IN THE FIELD Downloaded from https://academic.oup.com/ae/article/64/4/218/5232710 by guest on 24 September 2021 A Tale of Two Cliff Dwellings: Parallels Between Humans and Native Bees

MICHAEL C. ORR, FRANK D. PARKER, AND S. HOLLIS WOODARD

or most of you reading this arti- architectural feats than those going it for which nesting biology remains a mys- cle, your lifestyle defi nes your liv- alone. As if the title didn’t already make tery, singular reports cannot encompass Fing arrangements and vice-versa. it obvious enough, bees can be an excep- the true plasticity of any species. Bees, like Whatever your education or social status, tion to this rule made for exceptions. most , are complex, and how they you work in some form to provide safe Bees engage in a number of disparate live is determined in part by the resourc- shelter for yourself and those you care for. nesting strategies across almost the entire es in and challenges of their environ- From cellular phones to robotic vacuums social spectrum, though they don’t yet ments. For instance, Anthophora (Helio- that may one day become sentient and engage in homeowner’s associations, and phila) squammulosa Dours excavates the rule over us all with an iron dust brush, this makes them ideal for studying the deepest nests in the subgenus, perhaps the luckier of us have homes fi lled with dynamic trade-off s between an individ- to shield its off spring from the persistent everything we need and then some. ual’s investment and fi tness. Th e majority degassing of the rather unneighborly vol- Th e living arrangements of most ani- of the ≈20,000 total bee species are sol- cano on which it resides (Erenler et al. mals are rather more spartan. Grizzly itary, and the general structure of their 2016). A less extreme example is seen in bears must settle for hot springs, not hot nests can be summed up (in an over- Anthophora (Heliophila) curta Provanch- tubs, and they don’t make wrap-around simplifi ed way) as an entrance, tunnel, er, which has now been found nesting airplane pillows for giraffes (a prob- and nest cell(s). Branching out from that in desert pavement (Hicks 1934), hard- lem perhaps solved by sheer quantity?). basic design, though, things can get rath- packed silt, and loose, dry soil. Yet, in are often thought of as especial- er wild. Some of my favorites include the working with an undescribed species of ly austere, even further removed from largest bee species in the world (Megachile the same subgenus, I’ve had two more the realm of human luxury. Gary Larson pluto Smith), which nests in active termite females nest within fi ve feet of me as I comics aside, relatively few of us would mounds (Messer 1984), much like Antho- dug up the fi rst bee’s nest. Is this third liken our species to insects. There are phora (Heliophila) braunsiana Friese in species limited to sandy washes, or is exceptions, as one should expect among Africa (Rozen 1969). Of course, I’d also be that just the best nesting substrate for the millions of species out there remiss to not mention the beer-drinking this bee at that site? What are the limits (ants, termites, various wasps, and web- bees whose larvae are fed, at least in part, of any given bee’s nesting biology, and, spinners, to name a few). Common to on open-fermented yeasts (Roberts 1971). further, what mechanisms underlie their many examples is a high level of sociality, Although a diverse array of bee nest- choices? Anthophora squammulosa also which makes intuitive sense: individuals ing strategies is known, with Megandrena lives in areas without volcanoes, so why working together may achieve greater being the only North American bee genus would it ever nest in such seemingly

