Animals on the Move

Building a Habitat Suitability Model Part 1

We have posted blogs about a number of the research projects being done here at the ALSC and partner organizations. They highlight the fieldwork we do scooping poopobserving birds, and tracking tags, and the work we do in-house with some of our resident sea lionsseals, and birds. For many of us, those days out on mirror-flat seas and getting our hands dirty are why we got into this work. We loved being in nature, working with animals, and being curious about why the patterns we observed were happening.

We haven’t talked much about the other 80% of science: data and data analysis.

If you’re anything like my family, when I mention that for my postdoctoral research I’m working on ‘improving habitat modelling for juvenile Steller sea lions by integrating predation risk”  and that I do this using complex statistical programming, you likely imagine my day goes something like this:

IronMan

 

When in fact, most of my days are spent more like this:

 

Computer_AT

While at times it may be difficult, data analysis and modelling can be a powerful tool for conservation!

For example, Steller sea lions were listed as Endangered in the Western Distinct Population Segment (WDPS) in 1997. Under the Endangered Species Act, it is a requirement for any species listed as Endangered or Threatened to define what specific areas contain the physical or biological features essential to its’ conservation—it’s Critical Habitat.

So one question many researchers and managers might ask is:

Where do Steller sea lions spend their time?

My current work is studying the movements of juvenile Steller sea lions, as this age-class is particularly vulnerable and has low survival. But unlike some researchers who have the ability to follow their study animals around and observe them with ease—marine researchers have the complication that we can’t simply snorkel around or follow sea lions with a boat for months at a time. The use of cameras and individual markings can give us a glimpse of where they haulout and breed; but where they go when they are at sea is important information too.

difficult_tracking
How would you observe and track the movements of animals that migrate long distances, live in remote mountain areas, are entirely aquatic, or those that are semi-aquatic?

Satellite Tracking

 The ALSC has been working with free-ranging juvenile Steller sea lions since 2002. As part of a larger program looking at predation rates, life-history, and survival: over 70 animals have had satellite tags attached to provide information about the at sea behaviors of these young animals.

sattag
Example of a satellite tag developed by Wildlife Computers, Inc. for deployment on pinnipeds.

Satellite tags generate a LOT of data and fill-in some of the puzzle pieces of where animals go, where they are foraging, or how this changes seasonally. Just like your smartphone knows where the nearest Starbucks to you is, these tags can provide locations of animals in real-time (learn more about ARGOS here). The tags also have other sensors like a conductivity sensor to tell if the animal is wet or dry; or a pressure sensor to provide information about when an animal is diving, how deep, and for how long. There are also many other sensors being added to tags: like this one that records underwater noise and vocalizations!

One of the most commonly used functions however is to calculate animals’ positions. Since transmission to satellites doesn’t work underwater, for marine mammals this means the locations can only be recorded where animals either surface to breathe, or where they haulout of the water completely.

Amy-Video-2
The movements of a juvenile Steller sea lion from July – September in Prince William Sound. The animal initially makes several foraging trips around Glacier Island. It then heads south and spends time around the Seal Rocks haulout, before heading back north to Perry Island. {All procedures were carried out under NMFS permits #14335 and #18272. and ASLC Animal Use Protocols #02-15 and #03-007}

With this data, we can calculate the home range of the animal (the boundaries of their habitat use), and their core area (where they spend a greater proportion of their time). Then the next step is to integrate the movement data with environmental data in a habitat model to begin to understand what physical and biological features they prefer. In the case of this project and predation—we are planning to take that a step further and investigate what areas they might be avoiding!

Tracking the animals is the first step to building a habitat use model; so stay tuned for the next step: “A picture is worth a thousand data points”. 

Written by: Dr. Amy Bishop

BONUS Trivia Question:

I always enjoyed math in high school but like many other students, I couldn’t always see the applicability of what I was learning in the real world.

Can you name the infamous calculation we use to determine the distance animals move between points? (Hint: It is not too obtuse of a question!)

Answer next week!

_________________________________________

Photo Credits:

Iron Man Gif: http://gph.is/1ym0f7Z

Adventure Time Gif: http://gph.is/1cgH4PN

Migrating Geese: Delmas Lehman/ Shutterstock

Alpine Chamois: http://alpineibex.weebly.com/adaptations.html,

Whale Shark: https://www.tes.com/lessons/EuR8Aw2MwJYmuQ/whale-shark

Sea lion: https://www.flickr.com/photos/khaled100/8559509694

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