Dr. Kristen Ellis, a postdoctoral researcher at Colorado State University and USGS, tells us about her paper “The importance of functional responses among competing predators for avian nesting success”, how she got involved in ecology, as well as the pros and cons of being an ecologist.

Kristen Ellis at one of her study sites in western Utah.
Kristen Ellis at one of her study sites in western Utah.

About the paper

What is the background behind your paper?

Interactions between predator species that compete for shared prey can lead to varied effects on prey populations. For breeding birds, many nests fail due to predation, yet patterns of nest predation can be convoluted because predator identity is often unknown. We collected nesting data from a population of snowy plovers Charadrius nivosus, which are small shorebirds and a species of conservation concern. We were interested in how competing nest predators interacted within the breeding season, and how nest availability influenced specific predators. We found that predator species had different roles in how they contributed to nest predation, where certain species were more efficient when nests were rare and other species were more efficient when nests were abundant. We also noted instances of non-independence in nest predation (i.e., compensatory mortality), suggesting that competition or other interactions between species may limit predators. Further, these interactions between predator species varied throughout the breeding season. The non-independence in nest predation suggests that removing certain predators (through direct management) may not necessarily lead to higher nest success, because it may open opportunities for remaining predators to consume nests.

How is your paper new or different from other work in this area?

A female snowy plover with a newly hatched chick in the nest cup. Chicks leave the nest within hours after hatching.
A female snowy plover with a newly hatched chick in the nest cup. Chicks leave the nest within hours after hatching.

Analyses of cause-specific mortality are rarely applied to avian nests because specific sources of nest failure are often unknown. Because of this, little work has been done addressing the functional roles of specific nest predators. We had a relatively unique dataset which was acquired using remote cameras to monitor nests and identify nest predators. More broadly, our flexible approach may be useful to other researchers looking into functional responses of competing predators.

About the research

What does your work contribute to the field?

Many predators have generalist diets and in recent years, have increased in abundance and shifted in their distributions in conjunction with human development (e.g., coyotes and corvids). These altered predator communities may lead to shifts in historic predator-prey relationships. Our work has shown that patterns of predation can be predator-specific and understanding changes in prey populations requires an understanding of the predator community. A lot of management funding is often spent on removing certain predators in an attempt to increase avian productivity, but our work has shown that if compensatory nest mortality occurs between predator species, these strategies may not be effective. The idea of compensatory nest mortality isn’t new, but relatively few studies have empirically shown that this occurs.

About the Author

A kit fox consuming snowy plover eggs. Remote cameras allowed for the identification of nest predators.
A kit fox consuming snowy plover eggs. Remote cameras allowed for the identification of nest predators.

How did you get involved in ecology?

I think I have always known that I wanted to work with the natural environment in some way. I spent my time as a child watching birds, snakes, skunks, and porcupines in my backyard, and doing my own little experiments on ant hills. I had great advisors during my undergrad at Weber State University who were instrumental in getting me involved in research projects and then into graduate school.

What is the best thing about being an ecologist?

The ability to view the environment from a non-human perspective. The complexities of the natural environment mean that, as ecologists, we will never get bored because there’s always something interesting to investigate. Studying migratory birds is a bonus because I’ve been able to travel to other countries where birds spend their time during their annual cycle. Maybe this is an unpopular opinion, but I also really love the writing process and distilling my research into manuscripts.

What is the worst thing about being an ecologist?

Bug bites.

Read the paper in full here and the free plain language summary here. You can find Kristen on twitter @kgurrellis.