Why Male Mallard Ducks Attack Female Mallard Ducks

It's spring. Love is in the air. Ducks are pairing off and preparing to start new families. But something is definitely amiss. Why are groups of male mallards attacking a single, lone female mallard?

Sex Ratios

When mallards hatch and when the adult mallards migrate in fall, the ratio of male to female stays near 50:50.  This ratio is fairly consistent during spring and summer in natural habitats as well, making it easier for individual birds to pair off.  But in environments that have been modified by humans, there is a trend for a higher male to female ratio, especially during the spring and summer months.  As a result, a percentage of males will be unable to pair up with a female. 

Why Fewer Females?

During breeding season, female mallards undergo a lot more physical stressors than male mallards.  They are laying eggs, brooding nests and looking after their young.   These additional physical demands make it more difficult to fight off illnesses or injuries.  Female mallards are also much more vulnerable to predators (foxes, raccoons, dogs, cats) during nesting season.  By remaining in one spot while incubating eggs for 4 weeks, it is much more likely that she will be discovered by a predator.  This is compounded by the fact that urban mallards nest in manmade environments that are lanscaped, providing far less foilage coverage than what is normally available in more wild environments. 

Bachelor Groups

Paired up male and female mallards will disperse to different locations to select a nesting site.  The unpaired, single males that are left behind stay together in groups.    Although they are in a group, they each individually still want to pair up.  When they spot a female, they all compete.  The female flying by was likely taking a brief break from nesting, to meet her mate for a quick bite to eat and drink.  When the group spots her, they chase her relentlessly.  The end result is usually a horrific scene, leaving the female severely injured and/or dead.

What Can Be Done For The Female Mallard?

Female mallards that can be captured after having been attacked by a group of male mallards require medical attention by a wildlife rehabilitator, even if there are no visible injuries.  There is a strong likelihood that she was held under water for extended periods.  She will likely have extensive internal bruising and respiratory problems, requiring antibiotics.   Other common problems include extensive feather loss, skin lacerations (especially around the head and neck), and eye trauma.  Sadly, the nest of eggs or ducklings she was tending to will no longer have her protection and will likely not survive.

What Can You Do If You Witness An Attack?

Attempting to sidetrack the attack is the only real option.  The males will still be very fearful of humans and will hopefully disperse as you approach, long enough to allow the female to escape.