1. Interactions between hosts and pathogens are dynamic at both ecological and evolutionary levels. In the resultant “eco-evolutionary dynamics” ecological and evolutionary processes affect each other. For example, the house finch (Haemorhous mexicanus) and its recently-emerged pathogen, the bacterium Mycoplasma gallisepticum, form a system in which evidence suggests that changes in bacterial virulence through time enhance levels of host immunity in ways that drive the evolution of virulence in an arms race.

2. We use data from two associated citizen science projects in order to determine whether this arms race has had any detectable effect at the population level in the northeastern United States.

3. We used data from two citizen science projects, based on observations of birds at bird feeders, which provide information on the long-term changes in sizes of aggregations of house finches (host population density), and the probabilities that these house finches have observable disease (disease prevalence).

4. The initial emergence of M. gallisepticum caused a rapid halving of house finch densities; this was then followed by house finch populations remaining stable or slowly declining. Disease prevalence also decreased sharply after the initial emergence and has remained low, although with fluctuations through time. Surprisingly, while initially higher local disease prevalence was found at sites with higher local densities of finches, this relationship has reversed over time.

5. The ability of a vertebrate host species, with a generation time of at least one year, to maintain stable populations in the face of evolved higher virulence of a bacterium, with generation times measurable in minutes, suggests that genetic changes in the host are insufficient to explain the observed population-level patterns. We suggest that acquired immunity plays an important role in the observed interaction between house finches and M. gallisepticum.

Three of the four data files are collected by volunteer observers taking part in projects coordinated by the Cornell Lab of Ornithology; the fourth data file contains a set of latitude-longitude locations laid on in a grid across the study area.  The data describing the relative abundances of the bird species, the House Finch (Haemorhous mexicanus) were collected in Project FeederWatch.  The process of data collection, and examples of use of these data can be found in the following papers:

Bonter, D.N. & Cooper, C.B. (2012) Data validation in citizen science: a case study from Project FeederWatch. Frontiers in Ecology and the Environment, 10, 305-307.

Greig, E.I., Wood, E.M. & Bonter, D.N. (2017) Winter range expansion of a hummingbird is associated with urbanization and supplementary feeding. Proceedings of the Royal Society B: Biological Sciences, 284, 20170256.

States, S.L., Hochachka, W.M. & Dhondt, A.A. (2009) Spatial variation in an avian host community: implications for disease dynamics. Ecohealth, 6, 540-545.

Zuckerberg, B., Bonter, D.N., Hochachka, W.M., Koenig, W.D., DeGaetano, A.T. & Dickinson, J.L. (2011) Climatic constraints on wintering bird distributions are modified by urbanization and weather. Journal of Animal Ecology, 80, 403-413.

The data describing prevalence of disease caused by the bacterium Mycoplasma gallisepticum were collected and processed as described in the paper with which this data archive is associated, and is papers including:

Dhondt, A.A., Badyaev, A.V., Dobson, A.P., Hawley, D.M., Driscoll, M.J.L., Hochachka, W.M. & Ley, D.H. (2006) Dynamics of mycoplasmal conjunctivitis in the native and introduced range of the host. Ecohealth, 3, 95-102.

Dhondt, A.A., Tessaglia, D.L. & Slothower, R.L. (1998) Epidemic mycoplasmal conjunctivitis in House Finches from eastern North America. Journal of Wildlife Diseases, 34, 265-280.

Hartup, B.K., Dhondt, A.A., Sydenstricker, K.V., Hochachka, W.M. & Kollias, G.V. (2001) Host range and dynamics of mycoplasmal conjunctivitis among birds in North America. Journal of Wildlife Diseases, 37, 72-81.

States, S.L., Hochachka, W.M. & Dhondt, A.A. (2009) Spatial variation in an avian host community: implications for disease dynamics. Ecohealth, 6, 540-545.

The data files in this package are designed to be read into an R script that is a supplemental document published with the paper with which this data archive is associated.  Running this R script will read in the data files, and then run all analyses and generate all output that are used in this paper. The ReadMe file associated with this archive describes all of the variables in the data tables within this data archive. Note that there are 2 versions of this ReadMe document: (1) an ASCII text version that should be universally readable, and (2) a PDF version for which formatting will make the contents more comprehensible by anyone who can view the contents of the PDF version.