About Author: Susanne Marczak

Posts by Susanne Marczak


Braving Chilly Nights for Kangaroo Rats

A trap is opened and baited adjacent to an Stephen's kangaroo rat burrow.

A trap is opened and baited adjacent to an Stephen’s kangaroo rat burrow.

6:36 p.m. – The traps are set. Four of us have opened and baited them with millet seed, and all we can do now is wait and hope that they are enticing enough for some endangered Stephens’ kangaroo rats to go inside. We are trapping these k-rats at an experimental restoration site in Temecula, California, to see how the species is doing three years after our initial translocation and restoration efforts (see post, No Night-lights for Kangaroo Rats). As the sun goes down, so does the temperature, and we head to the truck to shield us a bit from the cold and crisp wind.

8:30 p.m. – My first shift to look and listen for coyotes begins. We operate in shifts so that we all get a chance to sleep at some point in the night. Our trap sites must be constantly monitored for coyote presence. They are a wily species and take any opportunity to try and pry one of our precious rats out of its trap for a snack. Can’t they find a species that’s NOT endangered to eat for dinner?!

Researchers collect data on a trapped Stephens’ A kangaroo rat is released back to its burrow.

Researchers collect data on a trapped Stephens’ kangaroo rat.

The coyotes themselves move silently across the grassland, so we vigilantly listen for their shrill yips or the rattling of a trap being disturbed by wild paws. The clouds have moved in, so the night feels even darker and colder than usual. If the temperature drops below 50º Fahrenheit (10 degrees Celsius), we will need to cease our trapping effort for the safety of the animals. I am hoping it stays well above that for the sake of us humans as well! I walk around the site and turn on my flood lamp; the beam of white light shines across our site. I scan all around us. No yellow eyeshine from coyotes, only the silver of our traps and the bright pink from our flags labeling the locations of kangaroo rat burrows.

11:27 p.m. – I feel a nudge on my arm. “Come on,” a voice says, “it’s time to check the traps.” I had taken full liberty to nap while someone else was on coyote watch duty. The cold air on my face is a brutal contrast to the warmth of my sleeping bag. To close my eyes again for just a few more minutes would be heavenly, but it’s time to check our traps and see what we got. Luckily, sleeping upright in a car is never too comfortable, so I welcome the opportunity to stretch my legs, even if it means being out in the cold for a while.

Working in the dark, researchers check to see if any kangaroo rats have been trapped.

Working in the dark, researchers check to see if any kangaroo rats have been trapped.

11:35 p.m. – Our first Stephen’s kangaroo rat of the night! It’s #2364, as indicated by the two small metal tags in its ears. After noting the capture on our data sheet, we let him go. Kangaroo rats are a super-docile species, and I can’t help but giggle a bit when, upon their release, they jump around our feet for a minute before scurrying back into their burrows.

12:41 a.m. – Finished our first trap check. Ready for another nap before our next and final check at 3:45 a.m.

1:48 a.m. – I’m awakened by a gust of cold wind hitting my face. My makeshift sleeping bag fort built precisely to prevent this from happening has failed me! Granted, it was propped up only by the brim of the baseball hat I am wearing, so it was bound to happen eventually. I reconstruct my makeshift fort the best I can and try to get some more sleep.

A Stephens’ kangaroo rat has a metal ear tag for identification.

A Stephens’ kangaroo rat has a metal ear tag for identification.

2:15 a.m. – Second coyote-watching shift of the night! Luckily for us, no coyotes tonight. 🙂

3:43 a.m. – That terrible nudge again indicating it’s time for our final trap check. I didn’t think anything would be more difficult than getting up the first time, but I was wrong. It’s only gotten colder, and my hands turn numb as I begin picking up the cold traps and closing them for the night. They’ll be open and set again tomorrow evening for another round of trapping. We check and double-check that all the traps are closed. I’m freezing, even with my two long-sleeved shirts, down vest, and two fleeces on. How do these tiny mammals manage to stay warm in the night? Imagining them in their cozy little burrows underground makes me a bit jealous as I dream of a bed with a big duvet to curl under.

