Interactions with Plants
From seed foraging to plant removal. Pogos
interacting with the plant life around them, in North America.
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![<span class="captionImageInfo"> ● Wanapum Rec. Area [Kittitas Co], WA USA [el. 190 m / 623 ft]</span> <a href="http://maps.google.com/maps/ms?ie=UTF8&hl=en&t=h&msa=0&msid=100103460138962878270.000470bd413e9e793ba1d&ll=46.905483,-119.9903&spn=0.164191,0.291824&z=11&source=embed"><span class="mapLink">view location in Google Maps »</span></a>
<span class="captionImageInfo"> ● 4/19/10 9:48AM sun, haze, air temp: 19°C / 67°F</span>
<div class="captionImageMain">A <a href="http://www.davidlouisquinn.com/pogolumina_PsalinusInfo.htm"><span class="glossLinkSm"><em>P. salinus</em></span></a> worker pauses for a few moments during a busy session of early spring <a href="http://www.davidlouisquinn.com/pogolumina_nestClearingInfo.htm"><span class="glossLinkSm">plant removal</span></a>.</div>](https://photos.smugmug.com/NorthAmericanPogosbyBehavior/Plants/i-HHWC43b/1/a6992024/L/2837_10_7Dc-L.jpg)
● Wanapum Rec. Area [Kittitas Co], WA USA [el. 190 m / 623 ft] view location in Google Maps » ● 4/19/10 9:48AM sun, haze, air temp: 19°C / 67°F
A P. salinus worker pauses for a few moments during a busy session of early spring plant removal.
![<span class="captionImageInfo"> ● Pyramid Lake Indian Res. (Paiute), NV USA [el. 1202 m / 3945 ft]</span> <a href="http://maps.google.com/maps/ms?hl=en&ie=UTF8&t=h&msa=0&msid=100103460138962878270.00048ab88a421ad2e2b90&ll=39.930801,-119.388428&spn=0.737146,1.167297&z=9&source=embed"><span class="mapLink">view location in Google Maps »</span></a><span class="captionImageInfo">
● 6/22/10 9:45AM sunny, air temp: 22°C / 72°F</span>
<div class="captionImageMain">[IMAGE 2 of 3] The ability of <a href="http://www.davidlouisquinn.com/pogolumina_PogonomyrmexInfo.htm"><span class="glossLinkSm"><em>Pogonomymrex</em></span></a> ants to carry excavated sand in their <a href="http://www.davidlouisquinn.com/pogolumina_psammophoreInfo.htm"><span class="glossLinkSm">psammophores</span></a> is well known and documented. But, despite a few vague references on the Web <span class="footnoteTag">[1]</span>, we have not yet found any descriptions of these ants using this structure to gather and/or transport seeds in the wild, under natural conditions <span class="footnoteTag">[2]</span> (nor have we observed this behavior ourselves, prior to 6/22/10).<br>
These <a href="http://www.davidlouisquinn.com/pogolumina_PcalifornicusInfo.htm"><span class="glossLinkSm"><em>Pogonomyrmex californicus</em></span></a> workers were picking up (and transporting) multiple <a href="http://www.davidlouisquinn.com/pogolumina_dsophia_seedInfo.htm"><span class="glossLinkSm">seeds of <em>Descurainia sophia </em></span></a> (a.k.a. flixweed). The nest of these ants was located in a sandy area, under a living <em>Salsola</em> (tumbleweed) plant - surrounded by many other plants including (and most abundantly) <em>Descurainia sophia</em>.<br>
The multiple-seed-gathering behavior was taking place approx. 60 cm / 2 feet away from the nest entrance - in an area strewn with the tiny orange <em>D. sophia</em> seeds. It was probably the high density of seeds (estimated to be 0.3 - 0.5 per cm²), along with their small size and proximity to the nest, that made this unusual type of foraging possible <span class="footnoteTag">[2]</span>. Workers returning from other areas, and from greater distances, carried only single items (as is usual for these ants). Individual workers were observed to successfully carry three of these seeds at a time, usually with one in the psammophore, and two 'stacked' in the <a href="http://www.davidlouisquinn.com/pogolumina_mandiblesInfo.htm"><span class="glossLinkSm">mandibles</span></a> (one worker was seen to have two seeds, side by side, in the psammophore). As can be seen in these images, the Pogos sometimes used the tips of their antennae to maneuver the seeds into position, before attempting to pick them up. Once fully loaded, they headed straight for the nest. There were many empty seedpods in the area where the seeds were being gathered, and it is possible that the ants had broken open the pods earlier and liberated the seeds - but it is just as likely that the seeds fell naturally. One worker was seen manipulating a seedpod, but it was already empty. <span class ="footnoteTag">[scroll down for additional notes/references]</span>
</div>
<div class="captionRefFootnote">ADDITIONAL NOTES/REFERENCES:
<em>
[1] Most notably, the Wikipedia article on Pogonomyrmex states "The psammophore are (sic) used for gathering small seeds, helping to increase the efficiency of transportation of fine sand and pebbles during nest construction, or to carry eggs."
