The Battle Between Sound and Habitat: How Habitat Influences the Transmission of an Acoustic Signal?
Contributed by Alexis Billings
Successful communication is relatively simple: (1) a sender encodes and transmits information through a signal. (2) The signal is sent through an environmental space where is it corrupted and degraded. And (3) the signal is received and decoded by a receiver. Most of the research in animal communication has focused on part (1) and (2), the senders and the receivers. Therefore, there is a huge gap in our understanding of animal communication in regards to the signal itself. In acoustic signals this is incredibly important because sound waves are extremely susceptible to numerous degradations from habitat structures.
My research focuses on mobbing calls, which are acoustic signals given by numerous bird and mammal species in response to predators. I am interested in each component of communication, including how these signals actually transmit through the environmental space and reach the receiver intact. To get at this component I have combined wave transmission theory from physics with the ecology and biology surrounding these signals.
Using black-capped chickadee “chick-a-dee” mobbing calls, I played exemplars through three different habitats (open, semi-open, closed) and re-recorded the signal at 1, 10, 25, 50 and 100 meters. I calculated how much relative power (measured in decibels) each frequency bin (23 Hz per bin) actually lost between 1 meter and the other distances. I then calculated the predicted loss of relative power for each frequency bin using wave spreading loss and attenuation equations from wave transmission theory. From these two calculations I can compare the predicted loss of power per frequency bin and the actual loss of power per frequency bin.
Below is a filter function of the transmission of a part of a black-capped chickadee ‘dee’ note through a closed habitat at 100 meters. The x-axis is frequency or pitch (measured in Hertz) and the y-axis in the loss in power (measured in decibels). Above the graph is a
sample of a black-capped chickadee “dee” note flipped horizontally to show frequency bands. Finally, the graph contains the measured (green, irregular graph) and calculated (blue, parabolic graph) loss in power. From graphs like this, I found that the frequency bins between 4000 Hz and 12,000 Hz are the most robust in the chickadee call and are also the most strongly degraded over distance in the closed habitat (the natural habitat of the black-capped chickadee). So, it seems that black-capped chickadee mobbing calls are optimally structured to combat the degradations imposed by their natural habitat so the signal can successfully reach the receiver.
Contributed by Jacob Lucero
If you’ve ever walked through a field and emerged with your socks full of pokey grass seeds or if you’ve ever popped a bike tire on a sharp thorn, you may have had a close encounter with an invasive plant. Many a hiker has paused to remove the seeds of cheatgrass (Bromus tectorum) from their socks, and the sharp seeds of puncture vine (Tribulus terrestris) have been the bane of many a bike ride. Although both cheatgrass and puncture vine are common in the western United States, neither is native to our region. Both plants hail from Eurasia; both have managed to hitch a ride to a new home (North America) and both thrive in their new environment. In addition to annoying hikers and bikers, exotic species can also perpetrate drastic ecological disruption, threatening the vitality of ecosystems and even jeopardizing human health. Accordingly, researchers, conservationists, and governments around the world expend considerable resources in fighting, preventing, and managing biological invasions. For example, David Pimentel and colleagues (2005) estimated that invasive species cost the United States over $120 billion in losses each year. Yet robust solutions to this worldwide threat remain elusive. So why, then, are invasive species so successful?
One of the most oft-cited explanations for the success of invasive species in novel environments is the enemy release hypothesis. This hypothesis suggests that natural enemies like competitors, predators, and diseases check the population growth of an organism in its native habitat. However, translocation across an ocean or a continent may allow that organism to escape the effects of its natural enemies. Without natural enemies to regulate its population growth in its new home, an introduced species could proliferate to become a noxious invader.
Although the enemy release hypothesis is touted in textbooks, classrooms, and scientific literature, it has rarely been tested empirically! To rigorously test the enemy release hypothesis, a researcher should protect a focal invader from natural enemies in both the native and non-native ranges. If the enemy release hypothesis is true, protection from natural enemies should only improve the invader’s population growth at home because natural enemies are assumed to be important only in the native range. Thus, parallel experiments must be executed in both the native and non-native ranges to test this hypothesis.
With the help of international collaborators, I am currently carrying out such parallel experiments in North America, Turkey, Iran, and Uzbekistan to test the enemy release hypothesis with respect to one of the most virulent invasive plants in the world, cheatgrass (Bromus tectorum). We predict that seed predators (important natural enemies) such as mice and ants limit the establishment of cheatgrass more strongly in Eurasia (the native range of cheatgrass) than North America (the non-native range of cheatgrass). Understanding the effects of natural enemies in both the native and non-native ranges of this invader could help us better understand the invasion process and illuminate the mechanisms that allow invasive species to become so successful in novel environments.
