Saturday, June 28, 2014

Nature Poetry

Rudolf Baumbach (1840-1905)
Die Gäste der Buche

Mietegäste vier im Haus
hat die alte Buche:
Tief im Keller wohnt die Maus,
nagt am Hungertuche.
Stolz auf seinen roten Rock
und gesparten Samen,
sitzt ein Protz im ersten Stock;
Eichhorn ist sein Namen.
Weiter oben hat der Specht
seine Werkstatt liegen,
hackt und hämmert kunstgerecht,
dass die Späne fliegen.
Auf dem Wipfel im Geäst
pfeift ein winzig kleiner
Musikante froh im Nest.
Miete zahlt nicht einer.

I remember learning this poem by heart and drawing the illustrations for my grandfather's seventieth birthday. I was 8 then and growing up in Germany. Today, I could still remember most of the verses, surprisingly, and google came to my help for the rest. The poem is about an old Beech Tree and the animals making it their home. Mouse and squirrel, woodpecker and warbler ...  Beech forest is the climax plant society of the Westfalian  low land where we lived and where I spent most of my free time exploring the forest. The poem reflects a romantic love for nature but also some ecological understanding. But translated into English it just sounds corny, so I won't even try. 
But, now living in Tucson, Arizona, I feel very much reminded of that childhood poem when I watch the coming and going of birds, squirrels, insects and reptiles in and around our big 'house saguaro' that so many animals rely on for food and nest sites. 

Friday, June 27, 2014

Late June at the Backyard Black Light

Around mid-June there was a drop in barometric pressure, clouds piled up over the mountains and some parts of town celebrated the first showers and even hail. All we got was a partial rainbow  that did not quite fit into the same frame as the spectacular raising full moon.

Male Palo Verde Root Borer, Derobrachus hovorei
But some insects got the message. Some male Palo Verde Root-borers appear now every night at the black light. They are over 2 inches long, but much smaller than the females that will probably show up soon. Other summer longhorn beetles are still around and some of the spring species are reappearing.
Typical Midsummer Longhorns are the tiny flighty Methia sp. with very short elytra.

Eustromula validum
Achryson surinamum
Megacyllene atennata
Methia sp.
There really has not been a mass emergence of any scarab species this year. Remember, I am in a very dry part of the lower desert and things may look different in the mountains or in Cochise County. The few species that I described in May still turn up sporadically.

Phyllophaga scoparia
Cyclocephala longula
Diplotaxis sp.
 The only typical June Bug that scrambles over the gravel of our driveway in numbers is Phyllophaga scoparia. At least two Diplotaxis sp. are present and as usual very hard to identify.

Epicauta sp.
Here is a Blister Beetle: A single individual of Epicauta sp. appeared on June 16. This could be Epicauta subgenus Macrobasis hirsutipubescens.

Anthicidae (Antlike Flower Beetles) are well represented this time of year, from the tiny very antlike Vacusus confinis that gets through every insect screen, to the genus Notoxus, recognizable by their cowls to Duboisius arizonensis which are unusually big for this family.

Hyporhagus sp.
When photographing at the black light, I pay attention to a lot of very small insects that might not thrill the collector. A decent macro-lens give insight into groups that may challenge the resolution capacity of many peoples eyes. Most of the beetles I am showing here are in the range between 2 and 7 mm and they are members of many different families. 

Diabrotica undecimpunctata (Spotted Cucumber Beetle) and Pachybrachis sp., Ptinus sp., Typhaea stercorea, Cymatodera aegra, Bembidion sp.

Pachybrachis sp., Hybosorus illigeri
There are also many True Bugs like Cicadellidae, Miridae and Coreidae, dozens of different species of Mutillids (wasps), alate ants and a few earwigs. 

Gyponana procera
Neivamyrmex sp. (Legionary Ants)
Vostox apicedentatus (Toothed Earwig)

Wednesday, June 25, 2014

Saguaro Fruit: Mid Summer Sustenance

In my early June blog, I still had to use Doris Evan's saguaro fruit image from the east side of the Tucson Mountains because here in Picture Rocks the saguaro fruits were still green and closed.

Since then the fruits on our 'House Saguaro' first blushed on the outside, then split open and revealed their signal red inside: ripe! Birds, come and get sweet pulp and seeds! For weeks this bounty (and 2014 seems to be a particularly good year)  has been a steady source of nutrition for the resident animals and entertainment for us.

Tiny Verdins and families of House Finches regularly gorged themselves,  Cactus Wren and Curved Bill Thrasher parents were feeding their fledgeling young. Gila Woodpeckers and Gilded Flickers were too shy for good photographs this year, but noisily announced their presence while peaking around from the back. 