[2] Pogonomyrmex ants have been known to transport multiple food items (using the psammophore and mandibles) when presented with bait piles consisting of cracked wheat, during controlled experiments. These bait piles offered the ants very small particles, at higher densities than would be found under natural conditions. During these experiments, <a href="http://www.davidlouisquinn.com/pogolumina_PoccidentalisInfo.htm"><span class="glossLinkSm"><em>P.occidentalis</em></span></a> workers did not start using their psammophores until seed densities exceeded 0.5 cm² As far as the use of psammophores by foragers under natural conditions, Porter & Jorgensen state, "Apparently, this behavior does not occur or it is very uncommon."
·Porter, S.D., and C.D. Jorgensen. 1990. Psammophores: Do Harvester Ants (Hymenoptera: Formicidae) Use These Pouches to Transport Seeds? Journal of the Kansas Entomological Society. 63(1) 138 -149
</div>](https://photos.smugmug.com/NorthAmericanPogosbyBehavior/Plants/i-Lbdvpbw/0/60e5fa6e/Ti/4365_10_7Dc-Ti.jpg)
![<span class="captionImageInfo"> ● Pyramid Lake Indian Res. (Paiute), NV USA [el. 1202 m / 3945 ft]</span> <a href="http://maps.google.com/maps/ms?hl=en&ie=UTF8&t=h&msa=0&msid=100103460138962878270.00048ab88a421ad2e2b90&ll=39.930801,-119.388428&spn=0.737146,1.167297&z=9&source=embed"><span class="mapLink">view location in Google Maps »</span></a><span class="captionImageInfo">
● 6/22/10 9:46AM sunny, air temp: 22°C / 72°F</span>
<div class="captionImageMain">[IMAGE 3 of 3] The ability of <a href="http://www.davidlouisquinn.com/pogolumina_PogonomyrmexInfo.htm"><span class="glossLinkSm"><em>Pogonomymrex</em></span></a> ants to carry excavated sand in their <a href="http://www.davidlouisquinn.com/pogolumina_psammophoreInfo.htm"><span class="glossLinkSm">psammophores</span></a> is well known and documented. But, despite a few vague references on the Web <span class="footnoteTag">[1]</span>, we have not yet found any descriptions of these ants using this structure to gather and/or transport seeds in the wild, under natural conditions <span class="footnoteTag">[2]</span> (nor have we observed this behavior ourselves, prior to 6/22/10).<br>
These <a href="http://www.davidlouisquinn.com/pogolumina_PcalifornicusInfo.htm"><span class="glossLinkSm"><em>Pogonomyrmex californicus</em></span></a> workers were picking up (and transporting) multiple <a href="http://www.davidlouisquinn.com/pogolumina_dsophia_seedInfo.htm"><span class="glossLinkSm">seeds of <em>Descurainia sophia </em></span></a> (a.k.a. flixweed). The nest of these ants was located in a sandy area, under a living <em>Salsola</em> (tumbleweed) plant - surrounded by many other plants including (and most abundantly) <em>Descurainia sophia</em>.<br>
The multiple-seed-gathering behavior was taking place approx. 60 cm / 2 feet away from the nest entrance - in an area strewn with the tiny orange <em>D. sophia</em> seeds. It was probably the high density of seeds (estimated to be 0.3 - 0.5 per cm²), along with their small size and proximity to the nest, that made this unusual type of foraging possible <span class="footnoteTag">[2]</span>. Workers returning from other areas, and from greater distances, carried only single items (as is usual for these ants). Individual workers were observed to successfully carry three of these seeds at a time, usually with one in the psammophore, and two 'stacked' in the <a href="http://www.davidlouisquinn.com/pogolumina_mandiblesInfo.htm"><span class="glossLinkSm">mandibles</span></a> (one worker was seen to have two seeds, side by side, in the psammophore). As can be seen in these images, the Pogos sometimes used the tips of their antennae to maneuver the seeds into position, before attempting to pick them up. Once fully loaded, they headed straight for the nest. There were many empty seedpods in the area where the seeds were being gathered, and it is possible that the ants had broken open the pods earlier and liberated the seeds - but it is just as likely that the seeds fell naturally. One worker was seen manipulating a seedpod, but it was already empty. <span class ="footnoteTag">[scroll down for additional notes/references]</span>
</div>
<div class="captionRefFootnote">ADDITIONAL NOTES/REFERENCES:
<em>
[1] Most notably, the Wikipedia article on Pogonomyrmex states "The psammophore are (sic) used for gathering small seeds, helping to increase the efficiency of transportation of fine sand and pebbles during nest construction, or to carry eggs."
[2] Pogonomyrmex ants have been known to transport multiple food items (using the psammophore and mandibles) when presented with bait piles consisting of cracked wheat, during controlled experiments. These bait piles offered the ants very small particles, at higher densities than would be found under natural conditions. During these experiments, <a href="http://www.davidlouisquinn.com/pogolumina_PoccidentalisInfo.htm"><span class="glossLinkSm"><em>P.occidentalis</em></span></a> workers did not start using their psammophores until seed densities exceeded 0.5 cm² As far as the use of psammophores by foragers under natural conditions, Porter & Jorgensen state, "Apparently, this behavior does not occur or it is very uncommon."
