(Last Updated On: November 24, 2016)

Wild bird species in decline. Are we destroying local wildlife with hormones and chemicals?

During Tuesday’s Autumnwatch, Michaela demonstrated the adverse effect the human population is having on wild birds and other wildlife. Michaela spent some time with a biologist looking in particular at Starlings. A study by the British Trust of Ornithology suggests that Starling’s numbers have dropped by 51% in the last 17 years. As a rule they are very good at stocking up for the winter, and generally spend time early and late in the day feeding. But, Starlings are very similar to humans from an evolutionary perspective and it has been suggested that those chemicals that are designed to affect the human brain may also be having an effect on Starling’s brains.

The adverse effect of hormones on Starlings.

Bio-accumulation is the build-up of chemicals in micro-organisms. Throughout the programme we looked at bio-accumulation within invertebrate life living within the UK’s sewage water filtering system. Everyday millions of us are using chemicals in a number of different forms. Anti-depressants, anti-biotics, anti-neoplastic and other hormones whilst all essential, end up passing through the water system. It’s here that the invertebrate species thriving in the water filtering systems are being exposed to the harsh chemicals which then travel up the food chain to our wild bird and other wildlife species.

The study suggested that wild birds species such as Starlings are exposed to anti-depressive drugs such as Fluoxetine. When exposed Starlings demonstrated a lowered interest in food and breeding and displayed lower levels of movement and flying. This lowered interest in breeding can have an adverse effect on the survival rate of the species. Lack of interest in food and a lowered level of movement may also damage the survival rate of the wild bird species as they will be more prone to become prey.

How about other wild bird and wildlife species?

Although the changes are small and subtle, when added together they may be having a big impact on Starlings in particular, but also other wild bird species and local wildlife populations. Other species are also being affected by other drugs such as Prozac. Otters, cuttlefish and crayfish are also demonstrating changed behaviour. It is feared that these species only represent a small portion of the UK species that could be adversely affected by drugs. UK otter species are displaying increased liver damage whilst camouflage technique used by cuttlefish is being impaired, meaning they are becoming quite obvious to predators.