This is MY space -- or perhaps I don't care much about it....

Patterns of Interactions

Each time I'm at Palo Verde, I watch the spatial pattern of animals, where they are physically located, and the places they use in their day. I observe the animals and their interaction (and try to understand why).                                                                                                                                                        

Kaplan

Animals may move for their own reasons; sometimes we may contribute to the relocation. Blue-Yellow-Brown (Kaplan) most often used a roof hide on the dining hall end of a building. But a roof leak necessitated repairs and he since moved to the opposite end of the building. Not a huge change by any means. Charcoal made the same shift and Miami uses a roof refuge very near Kaplan. They all stick their heads out in the morning and watch as we go into breakfast.

Two iguanas on branches

 In Big Tree, most of the iguanas are the same individuals observed in May. Physical movements from one refuge to another seem to be in terms of >100 m, most often >20 m.

Ctenosaura similis is described as a territorial species -- but rarely does an author define the meaning of territorial behavior. Sometimes we call the males 'resource polygynists' which tries to indicate that the males guard resources females find important. I have yet to see this in operation. (I can wholly see males guarding females from other males during breeding season -- but if they are guarding female resources at other times during the year, it's subtle beyond my means!)

Maher and Lott (1995) propose this definition of territoriality: a fixed space from which an individual or group of of mutually tolerant individuals actively excludes competitors from a specific resource or resources (1). Sounds good -- but I want to understand and better define the temporal patterns of territoriality. How often is an iguana actively excluding others from that important resource? How much time is spent on the exclusion behavior? If duration and frequency is minor compared to other activities of daily life, is territoriality an important illuminator or descriptor of Ctenosaura similis behavior? At present, I'm not convinced territoriality is the indisputable epicenter from which C. similis behavior springs.


(1) Maher, C.R and D. F. Lott. 1995. Definitions of territoriality used in the study of variation in vertebrate spacing systems. Animal Behavior, 49, 1581-1597.

My, How You Have Grown!

Am I really bigger?!

Have I really been gone from Palo Verde National Park for 6 months? In my absence, the OTS station was abuzz with changes, for humans and iguanas alike.

Pale Blue-Black-Red (Pb-K-R) has more than doubled in weight. If not for the beads, I wouldn't have recognized him! He also moved from the lab near Green-Green-Green to the Big Tree area near to White-Orange-Green.

Many other iguanas are larger, growing throughout the green (rainy) season. Adults look good and plump. This is day 2.5, and we are still rounding up the lizards (thank you, humane traps and bananas), but 19 of 53 are present and we expect to approach near 100% recapture by trip's end. We've also caught 3 new lizards.

For humans, buildings have received a fresh coat of paint, outdoor showers have been added, and the entire laundry area is shaded for staff, a great improvement. Faces are familiar and food is still good! Dry and cracked in May, the wetlands are full of water with incredible numbers of birds and and a few visible crocodiles.

Six of the 60,000,000 Black-Bellied Whistling Ducks at Palo Verde!

Am I Adapted to My Environment?

Am I Adapted to My Environment? Yup -- or you wouldn't be here!

When I think of environment, I often think of food, shelter, and weather, and oh yeah, behavior. Isn't behavior in service to the needs of foraging, avoiding predators, thermoregulation cycles? Well, yes, or at least, perhaps. But how is your behavior adapted to your environment? Doesn't your environment include conspecifics? In what ways do spend your time so that you learn and survive?

Behavior, especially interdependencies between individual animals, can have as much effect as good forage, appropriate refugia, and preferred optimum temperature zones. Individual behavior, then, should be adapted to the social structure in which an animal lives. Even in a non-cooperative animal like Ctenosaura similis, an understanding of which same-species animals might be a danger, or useful, or neutral might well tip the balance between surviving and thriving, between some offspring, and overall better fitness.

So, yes, you are adapted to your world!

Dynamic Networks

Today, this iguana fondly known as Blocky, is here, tomorrow he will be over there, the next day somewhere else...and so on. As for all the iguanas, the network structure I'll build through physical proximity will suggest a static set of interdependencies, when in fact relationships may change seasonally (wet/dry, breeding/nonbreeding) or at other temporal scales.