·Porter, S.D., and C.D. Jorgensen. 1990. Psammophores: Do Harvester Ants (Hymenoptera: Formicidae) Use These Pouches to Transport Seeds? Journal of the Kansas Entomological Society. 63(1) 138 -149
</div>](https://photos.smugmug.com/NorthAmericanPogosbyBehavior/Plants/i-gc6Vvfz/0/0ee003b4/Ti/4367_10_7Dc-Ti.jpg)
![<span class="captionImageInfo"> ● Wanapum Rec. Area [Kittitas Co], WA USA [el. 190 m / 623 ft]</span> <a href="http://maps.google.com/maps/ms?ie=UTF8&hl=en&t=h&msa=0&msid=100103460138962878270.000470bd413e9e793ba1d&ll=46.905483,-119.9903&spn=0.164191,0.291824&z=11&source=embed"><span class="mapLink">view location in Google Maps »</span></a>
<span class="captionImageInfo"> ● 5/10/09 12:43PM sunny, air temp: 23°C / 74°F</span>
<div class="captionImageMain">A <a href="http://www.davidlouisquinn.com/pogolumina_PsalinusInfo.htm"><span class="glossLinkSm"><em>Pogonomyrmex salinus</em></span></a> forager taking possession of a cheatgrass (<em>Bromus tectorum</em>) spikelet that had likely been cut from the plant by this ant, or by a nestmate - the object was then carried back to the nest as a potential <a href="http://www.davidlouisquinn.com/pogolumina_feedingInfo.htm"><span class="glossLinkSm">source of nutrition</span></a>.
<span class ="footnoteTag">[scroll down for additional notes/references - also see previous image]</span></div>
<div class="captionRefFootnote">ADDITIONAL NOTES/REFERENCES:
<em>
The introduced (and invasive) grass Bromus tectorum (cheatgrass), is common in many of the areas inhabited by <a href="http://www.davidlouisquinn.com/pogolumina_PogonomyrmexInfo.htm"><span class="glossLinkSm"><em>Pogonomyrmex</em></span></a> 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.
<a href="http://www.davidlouisquinn.com/pogolumina_PoccidentalisInfo.htm"><span class="glossLinkSm">Pogonomyrmex occidentalis</span></a> (a member of the same complex as P. salinus) has long been known to have an association with <em>Bromus tectorum</em>, 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
</em></div>](https://photos.smugmug.com/NorthAmericanPogosbyBehavior/Plants/i-DvnWVBM/7/f5c07b9b/Ti/2085_09_Rc-Ti.jpg)
![<span class="captionImageInfo"> ● NW of Mattawa [Grant Co], WA USA [el. 152 m / 500 ft]</span> <a href="http://maps.google.com/maps/ms?ie=UTF8&hl=en&t=h&msa=0&msid=100103460138962878270.000470f37e319b015bf28&ll=46.7596,-119.932433&spn=0.329276,0.583649&z=10&source=embed"><span class="mapLink"> view location in Google Maps »</span></a>
<span class="captionImageInfo"> ● 9/21/08 8:06AM overcast, air temp: 18°C / 65°F</span>
<div class="captionImageMain">The flip-side of <a href="http://www.davidlouisquinn.com/pogolumina_feedingInfo.htm"><span class="glossLinkSm">harvesting</span></a>, is the removal of inedible plant parts from the nest interior. Here, a <a href="http://www.davidlouisquinn.com/pogolumina_PsalinusInfo.htm"><span class="glossLinkSm"><em>P. salinus</em></span></a> worker carries an empty seedpod out to the refuse pile, or <a href="http://www.davidlouisquinn.com/pogolumina_chaffInfo.htm"><span class="glossLinkSm">midden</span></a>.</div>](https://photos.smugmug.com/NorthAmericanPogosbyBehavior/Plants/i-cGpwP4v/5/4f000507/Ti/1268_08_Rf-Ti.jpg)
![<span class="captionImageInfo"> ● Wanapum Rec. Area [Kittitas Co], WA USA [el. 190 m / 623 ft]</span> <a href="http://maps.google.com/maps/ms?ie=UTF8&hl=en&t=h&msa=0&msid=100103460138962878270.000470bd413e9e793ba1d&ll=46.905483,-119.9903&spn=0.164191,0.291824&z=11&source=embed"><span class="mapLink">view location in Google Maps »</span></a>
<span class="captionImageInfo"> ● 4/19/10 9:48AM sun, haze, air temp: 19°C / 67°F</span>