Contributed by Andrew Myers
What are we prepared to give up the name of nature and what will we do protect it?
This is the underlying theme of the RADIOLAB podcasts entitled ‘Galapagos’ and ‘For the Birds.’ In ‘For the Birds,’ a group of bird conservationists relocate a flock of whooping cranes, an endangered species, to a marsh in Florida. Once the birds arrive, attracted by birdfeeders, they start to inhabit a woman’s backyard. The conservationists ask the woman to remove her birdfeeders, she refuses. For her, the birds had become an integral part of her relationship with her husband who was suffering from Alzheimer’s disease. For the conservationists, her attitude and actions posed a threat to the future of the birds and what it meant to be wild. By asking her to remove the birdfeeders, they also ask her to give up a part of her relationship with her husband; while simultaneously, her refusal to remove the birdfeeders jeopardizes the very birds she treasures. This dilemma raises problematic questions that involve uncertain facts, opposing values, and may not have any right or wrong answer. They are much political as they are ecological, necessitating comprehensive approaches that integrate the expertise of many different disciplines.
What is a healthy forest?
For some, this involves little to no human activity, for others human activity (e.g., timber management) is critical to maintaining a healthy forest. In this case, the term “health” carries vastly different meanings, formed by different cultural values; “health” is fundamentally political, yet has serious ecological consequences. A healthy forest, in practice, is not defined by objective facts, rather, it is defined by power. For example, the forested landscapes in the U.S. have undergone many shifts, from the American Indians, to European settlers, commercial timber management, to environmental protection. In each of these eras, the health of the forest was defined by those with the most power, resources, and influence to do so, allowing them to implement their vision upon the landscape.
Are we willing to ask a woman to give up part of her relationship for an endangered bird, would we kill thousands of goats to protect turtle habitat, will we prevent timber production to protect bear habitat or will political and economic circumstances open up roadless forests for new roads and logging? While the answers to these questions are no doubt important, the more relevant detail is what the answers to these questions mean for how we live our daily lives. Addressing this point will lead us to a more productive debate about what is best for whom considering the needs and concerns of all living things rather than the perpetual debate about what the ‘correct’ answer is. Doing so requires collaboration across disciplines. Science of course, provides us with some of the necessary information for how our decisions will shape the world, and ultimately, our lives. The challenge, is remembering that we ourselves are political beings.
Bibliography and Further Reading
Berkes, Fikret. 2011. “Implementing Ecosystem-Based Management: Evolution or Revoltuion?”
Fish and Fisheries 13 (4):465-476.
Devlin, Vince. 2014. “Columbia Falls Sawmill Announces Layoffs, Cites Timber Blocked by
Litigation.” Missoulian, August 29, 2014. Accessed,
For the Birds. RADIOLAB audio podcast. Accessed, http://www.radiolab.org/story/birds/.
Galapagos. RADIOLAB audio podcast. Accessed, http://www.radiolab.org/story/galapagos/.
Ludwig, Donald. 2001. “The Era of Management Is Over.” Ecosystems 4 (8):758-764.
Neumann, Roderick, P. 2005. Making Political Ecology. London, England: Hodder Arnold.
Robbins, Paul. 2004. Political Ecology: A Critical Introduction. Malden, MA: Wiley-Blackwell.
Warren, William, A. 2007. “What Is a Healthy Forest?: Definitions, Rationales, and the
Lifeworld.” Society and Natural Resources 20 (2):99-117.
Contributed by Mark Douglas
Note: this post serves as an extended annotation to the work of Eigenbrode and others (2007)
Complexity in the sciences requires integrated insights among scientific disciplines. Primarily, it’s important to figure out how much integration is called for when dealing with research problems. This requires consideration of both the nature of the problem and the preexisting mutual understanding that exists among the people and their differing disciplinary backgrounds. The clarification of assumptions is imperative to successful integration of efforts involving multiple disciplines. Research across traditions must involve the deliberate identification and exploration of fundamental scientific assumptions that are implicit or explicit within the traditions involved.
The remainder of this post will consider challenges that are prevalent in scientific research across disciplines. The challenges covered here relate to (1) the level of integration; (2) linguistic and conceptual divides; (3) what constitutes valid evidence; (4) the social role and societal context of research; (5) foundational perceptions of reality; (6) reductionist and holistic versions of science. These issues are described below.
