New paper out in Behavioral Ecology and Sociobiology! Many bird use vocal cues from both their own and other species to find food, especially in winter. Through some very cold winter field work, we found that calls from Black-capped Chickadees were most effective at attracting birds to food, supporting the idea that chickadees play a key role in mixed-species foraging groups.
Photo of a White-breasted Nuthatch, a satellite species in mixed-species flocks at our study site.
How can wildlife be handled safely for ecological and veterinary studies? For carnivores, anesthesia is often necessary for animal and human safety. In our new study in PLOS One, we evaluate the use of medetomidine–tiletamine–zolazepam (MTZ) for field anesthesia in 11 mesocarnivore species. We show that MTZ is safe and effective for minimally invasive procedures like GPS collaring and sample collection.
Photo of a coyote being worked up while under anesthesia. This coyote's data contributed to the study.
Hannah's paper is out in Journal of Insect Science! European harvestmen - better known as daddy longlegs! - are common but introduced predators in North America. We present the first functional response estimates for this species and explore how predator sex, body size, leg characteristics, and environmental light levels influence foraging rates. This paper arose from Hannah's class project while she was a student in my Predator Ecology course at Cedar Point Biological Station. Congrats, Hannah!
Photo of a daddy longlegs being measured for the study.
Great news for habitat restoration! Using bird survey data collected across nearly three decades, we show that controlling invasive species, planting native vegetation, and other restoration strategies increase bird diversity in an urban park. Importantly, this increased diversity is coming from native birds, rather than the non-native species that are common in cities. This paper was a huge team effort and we're thrilled to see it out in Ecological Applications! I also had the honor of speaking with St. Louis Public Radio about this study and the importance of urban habitat restoration.
Photo of an Eastern Kingbird in restored habitat in St. Louis' Forest Park, where we conducted the bird surveys.
Check out our latest puma paper in iScience! We show that pumas who died of diseases like Highly Pathogenic Avian Influenza or Leptospirosis move abnormally prior to their death. These abnormal movements include altered step lengths and turn angles as well as increased periods of behaviors typically seen at kill sites or bed sites. These results refine our understanding of disease progression in free-living carnivores and help inform conservation efforts.
Photo of F320, a collared puma in the study, taken by Collin Eckert/California Carnivores Program.
Fitting a GPS collar onto an anesthetized raccoon with the amazing Jamie Palmer. We used movement data from raccoons in an urban greenspace to show that raccoons avoid crossing roads. We also used accelerometry data from the collars to explore activity patterns: total activity is highest during long nights but raccoons are more active per hour during short nights! The study was featured on St. Louis Public Radio and on the cover of the Journal of Mammalogy.
Arina's paper is out in Food Webs! While much research on predation rates and temperature is focused on warmer temperatures, Arina's work shows that cold temperatures are important too! Specifically, intraguild foraging rates of wolf spiders on ladybeetle larvae decrease during unseasonably cold temperatures, which are becoming more common in a changing climate. Because both wolf spiders and ladybeetles are biocontrol agents, these findings help inform biocontrol programs. Arina performed this experiment as an undergrad taking the Predator Ecology field course at Cedar Point Biological Station. Nice work, Arina!
Photo of a Hogna carolinensis at CPBS, taken by Arina Martin. This is the largest wolf spider species in North America!
A three-toed box turtle with a VHF tracking tag. Our paper in Journal of Thermal Biology shows that urban box turtles experience colder winter temperatures than rural box turtles. This is likely due to habitat fragmentation and degradation, which limit the ability of turtles to find suitable microhabitats. We also show that turtles that experience colder temperatures face increased mortality risk, highlighting the importance of overwinter thermoregulatory ability for the abundance and fitness of urban ectotherms.
A new FoRAGE paper is out in Ecosphere! We explore various biological and statistical explanations for the the emergence of type III (sigmoidal) functional response shapes. We found no clear predictor of the type III response, and we suggest that type III models often emerge as a result of stochastic noise.
Photo of an American ermine (Mustela richardsonii) with its prey, a Microtus sp. vole, in Colorado. See the iNaturalist observations for this photo here and here.
Our paper on prey diversity in raptor diets is out in Proc B. We find that, unexpectedly, many raptors have close to the maximum possible diet entropy. This suggests that raptors play key roles in food webs and help maintain biodiversity. This is the first paper using our new OS-Prey (Omnibus Study of Prey) database of raptor diets from around the world!
Photo of a Cooper's Hawk in St. Louis, Missouri.
