in order to efficiently count parasites such as Plasmodium in blood smears. Quantifying intestinal parasites, such as nematodes present in an individual, often it requires dissection of the animal, extraction and counting of the parasites. Other techniques to determine intestinal parasites exist which do not require dissection; such as detection of parasitic infections by fecal examination. This is a common practice in veterinary medicine and is used to calculate parasite load in domestic animals, such as cats and dogs. Methods of fecal examination include fecal smears and flotation methods. Fecal floats can detect reproductive means of endoparasitic (see endoparasite) organisms (eggs, larvae, oocysts, and cysts) that are passed through the digestive system and are therefore present in the feces. For analytical statistical methods used to study the extent and intensity of parasitic infection see Quantitative parasitology. Effects Sexual selection Parasite load has been known to effect sexual selection in various species. Hamilton and Zuk (1982) suggested that females of species could base their choice of mates on heritable resistance to parasites. This hypothesis proposes that the expression of secondary sex characteristics depends on the hosts overall health. Hosts coevolve with parasites and thus generate heritable resistance to parasites, which have a net negative effect on host viability. Therefore, females will select males with few or no parasites by basing their choice on whether or not the male has fully expressed secondary sexual, otherwise known as 'healthy' characteristics. One study found that parasite load predicts mate choice in guppies. When controlling for other variables, females were shown to prefer males with relatively few parasites with this preference being associated with higher display rates that occur in less parasitized males. This phenomenon has also been observed in other species. Behaviour Parasite load has also been shown to affect the behavior of the infected individual. Numerous studies have been done looking at the effects of number of parasites present in a host and how this correlates with behaviors such as foraging, migration, and competitive behavior. In a study performed at the University of Georgia, it was found that beetles with higher parasite loads won more fights than those with lower parasitic loads. When put up against beetles with no parasites present, the parasite-laden beetles lost the fights. Bird species have also exhibited behavioural effects in relation to parasite load. In passerine songbirds, high parasite load results in reduced song outputs, affecting the output