1. Level of Integration
· Multidisciplinary research entails the study of a single system through multiple methods. The interpretation of findings is often grounded in a discipline that emerged to have a dominant influence.
· Interdisciplinary research requires greater coordination to address multiply scaled research problems. The methods and approaches are often synthesized for a more cohesive approach.
· Transdisciplinary research involves problems that are uniquely formulated which can’t be captured within existing domains. Epistemological perspectives are forged and adopted emerge that are unique to the project. If an epistemological framework emerges this may be termed a “metadiscipline”.
2. Linguistic and Conceptual Divides
· The use of special terms by scientists working in different disciplines may invoke subtle concepts, perspectives, standards and worldviews can serve as short hand within one group while baffling members of another.
3. Validation of Evidence
· The differences in the ways scientists gather, interpret, and share information may create misunderstanding in their perception and confusion across scientific practices.
4. Social Context of Research
· The degree to which citizens play a role in science and policy as well as the degree to which scientists want their work applied in society can confound the process of generating knowledge and solving problems.
5. Perceived Nature of the World
· For some, the world is an objective place independent from the stance somebody takes as a scientist. These worlds allow the pursuit of the “ideal of objectivity”.
· For others, the world envelopes somebody being a scientist to the extent that people, places and things are considered as co-creators of reality. These worlds call for science to be practiced reflexively.
6. Reductionism and Holism
· Reductionist science isolates and analyzes the elements of a system for reproduction in and prediction in models.
· Holistic science examines the emergent properties first-hand for greater understanding.
These differences outlined above call for much more consideration in the performance of scientific practices. Eigenbrode and others (2007) go further by offering probing questions that serve as tools in the identification of views that may or may not be shared by scientists working on problems together. Readers are encouraged to learn more by accessing their work at http://www.bioone.org/doi/pdf/10.1641/B570109.
Eigenbrode, S. D., O'rourke, M., Wulfhorst, J. D., Althoff, D. M., Goldberg, C. S., Merrill, K., ... & Bosque-Pérez, N. A. (2007). Employing philosophical dialogue in collaborative science. BioScience, 57(1), 55-64.
Contributed by Sarah Castle
From the tropical Andes of Peru to the icefields of Alaska, glaciers are rapidly melting. As ice melts, we are left with an annually resolved gradient in soil development. Substrates closest to the glacial terminus are the youngest while substrates furthest from the terminus are older. Deglaciated landscapes, with their barren rock and lack of vascular plant cover, often appear to be devoid of life. On the contrary glacial soils, albeit low diversity, are teeming with microscopic organisms that take up residence immediately following the retreat of ice. Looking at how soil biota and the soil environment develop with time in these relatively simple landscapes may help us to unravel the relationships between community structure and ecosystem function that may be otherwise obscured in more complex soil systems.
In my own work as a Ph.D. candidate in the Department of Ecosystem and Conservation Sciences, I am examining microbial communities at glacial sites in both North and South American continents. It appears that young glacial soils host bacterial communities that are very different in terms of structure and function when compared to communities originating from older parts of the landscape. What is more interesting is that bacterial communities from distant locations (Peru, Washington, and Alaska) undergo successional change that results in a microbial community that is same regardless of where you are in the world.
Though glacial retreat is one specialized type of ecosystem disturbance, there are many other natural and human caused disturbances that influence microbial communities and their functions. The study of natural gradients may offer us some insight into how to maintain and restore degraded systems.
More information about Sarah Castle’s research can be found here: www.cfc.umt.edu/biogeochemistry
Contributed by Peter Ganzlin
The main reason I joined the ICN was how I could improve and assess collaboration within my research area: forest restoration. Forest restoration has continued to evolve out of the mistakes we finally have realized from decades of obsessive fire suppression throughout the United States. Much of our western forests have shown excessive fuel accumulation and density leading to severe wildfire, low biodiversity and stagnated rates of nutrient cycling and productivity. Restoration treatments include forest thinning, prescribed burning and other landscape manipulations. I see this field as collaborative by definition. The main questions which scientists, policymakers and forest managers alike seek to answer, in my view are: what is the longevity of forest restoration treatments? How do we define success of a particular treatment? What are the short and long-term goals of forest restoration?
Assessing and answering these questions require interdisciplinary collaboration. Of course, we can always design a forest restoration prescription that only fulfills a goal related to our area of expertise. I am certain that if we designed a forest restoration treatment to maximize habitat for pine marten and ignored other potential benefits, pitfalls and goals, we would fall short of the full potential that could be realized via collaboration. In the field of forest restoration, collaboration need not be limited to linking goals and concerns of scientists, policymakers and managers, as is commonly emphasized, but also by fostering these linkages between scientists in other disciplines.
