NORTHERN MEXICO
FIELD NOTES: SUMMER 2007 OCELOT FIELD RESEARCH
FIELD NOTES: SPRING 2007 OCELOT WRE
SUMMER 2007 OCELOT FIELD SESSION
June 6, 2007
I arrived at Laguna Atascosa National Wildlife Refuge today to start the final rodent-trapping session of my ocelot prey study. Everything looks pretty green and lush, thanks to the rain of the past winter and spring. It hasn’t been enough to make up for the preceding years of drought, though; many of the wetlands are mostly dry, cracked mud, and the long, hot summer is just beginning.
We set out all of the rodent traps this afternoon and discovered that one area of the Refuge, where two of the five traplines are located, is experiencing a grasshopper outbreak of plague proportions. It’s really rather alarming, like something out of a bad horror movie! They land all over the outside of the truck as we drive down the road, and when we walk into the brush to a trap site, they jump away from us through the bushes by the hundreds. The noise of all the little bodies hitting leaves and shaking branchlets makes me think for a moment that I’m disturbing a mammal or a snake. They represent so much potential food that it seems there should be flocks of birds there devouring them, but there aren’t. The weirdest thing is that they are apparently restricted to a small area of the Refuge which to my eyes is very similar to much of the rest of the Refuge. If they spread, things won’t look so lush any more; they’re denuding the plants and leaving the ground covered with tiny chewed leaf bits.
June 7, 2007
It was a spidery sort of day. I saw a big tarantula as we were checking the first trapline this morning. Then Seth, the volunteer who’s helping me, found a black widow in one of the traps on the fourth trapline. He shook it out, thinking that a mouse probably wouldn’t be very happy to be sharing the trap with it. And in the evening, as I was setting out for my rabbit survey, I saw something I’ve heard and read about but never seen before: a tarantula hawk wasp dragging a paralyzed tarantula off to lay an egg on it and bury it. These huge wasps sting tarantulas to paralyze them, and then leave them for their young to feed on as they mature. What a gruesome way to go! Paralyzed, buried alive, and having your guts sucked out by a larval wasp. I just hope the spiders aren’t aware of what’s happening to them!
Only a moment after watching this violent scene, I came across its polar opposite. I think maybe I even said “awwwww.” It was a cottontail sitting by the side of the road with about two feet of grass sticking out of his mouth. He was steadily chewing away, making the stiff grass blade bob up and down as it slowly disappeared into his mouth. It made me think of Lady and the Tramp sucking down spaghetti.
June 8, 2007
Today was a good day for carnivore sightings. En route from our second trapline to our third this morning, Seth yelled “There goes an ocelot!” and leapt out of the back of the truck. Fortunately, I had stopped the truck to ask him something, so he didn’t go somersaulting into a ditch. Unfortunately, I had stopped to ask him something, so I was turned around to talk to him and didn’t see the ocelot as it ran across the road in front of us. Seth was riding back in the truck bed rather than the seat because there was a reporter from the Dallas Morning News with us working on a story about the Zoo’s involvement with ocelot conservation. She was also looking back at Seth, though, and so missed probably the only chance she’ll ever have to see an ocelot in the wild. I’ve seen them before, but Seth never had, so he was thrilled. And I was thrilled for him; I feel like that sighting compensates him a little for all the hard work he’s putting in for me this week. Just a few minutes later I spotted a bobcat crossing the road in front of us and pointed it out to the reporter, so we did at least manage to see a cat. That’s always exciting for me, no matter what species it is.
