Research

Teaching

Field Notes

Natural History

Schedule

The goal is to have 10 person-weeks of sampling at each site during the wet season, 2003. Project leaders in bold.

IMPORTANT NOTE TO PROJECT LEADERS:
Every site is different. We are standardizing our methods the best we can to get comparable data. But it is the responsibility of the project leaders on the scene to determine which protocols will be used and how they will be used, taking into account safety and feasibility.

Mike Kaspari

Trail Walking

The backbone of this study is simple and effective. Rettenmeyer (1983) estimates that about 20 species of army ants can be found in a given Neotropical rainforest. In 40 h (ca. 80 km) of nighttime trail walks on Barro Colorado Island, I located and collected data on 69 army ant colonies representing 10 species (Kaspari 1996).  When combined with checks of underground pitfall traps and plot watches, trail walking is a standardized method for comparing army ant activity at different sites, habitats, and microhabitats. Trail walking is biased toward the larger species whose columns are more conspicuous.

Protocol
1)  There will be a daily walk at each site along a loop of trail about 3 km in length (the BCI loop is ca. 3.5, and the La Selva loop is ca. 4.7 km).  The loop is fashioned to maximize heterogeneity of topography and, if possible, forest type. Once the loop have been established, it is necessary to establish the proportion of macrohabitats available to the ants. This will allow us to compare sites more readily by their topography, and will allow us to establish preferences of species for types of macrohabitats (by comparing % observations to % availability along the loop). A reference value should be taken every 20 m (=100 reference points).
2) The loop is walked slowly over 2-3 h. There are four trail-walking start times:  4:30, 8:30, 1330 and 1930 h. This will allow us to cover dawn/dusk crepuscular activity, as well as morning, and afternoon activity during daylight hours. Given that the mid-morning walk yields the highest opportunity for 1) rain-free completion and 2) daylight discovery of swarm raids, it is recommended to perform at least 2: 8:30 walks for every walk at the other start times.
3) Record weather at outset (see data template). If heavy rain begins during the walk record the time in the Notes.  If you are observing a raid column, monitor it until it stops.
4) When a raid is encountered, note the time, temperature and humidity (if possible). Note the forest type and topography (e.g., slope, ridge, valley, up to two descriptors along the axis of the trail and its perpendicular, i.e., slope/ridge) Note the type of column (emigration, raid column, swarm) and microhabitat (where is the column, on ground, liana, coming down from tree? see data template). Spend up to 10 minutes collecting prey samples (or until 20 prey samples have been collected). At the conclusion of the sample, collect the variety of castes/range of body sizes observed (except for queen if you are so lucky). It is particularly important to collect the largest member of the sterile case for taxonomy. If a column remains "prey-free" at ten minutes, move on.
5) Back at the lab, prepare two vials with 95% EtOH for each raid column sampled with a unique ID (MEKOU numbers for BCI, La Selva, Tiputini, Lattke numbers for Sta. Maria) and locality label. The first should contain vouchers of the ants themselves (make sure to include majors whenever possible), the second should include prey samples and associates. Its my experience that associates like staphylinid beetles and phorids often wind up in pooter samples unintentionally (I've yet to poot a spotted antbird).  Notes on the identity of brood sampled useful but not necessary.

Notes
I've dropped the velocity measures based on this correspondence with Scott Powell.
Soil moisture index from John Lattke--

saturated	If one makes a depression in the soil, then water oozes from the sides. Leaf litter should stick together as well.
humid	Soil feels humid to touch, but water will not ooze from soil if a depression is made. Leaf litter does not stick together, leaves can be wadded in hands without cracking (some larger veins may crack but not the leaf lamella)
dry	Dusty and no humidity to touch. Thin film of dust may stick to finger, trowel. Leaf litter does not stick, if wadded in hands will crack and crumble.

Equipment (see also "the well-stocked trail pack)                  Data Template

• Headlamp

• Thermometer (we have two portable hygrothermographs the size of cigars. I will try to find more of these to allow everybody to take humidity readings. An alternative is a sling psychrometer, but these are hard to place on the ground!)

• Surveyor flag marked at 1cm increments for litter depth

• GPS or GIS for elevation and lat/long

• 1-L size plastic bags for collection of workers

• Aspirators and forceps and ETOH vials to collect prey.

