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About Author: Colleen Wisinski

Posts by Colleen Wisinski

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A Closer Look at Burrowing Owls

Note the difference in coloration (female on left, male on right) with this burrowing owl pair.

Note the difference in coloration (female on left, male on right) with this burrowing owl pair.

For the past two years, our burrowing owl project has been focused on how to effectively relocate California ground squirrels to help re-engineer nonnative grasslands and make them more amenable to burrowing owls (see Burrowing Owls: Closer than You Think and Digging into Burrowing Owl Recovery). But this year, we get to take a closer look at the owls themselves. Don’t get me wrong, I love the squirrels (more than I ever thought I would), but I’m a bird biologist, so I’m really excited to start working directly with the burrowing owls!

Burrowing owls range widely across the western US and make use of a variety of “grassland” habitats, from open prairie to empty suburban lots to airports. But their populations are declining, mostly due to loss of habitat and eradication of the fossorial (digging) mammals that they depend on to build burrows. One solution is the installation of artificial burrows. However, artificial burrows are not self-sustaining like natural squirrel burrows and, although we know the owls use them, we don’t know how they compare to natural burrows.

A male burrowing owl guards his burrow entrance.

A male burrowing owl guards his burrow entrance.

This year, one of our main objectives is to compare reproductive output, food provisioning, and predation at natural versus artificial burrows, using camera traps and banding the birds to accomplish this. The camera traps allow us to see what is going on at the burrow while we aren’t there, and the banding allows us to identify each individual (see Bling with a Purpose).

At this point, the breeding season is in full swing. We are monitoring almost 30 nest burrows (both natural and artificial); this includes placing camera traps at about 20 of the burrows. We check on each burrow about once a week (we don’t want to visit too often and risk disturbing the birds) and do any camera trap maintenance needed, such as changing batteries and switching out the memory cards that contain our priceless data in the form of photographs. We also watch the birds from a distance to figure out what stage of the breeding season they are in—for me, this is the best part!

A camera trap photo shows a burrowing owl pair allopreening at their burrow entrance.

A camera trap photo shows a burrowing owl pair allopreening at their burrow entrance.

Over the last two months, we have been inventorying burrows and following their progression through the breeding season. On any given day, we head out to the field in the morning and work our way through our route for the day checking on each burrow as we go. When we arrive at a burrow, we observe from the truck (which acts as our blind) from a safe distance to see what is going on at the burrow. Early in the breeding season, we might see both parent birds or just the male standing guard at a burrow. In general, the males are lighter in color than the females, because they spend more time outside so the sun bleaches their feathers. As the breeding season progresses, the difference in plumage becomes more marked, as the males get more and more bleached. By the end of the summer, though, it can be hard to tell the males and females apart as both get bleached by the sun.

Two burrowing owl chicks rest at the burrow entrance while Mom stands guard. Camera trap photo.

Two burrowing owl chicks rest at the burrow entrance while Mom stands guard. Camera trap photo.

Once the pair has chosen their nest burrow, we usually only see the male of the pair; he is often standing watch over the burrow from nearby (often at the entrance of a satellite burrow where he spends much of his time—we call it the “man cave”). At this point, the female is spending most of her time in the burrow incubating the eggs. After about a month, the eggs hatch, and two weeks after that, the young start to come out to the burrow entrance. We usually do a quick examination of the photos in the field to help us determine if there are chicks present, but we also get good clues from the female’s behavior. If she is very protective of the burrow or stays very close to the burrow when we approach, it’s a safe bet that there are babies in the burrow.

Currently, we have nests in all different stages of breeding—some have pretty large chicks, some still have eggs, and some still seem to be deciding if they are even going to breed. In the coming weeks, we will band all of the owls from burrows that have camera traps, and over the next several months, we will pour over the hundreds of thousands of camera trap photos to catalogue how often prey was delivered to the burrow, what type of prey was brought, what types of predators come to the burrow, and other pertinent information. This is a huge undertaking, since we have almost 40 camera traps set up that can take over 30,000 pictures in one week alone! Any volunteers? Seriously, if you’re interested in helping, visit our volunteer page and sign up! Who wouldn’t want to spend their time looking at pictures of these adorable and comical little birds?!

Colleen Wisinski is a senior research technician for the San Diego Zoo Institute for Conservation Research.

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Bling with a Purpose

Bands used on cactus wrens and burrowing owls, far left is aluminum wren band, middle are wren color bands, far right is alphanumeric band for owls.