Amputee felids with GPS collars. Our study in Ecology and Evolution uses movement data from bobcat, snow leopard, and Iberian lynx to show that amputee felids in the wild move similarly to four-legged individuals. We further find that these felids can successfully hunt and reproduce in the wild, showing that severely injured felids can go on to live healthy lives in the wild and contribute to local populations. This is especially great news for the Iberian lynx, a threatened species.
As part of my research with the Forest Park Living Lab, we deployed GPS tags on three diurnal and two nocturnal raptor species, as well as eight other species of reptiles, mammals, and birds.
Left: Fitting one of St. Louis' coyotes with a GPS collar. This research was featured in the St. Louis Post-Dispatch as a Sunday paper cover story. Photo by Stephen Blake.
Right: A Red-tailed Hawk with a solar GPS tag This hawk has traveled from St. Louis to Canada and back multiple times, stopping at various towns along the way. Photo by Jamie Palmer.
The last big chunk of my dissertation! This paper published in Ecology Letters shows how the functional responses of wild arthropods can be estimated by combining dietary metabarcoding data, DNA detection half-lives, and prey density data. These field functional responses are considerably lower than lab-estimated functional responses, suggesting that we need to be careful about how we use foraging experiments in the lab to draw conclusions about what happens in nature.
Photo: a Hogna baltimoriana wolf spider from my dissertation.
A male Tree Swallow with food provisioned for his nestlings at Cedar Point Biological Station. In 2022, we built a Motus tower at CPBS, connecting the station to an international, collaborative network designed to study the movement patterns of aerial animals.
A wolf spider eating a metamorph toad in Keith County, Nebraska, USA. A natural history note on this observation is published in Herpetelogical Review.
Gut content samples ready for DNA extraction and metabarcoding to determine what prey the predators consumed. To quantify this type of data, half-lives can be used to describe how long prey DNA is detectable in the predator, but these half-lives are typically found using resource-intensive feeding trials. We show how these half-lives can be predicted and present a new method for improved metabarcoding quantification in our paper in Molecular Ecology Resources.
FoRAGE is our publicly-available, ever-expanding database of functional responses. Our meta-analysis of FoRAGE in Ecology confirmed known effects of predator and prey mass, revealed optimum foraging temperatures, and showed that dimensionality and taxonomic identity can profoundly influence functional responses. We are always adding to FoRAGE, so please reach out with new functional responses!
Photo: A Bold Jumping Spider (Phidippus audax) with its prey, a Salt Marsh Moth (Estigmene acrea) on a window at Cedar Point Biological Station in western Nebraska. See the iNaturalist observations for this photo here and here.
Paramecium caudatum, an approximately 0.15 mm long protist and the subject of our study in Ecology and Evolution. We exposed replicate populations to either a constant temperature or temperature fluctuations and to either predation or no predation. Our study revealed that these challenges produce conflicting selective pressures and that responses to these pressures are constrained by trade-offs between cell morphology and thermal performance.
Photo by Miranda Salsbery.
Hogna wolf spider in a respirometry vial as part of our study in Ecological Entomology. As the spider respires, the oxygen concentration in the air-tight vial decreases. The sensor spot at the bottom of the vial detects these changes over time when the vial is placed in a respirometer. Our study shows that spiders with bigger opisthosoma (abdomens) - indicative of recent foraging success - have higher respiration rates for their size.
Still from a video of Drosophila melanogaster walking in arenas of different sizes. Using tracking software, we followed individuals' paths and found that the flies - and their predators - preferentially stayed near arena edges. Our study in Behavioral Ecology describes how this behavior, called thigmotaxis, causes arena size to have a pervasive effect on predation rates.
Lady beetles from an alfalfa field, including the native Hippodamia convergens (upper right) and the invasive Harmonia axyridis (lower right). Because they are a common biocontrol agent, there is an abundance of predation literature focused on lady beetles. A meta-analysis of this literature reveals that arena size has a large impact on the outcomes of predation experiments with lady beetles. This critical finding suggests that pest management decisions can be misinformed if laboratory experiments do not take arena size into account. Published in the Journal of Applied Ecology.
Damselfly nymph from research published in Oecologia. Damselflies are voracious generalist predators, and in our experiment we fed them Daphnia, copepods, and Chydorus. We found that, across all three prey types, nymphs forage best at an intermediate predator:prey size ratio. This was also our first study where we found evidence that experimental arena size (in our case, Petri dish size) plays an important role in determining predation rates.
