Current Postdoctoral Research.

How do blackbirds make decisions when defending their nests against various predators?

Red-winged blackbirds face many threats to their nests, from harmless animals to deadly predators. I am currently working on a field study where I present breeding blackbirds with different models, including a venomous snake and its non-venomous mimic, to explore how they adjust their defense behaviors depending on the threat type. I’m especially interested in whether the type of defense the birds engage in (vocal vs physical) differs based on how dangerous the nest predator is to the adults. I'm also exploring how their responses shift over time, from when eggs are laid to when chicks hatch, to better understand how blackbirds weigh risks and make decisions regarding defense of their young.

Models being presented at blackbird nests of various nest threats. Top row from left to right: Gopher Snake (sympatric nest predator), Northern Pacific Rattlesnake (allopatric nest predator), California Ground Squirrel (sympatric nest predator). Bottom row from left to right: California Scrub Jay (sympatric nest predator), female Brown-headed Cowbird (brood parasite), Song Sparrow (control).

A hand-reared fledgling red-winged blackbird.

Do blackbirds recognize snakes and their features without prior experience? 

To test whether birds need experience to recognize dangerous predators, I will be testing hand-raised blackbirds that have never encountered snakes. Using realistic snake models with different visual features associated with venom (e.g. triangular head shape, tail rattle, color banding), I aim to explore which traits trigger fear or aggression in naïve birds. These tests will help reveal which traits are used in predator recognition of dangerous snakes, and if any aspects of recognition are innate vs learned through experience or observation.

Does fledgling personality and boldness predict responses to threats as adults? 

To explore how early-life personality shapes later responses to threats, I'm tracking behaviors like boldness and aggression in fledgling red-winged blackbirds. This video shows a mirror trial, where we measure how birds respond to their own reflection--such as with curiosity or aggression—using DeepLabCut, a deep learning tool for automated behavior tracking. These early traits may help predict how individuals react to real threats as adults.

Can blackbirds enhance their recognition of predators through social learning?

Using the hand-raised blackbirds, I will test whether naive blackbirds can learn to fear a predator simply by observing another bird’s reaction. After exposing naïve birds to “social training” sessions—where they see a peer react fearfully or aggressively toward a snake model—I will measure how their own behavior changes pre and post training. This experiment will examine the power of social learning in shaping fear responses in inexperienced birds.

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Previous Doctoral Research.

Yellow warbler responses to playbacks signaling threats to the nest

Yellow Warblers need to respond appropriately to various threats at near their nest, whether they be brood parasites or nest predators. These threats also vary in severity across the nesting cycle, and Yellow Warblers use different calls to differentiate threats. Chip calls are used as a general alarm call towards predators and conspecifics, while seet calls are a specialized alarm call used solely against cowbirds. As such, seet call production is high during laying/incubation when cowbirds are a threat, and low during nestling stage when brood parasitism is no longer a risk.

This referential call for a brood parasite is unique to yellow warblers, and provides a fantastic system to ask questions regarding context-specific and socially-informing alarm calls.

During my dissertation we found that alarm call responses by males are also low during breeding season but before nesting begins, with little to no chip responses towards nest predators or seet responses to cowbirds. Yellow Warbler alarm calling towards nest-specific threats seems to be mediated by pairing status and presence of a nest. 

We also presented playbacks to female warblers as a quasi-replication to test if responses to parasites and predators are similar between model presentation experiments and our playback experiment, which we found to be the case.

Photo by Shelby Lawson

Photo by Sarah Winnicki

Red-winged blackbirds eavesdrop on seet calls

During our Yellow Warbler playback experiments we stumbled upon a new discovery - Red-winged Blackbirds were eavesdropping on seet calls and responding aggressively to our seet playbacks. To further explore these, we presented playbacks of cowbirds, seet calls, a nest predator and a control to measure blackbird responses. We found that similar to Yellow Warblers, Red-winged Blackbird males and females responded similarly aggressive towards cowbird and seet playbacks, and that this was affected by brood parasitism risk via nesting stage. Through these studies we discovered the first instance of heterospecific eavesdropping on a referential call for brood parasitism.

Yellow warblers alter future behavior based on brood parasitism risk

Female warblers swiftly move to sit on their nests in response to seet calls, which may prevent parasitism by physically blocking female cowbirds
from inspecting and accessing the nest. However, cowbirds lay their eggs just prior to sunrise, not during the daytime. So we tested whether female Yellow Warblers more closely monitor their nest the morning following playbacks of seet calls in contrast to chip calls or silence. We found daytime seet call playbacks caused female warblers to leave their nests less often the following morning, relative to playbacks of generic antipredator calls. Thus, seet calls may also convey parasitism risk and elicit mental time travel to protect the nest when it is vulnerable to egg laying by cowbirds.

Photo by Tom Sheley