218 American Entomologist • Winter 2018 inhospitable places if it can use other specific system, and fewer than 10 bee that could get confusing, but most of them substrates? (I’m betting on microhabitat species are reported to excavate sand- are magnificent nonetheless, especially limits, as the group generally likes deserts stone nests worldwide (of the aforemen- those hidden at the end of any of the net- and it seems more tied to volcanoes in tioned ≈20,000 total). In contrast, many work of unpaved and often challenging the more tropical parts of its habitat, but species will reuse the tunnels that these roads that reticulate the Colorado Plateau. that’s a study for another time.) two bees excavate, and some appear to In such places, often sheltered beneath We cannot answer these or other ques- simply excavate their relatively small nest overhangs prevalent wherever water his- tions about bee nesting biology without cells directly off of pre-existent, larger nest torically did or presently does cut the more information about where and how tunnels. More never excavate, instead sim- terrain, they made their homes. Where bees live. Successful nesting is fundamen- ply nesting in the tunnels themselves. In the bees bore through sandstone, the tal to bee survival, and therefore bee con- total, roughly 20 insects are now known Ancestral Puebloans instead built up walls servation, but this work is not easy and to reuse tunnels within the A. pueblo sys- with sandstone blocks. Though humans few fully recognize its importance. At the tem alone. Given the putative benefits of and bees differ in their methods, both most basic level, the effort a bee must sandstone and the demonstrated ability humans and bees use a mortar of sorts Downloaded from https://academic.oup.com/ae/article/64/4/218/5232710 by guest on 24 September 2021 expend to successfully produce each of of other species to exploit pre-existent to improve the structural integrity of their its offspring will determine its fitness and, tunnels, more of these freeloaders likely homes; the bee uses secretions to close its ultimately, the persistence of its species await discovery. nest cells, and to line them to better main- at a given site. It makes intuitive, economic sense that tain relatively consistent environmental Although talk of busy bees may at first more species would exploit the efforts of conditions. The hard work of the Ances- evoke the rowed metropoles of honey sandstone excavators than would excavate tral Puebloans remains even today, those bees, or perhaps the resinous megastruc- nests themselves. Even if the benefits of ruins evincing the structural strength of tures of stingless bees, many solitary bees living there offset the costs, it makes sense sandstone. It is this durability, this bene- are also suitably busy for the old adage, to avoid the costs altogether when possi- fit to either group, that I’ve focused on so especially on a per-bee basis. For example, ble. Why work when you could choose not far and will return to, but there are other haynesi Viereck and Cockerell to (says the Ph.D. candidate pursuing an meaningful parallels. will excavate nest burrows in sand that academic career and the manic lifestyle Ever since learning that A. pueblo had are up to three meters deep (Parker and that entails)? Nonetheless, there remains nested within the sandstone blocks of a Griswold 1982). Anthophora (Anthopho- one sandstone-inhabiting , a true ruin at Mesa Verde National Park (at Site roides) pueblo Orr might initially seem ecosystem engineer, that is indisputably 3 in Orr et al. 2016), I’d been thinking lazy in comparison, because their nests better known by both researchers and the about the confluence of bee and human are scarcely found more than a handful general public: humans. More specifically, lifestyles. How often were bees and people of centimeters below the surface. I think I refer here to the Ancestral Puebloans (a found at the same site? What about at the that it gets a pass, though, given that what term preferred over “Anasazi,” a Navajo same time? As with many other questions, a bee nests in can also cause some hard- word for the group that roughly means these were sequestered away, waiting ship. Sandstone is a bit harder to deal “ancient enemy”). for an opportunity to be answered while with than sand, after all. There are a number of ways in which I worked on my dissertation. Needless Why would a bee, or anything else, one may draw parallels between human to say, I jumped at the chance to visit a really, ever choose to chew through sand- and bee uses of sandstone, but this dis- ruin site where Curtis Frazier (Utah State stone to make its home? (I encourage you cussion has largely focused on the bees University Eastern) had found sandstone to try this at home if you don’t already so far. Although you probably know more bee nests. agree that it’s generally a bad idea.) This about humans than bees, in general, some As with all others I take, the trip was question drove our recent paper, in which additional background information on this multipurpose. It started in Grand Stair- we described A. pueblo and explored specific topic might prove valuable. First case-Escalante National Monument in the selective forces which appear to act off, what little we know about the Ances- Southern Utah, where I found a few dozen upon it (Orr et al. 2016). We found that tral Puebloans is based upon archaeolog- new sandstone nest sites, gave two pre- the energy, time, and wear costs incurred ical work on the ruins they’ve left behind, sentations, and heard of several more in excavating sandstone may be offset because they’re believed to have aban- sites from attendees. Then the trip near- by the durability of this substrate, which doned this lifestyle when they emigrated ly ended when the key stopped working enabled bees to reuse nests while per- from their settlements somewhere around on my car’s door, though thankfully it sisting at aggregations for up to almost 1300 CE. These ruins are found, generally, was kept alive by a six-hour detour to a four decades (the minimum age of Site throughout the Four Corners region and dealership in Grand Junction, Colorado. 1 from Orr et al. 2016). Further, prelimi- its periphery, in Arizona, Colorado, New It took a bit longer than expected to make nary evidence suggested that nesting in Mexico, and Utah. Envision the environ- it to Blanding, Utah, but I arrived safely, sandstone reduces parasite buildup across ment that you’ve seen on a postcard from if not in the best frame of mind. years and may impede pathogens, both Grand Staircase-Escalante National Mon- I met Curtis the next day at a gas station of which can have devastating effects on ument, Mesa Verde National Park, or any on the edge of town. After a quick intro- bee populations. of the other many parks or monuments duction, both of us eager to visit the site, Even with these benefits, Anthophora nearby. Sagebrush, juniper, rabbitbrush, we convoyed eastward. Highway 95 took (Heliophila) peritomae Cockerell is the and so on…oh right, and sandstone. The us over fields of red, from which exten- only other confirmed excavator in this canyons aren’t all called Grand because sive patches of white sprouted wherever