<div class="captionImageMain">A <a href="http://www.davidlouisquinn.com/pogolumina_PsalinusInfo.htm"><span class="glossLinkSm"><em>P. salinus</em></span></a> worker pauses for a few moments during a busy session of early spring <a href="http://www.davidlouisquinn.com/pogolumina_nestClearingInfo.htm"><span class="glossLinkSm">plant removal</span></a>.</div>](https://photos.smugmug.com/NorthAmericanPogosbyBehavior/Plants/i-HHWC43b/1/a6992024/Ti/2837_10_7Dc-Ti.jpg)
![<span class="captionImageInfo"> ● south of Madras [Jefferson Co], OR USA [el. 911 m / 2989 ft] </span> <a href="http://maps.google.com/maps/ms?ie=UTF8&hl=en&t=h&msa=0&msid=100103460138962878270.00047a549be715f0192d9&ll=44.483795,-121.040835&spn=0.685829,1.167297&z=9&source=embed"><span class="mapLink">view location in Google Maps »</span></a>
<span class="captionImageInfo"> ● 7/21/09 8:07AM sunny, air temp 21°C / 70°F</span>
<div class="captionImageMain">A dead plant stem is inspected by a foraging <a href="http://www.davidlouisquinn.com/pogolumina_PsalinusInfo.htm"><span class="glossLinkSm"><em>P.salinus</em></span></a> <a href="http://www.davidlouisquinn.com/pogolumina_workerInfo.htm"><span class="glossLinkSm">worker</span></a>, in central Oregon. The long hairs that make up the ant's <a href="http://www.davidlouisquinn.com/pogolumina_psammophoreInfo.htm"><span class="glossLinkSm">psammophore</span></a> can be seen in this image</div>
<div class="captionRefFootnote">ADDITIONAL NOTES/REFERENCES:
<em>We commonly see <a href="http://www.davidlouisquinn.com/pogolumina_PsalinusInfo.htm"><span class="glossLinkSm"><em>Pogonomyrmex salinus</em></span></a> workers 'testing' miscellaneous pieces of plant matter with their antennae, mandibles and mouth-parts. These objects are sometimes picked up and carried back to the nest as <a href="http://www.davidlouisquinn.com/pogolumina_feedingInfo.htm"><span class="glossLinkSm">potential food items</span></a>, but often they are briefly inspected and abandoned.</em></div>](https://photos.smugmug.com/NorthAmericanPogosbyBehavior/Plants/i-wxjpjwF/6/437b9e66/Ti/0743_09_40f-Ti.jpg)
![<span class="captionImageInfo"> ● Horse Ridge area, SE of Bend [Deschutes Co], OR USA [el. 1310 m / 4297 ft]</span> <a href="http://maps.google.com/maps/ms?ie=UTF8&hl=en&t=h&msa=0&msid=100103460138962878270.00047a3daca81cf459487&ll=43.912533,-121.007083&spn=0.086565,0.145912&z=12&source=embed"><span class="mapLink">view location in Google Maps »</span></a>
<span class="captionImageInfo"> ● 7/20/09 7:42AM sunny, air temp: 12°C / 54°F</span>
<div class="captionImageMain">At two separate locations in Oregon, we have observed <a href="http://www.davidlouisquinn.com/pogolumina_PsalinusInfo.htm"><span class="glossLinkSm"><em>Pogonomyrmex salinus</em></span></a> workers transporting (or <em>working on</em> in some way) Juniper (<em>Juniperus occidentalis</em>) 'berries' . This ant was in the process of cutting away the outer covering of one, and a seed can be seen inside (a variety of haphazard cutting techniques were employed). This <a href="http://www.davidlouisquinn.com/pogolumina_workerInfo.htm"><span class="glossLinkSm">worker</span></a> apparently lost interest, and walked away shortly after this image was captured. <span class ="footnoteTag">[scroll down for additional notes/references]</span></div>
<div class="captionRefFootnote"><span class ="footnoteTag">ADDITIONAL NOTES/REFERENCES:</span>
<em>Juniper 'berries' are really highly modified seed cones, with fused, fleshy scales. We saw these objects on the ground in every state of ripeness and decomposition (at this location and one another in central Oregon). The color ranged from almost black to bright orange - sometimes with a white powdery coating, as in this image. The differences in color and texture presumably are a function of how long the berries had been lying on the ground. The ants did not seem to have a preference, and were seen retrieving ones that were in some cases, highly decomposed. We observed 2 of these objects actually being taken into a nest.
