspring with other males.
Lead researcher Dr Julia Schroeder of the Department of Life Sciences at Imperial College London said: “Males changed their behavior based on their partner. When they switched from a faithful partner to one prone to infidelity, they provided less food for their brood.” Females might also change their behaviour when paired with a less lazy male, cheating less with a more attentive father.
Biologists believe that the male birds are unfaithful to ensure that they father as many chicks as they can, while females are unfaithful with males of better ‘genetic quality’ – ones that are fitter and could produce stronger offspring.
However, cheating comes with a cost – the cheating female’s partner will provide less food for their nest of young. It has long been suspected that males know that not all the chicks in their nest are theirs, and so make a decision to provide less. But an alternative explanation is that cheating females and lazy males tend to pair up naturally.
The research showed that males cannot actually identify whether all the chicks in their nest are theirs or not, and instead base their feeding decisions on who their female partner is.
“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 Dr Schroeder. “Instead, the males may use cues from the female’s behaviour during her fertile period – for example how long she spends away from the nest.”
The study followed 200 males and 194 females as they formed 313 unique monogamous pairs and hatched 863 broods on Lundy. Some sparrow ‘divorces’ occurred – but most changes of life partner were due to a death.
The team DNA genotyped every sparrow, allowing them to build up precise family trees, and find out which females were most unfaithful and who their cheating males were. “Lundy is a unique natural laboratory because it is almost a closed system – very few birds leave the island or arrive from the mainland. In the entire 12 years only four birds immigrated to Lundy, possibly carried by boat.”
Being unfaithful may be a costly behavior for females because they only lay a limited number of eggs, and it may be a hangover from when their ancestors were not monogamous, rather than a useful strategy for getting the strongest offspring.
Dr Schroeder and her team are continuing to study the Lundy sparrows to uncover how and why social behaviors like monogamy arose.Follow @gorkhapost
2 injured as bomb goes off at Ward Chair’s house
DAMAK — An unidentified group detonated a bomb at the house of Bhim Poudel, a Ward Chairperson of the Damak Municipality Ward Number 7, last night, injuring two people including a woman.
The injured were hit by shrapnel due to the explosion. The explosion has also caused minor damages to the house which is located some 500 metres to the east of the Area Police Office, Damak.
It was a powerful explosion and it is not known who carried it out, police said.
Those injured in the incident are Semu Rai and Tilochan Pokhrel who had come to visit their relatives at the house next to Poudel’s house.
Both them who have been wounded in the hands and legs are being treated at the Lifeline Hospital in Damak. Rai is a staff at the same hospital.
Police has started an investigation into the case. Meanwhile, the Nepal Communist Party led by Netra Bikram Chand (Biplav) has today issued a press release saying those playing main role in evicting the landless squatters in the disputed market area in Damak. It had specifically named Wrad Chair Poudel and Mayor Romnath Oli.
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