I even get excited about seeing coyotes, but I suppose I’m pretty unusual in that regard. I saw two of them during my evening rabbit survey, and one was out on a mud flat, so I got to watch him for a few minutes. He trotted straight out and into the shallow water, where he immediately stopped to urinate. It took him a long time, so he must have had a pretty full bladder. Then he trotted along the edge of the water, stopped again to defecate, and went galloping back off the mud flat. Canids (members of the dog family) like coyotes and foxes often choose to defecate in open, obvious places like roads. It’s their way of advertising occupancy f an area: leaving a “Keep out!” signal where a potential intruder is likely to notice it. Foxes will even do handstands to get their hindquarters up high enough to defecate on top of large rocks. Canids also advertise with urine, but as anyone with a male dog knows, they tend to do that on vertical surfaces. That leaves the signal at optimum sniffing height and it makes it less likely to get washed away by rain or covered up by debris. So it seems counterproductive to go out and urinate in the water, where it will immediately dissipate. I’m puzzled as to why the coyote chose to do that, unless he’s not an established resident. Maybe he’s a transient trying to avoid being detected by the resident male. If so, that’s a pretty amazing strategy to have evolved.
June 9, 2007
Well, now I have seen a flock of birds preying upon that horde of grasshoppers, but it wasn’t quite what I expected. They were seagulls! Laughing gulls, to be exact, and they were swooping back and forth low over the treetops, hovering over the taller mesquites, then suddenly dropping down to pluck grasshoppers out of the top branches without ever landing. It struck me as a very odd way for gulls to behave. I don’t expect them to be eating insects, and I certainly don’t expect them to be foraging in trees! But as Seth reminded me, seagulls are famous in Utah for saving the early Mormon settlers by wiping out a horde of locusts (locusts being the swarming forms of certain grasshopper species) that was devouring their crops, so I guess I shouldn’t be too surprised.
June 10, 2007
Adrienne, the intern who helped me during my last trapping session here, came back to help me today on her day off from her current job. Luckily for me, she likes rodents. In the afternoon she gave me a tour of the Sea Turtle Rescue Center on South Padre Island, where she’s now working. I learned all kinds of things about sea turtles, like that they have a lot of feeling in their shells and enjoy being scratched/rubbed/brushed on the back. Also that they have cute, appealing faces, with big round eyes. It makes them look sweet and harmless, but they have incredibly strong jaws, and apparently some of them try to bite their keepers every chance they get. I watched a video demonstration of a Turtle Excluder Device, which helps keep turtles from being caught and drowned in shrimp nets. I had always been curious about exactly how they work, and now I know. But I also learned about another serious fishery‑related threat to sea turtles that hasn’t been addressed yet. Hundreds of thousands of turtles die every year when they get caught on longlines being used for tuna and swordfish. The fishermen attach lightsticks to the lines to help attract the fish, and as was just demonstrated in a study published last month, sea turtles are also attracted to lightsticks. There are a lot of bioluminescent sea creatures, so presumably predators like tuna and sea turtles interpret glowing underwater objects as food. Now that the fishing industry understands what’s going on a little better, I hope they work on coming up with a way to make tuna “turtle‑safe” as well as “dolphin‑safe”. If not, biologists are estimating that leatherbacks, the largest sea turtle species, may be extinct in the Pacific Ocean in under 10 years .
June 11, 2007
As suburban neighborhoods go, mine (in Arlington) seems to be a pretty wildlife-friendly one. While walking my dogs on the neighborhood streets, I have at various times seen an armadillo, an opossum, a gray fox and a bobcat. Much to the dogs’ delight, we see rabbits almost every day during the summer. I regularly see several species of hawks, and I’m fairly sure Mississippi kites, screech owls and great horned owls have nested nearby. I occasionally see white-winged doves and scissor-tailed flycatchers on the soccer fields of the park a block from my house, and two summers ago I watched a killdeer successfully incubate four eggs there in defiance of passing dogs, soccer-playing kids, and the groundskeeper’s weekly rounds with a huge tractor-pulled mower. And yet, as I was doing my rabbit survey this evening, I was mourning the fact that it was my last one and I was about to go back to the city. Sunset is my favorite time of day, and especially during hot weather, natural areas like the Refuge seem to blossom with life at that hour. The roadsides were thick with rabbits and roadrunners. Mockingbirds, long-billed thrashers, yellow-billed cuckoos and green jays were popping in and out of the bushes. On the back roads I startled a couple of collared peccaries and some white-tailed deer. And as it got dark, pauraques and tarantulas began to appear on the road, along with a four-foot indigo snake, which I was thrilled to see. They’re such handsome creatures, and this was the first one I’ve seen on this trip, although I’ve seen lots of them here before. Actually, it was the first live snake of any kind I’ve seen on this trip; I had only found a couple of small racers squashed on the road earlier.
