Density-dependent decline of host abundance resulting from a new infectious disease.   Hochachka, Wesley M. and André A. Dhondt. 2000. Proceedings of the National Academy of Sciences of the USA 97:5303-5306

Although many new diseases have emerged within the past two decades, attributing low numbers of animal hosts to the existence of even a new pathogen is problematic. This is because very rarely does one have data on host abundance before and after the epizootic as well as detailed descriptions of pathogen prevalence. We tracked month-by-month the spread of the epizootic of an apparently novel strain of a widespread poultry pathogen Mycoplasma gallisepticum (MG) through a previously unknown host, the house finch whose abundance has been monitored over past decades. We are here able to demonstrate a causal relationship between high disease prevalence and declining house finch abundance throughout the eastern half of North America because the epizootic reached different parts of the house finch range at different times. Three years after the epizootic arrived house finch abundance stabilized at similar levels although house finch abundance had been high and stable in some areas, but low and rapidly increasing in others. Although not previously documented in wild populations this result is as expected from theory if transmission of the disease was density-dependent.