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pogolumina  > Preview > Preview
Here are few of our favorite images (so far). You will find all of them, and many, many more - all with detailed descriptions, in the various galleries on this site... Click pictures to enlarge, and scroll down for description and link to original gallery. Words/phrases highlighted in red are clickable for more info. More images to come! After you finish viewing this mini preview, you may want to start in the 'North American Pogos by Behavior' section - we hope you enjoy your visit!
gallery pages:  1  
pogolumina > ● Duval Mine Rd, Sahuarita [Pima Co], AZ USA [el. 882 m / 2893 ft] view location in Google Maps » ● 11/06/10 10:01AM sunny, air temp: 24°C / 76°F [IMAGE 1 of 5] Whenever we approached either of the two P. bicolor nests at this location, one or two workers would immediately climb a grass stem and remain there, while appearing to watch us closely. Occasionally, the mandibles would be opened in a feeble defensive display. The rest of the workers (on the ground) went about their business, and ignored us completely. As mentioned earlier, the ants made no attempt to bite or sting, no matter how closely we approached. The very fine and silky-looking surface sculpture can also be seen in these images.
● Duval Mine Rd, Sahuarita [Pima Co], AZ USA [el. 882 m / 2893 ft] ...
pogolumina > ● Catalina State Park, Tucson [Pima Co], AZ USA [el. 800 m / 2625 ft] view location in Google Maps » ● 11/02/10 9:39AM sunny, air temp: 24°C / 76°F The sharp, and powerful mandibles of this Acromyrmex versicolor worker can be seen clearly in this image. These cutting and grasping tools allow the ants to efficiently remove large amounts of vegetation from a wide variety of plants. The freshly cut plant material is then brought back to the nest where it serves as a medium for the growth of a nutritious, symbiotic fungus.
● Catalina State Park, Tucson [Pima Co], AZ USA [el. 800 m / 2625 f ...
pogolumina > ● NW of Mattawa [Grant Co], WA USA [el. 152 m / 500 ft] view location in Google Maps » ● 5/9/10 12:15PM sunny, air temp: [not measured] Silhouetted against the bright background, this P. salinus worker searches a fiddleneck plant (Amsinckia sp.) for nectar, in central Washington state.
● NW of Mattawa [Grant Co], WA USA [el. 152 m / 500 ft] view locat ...
pogolumina > ● Fernley [Lyon Co], NV USA [el. 1271 m / 4171 ft] view location in Google Maps » ● 6/23/10 6:27AM partly cloudy, air temp: 17°C / 62°F [IMAGE 2 of 2] A beautiful Pogonomyrmex californicus worker pauses briefly after emerging from her nest (cropped view).
● Fernley [Lyon Co], NV USA [el. 1271 m / 4171 ft] view location in ...
pogolumina > ● Estero del Yugo, Mazatlán, Mexico [el. approx. sea level] view location in Google Maps » ● 01/24/12 12:14PM sunny, air temp: 24°C / 76°F A very small Atta mexicana worker explores the tip of a leaf that has already been cut multiple times by her nestmates. Typically, we saw minor workers of this size performing nest maintenance duties - bringing excavated soil up from the subterranean portions of the nest. These smaller workers also work inside the nest to 'process' incoming vegetation, as well as taking care of the developing brood. Sometimes, they will even ride along on top of a leaf that is being carried back to the colony by a nestmate. By doing so, they ward off attacking parasitic flies attempting to lay eggs on the burdened (and therefore mostly defenseless) workers. [scroll down for additional notes/references] ADDITIONAL NOTES/REFERENCES: Ants of the genus Atta (at least 15 species, all in the New World) can have enormous colonies, often with several million inhabitants. A variety of differently sized worker subcastes comprise "the most complex systems of division of labor known in ants" [Hölldobler & Wilson 2011]. Mid-sized (media) workers are the ones most often seen cutting pieces of leaves from plants and trees, and carrying them back to the nest in long lines. Inside, smaller workers (minors) chop up the plant matter into tiny fragments. Yet still smaller nestmates pulverize the material further, then add fecal droplets. Tiny strands of fungus are then added (by even smaller workers), and the pulverized plant material now acts as a growing medium for the fungus. Ultimately, the very smallest workers tend the fungus gardens, keeping them free of mold and other contaminants. All of the workers are non-reproductive females - winged (reproductive) females and males are produced, and take part in occasional mating flights. The males die soon after mating, and make no other contributions to the colony. The cultivated fungus serves as food for the ants, especially the larvae. Adult leaf cutters probably have much of their nutritional requirements met by consuming plant sap directly, as they cut fresh vegetation.