Most of these species that have been delighting me with their abundance this past week don’t occur in the Metropex. One that is common to both places, though, is the foolhardy killdeer. Here a female has chosen to nest in the middle of an intersection of two gravel roads, one of which is heavily traveled by Refuge staff. She had laid one egg when I first saw the nest on Friday, and she now has three. She valiantly attempts to lure away threatening cars with her broken-wing display, but I think the bright orange traffic cone that one of the volunteers put next to the nest will probably do a better job of keeping the eggs from being run over.
June 12, 2007
My final field session for this study is now over. For what I fervently hope is the last time ever, I have disassembled, scrubbed, and reassembled 100 Sherman traps. Well, I didn’t do them all; Seth was an equal participant in the fun, for which I am extremely grateful. We caught a total of 89 rodents of 7 different species this week. We did not catch another ground squirrel (which I discussed in my March field notes), but I did see several of them as I was driving around, so I know that they are still active.
I love field work, but it does make for some awfully long work days. Wildlife research tends to happen either early in the morning or late in the evening, because that’s when many species are most active, and I’ve been burning the candle at both ends this week. We’ve been going out to check traps at 7:00AM, and I’ve been finishing up my rabbit survey around 9:00PM. Add on a half-hour commute to the house where I’m staying, and what do you get? Less than a full night’s sleep, that’s what. So although at sunset I’m sad to be leaving, by the time I get in bed I will be glad not to be facing the prospect of checking traps at dawn the next morning. And after a couple of months of desk work, I will be eager to get into the field again! Look for me in November…
March 3, 2007
To Harlingen, Laguna Atascosa National Wildlife Refuge
The WRE volunteers all arrived in Harlingen by noon, and we had a beautiful afternoon for our field trip to LANWR: warm sun and cool breeze. Although the drought eased somewhat this winter, it’s still very dry there, and we saw very few waterfowl or wading birds. There was one big raft of ducks out on the Laguna Madre, but they were too far away for me to identify. I was also surprised at the relative scarcity of raptors. Normally I see several Harris hawks in the course of a drive around the refuge, but we didn’t see a single one. Luckily, the green jays were putting on a good show around the visitor’s center, and they were joined by several cardinals and a huge flock of migrating red-winged blackbirds, making for some striking color contrasts.
The yuccas are flowering, and they’re really stunning. In my previous trips to LANWR, I hadn’t noticed how abundant the yuccas are, but when they’re in bloom they dominate the landscape, and you feel like you’re in a yucca forest. There was a sign on the door of the visitor’s center warning that people have been poaching the flowers to sell, which of course prevents the plants from reproducing.
One of the Refuge interns took us to see a medium-sized alligator that has taken up residence in a 40-square-foot concrete water tank. It was posing quite photogenically with its chin on the edge of the tank, wearing an elegant coating of duckweed. The high point of the afternoon, though, was definitely the coyote that we watched foraging next to the Bayside Loop road. It was hunting slowly through the tall grass in the ditch, ears on the alert for any sign of rodent activity, undisturbed by the cars full of tourists following along beside it.
March 4, 2007
Harlingen to Los Ebanos
In Florida they’re called snowbirds; here they’re called winter Texans. I noticed this morning how many cars in the hotel parking lot had Canadian license plates. It had been a long time since I’d seen a block heater plug hanging out of a grill! I can’t imagine choosing to spend the winter at the Harlingen Econo Lodge, but that’s what the owners of those cars are doing. Some of them have obviously put a lot of effort into decorating their rooms, and they hold cocktail hour with their neighbors on the edge of the motel parking lot just as though they were on their patio at home.