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Fig. 1. The Cave Tower Ruins site. The visited ruins are located along the left sandstone face. erosion had made itself known. Atop this warm up quickly through exposure to the overhang. Patches of thick moss clung to somewhat irregular checkerboard sat dull morning sun. Humans use harder sand- the base here and there, pointing inward, green vegetation in all forms, juniper stone than the bees, given that they build deeper into the alcove, toward the pat- and sagebrush predominant. Silty tan- rather than bore. It was the discussion of tering seeps that fed a narrow, intermit- to-brown water lay within many of the these parallels and differences with Cur- tent creek into the bottom of the canyon canyons we passed; it was mostly inter- tis that day that prompted me to write below. We’d found the all-important water mittent, but that was all the bees need- this article. source, a prerequisite for both human ed. I was convinced they were out there After some more driving and a bit of and bee prosperity. The bees had to be before I even reached the site. walking, we were standing before an present. Even though these sandstone nesters impressive chasm that dropped sever- Enthusiastically, perhaps manical- are relatively uncommon, it’s precisely al hundred meters to the increasingly ly, I began searching the vertical sand- the constraints imposed by their unusual green canyon floor below (Fig. 1). Along stone faces as we ascended from the lifestyle that make it possible to predict the terraced descent, there were numer- seep toward a generous ledge. I almost their presence. Although sandstone isn’t ous sheltering overhangs, and these were immediately caught sight of the first sand- in short supply in the Colorado Plateau, reduced in places to little more than a foot stone nest site. They were on a terrace these bees strongly prefer to nest in ver- of navigable space before opening back up high above, clustered together where the tical banks or other areas sheltered from into more than 20 feet of livable space. On sandstone was lighter and, presumably, rain—the latter reminiscent of the places the largest ledge, we could make out what weaker. Though the nests were not obvi- preferred by the Ancestral Puebloans. appeared to be living quarters. It all spoke ously abandoned, the timing was wrong; However, life in the desert is a delicate of a difficult but seemingly secure way of it was much too late for the spring-flying balancing act. While the human need for life. So did the towers rising along the rim A. pueblo, and the fall-flying A. peritomae water is obvious, many desert bees get all of the canyon, for which the site was des- wouldn’t be out for a few weeks. We con- the water they need for sustenance from ignated “Cave Tower Ruins,” though we tinued along the ledge, hoping for more nectar and metabolic water generation. can’t be certain of their exact function. nests—but only for a minute, because However, A. pueblo carry water to their (Defensive outposts? Communication tens more lay in wait around a corner, nests to weaken the sandstone and enable with other towers, between communities? the characteristic opaque white lining of easier excavation. Although both species Spiritual activities?) Many such mysteries the older, exposed nest cells confirming avoid direct exposure, they still benefit remain, given that we can no more ask that they were made by Anthophora. As from water’s proximity. Of course, I’m not the original builders about their intentions expected, they preferred this area, where saying that bees and humans are the same than we can talk to the bees. the sandstone wall turned to face south. in all ways; there are differences in how All that in mind, we descended, rock by Satisfied after a brief break to look over they use and are limited by sandstone. well-trod rock, to the level below the living the valley below, we backtracked to a The bees almost exclusively nest in south- quarters. The ground became damp as it spot at which we could scramble up to or east-facing sandstone so that they can leveled off beneath a bleached sandstone the living-quarters terrace above.

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Fig. 2. Nests of Anthophora occidentalis, discovered within the mortar of a granary.