6:33 a.m. – All the traps have been checked and closed, and we begin the drive back to our hotel.

6:58 a.m. – Like a bunch of sleep-deprived zombies, we all shuffle into the hotel lobby. The smell of hot coffee and fresh waffles fills the air as guests enjoy their breakfasts. They must be thinking we are a group of vagrants hoping to score a free continental breakfast as we haul in with our warm clothes on and sleeping bags in our hands. Right now, all I want is some proper sleep—the kind one has in a bed, not the front seat of a truck! I need to rest up, because we still have one final night of trapping ahead of us. It is a grueling schedule, but we are all happy to work it so as to help conserve this amazing grassland species.

Susanne Marczak is a research technician for the San Diego Zoo Institute for Conservation Research. Read her previous post, Banding Burrowing Owls.


Banding Burrowing Owls

A chick is banded with its new identifier, 48X.

A chick is banded with its new identifier, 48X.

This summer, I had the opportunity to assist with the San Diego Zoo Institute for Conservation Research’s western burrowing owl banding effort in San Diego County. A team of researchers worked this spring and summer to trap, band, and observe burrowing owls in South County to monitor the population in the area (see My Summer Staycation: Burrowing into Owl City. The bands serve as unique identifiers and allow us to track individual birds over the course of their lives, monitoring such things as survivorship, breeding success, and home range. For the previous two years, I have been researching California ground squirrel and burrowing owl habitat requirements in San Diego County grasslands, so it was very exciting to finally participate in some work with the actual owls.

On a summer afternoon in late June, we arrived at our site. We pulled off the main road to a place where we could observe the owls’ behavior without disturbing them. We set up our scope and saw them: two adults hanging out by a California ground squirrel burrow they had chosen as their nesting site earlier in the year. The chicks were hidden inside the burrow.

We take morphological measurements of a burrowing owl chick.

We take morphological measurements of a burrowing owl chick.

It was especially meaningful for me to help out with trapping and banding the chicks at this site, as I had visited this location earlier in the year to conduct ground squirrel surveys and gather habitat data and soil samples. On our last day of ground squirrel surveys here in April, we had seen a male burrowing owl using one of the squirrel burrows. I wondered at this moment if this was that same bird I had seen months before, now paired with a female and with chicks of his own.

As we approached the nesting burrow, both adults flew away, in an attempt to distract us from their chicks, and continued to keep a close watch on what we were doing. We used burlap sacks to block all but the main burrow entrance at the nest, and then placed a one-way door trap at that entrance. While the chicks could exit the burrow and enter the trap, they would be unable to leave the trap once inside.

We returned a short time later to find three burrowing owl chicks inside the trap—success! Carefully removing the chicks from the trap, we placed them in a pet carrier so they would be more comfortable as they waited to be banded. During the banding process, we took morphological measurements such as weight, wing length, bill length, and tarsus height and length. A small blood sample was also taken from the birds for genetic analysis. We moved quickly so the chicks could be returned to their burrow as soon as possible.

Upon their release, the chicks scurried back into their burrow with their new bands on. I hope they will survive the rest of the non-breeding season, and we’ll see them again in the spring—maybe with chicks of their very own!

Susanne Marczak is a research technician with the San Diego Zoo Institute for Conservation Research. Read her previous post, Citizen Science: Engaging People in Conservation Research.


Citizen Science

Zoo Corps volunteers helped the Institute’s Applied Plant Ecology Division plant cactus to restore coastal sage scrub environment.

Zoo Corps volunteers helped the Institute’s Applied Plant Ecology Division plant cactus to restore coastal sage scrub environment.

Recently I had the opportunity to attend one of the first meetings of the newly formed San Diego Citizen Science Network. A multitude of stakeholders attended including educators, university graduate students, local government officials, and researchers from the San Diego Zoo Institute for Conservation Research (“the Institute”). It was very exciting to be with people from so many different backgrounds and institutions who all shared the same vision: to increase and streamline the potential for citizen science opportunities throughout San Diego County.