It seems to always be overcast when I cross into Mexico, which I find appropriate for driving through the Rio Grande valley. It depresses me to see the vast expanses of agriculture where there used to be ocelot habitat, and to know that the river is being sucked dry to irrigate such fields. In the fall, after the crops have been harvested, the air is brown with topsoil that’s being carried away by the wind. The air was mostly clear today, which made the plume of sulfur-yellow smoke above the electrical power plant really stand out.
Charlie, our van driver, said the blue-gray rippled cloud cover above us looked like the ocean turned upside down.
March 5, 2007
I had to get up at 2:00AM this morning to turn on the satellite radiocollar I have for our juvenile dispersal study. I needed to start it on a schedule of transmitting from 2:00 to 8:00AM so that it will be ready if we catch an ocelot we want to put it on. That’s the best time of day for us to get locations, because that’s when ocelots are most active. It’s not my favorite time of day, however, and I was particularly loath to get up last night, because it was a very cold night!
Today was beautifully sunny and cool, and we spent the first part of the morning doing radiotelemetry. It gave me a chance to birdwatch while the volunteers were practicing. I was delighted to see some old favorites, birds that I often see in that pasture, such as a vermilion flycatcher and a white-tailed kite. I was even happier to get a good look at a bare-throated tiger heron, as that’s a species I’ve rarely seen. There must have been plenty of rain here this winter; all the ponds and reservoirs are full of water and the pastures are green and lush. The roads aren’t muddy, though, so apparently it hasn’t rained much recently. Lucky for me, because I didn’t bring any rubber boots this time! I had so much stuff to pack, because I’m combining three trips into one, that I decided to gamble that I wouldn’t need them. It usually rains very little here in the spring.
We put out the traps this afternoon, giving the volunteers their first exposure to pinolillos, the teeny-tiny ticks that can suddenly make your pant legs look like they’ve been heavily sprinkled with pepper. Most of the volunteers were busily mounting a DEET-and-duct-tape defense, but Dan didn’t even bother to check himself for ticks. I wonder how many bites he got!
March 6, 2007
There weren’t any cats (or anything else) in the traps this morning, but we made up for it by catching three hawks this afternoon! They were really easy captures, too: the kind where the hawk flies down to the trap before we’ve even finished backing the truck away and gets thoroughly stuck in the fishing line loops in less than a minute. It was very satisfying for the volunteers to see how well the traps performed, since we had just spent a couple of hours at the finicky, tedious task of tying loops. All of the captured birds were roadside hawks, which is by far the most commonly caught species here. Since there are only four volunteers on this trip, they’ve almost all gotten to release a hawk already! Releasing a hawk is always an adrenaline rush, and it’s especially thrilling if you’ve never held a bird of prey before.
March 7, 2007
Boy, this trip is really starting out with a bang! There was a collared forest-falcon in one of the cat traps this morning. We hadn’t caught one of those since 2004. Collared forest-falcons are tropical raptors that are rarely seen anywhere, because they live in the forest understory. They hunt by flying low along the ground, which is how they end up in our traps. They weigh less than a kilogram, so a chicken seems like a big prey item for them to attack, but Arturo said he saw one that had killed an adult male turkey once.
But the forest-falcon wasn’t even the highlight of the day. We put out the rodent traps for our prey base survey this afternoon, and as we were setting the last of them Arturo and Ebodio discovered that there was an ocelot in one of the cat traps that was nearby! We had found the chicken dead and half-eaten when we checked that trap in the morning, so we had hung the remains inside the main compartment of the trap, in hopes that whatever had managed to kill it through the mesh of the chicken compartment would come back for the rest and get caught. Sure enough, it was an uncollared adult male ocelot, who was so eager to finish his meal that he came back in the middle of the day! Because we processed him in the late afternoon, we ended up releasing him at 8:30 at night, which made getting good pictures of the release even more challenging than usual. Driving out to release him gave everyone a good opportunity to enjoy the stars. Orion and the Milky Way were really standing out. I can’t even see the Milky Way at home, because of all the city lights, so it feels like I’m reuniting with a long-lost friend when I do get a chance to see it. It’s not completely dark at night here either, but the light is coming from the stars themselves.
