It usually forages in warmer waters, though does hunt in areas of cooler currents such as the Gulf of California. The species has also been recorded foraging in salt wedge estuaries. Relationship with humans The red-billed tropicbird, a bird not indigenous to Bermuda, was displayed in error on the $50 Bermudian dollar and was replaced in 2012 by the white-tailed tropicbird, the tropicbird that can be found in Bermuda. Status Accurate assessment of red-billed tropicbird numbers is difficult due to the remote locations of nesting sites and vast areas of the sea where they might be found. This bird is considered to be a least-concern species according to the IUCN. This is due to the fact that the range, declination, and numbers of this species, although small, do not meet the criteria required to be considered a vulnerable species. The range of this species is believed to be , with an estimated 3,300 to 13,000 mature individuals. In the western Atlantic, a more precise number was given for the population there in 2000; about 4,000 to 5,000 pairs. The population is declining, mainly due to human exploitation of the bird's environment and predation by invasive species, such as rats. These predators have the potential to drive populations of the red-billed tropicbird into serious decline. It is estimated that this bird experienced a population bottleneck about 450 to 750 years ago, likely due to exploitation by humans. This has resulted in low genetic diversity in this tropicbird, which makes the likelihood of it adapting to sudden environmental changes low. In Mexico and Brazil, it is considered to be threatened. Threats and survival The eggs and chicks of red-billed tropicbirds are prey for both brown and black rats in places like Abrolhos Archipelago, where these rats are invasive species. Feral cats are also predators of breeding tropicbirds, with the birds providing about 3% of the diet of the cats in locations such as the Caribbean island Saba. On Saba, the problem has only arisen since about 2000. On Ascension Island, the effect of the eradication of feral cats was the increase of the red-billed tropicbird population there by about 1.6% in a year. On the Galápagos Islands, the short-eared owl (Asio flammeus) occasionally eats young birds. Toxoplasma gondii, an intracellular parasite, can be found in this bird. About 28% of red-billed tropicbirds produce antibodies for T. gondii. Under normal conditions about 75%