The thought of seabirds might evoke memories of a perfect beach day ruined by a flock of noisy gulls stealing your lunch and defecating on you or your belongings. While you were shooing away the unwelcome visitors, you probably thought “What good are gulls anyway?” 

Researchers from the Universidade Federal de Goiás in Brazil now have an answer to your question. Seabirds like your annoying beach companions produce incredibly important and valuable excrement that is rich in nutrients such as nitrogen and phosphorus. This excrement (called guano) has been used as organic fertilizer since ancient times and is still collected and used in countries like Peru and Chile. Those two countries alone collected 27,000 tons of guano in 2018, which sold for $12.2 million USD. 

But bird guano isn’t just an important fertilizer for humans, it also fuels ocean ecosystems. To estimate just how important seabird excrement is, the researchers calculated how much it would cost to replace the nutrients excreted by seabirds with man-made versions, and found that seabird poop could be worth over $473 million per year. 

And that value does not even take other ecosystem benefits into consideration. For instance, a lot of reef fish rely on bird guano. The researchers valued the impact of bird guano on commercial reef fisheries at $650 million per year, increasing the total value of seabird guano to over $1 billion per year!

It may seem silly to put a dollar value on bird poop, but doing so is critical for improving conservation of these highly threatened species. So next time you find yourself cursing while wiping the bird poop off your favorite beach blanket, remember how valuable that bird and its poop can be.