Research in the lab explores elements of individual variation in a number of different systems. Much of my current work involves how the timing of nesting affects recruitment processes in Franklin's gull. This bird builds floating nests on large wetlands in the Missouri coteau and Northern Plains, but winters on the coasts of Peru and Chile. Thus the timing of nesting affects how much time chicks have to develop (and adults to recover) before starting their 7000+ km fall migration. Indeed, we found that embryos develop more quickly in eggs laid at the end of the nesting period compared to embryos from eggs laid at the start of nesting (Clark and Reed 2012). And chicks hatched from later-laid eggs grow wings more quickly than chicks hatched from eggs laid at the start of the season (Reed and Clark 2016). This work was done in collaboration with Dr. Wendy Reed, with initial funding from North Dakota Department of Game & Fish. We continue to explore factors associated with, and affects of, the timing of nesting in Franklin's gull. As the phenology of breeding has shifted for many migratory birds, understanding how individual physiology, development and growth relate to the timing of breeding will be critical to understanding how these shifts impact recruitment and population dynamics.
We recently began studies on the demography of Bigmouth buffalo, a catostomid fish native to the Red River of the North basin and the Mississippi River basin. Initial findings indicate individuals can live more than 100 years in some populations (Lackmann et al. 2019). This work is led by postdoctoral fellow Dr. Alec Lackmann. Data also suggest females reach significantly larger sizes than males. M.S. graduate Derek Sauer, with collaboration of Dr. Britt Heidinger, examined relationships between chronological age and biological markers of age such as telomere length in this species. North Dakota Water Resources Research Institute provided fellowship support to Alec for the early part of this project.
In 2014 we attached small, solar-powered PTT transmitters to 6 Franklin's gull adults nesting in North Dakota. The transmitters provided location information on the birds that was transmitted to us via satellite, so that we could quantify individual migratory movements. Our findings suggest that individuals initiating nesting later also initiated fall migration later. Our data also establish that Franklin's gulls are philopatric to their previous breeding site. This work was done in collaboration with Dr. Tim Greives as well as Dr. Wendy Reed. Funding for this project was mostly from NDSU (with contributions from the Clark retirement fund), and we are in the process of analyzing and submitting our findings for publication.
We also found that timing of nesting explained significant variation in the size and growth of American white pelican chicks. Chicks from eggs laid later in the season had smaller skeletal size, but faster growth rates for mass, tarsus and wing than chicks from eggs laid earlier (DiMatteo and Clark 2017). Effects of timing of nesting also explained some among-year variation in growth, as chicks exhibited faster growth rates in years in which nesting occurred later in the season (DiMatteo and Clark 2017). Decisions on the timing of nesting in American white pelicans may be related to trade-offs among safety from predators, risk of flooding and chick development (DiMatteo et al. 2015). This research was funded by the Minnesota Department of Natural Resources.
In Fall 2017 we completed an infectivity study of Cryptosporidium isolates found in microtine rodents. This work was led by Dr. Martin Kváč from the Institute of Parasitology at Biology Centre of the Czech Academy of Sciences and Dr. John McEvoy, Head of the Department of Microbiology at NDSU. Cryptosporidium is a water-borne, parasitic Protist that can infect most vertebrates (including humans), yet its ecology and evolution are poorly understood. The infectivity study is a final step in classifying a new species of Cryptosporidium that is host-specific to voles. This work built from a long collaboration examining Cyrptosporidium in wild rodent populations that was initially funded by the United States Department of Agriculture.