This is the only Pogo we have seen actually cutting open a Juniper berry, the others were being transported whole.</em>
</div>](https://photos.smugmug.com/NorthAmericanPogosbyBehavior/Plants/i-pDbDZZP/9/7e607ca3/Ti/0570_09_40f-Ti.jpg)
![<span class="captionImageInfo"> ●Wanapum Rec. Area [Kittitas Co], WA USA [el. 190 m / 623 ft]</span> <a href="http://maps.google.com/maps/ms?ie=UTF8&hl=en&t=h&msa=0&msid=100103460138962878270.000470bd413e9e793ba1d&ll=46.905483,-119.9903&spn=0.164191,0.291824&z=11&source=embed"><span class="mapLink">view location in Google Maps »</span></a>
<span class="captionImageInfo"> ● 5/17/09 11:21AM sunny, air temp: 23°C / 74°F</span>
<div class="captionImageMain">As mentioned earlier, many <a href="http://www.davidlouisquinn.com/pogolumina_PogonomyrmexInfo.htm"><span class="glossLinkSm">Pogo</span></a> species are intolerant of plants growing on their nest mounds, or even within a certain distance of them. Here, several <em>Pogonomyrmex salinus</em> workers were attempting to <a href="http://www.davidlouisquinn.com/pogolumina_nestClearingInfo.htm"><span class="glossLinkSm">cut down</span></a> a tansy-mustard plant (<em>Descurainia sp.</em>) growing too close to their nest entrance (approx. .3m / 1ft away). The seedpods of these plants are frequently collected by <em>P. salinus</em>, so this operation could presumably result in the plant's removal, as well as a <a href="http://www.davidlouisquinn.com/pogolumina_feedingInfo.htm"><span class="glossLinkSm">source of food</span></a> for the ants. We did not, however, observe these ants collecting any of the removed seedpods, or other material. Willard & Crowell noted that <em>P. salinus</em> workers in central Oregon <em>did not</em> take <em>Descurainia</em> plant material into the nest during these removal operations, despite the fact that these ants actively forage for this same material as a food source, at other times. <span class ="footnoteTag">[scroll down for additional notes/references]</span></div>
<div class="captionRefFootnote">ADDITIONAL NOTES/REFERENCES:
<em>Descurainia (tansy-mustard) species thrive in dry (and often disturbed) soils, and are quite abundant in many areas where Pogos live. <a href="http://www.davidlouisquinn.com/pogolumina_chaffInfo.htm"><span class="glossLinkSm">Nest middens</span></a> are often full of empty Descurainia seed pods. We have observed and imaged P.salinus workers interacting with these plants in several locations in Washington state. These interactions encompass a range of behaviors, including the foraging of seeds/seed pods, removal of empty seed pods from nests, and the <a href="http://www.davidlouisquinn.com/pogolumina_nestClearingInfo.htm"><span class="glossLinkSm">removal of entire plants</span></a> from nest mounds and adjacent areas. Pogonomyrmex salinus has also been observed to collect the seeds/seed pods of various Descurainia species in Oregon and Idaho, and one study indicates that in central Oregon, Descurainia pinnata (western tansy-mustard) is one of the 5 most frequently collected seeds by P. salinus. The others were: Bromus tectorum, Phacelia linearis, Hordeum jubatum, and Sisymbrium altissimum.
·Jorgensen C.D. & Porter, S.D. 1982. Foraging Behavior of Pogonomyrmex owyheei in Southest Idaho. Environmental Entomology, Vol. 11, No. 2, April 1982
·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</em></div>](https://photos.smugmug.com/NorthAmericanPogosbyBehavior/Plants/i-bZ7J2bQ/7/a2d42e24/Ti/2386_09_Rf-Ti.jpg)
![<span class="captionImageInfo"> ● Wanapum Rec. Area [Kittitas Co], WA USA [el. 190 m / 623 ft]</span> <a href="http://maps.google.com/maps/ms?ie=UTF8&hl=en&t=h&msa=0&msid=100103460138962878270.000470bd413e9e793ba1d&ll=46.905483,-119.9903&spn=0.164191,0.291824&z=11&source=embed"><span class="mapLink">view location in Google Maps »</span></a>
<span class="captionImageInfo"> ● 5/17/09 10:35AM sunny, air temp: 20°C / 68°F</span>
<div class="captionImageMain">This was a particularly difficult image to capture, as the grass stem and ant were bobbing up and down wildly! A determined <a href="http://www.davidlouisquinn.com/pogolumina_PsalinusInfo.htm"><span class="glossLinkSm"><em>Pogonomyrmex salinus</em></span></a> worker using her <a href="http://www.davidlouisquinn.com/pogolumina_mandiblesInfo.htm"><span class="glossLinkSm">mandibles</span></a> to cut away a dried cheatgrass (<em>Bromus tectorum</em>) spikelet. Keeping her head perpendicular to the stem, she rotated from side to side, cutting a deep groove. 23 seconds later, the spikelet detached and fell, sending the ant catapulting backward - then falling to the ground. She ran off in the direction of the nest. Presumably the spikelet was eventually picked up by one of the many other <a href="http://www.davidlouisquinn.com/pogolumina_workerInfo.htm"><span class="glossLinkSm">workers</span></a> in the immediate vicinity. <span class ="footnoteTag">[scroll down for additional notes/references]</span></div>
<div class="captionRefFootnote">ADDITIONAL NOTES/REFERENCES:
<em>The introduced (and invasive) grass Bromus tectorum (cheatgrass), is common in many of the areas inhabited by <a href="http://www.davidlouisquinn.com/pogolumina_PogonomyrmexInfo.htm"><span class="glossLinkSm"><em>Pogonomyrmex</em></span></a> 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.