March 8, 2007
Another day, another ocelot... A young female this time, probably pregnant with her first litter, possibly fathered by the male we caught yesterday. She was extremely calm in the trap. After Arturo got the anesthetic into her and we backed off, she lay down and started washing her feet. A few minutes later she just put her head down and went to sleep, curled up as if she were on her favorite bed. I’ve never seen an animal so mellow about being knocked out!
The volunteers are starting to look back at the notes in the visitors’ book from previous trips, thinking about whether we might end up setting some records for number of captures. I just hope we continue to do well enough that they don’t leave feeling disappointed, because the last part of the trip wasn’t as exciting as the first part. That’s the thing about field work – you just never know what’s going to happen or when.
March 9, 2007
I saw a peregrine falcon this evening! It was the closest I’ve ever been to one in a natural setting. (Even though they were wild birds, I wouldn’t call being on the other side of a Minneapolis skyscraper window from a peregrine a natural setting.) This is an incredible place for raptors. Just today, I’ve seen caracaras, ospreys, roadside, gray, black, and white-tailed hawks, a white-tailed kite, kestrels, a peregrine and I think a merlin. Within the last few days I’ve also seen greater black hawks and a collared forest-falcon, and the other group saw an Aplomado falcon. Really, it’s an incredible place for bird diversity in general. The other morning I took a picture of four birds sitting within a few feet of each other in the top of a tree: a kiskadee, an Altamira oriole, a golden-fronted woodpecker and a cedar waxwing. Four completely unrelated species, three tropical and one temperate, all strikingly colored. How cool is that?
March 10, 2007
Radiotracking sounds like a pretty easy way to get data: you gather information on an animal’s movements and activity remotely, without having to see the animal or go into the woods or even get out of your truck. In reality, though, it can be quite difficult and frustrating. Just figuring out what direction a signal is coming from when you’re listening to it can be a challenge, but the biggest challenge is picking up the signal. Topography, vegetation, electromagnetic interference and the orientation of the transmitter’s antenna can all affect reception. There have been occasions when the signal seemed so strong that I thought I was just about on top of the animal I was tracking, but it turned out to be almost a mile away. At other times I have barely been able to hear the signal from an animal that was only a couple hundred yards from me. Today we drove up and down half the length of the ranch, listening from nine different spots, and never managed to get a good location for the male ocelot we caught three days ago. We heard him very faintly a few times and I think I know approximately where he was, but when we went to spots where we thought we should pick up the signal well, we couldn’t hear it at all. We did get a location for the female, so we weren’t completely frustrated, but I hate putting all that effort into trying to figure out where the male was and never really getting an answer!
March 11, 2007
The only predictable aspect of field work is that things never happen the way you plan. Today is Sunday, which is supposed to be a day off for the volunteers. Of course, the traps have to be checked, but we don’t plan any hawking or radiotelemetry, so after checking the traps there should be plenty of free time for horseback riding, going to the beach, canoeing or whatever. So naturally, today was our most successful trapping day yet! We caught another ocelot and two opossums, which meant that most of the day was spent processing animals. Two of the volunteers did get in a short ride, but it wasn’t much of a day off! It was also our least pleasant day yet weatherwise, though: cloudy all day, with occasional drizzle. Hopefully we’ll get a chance to go to the beach on a nice day later in the week. Meanwhile, we now have three newly collared ocelots to track!