• Field notebook

1. 0.25m² quadrat frame

2. 10 cloth bags (2 liter capacity) to store litter

3. 40 surveyor flags to mark sample quadrats for swarm-raider study

4. Litter sifter (or it can be sifted in the lab)

5. Map of site

6. Aspirator for sucking up army ants and their booty

7. Plenty of vials for aspirator

8. Squeeze bottle of 95% EtOH to squirt into aspirator vials

9. Forceps

10. Headlamp

11. Spare flashlight and batteries

12. Water bottle

13. Gloves if you wish to avoid the occasional sting

14. Large garbage bags to carry

15. Field notebook and spare pencils

Plot Watches

Plot watches are a low-tech way to see under the litter. They are based on observations that many of the smallest army ants, particularly the Neivamyrmex, are rarely seen on top of the litter but can often be found running on the soil under the litter. By clearing 1 m² patches of litter, it is not unusual to find a Neivamyrmex column moving through the litter. The same principle is used in trail walks, but plot watches can catches a column moving in all 4 cardinal directions.

Protocol
1) Lay out a transect of up to 20 m² plots, 10 m apart. Running transects cross-country, especially at night, can be problematic.  Placing these plots 3 m or more off-trail is thus preferred. This will allow you to lay out plot watches along the routes of trail walks. Our goal is to have at least 90 plots observed per site.

2) The basic methodology is to remove  or rake the litter from each plot so that mineral soil is exposed.  These transects should be placed to sample the available heterogeneity. Litter removed from m² plots can be checked for ant nests, or just pushed aside. It is in the process of removal that army ants are often discovered.

3) Once cleared, "window" allows you to peer at the soil/litter interface. Each plot on the transect should be checked in 30-minute cycle for 3 hours. Note if the plot is baited as some species like Labidus coecus will erupt from the soil to use baits like pecan sandies.

4) Record the presence of any column and sample as you would a trail walk column.

5) Back at lab, fill in template and process samples as you would in trail walk.

Equipment                                                            Data Templates
(same as above)
 

Underground Baited Pitfalls

An undetermined but undoubtedly large amount of army ant activity occurs belowground. Berghoff et al (2002) use a system of oil traps buried in the ground to get at this. I have experimented with a similar setup pictured here. The simple system outlined below appears to work well. Of 10 UBTs that I put out in a valley, 2 were hit by LABIcoec, and a number were *swarming* with Solenopsis, including one subterranean species that I rarely see. The rest were either inactive after 6 and 18 h, or had a handful of common Pheidole and Solenopsis Diplos. The only problem is that when I repeated the experiment the next day, a Coati/Agouti discovered them and dug up each one. So we would see attrition. However, if we placed them in different habitats each time (and 20 traps take about 40 minutes to put out), this would be less of a problem. A further set of trials in June 2003 suggest that army ant hits are more likely in valleys than ridge tops (perhaps due to moisture?) but that is a clearly a working hypothesis.

Protocol
1) Set out traps 10 m apart alone, or whenever you run a plot watch (placing the trap 20 cm to one side). The goal is to sample as many habitats (and get as many reps of habitats) as possible.
2) Use bulb planter to core hole 11 cm deep. Place bait (2-3 ml of peanut butter--oil, sugar, and protein, doesn't disappear quickly) at bottom of hole. If impossible to find, grind peanuts and mix with a bit of oil and sugar to form a paste. Use 3oz SOLO plastic drink cups with ca. 1 cm hole bored out bottom with pocket knife. Place some bait in cup and place at bottom of hole. Invert a 7oz plastic drink cup and fit it snugly about halfway down into hole. This makes a nice soil chamber, with the lips of the cup sealing the bottom cup off from the surface. Cover it with leaves and mark it a 1 m away with a flag, or a bit of flagging tape.
3) Leave out for 6 h. Alternate between setting out ca. 0800 and harvesting 1400, and setting out 1400 and harvesting 2000.
4) Record activity (ants present, absent, and bait present or depleted) on each visit. You can inspect the bait through the clear plastic cup, and harvest the cup into a large whirlpac/plastic bag. If there is only activity at the bottom of the hole, use a spoon to transfer some soil into whirlpacs. I would suggest the minimal specimen processing should involve sampling only the army ants. Each investigator, of course, may use his own discretion as to whether to collect other ants. However, it is important to note if a bait is occupied by non-army ants, as this may reflect its inability to sample army ants, even if they are nearby.
5) Back at the lab transfer ants to vials and process with the template below as before.

Equipment                                                            Data Templates

• 2 sizes of plastic drinking cups

• peanut butter for bait (can be loaded into a large syringe or toothpaste tube and squirted in)

• Vials, bags, forceps and other collecting paraphernalia

• A bulb planter for excavating the hole

Swarm Raider Impact Studies

We propose to study the impact of Eciton burchelli and Labidus praedator species (and any other swarm raiders we find) on the litter arthropod community. Of particular interest is the degree to which the highly size-divergent species sweep through the litter like nets with different sizes of "mesh", capturing different prey.  We will combine hand searches through litter with winkler eclectors/berlese funnels that efficiently extract invertebrates <1mm in size.  The goal is to have 10 Eciton and 5 Labidus swarm impacts harvested.