A Mourning Dove and a White Winged dove actually moved into the big cactus, their nests not even two feet apart but separated by one of the massive arms. By now the first set of chicks has flown out and the White Wings have started another batch of eggs. 

Even a pair of ravens brought 4 youngsters around, causing the other birds to break into loud, angry mobbing. The fruits are surprisingly sturdy, safely supporting those huge birds. The tall columnar cacti firmly hold onto their fruit, even after they are ripe and split open. Why?
The saguaro relies on zoochory (seed dispersal by animals) and especially on the dispersal by birds.
Birds have great color vision and can easily reach the top of the saguaro. The spontaneous splitting of the tough skin allows them access. They devoure the sweet pulp with the seeds, fly good distances, and then excrete the unharmed seeds.

Photo by Rich Hoyer
Rodents and ants would also carry some seeds around, sometimes bury them and forget their cache, so that later clusters of seedlings might emerge. But their action radius is limited compared to that of birds and they also tend to chew the seeds and destroy them. So for the columnar cactus it 'makes sense' to keep the fruits out of reach of the ground dwellers and instead allow easy access to gently digesting long distance travelers who lack gnawing tools by presenting the open fruits on top of the inaccessible column (compare to the different 'strategy' of the barrel cactus)   (Quotation marks indicate my flippant teleological descriptions of intricate evolutionary adaptations.)
After the birds had their turn, the fruits are finally falling and landing on  the ground with an audible plop. The star-shaped hulls usually still contain enough seeds and pulp to attract some  hungry quail that don't like the height of the saguaro top and many ants, flies, flightless beetles and rodents.

So the food chain of the desert floor is set into motion. Soon photo-shy Tiger Whiptails arrive to hunt for insects.

Our resident rattler seems to patrol at least once a day. Who knows what goes on at night when the packrat collects the hard dry hulls to decorate her nest? Coyotes and bobcats are hanging around more than usually. The opportunistic coyotes will of course take the dinner as well as the diners. Jan Emming showed in a facebook post that canines can be pretty efficient seed dispersers.

The packrat takes empty hulls and dry flower stalk to its midden
At dusk I surprised a Cottontail and a Mourning Dove snacking on the sweet stuff
One can hardly overestimate the importance of the saguaro fruit harvest for the desert dwellers who have by now endured over 3 months without measurable rainfall. In addition, many young animals were born in spring and became independent of their parents at this time, just when the heat becomes merciless and the monsoon rain is still only a cloudy promise at the horizon. Saguaros have horded the winter rains in their immense succulent bodies and thus have the ability to offer (for dispersal services) nutrition and some fluid during the season when it is needed most.

Stella Tucker harvesting Saguaro fruit.  Watercolor
The Tohono O'odam are the desert people most intimately acquainted with the saguaro. To them the ripening fruits on the saguaros signaled the beginning of celebrations and prayers for a good rainy season. They use the long ribs of dead saguaros, with a small cross piece attached to one end, to push the fruit down when they are ripe, but not yet open. Then they split them with the built-in knife which is the hard, dried flower that is still attached to the fruit. Saguaro pulp was one of the few sweet treats available to the desert people. Some of it was made into preserves, but most of it was collected in ollas with water and allowed to ferment to make the ritual saguaro wine, an integral part of rain dance ceremonies that are held to ensure another life-bringing monsoon.
Years ago Stella Tucker, a Tohono O'odam story teller and historian, showed me how the long collecting pole is used and I found out how hard it is to dislodge the fruits before their time.  In my painting Stella is holding the saguaro rib, and the back of her shirt is patterned with petroglyphs depicting the harvest.

Sunday, June 22, 2014

A Solstice Party in Tucson

 Several of our naturalist friends  forwarded Mark Dimmit's (former botanical curator of the Arizona Desert Museum) generous invitation to us:

'You should come  if you can, these are always fun!'

'Don't know if you got this announcement, but if you didn't, this is THE PLACE TO BE.  Mark always has a good gang, with good food, and best of company.  A definite must.'

Mark's place is in the foothills of the Tucson Mountains, but on the east side while we live on the west side. We celebrated under huge Mesquite trees that were a big part of the local charm. 35 years old! The garden must have looked very different when the parties started 35 years ago.

in the middle with hat: our host (Photo Jan Emming)
 There was a potluck, and the food was exceptional. So many mysterious, delicious, healthy dishes! and one could just taste that a lot of the ingredients were backyard grown. There were also big bins full of beautiful tomatoes to take home after the party. Too bad that I completely missed walking down to the vegetable garden. I spent time in a 'Wasp Garden' instead. It was too late in the day to actually see wasps, but the variety of milkweeds from colorful annuals to sturdy shrubs already covered in prickly (!) pods was amazing.

