Animal Signaling and Stress Physiology

mwcsAnimals use signals to communicate, much like how we use our words, facial expressions, and hand gestures. Status badges, or special patterns or color markings that indicate dominance, are a type of animal signal that facilitates rival assessment. A central concept to status badge theory is reliability; in order for a status badge to be reliable, it must meet 3 criteria: (1) the size or coloring of the badge must consistently correlate with a physical characteristic or capability (e.g. fighting ability, size); (2) the badge signal must be recognized by the receiver; (3) there must be costs associated with false signal displays.

A good way to conceptualize a status badge is to think of karate belts (Tibbetts and Lindsay 2008 Biolkarate_belt Lett). By convention, black belts are worn by the best fighters but there is no reason why an unskilled individual can’t wear a black belt, nor is there reason to believe that the belt itself provides any actual physical advantage. However, one would presume that if a true orange belt donned a black belt and fought in a match against a true black belt, then he or she would suffer the appropriate punishment for bluffing – some sore spots and a healthy dose of embarrassment. This concept of tangible costs to bluffing is central to the maintenance of a signal over time.

crownI investigated whether the prominent white crown on male Mountain white-crowned sparrows (MWCS), small passerine birds that migrate seasonally to breed in high elevation alpine meadows in the Rocky Mountains, is a reliable
status badge. My research goals were threefold; each aligned with the above-mentioned requirements of a reliable signal. morphologyFirst, I examined the relationship between size of the crown badge and morphological characteristics indicative of fighting ability. Next, I quantified aggressive response to simulated territory intrusions with decoys to determine whether the size of the badge is actually recognized by live birds. Finally, I decoymeasured stress hormone levels in birds with naturally large crowns and compared it to those with experimentally enhanced (painted) crowns to determine whether there are costs to badge bluffing. I found that birds with a larger body size had a larger status badge, and that birds were more aggressive towards decoys with larger signals as compared to smaller signals. Further, birds whose feathers were painted to represent ‘bluffs’ (e.g. larger badges than their natural badgcrown_painte) not only had higher stress hormones after interacting with other birds but also, when I introduced an acute stressor, these birds were not able to mount an appropriate stress response. These findings indicate that status badges can encode reliable information about social status and that detection of signal bluffing influences aggressive behavior and physiological stress response (Laubach et al. 2013 Behav Ecol Sociobio).

In the same population of sparrows, I also explored the determinants of parental care. Taking care of offspring is costly, and the costs-to-benefit tradeoffs are thought to depend on the quality of the parent, the contribution of the partner, and/or the reproductive value of offspring. Among pairs of nesting birds, I examined the association between an individual’s own and its partner’s morphological, physiological, and status badge characteristics with rate of food provisioning to offspring. I found that males increased their feeding rate when paired with partners that had larger status badges. These results imply that partner quality can affect the level of parental care, and thus partner quality may be important to consider as part of the early-life environment Laubach et al. 2015 Auk).

 

For this research I worked with my master’s thesis advisors Dr. Johannes Foufopoulos and Dr. Bobbi Low (UM). Dr. Wei Perng, also (UM) provided statistical consulting and support. I collaborated with Dr. Daniel Blumstein (UCLA) to develop field experiments and interpret behavioral data, and I conducted hormone assays in Dr. Michael Romero’s lab (Tufts). Our field site and study population of Mountain white-crowned sparrows were at Rocky Mountain Biological Research Laboratory, near Gothic, Colorado.

 


 

Spatial Analysis and Remote Sensing

Spatial analyses, geographic information systems (GIS), and remote sensing are powerful research tools that are used in a broad range of disciplines from environmental science and public health to behavioral ecology and conservation biology. I have used these tools in a number of research applications. As an undergraduate at Juniata College, I developed, implemented, and analyzed results from two independent research projects under the guidance of Dr. Uma Ramakrishnan, Dr. Neil Pelkey, and Dr. Dennis Johnson. My first project used distance sampling and Geographic Information Systems (GIS) to estimate white-tailed deer populations and distributions around Raystown Lake, near Huntingdon, PA. I also collaborated with the Pennsylvania State Game Commission to investigate seasonal and time-of-day patterns of space use and activity of GPS collared male white-tailed deer.

I also worked for Michigan Technological Research Institute (MTRI) as an intern, then as a Research Scientist. My position involved primary data collection, remote sensing, GIS, and advanced spatial analysis in wetland mapping and ecology projects funded by the EPA, US Geological Survey and US Fish and Wildlife Service. Under the tutelage of Dr. Laura Bourgeau-Chavez and Dr. Mary Ellen Miller I used satellite radar signal processing and machine learning algorithms, such as Random Forests, to study wetlands and invasive species in the Great Lakes Basin (Bourgeau-Chavez et al. 2015 Taylor and Francis Pub). These projects resulted in a Great Lakes Basin wide map of the distribution of the invasive species Phragmites australis (Bourgeau-Chavez et al. 2013 J Great Lakes Res), and a bi-national Great Lakes Basin Coastal Land Use, Land Cover map (Bourgeau-Chavez et al. 2015 Rem Sens).

In collaboration with several members of my lab at MSU, I am currently working on mapping the Masai Mara National Reserve using Random Forests to analyze publically available LandSat satellite imagery. We hope to use these maps to assess change in vegetation over time and to better understand the ecology and movement of spotted hyenas and other large mammals in this region.