Territoriality itself could change. C. similis is a central-place territorial holder focused on a refuge. At that location, an iguana may chase off conspecifics while when foraging at a different location, appears to give no thought to the refuge presently undefended or the iguanas now tolerated.

Humans are also central-place territory holders -- we want to sit in 'our' seat in a classroom, feel possessive of it, but never give a thought to who occupies it next once the class is over. Our possession, like the iguana, is contextual. 

Ah....just 12 days and I'm back to Iguana Toast Land, where Ctenosaura similis roam free, and the average temp must be greater than my current 7 degrees F!

Since May, I've completed the first semester of my doctoral degree, taking courses, attending seminars, reading more papers than I'd like to count, and getting a research grant from my university. While every moment has not been 100% successful, the challenges have been rewarding in very good ways.

Still, I want to keep my research and thinking steeped in field situations. I see the sheer do-ability of lab organisms, but suspect I am better suited to the challenges of in-situ projects. For 15 years, I've had the honor observing I. iguana in a captive group, and during that time, numerous occasions to observe endangered wild iguana species. They are captivating, physically attractive, socially complex, exciting animals. In the case of C. similis, they are observable and often tolerate living among humans. I'm always thrilled I get to see this incredible animal live free, and to attempt to understand the basis of its social organization.

This trip I'll have along one of my favorite field colleagues, my husband. We will catch and process iguanas, explore Palo Verde National Park, and spend Christmas in the neotropics. He'll see my study site, the cast of iguana characters, and help open my second study population.

I'll be posting throughout the trip and beyond -- stay tuned!

The 5th Dimension

My head feels awash in neurogenesis -- surely five days at the Animal Behavior Society's conference in Boulder has initiated new brains cells!

I attended a good behavior and conservation workshop, attempting to find solutions to four real world, sticky problems. It reminded me why my own research feels a great refuge from such messes. Yet basic research, and perhaps especially understanding animals in their own world, could save us from so many calamities before they begin. But that's another day.

I'm humming about social networks and the insights I gained during the conference -- everything from how connections suggest certain group and individual attributes to data collection goals.

The origins of social behavior are not in cooperation (provisioning young, dueting, chasing away predators) but, more likely, simple tolerance. Not a a gaggle of geese but an aggregation of iguanas. The members of the aggregation are connected to each other, perhaps in 'neighborhoods' -- each member knows a subset of the entire group, just like a group of people who are Facebook friends. (I'm the big red dot in the middle and you can easily see neighborhoods.)

Social networks suggest interesting questions related to personality, behavioral syndromes, learning, parasite load, and fitness (meaning who produces the most offspring who produce the most offspring).

For example, if an animal is bold toward potential predators, does the animal also have many connections to other animals in its group, and does that predict who the animals learns from and its parasite load? Does a young female iguana learn the best nesting site from the most connected iguana in her 'hood? Are the neighborhoods assemblages of related animals? Or are neighborhoods avoiding inbreeding and making sure the mix of animals are unrelated? An how do those layers operate to produce better or poorer fitness? 

While the iguana may look like it has no preferences, no likes or dislikes (let's not forget iguanas do not have facial muscles so their lack of 'smiling' isn't terribly revealing), for all we know the aggregation is a powerful kin or even fictive family. 

The chessboard base is the social network: individually known iguanas, their attributes, and their connections. And then there will be a relatedness dimension. And personality. And so on...let the sunshine in!

Food and Fun

With rain comes new life -- trees, plants, insects, baby iguanas. New life means new foods:

Bignoniaceae spp.

Iguanas ate these small blue flowers today.

Guess who?!

And WOG felt like sampling the goodies in the Wire Treat Box.

Some of the iguanas seem 1/3 larger than in March while others are likely at their maximum size and growing little. Still, the bounty is lush and some feeding sessions last for many minutes.

KPbG

Remember that KPbG's refuge was covered for a few days? Once uncovered, back in use!

Kaplan

A beautiful, breezy day today, iguanas out and about. Kaplan hung out on his roost for several hours.

Tomorrow, some packing and last observations before I leave.