● Estero del Yugo, Mazatlán, Mexico [el. approx. sea level] view l ...
pogolumina > ● Old Spanish Trail Rd, near Colossal Cave Mountain Park [Pima Co], AZ USA [el. 1049 m / 3442 ft] view location in Google Maps » ● 11/04/2010 4:05PM sunny, air temp: 26°C / 79°F At this P. xerophila nest near Tucson, AZ, it was obvious that the minor workers were performing the bulk of the foraging duties. They were frequently accompanied by a small number of majors, however. These large workers were also occasionally seen traveling the foraging trails alone, like this one. They were not observed to be transporting any food items - their duty was apparently to defend the minors.
● Old Spanish Trail Rd, near Colossal Cave Mountain Park [Pima Co], ...
pogolumina > ● SW of Pyramid Lake [Washoe Co], NV USA [el. 1323 m / 4341 ft] view location in Google Maps » ● 6/24/10 8:20AM mostly sunny, air temp: 22°C / 72°F [IMAGE 5 of 5] About two dozen P.occidentalis workers started foraging along an approximately 4.5m / 15 ft long trunk trail [1], that extended from the nest in a northwesterly direction. Some of them began finding petals from saltbush plants (Atriplex sp.), and carrying them back to the nest from as far away as 3m / 10 feet. [scroll down for additional notes/references] ADDITIONAL NOTES/REFERENCES: Pogonomyrmex occidentalis, and P.salinus are generally regarded to be 'trunk-trail foragers'. In many cases, multiple, well established trails lead away from the nest in different directions. Workers travel along these paths to the end, and then disperse, or 'fan out' to search individually for seeds or other food items. After securing something (or in many cases failing to do so), the ants return individually to the nest by way of the trunk trail. In many Pogonomyrmex species, trunk-trails have been shown to be oriented so that foraging ants from neighboring colonies avoid mass confrontations during their searches for food. This allows there to be a greater density of nests in a given area, with minimal conflict. These trails are initially established (and reinforced) by pheromones laid down by the ants. In at least one species (P. barbatus), foraging workers are influenced in their choice of which of multiple trails to utilize on a given day, by 'patrollers' - workers who leave the nest first in the morning, and scout the area. They then lay a short chemical trail with secretions from the Dufour's gland, from the nest entrance to the start of a particular trunk-trail(s). Evidence suggests that the direction chosen by the patrollers is not so much based on food availability, but by their encounters with patrollers from neighboring colonies. The visibility and length of trunk-trails can vary greatly. The P.salinus trails we have observed so far (in Oregon and Washington states), while occasionally very visible (and free of vegetation), are more often indistinct, and not easily observable unless ants are traveling along them. As mentioned elsewhere on this site, we have observed trunk-trails of Pogonomyrmex salinus 9m / 29.5ft or more in length - though it is our experience that they are usually much shorter - and many nests (the majority in some locations) have no visible trails. We also observe these ants foraging individually near the nest, in Oregon and Washington states. ·Greene, M.J. & D.M. Gordon. 2007. How Patrollers Set Foraging Direction in Harvester Ants. The American Naturalist, Vol. 170, No. 6, December 2007 ·Hölldobler, B.1974. Home Range Orientation and Territoriality in Harvesting Ants. Proceedings of the National Academy of Sciences USA, Vol. 71, No. 8, pp. 3274-3277, August 1974 ·Hölldobler, B. & E.O. Wilson.1990. The Ants. Cambridge, MA, Belknap/Harvard Press ·Johnson, R.A. 2000. Seed Harvesting Ants (Hymenoptera: Formicidae) of North America: An Overview of Ecology and Biogeography. Sociobiology Vol.36, No. 1, 2000 ·Jorgensen C.D. & Porter, S.D. 1982. Foraging Behavior of Pogonomyrmex Owyheei in Southeast Idaho. Environmental Entomology, Vol. 11, No. 2, April 1982
● SW of Pyramid Lake [Washoe Co], NV USA [el. 1323 m / 4341 ft] vi ...
pogolumina > ● Catalina State Park, Tucson [Pima Co], AZ USA [el. 800 m / 2625 ft] view location in Google Maps » ● 11/02/10 9:41AM sunny, air temp: 24°C / 76°F Climbing over many obstacles on her way back to the nest, this A. versicolor worker carries a mesquite leaflet. Leafcutter ants (of many different species) often transport their cargo in this manner; grasped in the mandibles, with the object held backwards over the ant's body. Because of this, leafcutters are often referred to as 'parasol ants'.