Protocol
1) Since both species are likely to be found on litter walks, it will be necessary to have a backpack with a frame and 10 litter bags to use when the opportunity arises (see sidebar). Quantify the breadth of the swarm raid. Get an estimate of its velocity, as you will need to place and harvest 5 quadrats ahead of the front. It is my experience that morning walks are best for this discovering, and capitalizing on, swarm raids.
2) Ca. 5 m ahead of the swarm throw down the quadrat frame into an area of leaf litter. It should be at least 1 m away from the last frame. Measure litter depth 4 times (3 cm in from each corner) to mineral soil with a marked wire surveyor flag.
3) Quickly scoop up leaf litter and twigs into a cloth bag. Leave behind pieces of hard wood (wood which cannot be broken by hand). Repeat 4 times.
4) Repeat ca. 3 m behind the swarm. Here, the raid is represented by a series of intertwined columns. Insert the quadrat between the columns, and perform the sampling as before. This may be a good time to wear gloves. Repeat 4 times.
5) Sample prey according to Trail Walking protocol.
5) Back at the lab, have your sifter close at hand and a white tray for sorting litter. The winkler/ berlese cup/bag of 95% ethanol, with label and collection number already floating inside, should be at hand. Open the bag of litter and scoop it into the white tray. The function of the tray is twofold. First you can harvest and transfer large arthropods (those that will not pass through the berlese/winkler mesh) from the white tray directly into the cup. Also, you can crack any twigs and fragment any rotten wood before it goes into the sifter. Litter ant nests can be emptied directly into the cup of ethanol. After processing the litter, scoop it into the sifter (it usually takes me 10-15 minutes to process a bag of litter from a plot with 4 cm of litter). Vigorously sift the litter for 30 seconds, and transfer the residuum to the winkler/berlese.
6) Let the winkler/berlese work for 48 h. When finished, empty contents of cup into vial or whirlpac. Empty depleted litter into a glass cylinder and measure volume of this "residuum".  Litter depth, and residuum amount, are two ways of measuring the amount of litter harvested from the 0.25m² plot.
7) Use data template to curate samples. Add prey sampling from part 5 to Trail Walking data sheet, indicating if this was part of a regular trail walk or a special trip to harvest a known colony.

Equipment                                                            Data Template

• 0.25m² sampling frame

• 10 cloth litter bags for collecting litter

• backpack to carry this out, and litter samples back

• 10 winklers/berlese funnels

• white-bottomed sorting tray

• litter sifter

After the field work

At the conclusion of a site study, please send me copies of the following:

1. All four excel files plus the log of field notes;

2. A summary of time spent in each of the activities.

3. A financial accounting of National Geographic money used.

4. Appropriate supplementary material (copies of permits, maps, photos, drawings).

I will compile these data and share them among the group.

This study is specimen intensive, and it is thus important to make sure specimens are deposited in the host country, and a central repository. As at least Lattke and Kaspari have working ant collections of their own, this suggests that specimens need to be routed to at least 4 collections. Specifically,

Trail Walking/Plot Watches-will generate vials of clean army ant species in EtOH, and mixed collections of booty in EtOH. The Kaspari lab will take responsibility for putting names on BCI, La Selva, and Tiputini army ants and for their deposition at the Museum of Comparative Zoology. Lattke will curate and identify army ants from Sta. Maria, and will send a representative sample to Kaspari for deposition.  Booty samples will be shipped to Kaspari for enumeration. Please use labeled plastic bags (ziplocks or whirlpacs) to group the samples by week, labeled:
     Army Ant (Trail Walking or Plot Watches, as appropriate)
     Site Name
     Date(s) encompassed by samples
     Collection numbers encompassed by samples.

Underground Baited Traps-will generate collections of army ants. Please process as above. Please bag as above, labeled UBTs

Swarm Raider Impact Studies-will generate messy winkler/berlese samples as well as vouchers of the swarm raiding species. Please send the former to the Kaspari lab for enumeration, and treat the vouchers as above. Again, please bag separately the 10 samples from each impact sample, labeling as Impact

Also, please circulate to the group any good photos you would want to share for our respective seminars.

References

Kaspari, M. 1996. Litter ant patchiness at the m² scale: disturbance dynamics in three Neotropical forests. Oecologia (Berlin) 107: 265-273.

Kaspari, M., and S. O'Donnell. in review. Army ant raids and the case for a latitudinal gradient of predation. Evolutionary Ecology Research