The area in which the living quarters My first guess was that the builder was are a bit harder to answer than “What bee were built was well protected from the ele- Anthophora (Melea) occidentalis Cres- made these nests?” ments by what appeared to be the largest son; some of the old, exposed nest cells Climbing over a few boulders and overhang at the site, and, unlike the other had the same white lining characteristic traversing yet another narrow ledge, we structures present, it was distanced from of the tribe Anthophorini. Narrowing my eventually encountered another granary, the wall. There were 12 rooms in total, options further, I could also make out the its side walls the only remnants of what it linked by shared walls, and many of the remains of turrets at the entrances, and had once been (Fig. 3). Curtis noted that rooms were only slightly larger than the this feature indicated the subgenus Melea, he hadn’t been here on his prior trip. Few granaries nearby. It was difficult to make of which A. occidentalis is the only species people likely had; it was hard to see from out the details of their design, as blocks large enough. This was now the second below, where we’d been earlier, and it was were strewn about and the remaining Anthophora known to nest in Ancestral shielded from above by an exceptional walls were scarcely taller than half a meter. Puebloan ruins, but did they nest sub- sandstone roof. Small blocks, potentially The mortar was also gone in many places, sequently, or were they contemporaries from disarrayed ruins, were also strewn which explained why it had fallen apart. with the Ancestral Puebloans? In either throughout, giving the area a jumbled Even in disrepair, it was impressive, as case, did the bees have any cultural sig- and unremarkable appearance at first some pieces were about as long as I am nificance? Unfortunately, these questions glance. It was only once we moved past tall, a testament to the hard work involved in the construction of the cliff dwellings. These living quarters were easily the larg- est structure we found at the site, but a nearby granary held my attention longer. Nearly complete, it ran from the ground to the overhang above, and the mortar was also largely intact, save for the dozens of nest entrances spread throughout it. We already had record of A. pueblo nesting in ruin walls, within a block, but this time, the mortar was chosen as the nest substrate (Fig. 2). It didn’t seem likely that the nest was made by the same bee, as A. pueblo isn’t known to nest in clay.

Fig. 3. The kiva area. The circular edge of the kiva is visible near the center of the image.

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Fig. 4. The well-preserved “ruin” nests. The level of wear precludes identification below the genus Anthophora. the granary that we saw the distinct, cir- get a better look at the adjacent granary, the rest of the day’s. This was especially cular outline of a kiva, a structure believed something low to the ground caught my strange, considering that other nearby to host communal gatherings. Scanning eye. Some things, actually: a series of holes patches of weak sandstone were unoccu- the surrounding area, I realized that the on the eroded edge of a fallen slab (Fig. 4). pied. Further, the angle was all wrong, as scenery was familiar, but that I’d originally These nests were definitely abandoned, many of the entrances were open to the seen it from a different angle. Looking up the end of each tunnel fully visible, but sky such that water could flow into them. from the kiva, scanning a band of weaker I’d found many of them vacated before. I’d never seen that before, and weathering sandstone, I again saw the first nest patch In itself, a patch of deserted nests was of the sandstone couldn’t explain either I’d noticed from a lower terrace. nothing special. Even sandstone nests phenomenon. Looking up again, I could Curtis decided to investigate the area can’t last forever. see that the spot this particular piece fell around the kiva, while I moved past it. The placement of the nests was a bit from would have been just about in line, Numerous boulders lay beyond the kiva, unusual, however, so I examined them in terms of height, with that same first behind which a mostly intact granary sat. further. A neighboring boulder blocked patch of nests I’d noticed at the site; nests As I maneuvered around the boulders to the nests from the morning sun, if not were typically limited to specific bands

