Published: March 23, 2015

The plight of Ivory Gulls illuminated by museum specimens

John Bates, Curator and Section Head, Life Sciences, Negaunee Integrative Research Center

Ivory Gull (Pagophila eburnea) is one of those species, birders will travel across the country to try to see if one shows up somewhere in the lower 48 states. Birders from around the country flocked to see one in Quincy, Illinois this January. The bird’s presence even made it to the front page of the Chicago Tribune. Those that saw it will be talking about it for years, as will those that didn’t (like me).  The reason is that this beautiful all white bird normally lives at the highest latitudes in the Arctic even in the winter. The photo here is one Josh Engel took of the Quincy bird. 

However, this blog post is not really about that bird. It is about what a newly published study on Ivory Gulls and what may be behind a precipitous decline in their populations. This study, by Alex Bond, Keith Hobson, and Brian Branfireun just appeared in the Proceeding of the Royal Society of London, series b, and it used museum specimens in a way that the original collectors of these specimens could never have imagined. The Bond et al. study was carefully designed to assess the temporal patterns they were investigating, the study highlights that the activities of humans are influencing the entire planet in ways that go far beyond climate change. Mercury is a rare element in the natural environment.  However, it can accumulate and it has been accumulating fast in marine systems especially at high latitudes. It gets concentrated in animals that are at the top of the food chain. Ivory Gulls may not seem like something that would be at the top, but they are.  They frequently scavenge on carcasses of marine mammals, so Ivory Gulls are eating top carnivores. The authors sampled feathers from 80 museum specimens going back to the 1870s.  Only 2 of our 44 Field Museum specimens of this species met the geographic criteria they were looking for; these two birds were collected in 1896 in Newfoundland. Their analysis shows that Ivory Gulls today have significantly increased amounts of mercury than they did in the past. The authors also gathered data on nitrogen isotopes and found that the ratios of these isotopes did not vary for the same samples.  Nitrogen correlates with aspects of diet and the lack of change across 130 years indicates that the mercury accumulation in modern Ivory Gulls is not due to changes in the diets of these birds through time, which bolsters their conclusion that this accumulation appears to be due to the general increase in the environment as a whole. 

In their discussion, Bond et al. cite other studies of other birds including Rusty Blackbird (Euphagus carolinus), Wandering Albatross (Diomedia exulans) and Clapper Rails (Rallus longirostris) where high mercury levels are thought to reduce breeding activity and success. The Bond et al. paper is just another example of the incredible ways in which the time series of specimens in museum collections can be used.  Ridding the high arctic environments of an excess of mercury will not be easy, but we have to recognize these problems if we are going to find solutions. 

John Bates
Curator and Section Head, Life Sciences

Contact Information

The tropics harbor the highest species diversity on the planet.  I am most intrigued by evolution at the tips of the tree of life.  My students and I study genetic structure in tropical birds and other organisms to address how this diversity evolved and how it continues to evolve as climates change and humans continue to alter landscapes.

We study comparative genetic structure and evolution primarily in the Afrotropics, the Neotropics, and the Asian tropics.  I am an ornithologist, but students working with me and my wife Shannon Hackett and other museum curators also have studied amphibians and small mammals (bats and rodents) and more recently internal, external and blood parasites (e.g., Lutz et al. 2015, Block et al. 2015, Patitucci et al. 2016).  Research in the our lab has involved gathering and interpreting genetic data in both phylogeographic and phylogenetic frameworks. Phylogenetic work on Neotropical birds has focused on rates of diversification and comparative biogeography (Tello and Bates 2007, Pantané et al 2009, Patel et al. 2011, Lutz et al. 2013, Dantas et al. 2015).  Phylogeographic work has sought to understand comparative patterns of divergence at level of population and species across different biomes (Bates et al 2003, Bates et al. 2004, Bowie et al. 2006, I. Caballero dissertation research, Block et al. 2015, Winger and Bates 2015, Lawson et al. 2015).  We also have used genetic data to better understand evolutionary patterns in relation to climate change across landscapes (e.g., Carnaval and Bates 2007) that include the Albertine Rift (through our MacArthur Grants, e.g., Voelker et al. 2010, Engel et al. 2014), the Eastern Arc Mountains (Lawson dissertation research, Lawson et al. 2015), the Philippines (T. Roberts and S. Weyandt dissertation research) and South America, particularly the Amazon (Savit dissertation research, Savit and Bates 2015, Figueiredo et al. 2013), and we are entering into the genomic realm focusing initially on Andean (Winger et al. 2015) and Amazonian birds (through our NSF Dimensions of Diversity grant). Shane DuBay is doing his dissertation research in the Himalayas on physiological plasticity in Tarsiger Bush Robins.  Nick Crouch, who I co-advise at U. Illinois, Chicago with Roberta Mason-Gamer, is studying specialization in birds from a modern phylogenetic perspective.  We seek to create a broader understanding of diversification in the tropics from a comparative biogeographic framework (Silva and Bates 2002, Kahindo et al, 2007, Bates et al. 2008, Antonelli et al. 2009).  João Capurucho (U. Illinois, Chicago, co-advised with Mary Ashley)  is studying phlylogeography of Amazonian white sand specialist birds and Natalia Piland (Committee on Evolutionary Biology, U. Chicago) is studying the impact of urbanization on Neotropical birds.  New graduate student Valentina Gomez Bahamon (U. Illinois, Chicago) is also working Boris Igic and me, after doing her Master Degree in her native Colombia on genomics and the evolution of migrating Fork-tailed Flycatchers (Tyrannus savana).  Jacob Cooper (Committee on Evolutionary Biology, U. Chicago) is studying the diversification of birds in Afromonte forests

Josh Engel and I are working up multi-species phylogeographic studies of birds across the Albertine Rift, based the Bird Division's long term research throughout the region.  We are working up similar data sets for Malawian birds.  Our current NSF Dimensions of Diversity grant on the assembly of the Amazonian biota and our NSF grant to survey birds and their parasites across the southern Amazon are generating genomic data for analysis in collaboration with paleoecologists, climatologists, geologists, and remote sensing experts from the U.S. and Brazil.  These large collaborative projects are providing new perspectives on the history of Amazonia.