A publication I review and reflect on frequently was written by Maria Ruiz-Jaen and T. Mitchell Aide in 2005 and published in the journal Restoration Ecology. It is titled “Restoration Success: How is it being measured?”. The authors identify nine common goals to forest restoration treatments and posit them as indicators of restoration success. These “ecosystem attributes that define restoration success” include”
· Similar plant and animal diversity and community structure to a ‘reference site’
· Presence of indigenous species
· Presence of functional groups necessary for long-term stability
· The capacity of the physical environment to sustain reproducing populations
· ‘Normal’ ecosystem functioning
· Integration within the broader landscape
· Elimination of potential threats to the ecosystem (e.g. severe, uncharacteristic wildfire, bark beetle outbreaks)
· Resilience to natural disturbance
A quick perusal of this list shows the need for a host of scientific disciplines: plant ecology, forest management, community and landscape ecology, biogeography, wildlife ecology, entomology and fire ecology – just to name a few. I am excited by the opportunity for collaboration this field affords – and demands. I am concerned, however, by the rapidity that forest restoration treatments are being implemented on the landscape. There is still a lack of long-term data assessing the effect of these treatments on the landscape and its inhabitants. I think by linking the scientists who can determine the most effective, long-lasting restoration treatments with managers and policymakers who ultimately decide funding and implementation will be crucial before we attempt to conquer fire suppression’s legacy on a whim.
Contributed by Mandy Slate
We’ve probably all encountered both journalistic misrepresentation and poorly communicated science at some point. When the two collide we sometimes see the blame placed on the journalist for misinterpreting the science (there is even a prize for the most flagrant of these examples see: http://deevybee.blogspot.com/2010/06/orwellian-prize-for-journalistic.html) or conversely the academic may be criticized with being too dense. But perhaps neither of these assumptions are entirely fair.
The translation of science through the journalistic lens shouldn’t be as difficult as it is after all both parties generally have the same goal of clearly and precisely communicating a concept. In reality, this is not so easily played out. Academics often fill their explanations with undefined jargon and/or move too quickly through complicated concepts. In fact, this challenge is not exclusive to the academic-journalist interaction. Scientists are renowned for their inability to clearly communicate their research to academics outside of their discipline and oftentimes even fail among their own research cohort.
As a result of this communication barrier, journalists become imperative as they attempt to bridge the information gap between the academic world and the rest of society. Academics require public support for funding and policy issues. Additionally, oftentimes the topic of the research itself directly pertains to the general public either through its relevance to our health or environment. People are better equipped to make conscientious decisions on these complicated subjects when the oftentimes bewildering complexity of a subject can be made plain. As far as the public is concerned, the value of science will grow in proportion to its direct relevance.
There are a few simple things we, as academics, can work to incorporate into our verbiage to facilitate this cross-communication. 1) Learn to use understandable measurements: Although this is not likely to work in scientific publications, in communiques that are directly intercepted by the public we can try and translate less common measurements like hectares to more easily interpreted dimensions like the size of a football field or an amount of water could be compared to the capacity of a local lake. Using metaphors (and using them well) can really be to the academics benefit in these cases. 2) Avoid jargon whenever possible: There are many levels of this but in general if you can describe the idea to a third grader (and have them understand it) than there is a good chance that you are being clear enough. 3) Practice: I have many times heard researchers say that their work is not glossy or hot and thus it will never be picked up by the press. I don't buy this. Something drew you to this research topic so deeply that you now lose sleep, suffer socially, and ignore your general well-being to pursue it. Practice communicating this essence that has so infiltrated your life. Make it beautiful and fascinating. Passion can be contagious.
Contributed by Annie Cooper
My name is Annie Cooper, and I am a graduate student in the Department of Forestry and Conservation at the University of Montana. My research focuses on the interactions between climate, carbon, and ecological disturbances. More specifically, I look at how bark beetle epidemics can impact the ability of forests to take up and store carbon dioxide. Bark beetles can be a significant disturbance on the landscape, despite their diminutive size. When bark beetles reach epidemic levels, as they have recently, they have the potential to kill massive quantities of trees. Diminished numbers of live trees may lead to lower levels of carbon sequestration by the affected forest for a period of time. I use remote sensing, field data, and computer models to quantify the impacts of bark beetle attacks on forest carbon stocks and fluxes around the western United States. Right now, I am using satellite data combined with aerial imagery to determine the biomass contained in beetle-killed wood in forests across the West. The satellite data provides information on decreases in vegetation “greenness,” indicating tree death, and aerial imagery provided by the Forest Service documents the extent and location of beetle outbreaks. I will use the biomass information to determine the amount of carbon dioxide that might be released from affected areas into the atmosphere as a result of decomposition or combustion of dead wood. This information is important because it can help to inform management decisions such as whether or not to harvest dead trees, or how to assign carbon credits in the future.