The term “citizen science” is a reference to public engagement opportunities in scientific investigations. Even though participants often have limited or no scientific background, they can still play a crucial role in asking questions, collecting data, and interpreting results that support meaningful scientific research. These types of programs provide an opportunity to increase public scientific literacy and involve individuals in various components of the scientific process. This can prove especially useful for answering scientific questions that require data to be gathered or processed over long periods of time and large geographic areas.

Citizen science is an extremely vital component of the work that we do here at the Institute. Without our many passionate volunteers who assist with data collection and entry, we would not be able to conduct research at the same magnitude that we currently realize. Improvements in technology (and its associated decreasing costs) have led to an exponential increase in the amount of data we are able to collect (a single camera trap can generate thousands of images a week!). Trained volunteers able to identify species and individual animals in photos have substantially helped our efforts to evaluate the survival and overall success of translocated squirrels and to monitor western burrowing owl nests. Volunteers also participate in surveys for coastal cactus wrens, observe giant panda behavior, help with planting of cacti to restore local habitat, and help us collect feedback from guests about their experiences at the Zoo and Safari Park.



The acoustic structure of a gibbon “duet call” becomes longer and more complex over time. Recordings made by guests can provide researchers with a better understanding of how and why these changes occur and how they can be studied to estimate population numbers in the wild:

Public participation in scientific data collection can also serve to enhance the guest experience at our facilities where guests can have opportunities to engage and connect with wildlife in novel ways. For example, the Institute’s Behavioral Biology Division plans to create a smartphone/tablet application that will allow guests to collect valuable biological data on the animals they are enjoying while visiting the Zoo or Safari Park. Such observations (including both behavior and associated vocalizations) can provide us with a greater understanding of how animals utilize their enclosures and how individuals interact with each other. This level of interaction also gives the guest the chance to be a direct participant in the scientific process and learn more about how we collect and use data.

The creation of this local citizen science network is really exciting. It will serve as a great tool to bring researchers, educators, and the general public together—a sort of match-making service for individuals and organizations wanting to be involved. This kind of collaboration allows researchers to help educators develop scientifically rigorous protocols for data collection and serve as mentors for students. Participating land managers and institutions can also provide property access, different groups can collect data for the same project across a large landscape over multiple years, and all teams collectively build an essential dataset to answer a research question.

Everyday people across the world help collect scientific data, from studies in museums where individuals are examining specimens that have been in storage for years to activities in cities and parks where counting and identifying birds provides much-needed data on avian populations. People are looking in their own backyards and recording when flowers bloom and when leaves fall to contribute to our understanding of changing climates and environments. There are so many ways to get involved as a citizen scientist, and I encourage you to participate in any way you can. As a researcher here at the Institute, I can truly testify to the invaluable contributions that volunteers make to our projects. Get involved as a volunteer with San Diego Zoo Global or another organization that interests you and begin your own adventure as a citizen scientist!

Susanne Marczak is a research technician with the San Diego Zoo Institute for Conservation Research. Read her previous post, Muddy Days in the Soil Lab.


Muddy Days in the Soil Lab

Soil tins are ready for processing after drying in the soil oven.

When describing an environment, you might not necessarily think to look right below your feet at the ground and the soil that it is made of. But it is that very soil that influences which plants can grow, where water collects, and which animals are able live there. For a fossorial animal (one that is adapted to dig), soil is an especially important predictor of where it can choose to live. The soil has to be sturdy enough to support a burrow but be of the right composition to be able to dig through without too much difficulty. Depending on the size and typical behavior of the animal, these needs can be very species-specific.

During the spring and summer, I worked on a team to collect soil samples from grassland habitats around San Diego County to create a habitat suitability model for California ground squirrels. Why do we care about ground squirrels and where they live? Ground squirrels serve as the “ecosystem engineers” of grassland environments by clearing vegetation and serving as anti-predator sentinels for some species (and dinner for others!). Their burrows also can serve as homes for other animals including the western burrowing owl, a species of concern in San Diego County. By better understanding the type of grassland habitat that ground squirrels prefer, we can also gain insight into what constitutes suitable burrowing owl habitat (see previous post Squirrels: There’s No Place Like Home for more information).