222 American Entomologist • Winter 2018 of more eroded sandstone. I was accompanying the first author certain now that the nests were there. The first author person- made before this boulder fell, but ally thanks Jerome G. Rozen, Jr., when had that happened? for encouraging in him a deep One does not normally expect appreciation of the importance an easy answer to this kind of of nesting biology. We also thank question, but I was about to get the Bureau of Land Management lucky. To my surprise, rounding and associates, especially Kevin the boulder to examine the gra- Miller and LeAnn Skrzynski, for nary, I found that the granary had their assistance during fieldwork in actually been built atop it (Fig. 5). Grand Staircase-Escalante National As Curtis approached the grana- Monument. ry, I remarked that there were old nests on the boulder below References Cited Downloaded from https://academic.oup.com/ae/article/64/4/218/5232710 by guest on 24 September 2021 it. Curtis’ train of thought appar- Erenler, H.E., M.C. Orr, M.P. Gill- ently paralleled my own, as he also man, B.R. Parkes, H. Rymer, and surmised that the nests, inhabit- J.M. Maes. 2016. Persistent nest- ing by Anthophora Latreille, 1803 ed or not, must have been there (: ) bees in since the granary was construct- ash adjacent to an active volcano. ed. The archaeology site number Pan-Pacific Entomologist 92: 67–78. was luckily located right beside Glowacki, D.M. 2006. The social land- that same granary, and the site scape of depopulation: the north- was apparently occupied around ern San Juan, AD 1150–1300. Ph.D. 1060–1300 CE, meaning that these Fig. 5. Granary constructed atop the boulder in which the dissertation, Arizona State Univer- “bee ruins” had persisted for at “ruin” nests were constructed. The edge of the boulder is sity, Tempe, AZ. visible in the bottom right. Hicks, C.H. 1934. Some reared insect least 700 years, probably longer parasites and their hosts. Universi- (Glowacki 2006). Sandstone nests ty of Colorado Studies. 21: 265–271. may not last forever, but that’s still a pret- longer, but their nests were shorter-lived? Messer, A.C. 1984. Chalicodoma pluto: the ty long time. Or were they simply more dispersed at world’s largest bee rediscovered living It seemed likely that this boulder’s nests Cave Towers due to limits on available communally in termite nests (Hymenop- were abandoned, at the latest, when it substrate? Many questions remain. tera: Megachilidae). Journal of the Kansas fell, but what if it had never fallen? Would My visit to those and other ruins even- Entomological Society 57: 165–168. the bees still be using these nests? Could tually elevated one question above all oth- Orr, M.C., T. Griswold, J.P. Pitts, and F.D. Parker. 2016. A new bee species that ex- other, more fortunate nest sites have ers: if the Ancestral Puebloans were forced cavates sandstone nests. Current Biology persisted for such long periods? I was to abandon their sandstone homes, could 26: R792–R793. reminded of Frank Parker’s first site, one the same thing happen to these bees? Parker, F.D., and T.L. Griswold. 1982. Bio- I revisited that he’d initially discovered Although there’s uncertainty about what logical notes on Andrena (Callandrena) in 1980, where the oldest nest remnants caused the Ancestral Puebloans to disap- haynesi Viereck and Cockerell (Hyme- were reduced to no more than dimples. pear from the Colorado Plateau, the bees noptera: ). The Pan-Pacific We had only confirmed 36 years of activity also face an uncertain future. The com- Entomologist 58: 284–287. there, but how long had the bees actual- bined effects of aridification through cli- Roberts, R.B. 1971. Biology of the crepuscular bee Ptiloglossa guinnae n. sp. with notes on ly been active there? Were those dimples mate change and increasing human water associated bees, mites, and yeasts. Jour- also ruins? consumption due to population growth nal of the Kansas Entomological Society Every site is different, and this makes are predicted to severely reduce water 44: 283–294. comparisons difficult. This new site was availability in many desert systems. Prior Rozen, J.G., Jr. 1969. The biology and descrip- much better protected from the ele- work suggests that A. peritomae is better tion of a new species of African Thyreus, ments, whereas the nests at Frank’s first able to use alternative substrates (Torchio with life history notes on two species of site should erode faster due to a greater 1971), but A. pueblo appears tightly linked Anthophora (Hymenoptera: Anthopho- degree of exposure. At the same time, the to sandstone (Orr et al. 2016). What will ridae). Journal of the New York Entomo- logical Society 77: 51–60. single, nested-in sandstone monument at become of this species? In the case of Torchio, P.F. 1971. The biology of Anthopho- Frank’s first site had hundreds of nests, our own species, it’s believed that the ra (Micranthophora) peritomae Cockerell far more than at any individual patch at Ancestral Puebloans successfully migrated (Hymenoptera: Apoidea, Anthophoridae). Cave Tower Ruins, perhaps even more southward, at least in part, to become part Contributions in Science, Museum of Nat- than were there at Cave Towers in total. of modern Puebloan groups. Adaptation ural History Los Angeles. 206: 1–14. This may be because sheltering reduces is a hallmark of humanity; however, will Michael Orr is now a postdoc fellow at the Insti- erosion and, correspondingly, suitably these bees be so lucky? tute of Zoology in Beijing, where he continues weak nesting areas. Did this mean that to study solitary bee biology and evolution. He the Cave Towers nests lasted longer, but Acknowledgments may be contacted at michael.christopher.orr@ populations were more limited; while We thank Curtis Frazier for discover- gmail.com. at Frank’s site the bees had been active ing the Cave Tower Ruins nest site and DOI: 10.1093/ae/tmy045

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