Contributed by Alexis Billings
My name is Alexis Billings and I am a PhD candidate in the Organismal Biology and Ecology program in the Department of Biological Sciences at the University of Montana. I study animal behavior and communication. My research is focused on alarm calls, which are acoustic signals animals give in response to predators. Alarm calls are varied in their acoustic structure to obtain optimal transmission and to encode important information about predator type, predator threat level and even predator behavior. The acoustic structure of an alarm call can have radical effects on how well an it travels over long distances and through different habitats. I measure the loss of energy of different types of alarm calls over different distances and in different habitats. I compare these measurements to the loss of power calculated from wave transmission equations used in physics. I can then estimate the transmission properties of different habitat types and pair acoustic structures to certain habitat types. This combines biology and physics and gives us an idea of how animals are making sure their signals are being received. Alarm calls can also encode important information about predators. This information is used by numerous individuals that span species and even taxa in what is called a communication network. These communication networks add a new level to our understanding of how species are interacting and even cooperating to avoid predation. My research has found that communication networks in western Montana include multiple species of birds such as chickadees, nuthatches, and woodpeckers, as well as red squirrels. I have also found that the information travels incredibly fast within a communication network reaching numerous individuals in a matter of seconds. Understanding how animals communicate about danger involves understanding the physics of sound and how sound travels as well as how animals are really using these signals to avoid predation.
Contributed by Katelyn Driscoll
One of the goals of the UM Interdisciplinary Collaborative Network is to encourage cross-disciplinary collaborations between UM students and colleagues outside the university community. With this in mind, the ICN met for our February seminar during which each member gave a five minute presentation on their background, interests, and research. It was a great opportunity to get to know each other better and I wasn’t surprised that each presentation went a bit over the time limit because everyone was engaged and had several questions about each member’s work.
As I was preparing my talk, I figured that the presentations would be fairly similar and that we all had a lot of interests in common. That could not be farther from the truth! I was surprised at the variation in topics and how much potential for collaboration exists within such a small group. The topics covered included effects of restoration treatments, cultural wilderness meanings, time use of Americans with and without disabilities, plant interactions that occur above and below ground, variations in habitat use, evolution of genomic architecture, the potential carbon release from bark beetle epidemics, modeling the behavior of irrigation networks, effects of discharge on aquatic habitat complexity, and biogeochemistry in tropical systems. Through these discussions, it became clear that not only do the ICN members have a wealth of knowledge concerning various topics, but also that we each have unique skill sets such as field sampling techniques, GIS, modeling, surveying, or specific laboratory techniques. I think this is another one of the strengths of being involved in the ICN. Great opportunity exists to approach a member who has a better understanding of a certain field or skill, if not to work together on a project, at least to answer some questions. Other members are a great resource for perfecting one’s own methods or project with a skill or technology that may have otherwise been impossible to figure out. With these connections, it seems that personal projects will only grow stronger.
With this in mind, I’m looking forward to meeting other members who could not make the meeting and hoping the group grows to include more disciplines including statistics, economics, policy, communications, and psychology. One of the most interesting points made in this seminar was how collaborations with psychologists could help scientists to convey their results most effectively. This is a topic that I think about frequently because my own project involves accessing rivers that flow through private property, mostly large ranches. Historically many scientists have been so removed and unapproachable that the general public view them in a negative light. Interacting with landowners, who can range from skeptical to hostile, has taught me that scientists have to figure out a way to be a part of the general public, not a removed, exclusive group. I was just recently told by a professor that the new generation of emerging scientists must be better at communicating our findings and convincing land managers, policy makers, and individuals of our results. We are facing numerous serious problems that will not be solved if scientists don’t figure out a way to successfully communicate and convey results. Because the ICN is a graduate student group, it seems there is no better time to start practicing these interactions and collaborations than at the beginning of one’s career. I really hope that in the coming months more students from diverse disciplines join the ICN so we can all continue to make these positive connections.