March 12, 2007
Hawking is getting more difficult. Half the hawks we see have bands on their legs because we’ve already caught them, and some of those that don’t have bands are the mates of those that do, who I think have learned by watching that it’s hazardous to go after a mouse in a cage. We did find a gray hawk today that I would have loved to catch, but it just wouldn’t cooperate. It swooped down over the trap a couple of times and then sat on a branch right above it. We waited for about 20 minutes, and I would have waited for another hour as long as the hawk was there, but everyone else wanted to move on. Arturo has been trying another hawking technique using nets and pigeons, but he hasn’t had any luck at all. We saw the peregrine again this evening, sitting on the same branch it was on three days ago! Seems like it might be a good candidate for the net technique…
March 13, 2007
We didn’t try for the peregrine, although we saw it again on the same perch this evening, but we did finally get a gray hawk! I think they are so beautiful; I just love the chance to see one close up and to hold it. I was glad the volunteers had the opportunity to see something besides a roadside, too. All raptors are cool, but roadside hawks are the least attractive raptor I know of. They’re just kind of a murky brownish gray, with no striking markings except for their yellow eyes. Gray hawks are a clear pearly gray that I find lovely, but I suppose other people might think they look kind of boring too. Arturo’s group caught a greater black hawk this morning, which of course is more exciting because they’re so much bigger. They have striking black and white coloration, but I just don’t find them that attractive. There’s something about the face and the long legs that makes them look a bit vulture-like, I think. Now, if we could just catch the Harris’ hawk that has been hanging around the area of the ranch houses, we’d have a bird that’s both big and beautiful, and we’d feel like we’d done an outstanding job of catching raptors on this trip!
March 14, 2007
Things are starting to wind down. The ocelot we caught on Sunday was in another trap this morning, but that was the only capture. Before lunch I washed out all the rodent traps, which is a nasty job and hard on my back. The weather finally cleared around mid-morning, so we spent most of the afternoon at the beach, burning ourselves to a crisp. The volunteers loved it, and two of them even went in the water. I just walked up and down the beach looking at shells and enjoying the lines of pelicans gliding overhead. My understanding is that flying into the wind creates lift, but they seem to do splendidly flying downwind. Watching a line of pelicans go by is one of the few things that makes me long for a video camera. I’m sure if I did videotape them, though, I’d be disappointed in the result. So I just try to savor the moments and the feelings of joy and admiration.
March 15, 2007
After dinner we went to the beach for a little farewell celebration: a fire, marshmallows to roast, and of course, tequila. The stars were absolutely spectacular. Sometimes when I lie on my back and look up at the stars I feel like I can really see the depth to the sky, as if the stars are floating in a sea, some near the surface, some far below, and I could dive in and swim among them. Remarkably, the real sea was also filled with light! Tiny organisms were phosphorescing in the waves, so that as the surf broke, green glowing lines of foam spread along the water. A few of them got thrown up onto the beach by each wave, like little green sparks burning for an instant on the sand. It was the perfect end to a fantastic trip.
March 16, 2007
Los Ebanos to Las Carreras
I’m always sad to leave Los Ebanos, because it means returning to the city and trading in vistas of green meadows and ocean for I-20 traffic jams and strip malls. I was much less sad this time, though, because I wasn’t going straight back to the city. After sending the volunteers on their way back to Texas with Charlie, Arturo and I went about 100 miles up the coast to another ranch, less picturesque and full of wildlife than Los Ebanos, but still worlds better than the Metroplex. We set out 100 livetraps to capture rodents for our ocelot prey base study. We’re training a Mexican college student in our field techniques so that he can complete the six-day trapping session after we leave on Sunday.
March 17, 2007
Edwin, the student, really had a trial by fire today! We caught 64 rodents, and it took us about 7 hours to process them all. He’s very careful, which in my book is definitely a good thing. Ideally, he will do the final trapping session in June, also, so we won’t have to find and train another person.
There are wildflowers all over here. Yellow, blue, pink…and huisache bushes everywhere covered with the fuzzy golden balls that are their flowers. All along the roads and forest edges in Los Ebanos there were yellow-flowering bushes that no one could tell us the name of. I find it remarkable that a plant so abundant and striking could not have a well-known common name. Don’t people want to say “Spring is here, the ----- are in bloom”? I’m seeing all of these flowers for the first time, and I already feel emotionally connected to them, and wistful at the thought that I might never see them again.