Jump, Swoop, Cut, Climb, and Upside Down

Portia in Palo Verde

Jumping spiders are incredible for their beauty and likely cognitive powers. This one jumped on the camera right after this shot.

Crane Hawk, Geranospiza caerulescens

That's a C. similis predator. Walking in between GGG and little PbKR,  I felt a gust of air and saw a silent but potentially deadly raptor fly in front of me, legs outstretched. A mad scramble and PbKR was gone, and several large iguanas were racing up large trees. I sat for the rest of the afternoon in hopes PbKR was safe. Yes, this is a natural predator, birds gotta eat, too, but I was concerned I'd actually provided incoming visual cover to the predator. The next morning all expected iguanas came out to bask, PbKR from his cement block.

Leaf Cutter Ant

At times, I wait at least an hour for an iguana to come from a tree or ground refuge in hopes I can test their reaction to a novel object. While waiting, I play insect games -- How Many Insects in the Next 5 Minutes? How Many Flying? Largest. Most Annoying (guess the winner!). To my delight, one of my haunts provides little green flags carried over long distances. It's a beautiful and incredible sight, and then the ants continue into their ground nest opening.

OYBr

Orange-Yellow-Brown was caught at the base of the Lower Tree where he has a refuge in a tree root. He traverses the road and climbs much smaller trees in the Woods.

YPbBr

Sometimes even a smallish iguana takes on a larger climbs with equal prowess. Yellow-Pale Blue-Brown climbs the largest tree in the Woods across the road.

Upside Down

This refuge is called "Bird House at Lower Tree," and this day the still unmarked male managed to get himself in upside down. He struggled enough to make me wonder if he was getting eaten by a snake but righted himself.

It sounds straightforward to test iguanas -- put out the object, and see what they do. However, field work will also end up at least on its side if not upside down. The iguana above comes down this tree facing North, follows the right side of the drive for a bit, crosses, and follows the left side of the drive, then moves across the road. The novel object needs to be along this route or it will simply be ignored. This may be evidence of habituation to such objects, outright avoidance, safety produced by routine, or something else.

Sharp Things

Prickly Bombacopsis quinata with iguana leg and nails.

For about 2 days I was ill with some odd fever and G.I. unhappiness that left me without energy. Great guilt surrounds lost field days but I found I was too unfocused to write notes and I went to bed. Luckily, the downtime was short-lived.

The Pochote tree above is the smaller of two trees that create 'Big Tree'. Amazing to see iguanas climb up its branches, rest on its thorns, stretch from those sharp points to eat leaves now and flowers during the height of the dry season. (This tree is an IUCN red list threatened species.)

Kaplan as a slug on a log.

Males quietly creep around the edges, coming a few meters into the station, slipping back behind a building or further into the woods. Their camouflage is very effective.

Tomorrow is more testing, a visit to a potential second study population, and finishing some writing. It rained twice this evening so should be a buggy day. Oddly, the bites, though annoying, aren't giving me waves of histamine so that I need to retreat. Not to test the fates, but I can hope I'm developing a smidge of resistance.

Mothra! and Iguana Jug Band!

Big Grasshopper Thing

Large Moth-y Creature: Eacles imperialis

Last night the air was close and heavy, and insects were everywhere. In the morning, the White Sign, aka Bug Board, was covered with various moths. Beautiful insects.

And tasty:

Iguanas gathered under the sign, climbed the sign, chased each other from this great food resource. Iguanas appear to be mighty good at reading social cues.

Kaplan on the dust pan, GWO on the broom. 

GWO has one refuge in a tree and another near the kitchen, just to the right of this stand. Visiting GWO was Kaplan, Romelia, and 3 other marked iguanas. A veritable club of lizards.

Hatchling C. similis getting on a fierce expression.

 The little lizard above has already made it across a field, a gravel road, up a hillside, and into the station. Let's hope this one survives and joins the great Palo Verde group.

Testing, Trapping, Toes, and Ticks

Orange-Yellow-Brown

This little male was caught at the end of the driveway into the station. Like clockwork, a few other UMs appeared. At least the presence of unmarked iguanas is consistent.