Bands used on cactus wrens and burrowing owls, far left is aluminum wren band, middle are wren color bands, far right is alphanumeric band for owls.

Bird banding is an important tool for researching wild birds, allowing them to be individually identifiable in the hand or by sight. This can be especially important for birds that are too small to carry tracking devices such as radio collars or GPS tags. Both conservation research projects that I work on involve understanding some aspect of the population dynamics of birds that are too small to put transmitters on: coastal cactus wrens and western burrowing owls. An alternative method of distinguishing individual birds is to mark them with color or alphanumeric bands, in addition to standard aluminum bands from the US government, which are required for all banded birds and have a unique ID number.

This cactus wren sports a unique color band combination.

This cactus wren sports a unique color band combination.

To mark cactus wrens, we use plastic bands that come in several different colors and also have our US government aluminum bands dyed green so as to distinguish them from bands used by other organizations also conducting research on cactus wrens in southern California. Each wren gets two bands on each leg (two plastic on one leg, one plastic and one aluminum on the other), giving us lots of combinations to work with so that each wren has a unique color combination. In the field, we use binoculars, spotting scopes, and photographs to identify individual birds. Because we know where and when each bird was banded, we can get a sense of how long the birds live, how far they move, and how they interact with each other.

Federal and state governments both require researchers to have a permit to band birds, and obtaining one can be a lengthy process because it involves gaining a lot of experience with bird handling and capture techniques. Throughout my academic and professional career, I have been involved with capturing and banding many different species of birds, but only at a trainee/apprentice level. Recently, I took a class in bird banding through University of California, Riverside, Extension to gain additional experience with mist netting and banding of small passerines (songbirds).

A Gambel’s white-crowned sparrow is caught in a mist net.

A Gambel’s white-crowned sparrow is caught in a mist net.

Mist netting is a commonly used technique for capturing songbirds; mist nets are made of very fine material that is difficult to see when set up properly. They are usually set up in high flight traffic areas (e.g. between trees or shrubs), and when the birds fly into them, they are caught in a pocket and become slightly tangled. The nets must be checked often or watched from an inconspicuous location so birds can be removed in a timely manner. Although we already use mist nests to capture cactus wrens, taking the class allowed me to gain a lot of additional practice in extracting birds from the nets. We also had the opportunity to work with many different bird species that we don’t usually catch.

After a bird was captured, we identified its species, banded it, determined its age and sex, and took standard morphometric measurements. Determining the age of birds can be very difficult, and in many cases you can only say that a bird is a juvenile of that year (a hatch-year bird) or an adult (an after-hatch-year bird). We learned how different feather wear and molt patterns can be used to determine the ages of the birds we caught. We also assessed body condition by looking at fat deposits on the breast and hips (birds have very thin skin, so it is easy to see the fat layer just below the skin). Over the course of the weekend, we captured and banded almost 300 birds! We also recaptured birds that were banded in the past and recorded their band numbers. All of the data collected will be given to the Federal Bird Banding Lab (part of the US Geological Survey) and used to look at trends in bird populations across the country.

Steve Myers (instructor) bands and takes body metrics of lesser goldfinches.

Steve Myers (instructor) bands and takes body metrics of lesser goldfinches.

This experience will help me in the permitting process and proved to be an invaluable opportunity to learn new skills and get lots of practice with banding and mist netting. I can’t wait to get out and put my new skills to use. Watch out, cactus wrens, here I come!

Colleen Wisinski is a senior research technician in the Applied Animal Ecology Division at the San Diego Zoo Institute for Conservation Research. Read her previous post, A Sense of Wonder for Wildlife.

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A Sense of Wonder for Wildlife

 

A young Colleen examines rocks.

October is Kids Free Days at the San Diego Zoo and San Diego Zoo Safari Park. During October, our Zoo 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, Go Play Outside!

I grew up in rural southeastern Wisconsin and was lucky enough to have a big backyard with a forest and a creek just down the road. I spent as much time as I could outside when I was a kid—I even had an imaginary friend that lived under the shagbark hickory in our backyard. My sister and I would spend hours playing outside; pretending our bikes were horses, we’d pack up our backpacks with “gear” to make mudpies and other goodies on our journeys. We’d “help” my dad in the garden, go for long walks to the park, or just play on the swing set to our hearts’ content.

Colleen fishing in northern Wisconsin.