● Catalina State Park, Tucson [Pima Co], AZ USA [el. 800 m / 2625 f ...
pogolumina > ● Wanapum Rec. Area [Kittitas Co], WA USA [el. 190 m / 623 ft] view location in Google Maps » ● 4/19/10 1:14PM sun, haze, air temp: 26°C / 79­­°F [IMAGE 4 of 4] Spring is a busy time for Pogonomyrmex salinus workers. While some colony members forage, or conduct maintenance on the nest below, others engage in the removal of plants that have sprung up on, or too close to the nest mound. Even with their powerful mandibles, these ants struggle to cut through tough plant stems, and leaves. This series of images was captured on our first outing of 2010, in Washington state. A dozen or so workers from a small nest were busy cutting down cheatgrass (Bromus tectorum) growing on, and around the edges of the nest mound [see additional images » ]. One worker was seen attempting to drag a bunch of fallen spikelets, possibly back to the nest - though it was unclear, as she was making no progress, and soon abandoned the effort. [scroll down for additional notes/references] ADDITIONAL NOTES/REFERENCES: The introduced (and invasive) grass Bromus tectorum (cheatgrass), is common in many of the areas inhabited by Pogonomyrmex ants, and is often a target of their foraging activities. One study in central Oregon found cheat grass (Bromus tectorum), to be one of the 5 most frequently collected seeds by P. salinus. The others were: Phacelia linearis, Hordeum jubatum, Descurainia pinnata, and Sisymbrium altissimum. Pogonomyrmex occidentalis (a member of the same complex as P. salinus) has long been known to have an association with Bromus tectorum, though there are indications that this ant prefers other species when they are available. In the Twin Falls, Idaho area, Cole found the seeds of B. tectorum to be harvested in great quantities "...primarily due to the predominance of Bromus tectorum in the semi-desert areas." He also notes that "the seed chambers of mounds in dense bromegrass areas often contain a greater quantity of other seeds and only a few colonies were located which seemed to harvest bromegrass seeds exclusively." This seems to be in keeping with the preliminary findings of a study of P. occidentalis in Colorado, by D. Wiernasz, where it was found that "Bromus tectorum was strongly avoided, and never exceeded 3% of seeds collected by foragers, even in high density areas." ·Cole, A.C. 1932a. The Relation of the Ant, Pogonomyrmex occidentalis CR., to its Habitat. Ohio Journal of Science, 32:133-46, Ohio State University ·Wiernasz, D. 2005. Granivore Activity on the Invasive Grass Bromus tectorum: a Factor in Establishment or Exclusion? University of Huston ·Willard, J.R. & H.H. Crowell. 1965. Biological Activities of the Harvester Ant, Pogonomyrmex owyheei, in Central Oregon. Journal of Economic Entomology Vol.58, No.3
● Wanapum Rec. Area [Kittitas Co], WA USA [el. 190 m / 623 ft] view ...
pogolumina > ● Wanapum Rec. Area [Kittitas Co] WA, USA [el. 190 m / 623 ft] view location in Google Maps » ● 5/10/09 12:23PM sunny, air temp: 23°C / 74°F A Pogonomyrmex salinus worker foraging on cheatgrass (Bromus tectorum) in central Washington state. [scroll down for additional notes/references] ADDITIONAL NOTES/REFERENCES: The introduced (and invasive) grass Bromus tectorum (cheatgrass), is common in many of the areas inhabited by Pogonomyrmex ants, and is often a target of their foraging activities. One study in central Oregon found cheat grass (Bromus tectorum), to be one of the 5 most frequently collected seeds by P. salinus. The others were: Phacelia linearis, Hordeum jubatum, Descurainia pinnata, and Sisymbrium altissimum. Pogonomyrmex occidentalis (a member of the same complex as P. salinus) has long been known to have an association with Bromus tectorum, though there are indications that this ant prefers other species when they are available. In the Twin Falls, Idaho area, Cole found the seeds of B. tectorum to be harvested in great quantities "...primarily due to the predominance of Bromus tectorum in the semi-desert areas." He also notes that "the seed chambers of mounds in dense bromegrass areas often contain a greater quantity of other seeds and only a few colonies were located which seemed to harvest bromegrass seeds exclusively." This seems to be in keeping with the preliminary findings of a study of P. occidentalis in Colorado, by D. Wiernasz, where it was found that "Bromus tectorum was strongly avoided, and never exceeded 3% of seeds collected by foragers, even in high density areas." ·Cole, A.C. 1932a. The Relation of the Ant, Pogonomyrmex occidentalis CR., to its Habitat. Ohio Journal of Science, 32:133-46, Ohio State University ·Wiernasz, D. 2005. Granivore Activity on the Invasive Grass Bromus tectorum: a Factor in Establishment or Exclusion? University of Huston ·Willard, J.R. & H.H. Crowell. 1965. Biological Activities of the Harvester Ant, Pogonomyrmex owyheei, in Central Oregon. Journal of Economic Entomology Vol.58, No.3
● Wanapum Rec. Area [Kittitas Co] WA, USA [el. 190 m / 623 ft] view ...
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All Images, Video and Text (unless otherwise noted) © 2010/11/12 David Louis Quinn