Research Assistant Frank Santana got over-enthusiastic with the mini-plunger. This reminds us that lab counters should never be white!

To date, we have hundreds of soil samples that are either from places where there are ground squirrel burrows or where ground squirrel burrows aren’t present. Our study focuses on the differences in soil characteristics between sites to determine if ground squirrels have a preference for particular soil types. After collecting our samples in the field, we took them to our project collaborators at the U.S. Fish & Wildlife offices in Carlsbad, who have been kind enough to train us and let us use their lab.

Components we look at include:

1) Bulk density – Using a soil corer, we collected a standard volume of soil from a standard depth below the surface. By taking the weight of the entire sample after it has been dried in an oven, we can calculate its density.

2) Percent gravel – After the density is determined, we take the whole sample and run it through a sieve (grated filter) to separate out gravel that is 2 millimeters (0.08 inches) or larger from the rest of the soil. Weighing the gravel and comparing it against the total weight of the sample gives us the percentage of the sample that is composed of gravel.

3) Soil texture – Soil is made up of essentially three components: sand, silt, and clay. Conducting a soil texture analysis allows us to classify soil samples into different categories based upon the percent composition. To figure out what percent of sand, silt, and clay make up our sample, we create a solution that contains a sample of our soil, water, and a chemical called sodium hexametaphosphate (a chemical common in most dishwashing detergents) that helps suspend the particles of soil longer than if we used water alone. We mix the resultant solution in a blender and put it in a graduated cylinder. Then we use a mini-plunger to mix the solution until it feels consistent and use a hydrometer to measure the specific gravity (relative density) of the liquid solution at different points in time: 40 seconds, 2 hours, and 3 hours after mixing.

Soil solutions in graduated cylinders await measurements at the 2- and 3-hour mark.

The idea is that sand, silt, and clay settle to the bottom of the mixed solution at different rates. Sand settles to the bottom first, then silt, then clay. Using a calculation related to the ratios of measurements, we can get the percent composition of the sample.

It takes about 3.5 hours to process a single sample, so we try to have as many running simultaneously as possible. It’s a hectic day of making solutions, mixing them up, taking hydrometer and temperature readings, and keeping track of which stage in the process we are at overall for each sample. We have hundreds of samples to process, so we are excited to see what trends we find in the data after we are finished.

Susanne Marczak is a research technician with the San Diego Zoo Institute for Conservation Research.


Squirrels: There’s No Place Like Home

Data is collected on vegetation type and height in ground squirrel habitat.

We are moving California ground squirrels from one location to another (tranlocating) to test if their presence can help restore grassland habitat and provide natural burrow homes for western burrowing owls. Currently, management of burrowing owl populations requires a lot of human intervention; artificial burrows are built in hope that owls will come and use them. However, there hasn’t really been enough focus on this issue from a grassland ecosystem restoration standpoint.

In areas where ground squirrels are relatively common, lots of native plants and other animal inhabitants benefit. Ground squirrels serve as “ecosystem engineers,” building intricate burrow systems, clearing large amounts of vegetation, and serving as anti-predator sentinels for some species. They also play the role of dinner, too!

A transect begins to search for California ground squirrel burrows.

But what determines where a ground squirrel likes to live? Sometimes it seems like they are everywhere: in parks, at the beach, alongside roads, and around our properties. But when it comes to grassland habitats in San Diego County, they’re not always present where you might initially expect them to be. Figuring out where ground squirrels can and prefer to live is especially important when you want to move them to places where they are going to be successful. After all, we want them to establish a new population in a place that will allow them to help the habitat as a whole.

