A Crab Spider and its Wasp

Doing a morning walk in Cuixmala on the trail along the Pistia-filled lake near Carretera 200 (across from the fundación), I came across something “floating” in the air in front of me.  Usually this is a caterpillar hanging by one of its silken threads.  As can be seen in these photos, that wasn’t the case here:

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Crab spiders (Family Thomisidae) are incredible in taking on larger and seemingly dangerous prey like this paper wasp (Polistes dorsalis) without the assistance of a web.  Instead, they hang out motionlessly and frequently camouflaged at flowers or on leaves with fallen flowers.  Here, they pounce on their prey and hold them with their first two pairs of legs while biting and injecting venom.  Crab spiders are not dangerous to humans but you have to think that their venom is pretty powerful.

What happened here?  While paper wasps don’t collect pollen to feed their offspring, they do occasionally visit flowers to feed on their nectar.  They also search plants for caterpillars and other insects that they feed their offspring.  For whatever reason, this one got too close to a crab spider.

While crab spiders don’t build webs, they still make and use silk.  Normally eating their prey where they catch them, this one shot a line of silk out and left its perch with the wasp in its chelicerae (jaws).  We can’t know exactly why it did this but perhaps a large ant or some other dangerous animal or potential predator got too close.

While the crab spider in the photos is holding the paper wasp by the base of its head, this doesn’t mean that’s where it delivered its deadly bite.  Crab spiders prefer to feed from the head where they inject digestive enzymes and then suck up the slurry.  What they suck up from the head must be very good.  One study of crab spiders feeding on fruit flies showed that they always started at the head and then switched to the abdomen to complete their meal.  If, however, a new fly appeared while a crab spider was feeding from the head of a captured fly, the spider would prefer trying to catch another fly rather than finish its meal at the other end of the captured one.

Anyway, shortly after the last picture the crab spider fell to the ground with its paper wasp where I presume it finished its meal.

References

Pollard, S.D. Oecologia (1989) 81: 392. https://doi.org/10.1007/BF00377089

Larceny of Wild Cotton Nectar by Jalisco Hummingbirds

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This spring I began to look at what pollinates a species of wild cotton (Gossypium aridum) found here in Jalisco. A chapter by Parra Tabla and Bullock in the Historia Natural de Chamela suggested that, given the floral characteristics of G. aridum, I was most likely to find that hummingbirds were the main pollinators.

It didn’t take much time to discover that hummingbirds did indeed visit G. aridum.  Initially these were mostly migrating female Black-chinned Hummingbirds (Archilochus alexandri) although males also occasionally visited. In all cases, though, these birds did not collect nectar through the floral opening but rather between the petals at the base of the flower.

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In the past, I would have called this nectar theft and as I thought of putting this post together, a number of witty titles came to mind.  However, in looking over some background for this post I ran across a note in the journal Ecology by David Inouye titled “The Terminology of Floral Larceny” where I discovered that using the term nectar theft for what I had seen would not be consistent with what the experts in the field would call it.

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A Mule and its Anis

 

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From southern Mexico to northern South America, one of the first birds a birder new to this part of the world will check off is almost invariably the Groove-billed Ani (Crotophaga sulcirostris).  Common in the kinds of disturbed environments nearly every visitor passes through and moving relatively slowly but noisily about in groups close to the ground, they’re hard to overlook.

Groove-billed anis have also been the focus of scientific research.  The famous Costa Rican naturalist and ornithologist Alexander Skutch first explored their natural history while groundbreaking behavioral biologist Sandra Lee Vehrencamp detailed their fascinating communal breeding system.  Others too have studied these birds.

The relative ease with which we can observe the birds and the fact that some very good researchers have done just that would suggest that we would have a solid handle on the basic natural history of these birds.  But there is one aspect of these birds’ behavior that’s been somewhat of a mystery.  Interestingly, it’s probably a mystery that countless campesinos could have answered for us had they wherewithal and any idea that anyone cared!

We have long known that Groove-billed Anis associate with cattle, horses, and mules. What hasn’t been clear are the forms this association takes.  We know that, like cattle egrets, Groove-billed anis occasionally follow large domestic mammals and catch the insects these animals scare out of hiding while wandering about.  Bent (1940) claimed, however, that Groove-billed Anis not only did this but also perched on cattle and even sometimes removed ticks.  Alexander Skutch, however, doubted that the birds did this. He suggested that people who thought they had seen this had confused anis with Giant Cowbirds, a similar-looking species well known for this kind of behavior.

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Nectar Feeding Tropical Parulas

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Once you know something about a group of animals, you come to expect that they will eat particular things.  When one thinks of the family Parulidae (New World Warblers) and their diet, the first thing that comes to mind are insects or other small invertebrates and most warblers have fine thin bills ideally suited for catching these things. Also, anyone who has watched these hyper-energetic little birds forage can’t but be impressed by how actively they search out their prey.

In terms of being energetic, the Parulidae are perhaps outdone only by the hummingbirds. Maybe it shouldn’t be surprising then that like the hummingbirds warblers might occasionally put their fine thin bills to use collecting floral nectar to satisfy their energetic needs. While the evidence that warblers do this is circumstantial — I know of no experiments or close observations ruling out the possibility that they are instead visiting flowers to catch small invertebrates — this evidence suggests that it is more likely that many are collecting nectar than not.

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The Nahua of Jalisco and hope through coffee: Organización “Color de la Tierra”

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Not well-known to many of those visiting the Costa Alegre part of Mexico (that area along the Pacific Coast of Mexico between Puerto Vallarta and Manzanillo) is that an ancient Nahua community of about 3,000 people — the Ayotitlán community — resides in the mountains above Manzanillo.  Most of the pueblos making up this community are within the Sierra Manantlán Biosphere Reserve, a place of remarkable natural beauty and a possible cradle for one of man’s most important crops, corn.

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The Nahua of Ayotitlán, like indigenous peoples the world over, have experienced a long history of marginalization and dispossession of their lands.  For these people, recent struggles stem from the fact that while the Ayotitlán’s Nahuas live in one of the most beautiful places on earth, that same place is also covered with valuable timber and underlain by nearly pure iron ore, two things that outsiders covet zealously and will go to almost any extent to obtain.

In the midst of this, one group of Nahua women on the northern edge of the Ayotitlan community have found a way to quietly better their lives and in the process are casting a ray of hope for their community and other communities like theirs. These women and their families have organized a collectiva, “Color de Tierra” that runs a remarkable little store in the pueblo of Cuzalapa, Jalisco.

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