Seabird guano on desert islands helps create dense cactus forests. By studying samples from a seabird island in the Gulf of California, researchers found that the nitrogen from seabird guano fuels the growth of cacti, especially the cardón cactus. The nitrogen levels in the soil and cacti on seabird islands are much higher compared to non-bird islands, leading to some of the densest cactus populations in the world. This shows that marine nutrients from seabirds play a crucial role in stimulating plant growth on desert islands.