March 18, 2007
Las Carreras to LANWR
What a long day! We spent about 5 hours processing rodents this morning, and then hastily packed everything up, left Edwin with all the field supplies and instructions we could think of, and headed off for Texas. Although we picked the border crossing with the least tourist traffic, because it’s out in the middle of nowhere, we still had to sit in line for two hours to get across. Arturo thinks it’s because of spring break. Whatever it was, it didn’t make the Harlingen airport any more lively than usual. When I went in to pick up my rental car the counter was deserted and the airport looked half closed. The woman behind the next counter over had to telephone someone to come wait on me. I rendezvoused with Jody (the ocelot biologist at Laguna Atascosa National Wildlife Refuge) so she could lead me to the house where I’m staying, which we got to at about 11PM. I hadn’t been there more than 15 minutes before a mouse ran across the floor in front of me. As Arlo Guthrie would say, I felt right welcome.
March 19, 2007
Well, the house itself leaves much to be desired, but the setting is great! It’s right on a resaca, which is a small waterway. The first thing I did after I felt semi-functional this morning was go out and stand on the dock. Just 50 yards down I saw 3 species of ducks and a nutria. Under my feet there were puffs of sediment rising up through the water from a foraging turtle rooting around in the muck on the bottom. I wished I could have just stayed there and enjoyed the morning, but my growling stomach was pointing out that I had to buy my groceries for the next week!
I spent the afternoon setting out 100 rodent traps. Again. This is by far the most difficult place to trap, because the National Wildlife Refuge is extremely restrictive about vegetation removal or disturbance. Whereas easy access to my trap sites in Mexico is quickly provided by a man with a machete, here we have to crawl in to half of them on our hands and knees with thorns scratching and stabbing us from all sides. Not to mention the ticks. Ticks in these habitat types are generally low in the vegetation, so I’m accustomed to always checking my pant legs after I go into the brush. Even several hundred pinolillos can be removed from a pant leg fairly easily with duct tape. But when you’re crawling in on your hands and knees… well, it’s not a pretty picture.
March 20, 2007
We found 44 rodents of 7 different species in the traps this morning. Pretty impressive for one day! It took us almost 6 hours, just because getting in and out of the brush to all the trap sites is so difficult and time-consuming. It looks like there may be a deer mouse population explosion going on. The overwhelming majority of individuals we caught were deer mice, and even a trapline which during my previous trapping sessions provided very few captures of any sort was full of them.
The mice in my house kept waking me up last night as they rummaged through my belongings and played hide-and-seek in plastic grocery bags in the kitchen. A hard day of trapping after a poor night’s sleep has left me completely exhausted!
March 21, 2007
I now have the answer to a question that has been bothering me for months. During my last trapping session here, in January, I caught birds several times in my rodent traps. They were all the same species, and I know I caught at least two different individuals, because one day we found birds in two traps at the same time. I was never able to hang onto one of them long enough to get a picture, because I was too worried about hurting them. I got good looks at them, though, and wrote down detailed descriptions. I searched through my bird book, but couldn’t find anything that matched. I described the birds to one of the volunteers here who is an extremely knowledgeable birder, and he told me what he thought seemed like the most likely possibilities, but when I looked them up, they didn’t look right.
Well, today we caught one of that same species on a different trapline from where we were catching them in January, and Adrienne, the intern who’s helping me here, was able to hold it long enough for me to take a few pictures. I showed them to Bob, the same volunteer who was trying to help me figure it out before, and he said “That’s an olive sparrow!” We looked it up in a couple of different bird books, and sure enough, that’s what it seems to be. I hadn’t found it before because it’s in my Mexico bird book, and I was looking in my U.S. bird book. Bob hadn’t thought of it before because when I told him it had a green back, he started thinking of warblers and vireos, not sparrows. Almost all sparrows are brown, but olive sparrows are, naturally, olive-green.