<a href="http://www.davidlouisquinn.com/pogolumina_PoccidentalisInfo.htm"><span class="glossLinkSm">Pogonomyrmex occidentalis</span></a> (a member of the same complex as P. salinus) has long been known to have an association with <em>Bromus tectorum</em>, 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</em>
</div>](https://photos.smugmug.com/NorthAmericanPogosbyBehavior/Plants/i-LXh8X97/6/5048cc35/Ti/2332_09_Rf-Ti.jpg)
![<span class="captionImageInfo"> ● Wanapum Rec. Area [Kittitas Co], WA USA [el. 190 m / 623 ft]</span> <a href="http://maps.google.com/maps/ms?ie=UTF8&hl=en&t=h&msa=0&msid=100103460138962878270.000470bd413e9e793ba1d&ll=46.905483,-119.9903&spn=0.164191,0.291824&z=11&source=embed"><span class="mapLink">view location in Google Maps »</span></a>
<span class="captionImageInfo"> ● 5/17/09 11:20AM sunny, air temp: 23°C / 74°F</span>
<div class="captionImageMain">Fiddle-neck (<em>Amsinckia sp</em>) is a plant that we have seen <a href="http://www.davidlouisquinn.com/pogolumina_PsalinusInfo.htm"><span class="glossLinkSm"><em>Pogonomyrmex salinus</em></span></a> interacting with at several locations.
This particular plant was located approx. .6m / 2ft from a <em>P. salinus</em> nest entrance. As can be seen in this image, the edges of some of the leaves had been 'chewed' (it is not clear if the Pogos, or some other insect had done this). There were about a dozen <em>P. salinus</em> workers on the plant, and they appeared to be gathering some sort of nectar or other plant exudate. We did not see any of the workers 'chewing', or cutting into the plant. We have also observed similar behavior on fiddle-neck plants in central Oregon, where no leaves had been damaged, and the plants stood at a considerable distances from the nests.
</div>](https://photos.smugmug.com/NorthAmericanPogosbyBehavior/Plants/i-bjkbbhM/7/679e7aa5/Ti/2380_09_Rf-Ti.jpg)
![<span class="captionImageInfo"> ● Wanapum Rec. Area [Kittitas Co] WA, USA [el. 190 m / 623 ft]</span> <a href="http://maps.google.com/maps/ms?ie=UTF8&hl=en&t=h&msa=0&msid=100103460138962878270.000470bd413e9e793ba1d&ll=46.905483,-119.9903&spn=0.164191,0.291824&z=11&source=embed"><span class="mapLink">view location in Google Maps »</span></a>
<span class="captionImageInfo"> ● 5/17/09 11:04AM sun, air temp: 22°C / 71°F</span>
<div class="captionImageMain">[IMAGE 1 of 2] With her powerful <a href="http://www.davidlouisquinn.com/pogolumina_mandiblesInfo.htm"><span class="glossLinkSm">mandibles</span></a>, a <a href="http://www.davidlouisquinn.com/pogolumina_PsalinusInfo.htm"><span class="glossLinkSm"><em>P.salinus</em></span></a> worker cuts through the tube-like leaf of 'Indian rice grass' (<em>Achnatherum hymenoides</em>), uncovering the not-yet-emerged inflorescence, with its many tiny flowers (florets), and seeds.
</div>](https://photos.smugmug.com/NorthAmericanPogosbyBehavior/Plants/i-p4QBhwF/5/276f5e72/Ti/2369_09_Rf-Ti.jpg)
![<span class="captionImageInfo"> ● Wanapum Rec. Area [Kittitas Co], WA USA [el. 190 m / 623 ft]</span> <a href="http://maps.google.com/maps/ms?ie=UTF8&hl=en&t=h&msa=0&msid=100103460138962878270.000470bd413e9e793ba1d&ll=46.905483,-119.9903&spn=0.164191,0.291824&z=11&source=embed"><span class="mapLink">view location in Google Maps »</span></a>
<span class="captionImageInfo"> ● 5/17/09 11:06AM sunny, air temp: 22°C / 71°F</span>
<div class="captionImageMain">[IMAGE 2 of 2] 'Indian rice grass' (<em>Achnatherum hymenoides</em>) and <a href="http://www.davidlouisquinn.com/pogolumina_PsalinusInfo.htm"><span class="glossLinkSm"><em>P. salinus</em></span></a> worker - 2 minutes and 13 seconds after the previous image. The ant has gained access to one of the florets (which contains the nutritious seed), and is continuing to free it from the stem. Less than 2 minutes later, she snipped the skinny pedicel (seen at the bottom of this image), and the whole floret dropped to the ground. This ant stayed on the plant, and continued working - leaving the retrieval of this <a href="http://www.davidlouisquinn.com/pogolumina_feedingInfo.htm"><span class="glossLinkSm">potential food item</span></a> to her nestmates on the ground. This large clump of grass was approx. .5 m / 2 ft from the nest entrance, but this appeared to be foraging activity only, and not an attempt by the ants <a href="http://www.davidlouisquinn.com/pogolumina_nestClearingInfo.htm"><span class="glossLinkSm">to remove the plant</span></a>.