More exploration-avoidance testing today. Some iguanas will climb inside a cloth bag for a prized food treat while others would not consider approaching anything. It's really interesting to see who does what. Iguanas will also quickly guard and fight over a new object.

Look, no beads!

Due to work in the lab, a stack of folders was outside blocking KPbG's refuge entrance. He eventually climbed the Lab/Cistern Guayacan tree, had a tussle with BrBrBr, and took his refuge. BrBrBR is hanging around the front of the dorm, and using a pipe as his refuge. Tomorrow I hope we can make available KPbG's old refuge, and see what happens -- he may prefer his new view.

Toes!

Little Pale Blue-Black-Orange (PbKO) with his toes off the sidewalk. Common behavior. Speaking of common behavior, observed today an adult male eating a dried up toad.

Another common item regarding iguanas -- ticks.  Below are just a few removed from an adult male for another researcher working on these beasties.

Bags, Babies, Butterflies, and Bufo

White-Black-Yellow explores the bag.

Today I ran a few exploration-avoidance tests. This is to see the how an animal reacts to different novel situations -- objects, food, etc. Even a baited trap might be used to see how quickly an animal approaches, how long the object is investigated, and if they will enter it. Lizards that previously tested shyer than others did not avoid the experience of the blue bag. In other words, shy animals may not predictably avoid new experiences.

Hatchling C. similis.

Really tiny!

Hatchling C. similis are around. I startled this one into the dining hall where I managed to catch him. Very young, the yolk sack not completely closed. Snout-to-vent length measured 54.91mm. Far too small to bead!

Swallowtail Butterfly

After two rains I'm seeing many more butterflies of all kinds, just don't ask me to ID them! C. similis is omnivorous and today younger animals were actively hunting low flying insects -- too fast to photograph. And an adult iguana ate a bat today -- photographed by park tourists. It seemed likely the iguana knew the location of the bats and had accomplished this feat before.

Bufo luetkenii female...

...and much smaller, differently colored male.

There are 3 young women from Nicaragua here working on scholarship, collecting and measuring amphibians along a pitfall trap line. Toads are pretty swell.

Lluvia and Drunken Toads

GGG

May Day -- back to work. Same place, everything slightly different. Green-Green-Green still absent. WOG I discovered on the roof of the office, Big Tree side.

Mid-morning I finally spotted GGG. He puttered around the lab plaza and then, weirdly, started a diagonal walk toward the office. He crossed the sidewalk, a threshold previously respected, proceeded across the parking lot! down the station entrance!! and crossed the road into the woods!!! Several iguanas that sleep in the Big Tree come down, cross the road, and then come back to Big Tree at the end of their day. Why GGG made the excursion is unknown, and he made it from a starting point much further away than Big Tree residents. He enlarged his known home range by at least 50%. (Known to me. GGG already knows his world.)

Pale Blue-Black-Red (PbKR)

This trip brings new hypotheses to test along with a bit of trapping. Today I captured 2 smaller animals including the newly dubbed PbKR.

I also collected some data regarding an individual iguana's boldness, and am thinking through testing an iguana's reaction to a novel object. I cannot contain my iguanas. They are free to ignore anything in their world and it is not always obvious what that behavior might mean. When climbing a tree or screened window, the iguanas seem cautious approaching their ascent. If I can figure out that certain trees and other station elements are attractive to iguanas, I would guess their predators also use such public information. A new object placed near a refuge might always be ignored because other important issues take precedence.

Black-headed Trogan

There is a lot to see at Palo Verde, and I have the advantage of being here long enough to view a great deal. This morning howler monkeys, including females with babies, crossed the canopy behind the dining hall. The black-headed trogans I observe near the library visited Big Tree and gave me some lovely photos.

In the afternoon rain finally arrived. It went on for hours, running off the roofs. WOG and others stayed out for ~15 minutes before taking refuge. In Colorado we would say deluge. In PV, just normal.

I thank my herpetology class and teacher for causing me to memorize Rhinophrynidae. This burrowing toad is the only member of its family and comes out after rains to engage in explosive breeding. The patio around the dining hall was (sorry) hopping with toads. Common name, sapo borracho, Drunken Toad.