So I’m quite pleased to have that mystery solved, but I’m still a little frustrated. I commonly find when I’m using field guides that I don’t seem to see animals the way the authors do. In this case, one of the most obvious marks that I notice when I look at these birds is a bright yellow spot right at the wrist joint of each wing. In three different bird books, however, I saw no mention or depiction of such a spot. How can that be?
March 22, 2007
I saw two nilgai antelope while I was doing my driving survey for rabbits at sunset. They are so freaking big! It’s such a shock to have one suddenly pop up in front of you, almost like having an okapi run across the road. And my mind immediately says “That doesn’t belong here!” - which of course it doesn’t. It saddens me that a National Wildlife Refuge has a thriving population of such a conspicuous exotic species, although in truth it’s probably unobtrusive invaders like plants and insects that do the most ecological damage. The worst that nilgai are likely to do is reduce white-tailed deer populations a little due to competition, but there are still far more deer here than nilgai. Exotic plants that outcompete native plants, as they are doing in Refuges and National Parks all over the country, throw the base of the food chain out of whack, with unpleasant ramifications for all the animals that occupy the higher levels. They may also impact ecosystem characteristics other than food supply, such as the availability of water and cover. And the worst part is that they’re almost impossible to get rid of, and the things that will kill them will also kill whatever native plants are still hanging on in the area.
March 23, 2007
We saw a rattlesnake in the middle of the road as we were driving from one trapline to another this morning. We both immediately grabbed our cameras and jumped out of the truck. I took 20 pictures; I think Adrienne must have taken 100. The snake posed beautifully for us, slowly pulling itself up into an ever-changing sculpture of threatening curves, rattling occasionally when it felt we were becoming too bold. Adrienne, who had never had the chance to photograph a rattler before, was excitedly professing her love for it as she knelt on the ground with her zoom lens. The snake clearly didn’t return her affections, and it eventually glided off the road and curled up under the protection of a yucca’s spiny leaves.
March 24, 2007
I caught my first squirrel ever! Specifically, a Mexican ground squirrel, bringing our total number of species captured during this trapping session to 9, a new record for me. Adrienne and I were both very excited about the squirrel. It was so different from everything else we catch, and so pretty, with its striped and spotted coat and bushy tail. Not nearly as bushy as a tree squirrel’s, of course, but compared to what we’re used to…! I never even see ground squirrels here, so although when I started the study I had hoped to catch some, I had pretty much given up on that. Now there’s only one species I expected to find that I have not yet captured: the smallest one, Merriam’s pocket mouse, that weighs less than 10 grams. Maybe in June!
March 25, 2007
We caught the ground squirrel again today, and were almost as amazed and excited as we were yesterday. He’s so cute! I’m going to have to find out if the ground squirrels here hibernate. I know many ground squirrels spend an incredibly large percentage of their lives, like 8 or 9 months each year, in aestivation/hibernation. Aestivation is going dormant during the heat of the summer, as opposed to the winter. If they do either or both here, they may have been dormant during both of the first two trapping sessions, and that may have been why we didn’t catch any until now. Or, maybe they’re just uncommon or trap-wary, and the fact that we caught this one was just a fluke.
The other excitement for the day was removing a huge botfly larva from a deer mouse. Having previously been parasitized by several botfly larvae myself, and having removed them while they were still quite tiny because they were so painful, I hate to think about what that mouse was going through. The larva was about half the size of the mouse’s head! Imagine having a maggot half the size of your head living under your skin…
Well, that ends my marathon field session, with 49 rodents captured at Los Ebanos, 114 here, and probably more than that at Las Carreras, although I won’t know the total until Edwin sends me the data. The WRE capture total was 3 ocelots, 3 opossums and 9 hawks. Although I love being in the field, after more than three weeks away, I’m eager to get home to my husband, my dogs, and my rodent-free house!
For more information, contact Dr. Booth-Binczik at (214)671-0777 or sbooth@mail.ci.dallas.tx.us. You can also visit Arturo Caso's website at www.angelfire.com/tx/margay/