One exciting thing I’ve been working on over the last few months is collecting data for the California ground squirrel habitat suitability model in order to determine what habitat variables predict the presence or absence of ground squirrels in a particular area. The idea is that the more we know about what makes excellent ground squirrel grassland habitat, the higher our chances of success will be when translocating them to a new environment that is in need of some “natural” restoration.

An old California ground squirrel burrow we found was actively being used by a pair of burrowing owls. Note the “white wash” (bird droppings) at the entrance.

At study sites around the county, we’ve been surveying for ground squirrel burrows and collecting data on the surrounding habitat characteristics, vegetation type, and height in the area and any potential burrow protection observed. We have also noted if we’ve seen squirrel predators in the area, like coyotes or red-tailed hawks. In addition, we’ve also been taking soil cores to determine soil density and other attributes, which we’ll assess later in the lab. Because ground squirrels are fossorial, we think soil type has a huge influence on their habitat preferences. I’m eager to process the samples and see the results after all the dirty work of collecting them. Working with soil has turned me into the filthiest-looking researcher in the building. I’ll be happy to know that all of those extra loads of laundry I’ve had to do have paid off!

Susanne Marczak is a research technician with the San Diego Zoo Institute for Conservation Research. Read her previous post, A New Nature.


A New Nature

A young Susanne explores the forest floor.

October is Kids Free Days at the San Diego Zoo and San Diego Zoo Safari Park. Our Institute for Conservation Research staff are sharing their interactions and connections with nature at a young age and how these connections put them on their paths to becoming conservation biologists. Read a previous post, Outdoor Survival Skills.

I grew up in a very different place than San Diego; I was born and raised in Nova Scotia, Canada, where towns were smaller and times seemed simpler, and seeking entertainment outdoors was the standard. Nintendo hadn’t yet been invented, car phones were the next big thing, and nobody could have imagined that something like the Internet could ever exist. Every day until dusk, life was filled with imaginary adventures that became the foundation for real memories I look back upon with great fondness.

I have always loved being outside. My family went camping when I was younger, and the outdoors seemed so limitless compared to the confines of buildings. I read National Geographic magazine and watched nature shows on television, dreaming of one day becoming a wildlife photographer. As I became older, my passion for nature fueled my desire to be part of the effort to conserve the plants, animals, and ecosystems that were part of it.

When I was 10 years old, I moved to San Diego with my family to a housing community where the imaginations of children took them not to lakes, woods, and open spaces but to tennis courts, swimming pools, parking lots, and the strip mall across the street. Not to say we didn’t have fun—kids are extremely capable of entertaining themselves in almost any situation; it was just that the opportunities to intimately experience the natural world became fewer and further between, especially with the advent of technological novelties such as video games and the Internet. As the entire community became more and more disconnected from nature, school field trips to the outdoors became a rarity, and media shifted away from accounts of wilderness toward the material and ephemeral. The San Diego Zoo was the first zoo that I ever went to, and it instantly became one of the few sources where I could be enlightened to the Southern California environments and the world beyond it.

Susanne admires a mussurana at the Las Cuevas Research Station in Belize.

Attending the University of California, Los Angeles, for my undergraduate work, I chose to pursue a degree in ecology, behavior, and evolution. As part of the requirement for the degree, I had to conduct my own field research project as part of an off-site field biology course; I was lucky to be accepted into the group that went to Nicaragua. There, I experienced for the first time a rain forest environment filled with a plethora of plants and animals that I had never before in my life seen or could have imagined. The opportunity gave me the chance to engage myself in scientific field research that could be directly applied to conservation. I knew then that my love of science and the outdoors could be combined and help fuel the knowledge and conservation of the planet.

Today I work for the San Diego Zoo Institute for Conservation Research, part of a team working toward learning about and conserving species and their habitats around the world. It was not just my hard work that allowed me to achieve my dreams—it was the passion I have in my heart for nature and its inhabitants that has been the driving force for the efforts I make to preserve this world for future generations and to ensure that they, too, have the opportunity to find meaning in doing the same.

Susanne Marczak is an administrative assistant at the San Diego Zoo Institute for Conservation Research.