I got to spend summers at our lake cottage or the family “hunting shack” in northern Wisconsin. Going “up north” was my favorite part of summer vacation. At the lake, I got up before sunrise to go fishing with my dad and then spent the rest of the day in my swim suit playing in the water. At sunset, stampedes of tiny little toads would take over the beach, and we would build sand castles for them to sleep in. At the shack, my dad and I explored the beaver pond, and he showed me the giant stumps from white pines that had been cut down almost a 100 years before. We picked wild blueberries to put in pancakes and looked for deer in the woods.

Colleen admires a snapping turtle.

All of my experiences in nature created a sense of wonder and awe, but most importantly, I learned that we are all part of nature, and it is our responsibility to take care of it. I knew from a young age that I wanted to work with animals, but it wasn’t until fourth grade and a forward-thinking teacher that I decided I wanted to work in wildlife conservation. I eventually received a bachelor of science in biology and Spanish and an masters in fish and wildlife management, and I got hooked on birds. I have had the opportunity to work with many different animals; I have also learned the importance of understanding and conserving habitat and have come to appreciate plants and all their amazing adaptations.

As a research associate in the Applied Animal Ecology Division at the San Diego Zoo Institute for Conservation Research, I work with coastal cactus wrens and golden eagles. My work includes studying and restoring habitat as well as monitoring birds. I am very fortunate to get to spend so much time outside and to work toward preserving native biodiversity. It is very fulfilling to work hard at something I feel so passionate about.

Colleen Wisinski is a research associate at the San Diego Zoo Institute for Conservation Research. Read her previous post, Golden Eagles: An Exercise in Patience.

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Golden Eagles: An Exercise in Patience

The view from our eagle observation point in the Sierra Juarez, Baja California, Mexico.  A nest that was occupied last spring is located on the other side of the ridge in the left side of the picture.
The view from our eagle observation point in the Sierra Juarez, Baja California, Mexico. A nest that was occupied last spring is located on the other side of the ridge in the left side of the picture.

I recently traveled with a few colleagues to north-central Baja California, Mexico, to conduct field research for the San Diego Zoo’s Golden Eagle Project (see previous post, Golden Eagle Helicopter Survey). A wind farm is being designed for future development in the Sierra Juarez, and the San Diego Zoo is involved with pre-construction research of habitat use and demographics of golden eagles. The objective of the project is to examine what parts of the mountain range are used by eagles and how and when they use each part. Our findings may help to minimize future interactions between eagles and turbines.

I am the new field ornithologist for the Zoo’s Institute for Conservation Research and just joined the team in August. Because so little is known about the eagles in the area, we’ve had to resort to good, old-fashioned detective work—that means sitting and waiting to see eagles. On our last trip in September, we saw several raptor species including turkey vultures, peregrine falcons, and American kestrels during our surveillance from our high perch at the edge of the desert, but no eagles (darn!). We have previously observed eagles in this area and know that they breed here because of nest surveys that took place last March from a helicopter (brrrrr). However, we don’t know if they stick around all year or if they leave after the breeding season is over. So we decided we needed to increase our surveillance effort for the eagles during the non-breeding season. Our objective in the week-long observation period was to make note of any eagle (and other bird) activity in the area—but Mother Nature had other plans for us.

The first day that we were there, it was really windy–the winds were gusting up to 65 miles per hour (105 kilometers per hour)! We know this because another part of our mission was to set up weather stations that send all the data they gather directly to us at the Institute’s Beckman Center via the Internet (in real time!). Birds (especially big, heavy ones like eagles) don’t like to fly when it’s too windy because it takes a lot of energy to stay in air in those conditions, so we only stayed out for half the day. We’re lucky nobody got blown off the mountain! We went back out the next morning to continue our surveillance, and it snowed! The snow only lasted for about 30 minutes, but the wind had shifted, and it was cold (which is saying a lot, because I’m from Wisconsin!). The rest of the day was sunny, but still a little windy, and we still didn’t see any eagles. Our week continued much the same way—clear and windy and no eagles.

I’m not going to lie; at times we got pretty bored. But we also got to spend a week outside without worrying about e-mails and cell phones and all the other activities that take up too much time in our lives. We got to enjoy just being out in nature, which is the reason most of us became ecologists—to save nature so future generations can enjoy it, too. So the lesson from this trip is that I have to be patient—sooner or later, I’ll see an eagle and, in the meantime, I’ve got a great view!

Colleen Wisinski is a research associate with the San Diego Zoo’s Institute for Conservation Research.