Green houses full of cacti and other succulents, epiphytic and ground orchids and bromeliaceae captivated everybody. One nice feature: instead of being moist and oppressively warm, these green houses are really shade-tents and have huge swamp coolers that take up whole walls, so the temperature was very pleasant for humans and plants.

Anna Lillia Reina and Randy admiring adenium plants

Mark is world famous for breeding Adeniums. Some years ago many of his most mature trees where shipped all the way to Singapore to be the permanent center piece of a big new plant museum there.
We just got a little foster-adenium from our friends from San Diego so it was nice to see them in their full glory.

The invitation said: This is a celebration for plant freaks and like-minded souls who love the desert because of the summers, not in spite of them.  If that describes you, then you're as welcome as desert rain! 

Photo by Jan Emming
So the best part were the people. Of all generations, ethnicities and nationalities and united by their interest in plants and nature in general. Scientists and hobbyists, botanists, entomologists, a bigfoot specialist, museum docents, gardeners, film makers and artists. People that I had met before and new friends. Conversations would easily spring up and sometimes just continue a thread begun a couple of years ago ... A great evening. Thank you so much Mark!

Good night! This is the sunset of the 20th of June (when I wasn't busy partying) 7:48 pm.  For my friends from more northern latitudes this may seem like a very short solstice day, but then our winter days aren't as short and dark as yours .....

Monday, June 16, 2014

Royal gifts among butterflies

 Butterfly Mist, Ageratum (Eupatorium) corymbosum, is blooming again in Tucson's gardens. Butterflies in the genus Danaus are visiting in great numbers. Most of them are Queen Butterflies (Danaus gilippus), but the occasional Monarch (Danaus plexippus) also shows up. Are they after nectar? But why just these two species but only a few individuals  of other groups that like it sweet?

Female and male Queen Butterfly. Note the scent-scale patches on the hind wings of the male (close to the abdomen)
 Looking more closely you'll find that the Queens and Monarchs are nearly exclusively males, recognizable by a black spot (scent-scale patches) on the hind wing that's missing in females.
 Aggregations of Danaus males can be found on several flowering plants - as far as I know all of them composite flowers that are related to Butterfly Mist.

In their nectar, the plants provide a pyrrolizidine alkaloid that male danaines (Monarch, Queen and relatives in the subfamily Danainae) need to produce danaidone. Danaidone is the substance that the coremata (Pheromone glands) of the male release to attract females. It works: in experiments males with access to Ageratum had much more mating success than those without, but artificial addition of danaidone to their coremata immediately made those poor guys as acceptable as the Ageratum feeders.

But we are not just talking about a pretty perfume here. The fragrance advertises a very real gift that the male has to give.  During mating, the alkaloid is transferred from the male to the female, and she then transmits the gift to the eggs. (should I add that in the typical gender stereotypical way he shares just 60% of his ingested alkaloid but she passes on 90 % of her share? 

Young Monarch caterpillar feeding on Desert Milkweed
In eggs and very young caterpillars the inherited alkaloid functions as a defensive deterrent against predation. This protection may last until the caterpillars have ingested enough milkweed toxins (cardiac glycosides) from their host plant. They sequester the glycosides in parts of their body (exoskeleton) and even carry them over into adulthood, providing lasting protection from predators. 

Stagmomantis often capture Queen Butterflies. They seem unaffected by the stored toxins
 I speculate that the alkaloids are better protection against ants, predatory bugs and other insects that feed on small prey while the cardiac glucosids are targeting birds and mammals that may seek larger prey? I have repeatedly seen adult Queens in the clutches of Mantids but experienced birds reportedly leave them alone. 

Thursday, June 12, 2014

Fire Ants in Arizona: No Reason to Panic

Solenopsis xyloni (Southern Fire Ant)
Two days ago we woke up to Fire Ants marching across the kitchen counter (after hummingbird food had been prepared there the evening before). A thorough scrubbing of all surfaces will convince them to stay outside, I hope. No new arrivals for a couple of days at least.

Polymorph workers: many different sizes
 On the brighter side, these are our little native Solenopsis xyloni (Southern Fire Ant), not the feared introduced Red Fire Ants, S. invicta, that I met in Florida on my last night of gator watching that left me literally scared for life.  

But our little guys can sting too. When they come to my black light at night to tackle any small scarab that falls and lands on its back, they sometimes also get my toes. They seem to always plan their attacks until several are in position ... just like their bigger relatives in Florida. Their stings burn and itch but are really just a minor irritation. In our kitchen they were so docile that I first doubted my identification. No attempts at stinging at all.

