A ten-year-old male Montagu's harrier named AU is currently the only known breeding male for his species in the United Kingdom. This prolific bird has sired sixteen offspring to date, providing a vital lifeline for a population that has faced near-extinction multiple times.
From 30 breeding pairs to a single male
The Montagu's harrier has endured a precarious existence in the United Kingdom for several decades. In the 1950s, the species was relatively stable with approximately thirty breeding pairs, but environmental shifts caused the population to vanish by the 1970s. As the report notes, the species saw a brief resurgence to thirteen pairs in the mid-aughts before crashing again to zero breeding pairs between 2000 and 2003.
These migratory birds must navigate a perilous annual cycle ,returning to Europe every spring from wintering grounds located in Africa and parts of Asia. This cycle of movement makes them particularly vulnerable to habitat changes in both their breeding and wintering territories.
AU's sixteen offspring and the "golden boy" legacy
The bird, known to researchers as AU—the chemical symbol for gold—has earned the nickname 'golden boy' for his extraordinary ability to sire offspring. The Royal Society for the Protection of Birds (RSPB) identifies this individual as the only known breeding male currently operating in the UK . According to Mark Thomas, the species lead for the RSPB, AU has sired sixteen juveniles throughout his life, with ten of those occurring in just the last two years.
This year, AU's acrobatic mating displays—which involve ascending to heights of a thousand feet—successfully attracted two females, resulting in six new hatchlings. These hatchlings represent a significant portion of the species' current reproductive output in Britain.
The danger of nesting in commercial farmland crops
Protecting these birds is complicated by their shift from natural marshes to agricultural environments.. Because their preferred lowland habitats are disappearing, Montagu's harriers have begun nesting in commercial crops, a move that exposes them to the threat of heavy agricultural machinery. To mitigate this, the RSPB works closely with landowners to locate nests and implement safeguards.
This year, the six new chicks are tucked away in two nests, located roughly one kilometer apart in a top-secret location on a British farm. To ensure their safety, researchers have installed physical barriers around the nests to shield the vulnerable young from both human interference and natural predators.
Will the two satellite-tracked juveniles survive their first migration?
The long-term survival of the species hinges on whether these new generations can successfully navigate their first journey to Africa and parts of Asia. To assist in this, scientists have attahced satellite trackers to two juveniles, one from each of the secret nests. this technology is intended to provide the RSPB with critical data on migration routes and wintering grounds.
While two of AU's male offspring from 2025 have already been spotted within the country,it remains unverified whether they will reach maturity and successfully return to breed.. The ultimate success of the species depends on whether these tracked juveniles can survive their first perilous migration and find their way back to the UK to expand the breeding population.
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