</div>](https://photos.smugmug.com/NorthAmericanPogosbyBehavior/Plants/i-3wVXtSb/5/bd3bd41b/Ti/2375_09_Rf-Ti.jpg)
![<span class="captionImageInfo"> ● Wananpum Rec. Area [Kittitas Co], WA USA [el. 190 m / 623 ft]</span> <a href="http://maps.google.com/maps/ms?ie=UTF8&hl=en&t=h&msa=0&msid=100103460138962878270.000470bd413e9e793ba1d&ll=46.905483,-119.9903&spn=0.164191,0.291824&z=11&source=embed"><span class="mapLink">view location in Google Maps »</span></a>
<span class="captionImageInfo"> ● 5/17/09 11:00AM sunny, air temp: 22°C / 71°F</span>
<div class="captionImageMain">Some Pogo foraging behavior can be quite comical ... here, a large balsamroot seed (<em>Balmorhiza sp</em>) with bright yellow petal-like <em>ray</em> attached, is being dragged back to the nest by an eager <a href="http://www.davidlouisquinn.com/pogolumina_PsalinusInfo.htm"><span class="glossLinkSm"><em>Pogonomyrmex salinus</em></span></a> worker. As is the case for most of the <a href="http://www.davidlouisquinn.com/pogolumina_feedingInfo.htm"><span class="glossLinkSm">potential food items</span></a> retrieved by this species, this large seed had fallen to the ground on its own, where it was picked up by the foraging ant. It is really much more unusual for us to see the ants foraging on the plants themselves.</div>](https://photos.smugmug.com/NorthAmericanPogosbyBehavior/Plants/i-q5vj2F4/6/403c7706/Ti/2365_09_Rc-Ti.jpg)
![<span class="captionImageInfo"> ● Wananpum Rec. Area [Kittitas Co], WA USA [el. 190 m / 623 ft]</span> <a href="http://maps.google.com/maps/ms?ie=UTF8&hl=en&t=h&msa=0&msid=100103460138962878270.000470bd413e9e793ba1d&ll=46.905483,-119.9903&spn=0.164191,0.291824&z=11&source=embed"><span class="mapLink">view location in Google Maps »</span></a>
<span class="captionImageInfo"> ● 9/27/09 12:24PM sunny, air temp: 25°C / 77°F</span>
<div class="captionImageMain">This <a href="http://www.davidlouisquinn.com/pogolumina_PsalinusInfo.htm"><span class="glossLinkSm"><em>Pogonomyrmex salinus</em></span></a> nest is located on a slope, with a vertically oriented cave-like entrance. On this day, a steady flow of <a href="http://www.davidlouisquinn.com/pogolumina_workerInfo.htm"><span class="glossLinkSm">workers</span></a> streamed from the entrance, carrying assorted plant matter (including colorful flower fragments) to be discarded a short distance away. All of the ants were dust-covered, and moving so quickly, that it was very difficult to image them. The presence of flower petals in the nest may be explained, at least partially, by the fact that these ants collect balsamroot (<em>Balmorhiza sp</em>) seeds - often with a large yellow petal (ray) attached. Presumably, after the seed is consumed, the ray is discarded outside the nest, in the <a href="http://www.davidlouisquinn.com/pogolumina_chaffInfo.htm"><span class="glossLinkSm">midden</span></a>.
Also, <a href="http://www.davidlouisquinn.com/pogolumina_PogonomyrmexInfo.htm"><span class="glossLinkSm"><em>Pogonomyrmex</em></span></a> ants have been observed to bring small flowers to the nest and arrange them around the larvae and pupae (brood), possibly as a way of increasing humidity in the brood chamber - these flowers are later discarded outside of the nest <span class="footnoteTag">[1]</span>. <span class ="footnoteTag">[scroll down for additional notes/references]</span></div>
<div class="captionRefFootnote">ADDITIONAL NOTES/REFERENCES:
[1]
<em>This was reported in a study of Pogonomyrmex montanus, P. rugosus, and P. subnitidus. We do not know if P. salinus engages in this behavior.
·MacKay, W.P. 1981. A Comparison of Nest Phenologies of Three Species of Pogonomyrmex Harvester Ants (Hymenoptera: Formicidae). Psyche, Vol. 88, No. 1-2, 1981
</div>](https://photos.smugmug.com/NorthAmericanPogosbyBehavior/Plants/i-2LNCDxb/4/32c2d14d/Ti/1542_09_40c-Ti.jpg)
![<span class="captionImageInfo"> ● Wananpum Rec. Area [Kittitas Co], WA USA [el. 190 m/623 ft]</span> <a href="http://maps.google.com/maps/ms?ie=UTF8&hl=en&t=h&msa=0&msid=100103460138962878270.000470bd413e9e793ba1d&ll=46.905483,-119.9903&spn=0.164191,0.291824&z=11&source=embed"><span class="mapLink">view location in Google Maps »</span></a>
<span class="captionImageInfo"> ● 6/4/09 10:25AM sunny, air temp: 29°C / 85°F</span>
<div class="captionImageMain">Running frantically over the hot sand, a <a href="http://www.davidlouisquinn.com/pogolumina_PsalinusInfo.htm"><span class="glossLinkSm"><em>P.salinus</em></span></a> worker carries an Indian rice grass (<em>Achnatherum hymenoides</em>) seed back to her nest. The seeds of this plant apparently serve as a significant <a href="http://www.davidlouisquinn.com/pogolumina_feedingInfo.htm"><span class="glossLinkSm">source of nutrition</span></a> for the Pogos at this location.
