 As with other bird families , pelicans are susceptible to a variety of parasites . Specialist feather lice of the genus Piagetella are found in the pouches of all species of pelican , but are otherwise only known from New World and Antarctic cormorants . Avian malaria is carried by the mosquito Culex pipens , and high densities of these biting insects may force pelican colonies to be abandoned . Leeches may attach to the vent or sometimes the inside of the pouch . A study of the parasites of the American white pelican found 75 different species , including tapeworms , flukes , flies , fleas , ticks and nematodes . Many of these do little harm , but flies may be implicated in the death of nestlings , particularly if they are weak or unwell , and the soft tick Ornithodoros capensis sometimes causes adults to desert the nest . Many pelican parasites are found in other bird groups , but several lice are very host @-@ specific . 