Tackling a Minute Black Scavenger fly
But outdoors they are voracious and attack insects much larger than their size and manage to subdue them. So I assume that the crack in the kitchen wall (?) that they must have found is now free and clean of any other bugs. OK. Just stay off my counter and the floor!

Southern Fire Ants in the compost bin
In the backyard, I have noticed a belligerent colony close to the compost bin. We have lots of space, so this is far from the house.

Southern Fire Ant on a barrel cactus fruit
Solenopsis xyloni are also usually found on barrel cacti. To get the photo for this blog I just pulled a fruit from a barrel in the front yard and immediately had a couple of volunteers. I knew this would be the case because I'd seen the ants on barrels even in winter when I was looking for nymphs of leaf-footed bugs that develop on cacti.

At this time of the year saguaro cacti drop their fruit. Birds have been feasting on the sweet seed pulp before the fruit falls, but there should still be enough left to make some ants happy. Under a free standing saguaro, I found some of those fresh bright-red stars. There were some very small extremely fast-running ants, a Pheidole species I believe, but no Fire Ants. Do they not like saguaro fruit? Or are their colonies simply too far from this cactus?

At nigh at my black light site: Southern Fire Ants taking apart a scarab beetle and gorging on sweet saguaro pulp
 To test my theory I moved a few of the fruits to my black lighting site because I know that Solenopsis xyloni lives around there. I turned on my lights for some hours after sunset (a gorgeous one with virga, rainbow, red clouds and early moonrise).
 When I returned the Fire Ants had performed to expectations: not only did they overpower a small scarab beetle (Acoma sp.) and were just testing the resilience of a much larger Oxygrylius, they were also all over my saguaro offering.   

I know that the time of day and temperatures also play an important role in an ant's activity, but I did find Solenopsis xyloni active in the afternoon on the barrels but not the saguaro. Since they obviously love the saguaro fruit, I am back to my idea that there simply is no colony close to the free-standing saguaro.  Why?
To the human eye areas around the barrels and the columnar giant looks quite similar. So is it the cacti themselves that make the difference? Their yearly cycles are quite different. The saguaro blooms in April/May, and has fruit in June. As far as I can tell, those are the only times when saguaros have anything to offer to ants.

Barrel Cactus, this year's flowers and buds surrounded by last year's fruit
 By contrast, the  thick-walled fruits of the barrel stay on the plant, often for years, so several 'generations' of fruit are constantly present, arranged in rings around the center that keeps producing new flowers once a year, in July/August. Eventually the fruit are chewed open by rodents and the seeds disappear, many carried away by ants that are collecting the sweet sticky pulp.
  Barrel cacti also offer sweet sap from extra-floral nectaries all year round. It could be that the barrel cacti (via coevolution) are 'making sure' that ants have a reason to hang around. The cacti may be employing armies of little fighters for their protection against other bugs and the distribution of their seeds by offering them sweets. I have seen the ants attack cactus-juice-sucking coreid nymphs in several cases.

A jumping spider killing a coreid nymph on a barrel cactus
It is possible that barrel cacti rely overall more on arthropods as allies than saguaros do. Saguaros have many avian house guests that nest in or on the cactus or feed on nectar and fruit pulp. Many of them are insectivore gleaners like cactus wrens that also peck many insects off their host's thick skin.
Barrels are very vulnerable to rodents so they are tightly covered by a mail of interlocking thorns. This formidable defense may keep many birds from spending too much time on a barrel, and at any rate barrels are not tall enough to provide protective spaces for nests. Ants and spiders however have the ideal size and agility to police that space under thorns and between ribs. 

 Both saguaro and barrel cacti eke out a living in spartan surroundings. There is not much more than sand, widely spaced creosote bushes and cholla cacti. Under these borderline conditions the reliable yearlong provider may win out over the once-in-a-year party host when the opportunistic Fire Ants are choosing a neighborhood to live in.

Pheidole sp. left and Messor pergandei right. Colonies close to the saguaro
 I am not saying that the saguaro neighborhood lacks ants: besides the Pheidole colonies, there is a huge permanent Messor pergandei colony. But those ants have a completely different social, foraging and storage system than the Fire Ants. 

With this blog, I would like to stress that not all ants are alike, every species has its own ecological niche, and not even all Fire Ants are alike. The imported, highly invasive Red Fire Ants are established all the way from Florida into Texas in the east and  in California in the west. But they need more moisture than they would find in southern Arizona and they may be too frost sensitive to live on the Colorado Plateau in the north. So they may never overrun Arizona.

Living with ants (and you will, if you live in Arizona) is easier and far more interesting if you learn about the different types, one species at a time. Theirs is a densely populated and highly socially organized world to discover.

Please do not contact me about methods 'to get rid of ants'. I have no experience in that field and - beyond my own kitchen counter - no interest in gaining any.