At the time this image was captured, the soil surface temperature had already reached 50.5°C / 123°F, and only a few ants were still active - most had retreated to the relatively cool nest interior. <span class ="footnoteTag">[scroll down for additional notes/references]</span></div>
<div class="captionRefFootnote">ADDITIONAL NOTES/REFERENCES:
<em>We usually see all Pogonomyrmex salinus activity cease when the soil surface temperature reaches approx. 55°C / 131°F. It is not unusual for the ground temperature to reach these levels in July and August, as solar radiation heats the sand/soil/gravel - even though the air temperature may only be in the mid 80s°F. When the weather is very warm, it is typical for Pogos to be inactive, and to remain within the nest from late morning, until late afternoon. In a 1965 study, workers of this species, taken from their nest and placed on sand with a surface temp. of 58°C / 136°F, were observed to perish within 30 seconds.
·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</em>
</div>](https://photos.smugmug.com/NorthAmericanPogosbyBehavior/Plants/i-9QBRxT3/7/c75ac4a4/Ti/2578_09_Rf-Ti.jpg)
![<span class="captionImageInfo"> ● Wananpum Rec. Area [Kittitas Co], WA USA [el. 190 m / 623 ft]</span> <a href="http://maps.google.com/maps/ms?ie=UTF8&hl=en&t=h&msa=0&msid=100103460138962878270.000470bd413e9e793ba1d&ll=46.905483,-119.9903&spn=0.164191,0.291824&z=11&source=embed"><span class="mapLink">view location in Google Maps »</span></a>
<span class="captionImageInfo"> ● 7/9/09 8:34AM sunny, air temp: 18.8°C / 66°F</span>
<div class="captionImageMain">In this image, a <a href="http://www.davidlouisquinn.com/pogolumina_PsalinusInfo.htm"><span class="glossLinkSm"><em>P.salinus</em></span></a> worker can be seen carrying a sage leaf (<em>Artemesia tridentata</em>) back to her nest. <span class ="footnoteTag">[scroll down for additional notes/references]</span></div>
<div class="captionRefFootnote">ADDITIONAL NOTES/REFERENCES:
<em>Most of the <a href="http://www.davidlouisquinn.com/pogolumina_PogonomyrmexInfo.htm"><span class="glossLinkSm"><em>Pogonomyrmex</em></span></a> habitat in Oregon and Washington can be described as shrub-steppe land dominated by 'Big Sagebrush' (Artemisia tridentata) - but we don't often see P.salinus interacting with this ubiquitous plant. Only very occasionally, do we see a foraging worker transporting a leaf, or seed of A. tridentata (the leaves are usually three-lobed, but double and single-lobed leaves are not uncommon). In keeping with our observations, a study in central Oregon showed A. tridentata parts to be <a href="http://www.davidlouisquinn.com/pogolumina_feedingInfo.htm"><span class="glossLinkSm">collected</span></a> infrequently by foraging Pogonomyrmex salinus workers.</em>
</div>](https://photos.smugmug.com/NorthAmericanPogosbyBehavior/Plants/i-xhqkGNb/8/af7080df/Ti/9806_09_40f-Ti.jpg)
![<span class="captionImageInfo"> ● NW of Mattawa [Grant Co], WA USA [el. 152 m / 500 ft]</span> <a href="http://maps.google.com/maps/ms?ie=UTF8&hl=en&t=h&msa=0&msid=100103460138962878270.000470f37e319b015bf28&ll=46.7596,-119.932433&spn=0.329276,0.583649&z=10&source=embed"><span class="mapLink"> view location in Google Maps »</span></a>
<span class="captionImageInfo"> ● 9/14/09 8:28AM 50% cloud, 23°C / 73°F</span>
<div class="captionImageMain"> Only dried plant fragments remain on the ground, as these two <a href="http://www.davidlouisquinn.com/pogolumina_PsalinusInfo.htm"><span class="glossLinkSm"><em>P.salinus</em></span></a> workers forage near their nest in central Washington state. Although foraging activity is much higher in spring, and earlier in the summer, we do see these ants <a href="http://www.davidlouisquinn.com/pogolumina_feedingInfo.htm"><span class="glossLinkSm">collecting some seeds and other plant matter (and scavenging dead insects)</span></a> even at this time of year. It is more common in very late summer/autumn, however, to see plant material being brought <em>out</em> of the nest <span class ="footnoteTag">[see next image]</span>, and dumped in the <a href="http://www.davidlouisquinn.com/pogolumina_chaffInfo.htm"><span class="glossLinkSm">midden</span></a>. <span class ="footnoteTag">[scroll down for additional notes/references]</span></div>
<div class="captionRefFootnote">ADDITIONAL NOTES/REFERENCES:
<em>As mentioned elsewhere on this site, it appears that Pogonomyrmex salinus does not build a store of seeds for the winter. Nests excavated in winter (in central Oregon) revealed a lack of stored seeds. It was also observed that the ants huddle in groups within the subterranean chambers of the nest - where they remain dormant until temperatures start to increase. Apparently, at least in some cases, they do not consume food in any significant quantity, during the winter months.
·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</em>
</div>](https://photos.smugmug.com/NorthAmericanPogosbyBehavior/Plants/i-hrJgbvG/6/0f57ad51/Ti/3678_09_Rc-Ti.jpg)
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