Scratch your back or suck your blood?

Birds are utilitarian creatures: they are part of the ecosystem, being essential to the food web as a predator (check out this past BIOTA blog post: http://biotatvorg.tumblr.com/post/141085388130/what-to-do-with-squirrel-phds-in-ecosystem) or important prey to animals.

They are also important to other animals by getting rid of an itch.

You’ve seen the following scenes before, either on animal shows or movies

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Or maybe this hilarious scene. (“Lion King,” anyone?)

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All credit goes to Disney.

Okay so maybe a rhino wouldn’t sit on a bird.

But we all recognize these scenes: a grazing water buffalo/ rhino/ hippopotamus with some small birds on top of it.


What the heck are those birds?

Most likely, those birds are oxpeckers. The oxpecker is a bird that belongs to the family Buphagidae. There are two species of oxpecker: red-billed and yellow-billed oxpecker. They can be found only in the Sub-Saharan Africa (endemic species for Sub-Saharan Africa). Oxpeckers inhabit the open savannas, grassy plains and areas with scattered shrubs.

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Why do they linger on large mammals? Well, like any other animal living in the desert, they’re trying to get a meal. Their meals of choice include ticks, flies, lice, worms that can be found on the fur of large mammals like buffaloes, giraffes, and large antelopes.

Oh yeah, and throw in a side of earwax for the oxpecker.  Scientists believe they use bacteria from the ear wax to facilitate digestion.  Also, ear wax is presumably high in energy.

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Through this mutualistic relationship, the oxpecker gets a meal and it’s choice large mammal gets rid of an itch. By removing the animal’s parasites such as ticks and lice , as well as gobbling up its earwax and grease, the oxpecker helps greatly cut short the animal’s grooming time and effort, making for CHOICE SALON service!

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But, Do Oxpeckers Seek something MORE?….than being a rosy pamperer? 

Though commonly called tick-birds, scientists have nicknamed oxpeckers ‘VAMPIRE BIRD.’  Recent research shows that in addition to supporting their host’s good hygiene, they also trim (snip) or peck at wounds on their hosts’ hides , potentially harming their host as they delay the healing process and attract more parasites to the area.  Studies have shown that the oxpecker’s favored food is blood, taken directly from a wound or in the form of a tick engorged in blood.  And it is the female tick they prey on since only the female bugs balloon themselves with host-blood.

This kind of vampyric behaviors has cracked open a debate on whether the oxpecker is more of a hindrance than a help and if it can be named a bonafide PARASITE.

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“I vant to suck your blood…”

So, as iconic as they are on the African Savannah seemingly just hitching a ride on an oxen’s back, there’s more to the red-eyed oxpecker.  Mutualist? Parasite?

Check out more evidence of vampires amongst our winged friends from this scientific article:

Weeks, P., 2000. Red-billed oxpeckers: vampires or tickbirds?. Behavioral Ecology, 11(2), pp.154-160.

Speaking of symbiotic relationships, we asked Danielle Bermudez, a Ph.D. Student from the School of Social Sciences, Humanities and Arts at the University of California, Merced, for her take on symbiosis.

What is/are your current occupation(s), vocation(s), proclivities and hobbies: I am currently a Ph.D. student in the Interdisciplinary Humanities program at UC Merced. I earned my B.A. in Feminist Studies from UC Santa Barbara. I enjoy hiking, photography, and hanging out with my rabbit Peanut.

How did you hear about BIOTA and what interests you about the program? I first heard about BIOTA from a fellow graduate student at UC Merced, Sabah, who presented about her research during our university’s second annual GradSlam competition. Later, Sabah held an event on campus for the premiere of BIOTA’s episode on the Vernal Pools in Merced, CA. It was really cool to see the project bring science and the humanities together to engage our local community with academia.

What symbiotic relationships; parasitic, mutual and/or commensal rivets you and why?Symbiosis is such a beautiful relationship. We all depend on each other in one way or another. As an example, human breast milk contains oligosaccharides, short chains of sugar molecules that provide no nutritional benefit to babies. So, why do mothers spend energy making these molecules? It’s to feed microbes that are important for the baby’s developing immune system. Microbes are essential for many organisms’ basic functions.

Nice relationship of choice, Danielle; symbiosis can either be large-scale or small. But regardless, it has a role in everything animals do, whether it’s in the human body or on the African Savannah.

The Tale of Cow-ungi-acteri-ant

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Figure1. Photo Credit: Alexander Wild, National Geographic

What happens when reps from three Kingdoms merge into a royal pact from the regal Families of Ant (Formicidae) from Kingdom Animalia, Bacteria from Kingdom Protista, and Fungi from…Kingdom Fungi?   We not only get a ‘microbial Cow’ or Cow-ungi-acteri-ant, but possibly the oldest farmers on this planet, nearly 50 million-years-old and counting!   This triad of super organismal allies includes the Leafcutter Ant, which, like a farmer growing and harvesting crops raises, nourishes and harvests not leaf or fruiting crops but a garden of fungi.  With bacteria sweetening this fungal-farming business by providing pest management services and fertilizer, all these players come together for a tale of multi-mutualistic symbiosis that seems to scream “team work! or die”.

Leafcutter or Atta ants live mostly in the tropics where they evolved in Central and South America.  As their name implies, they cut with scissor-like jaws fresh fragments of leaves from all sorts of plants and hoist them over their heads like a parasol to deliver to their underground nests.

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Figure 2.  A stream of Leafcutters carrying home the bounty

These nests can boast of being over 700 cubic feet in volume and house a society that constitutes a mega city with eight million individuals!

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Figure 3.  A singular nest with  200 fungal farms scattered about in Brazil

There, they mound the material in a big pile as a medium within which they cultivate and grow the fungus Lepiotaceae.

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Figure 4. A colony of Atta ants on the left feeding more leaves to the fungus garden to the right

Since many of the plants they collect have leaves containing lethal toxins like tannins and flavonoids, the ants rely entirely on the fungus to help neutralize the harmful chemicals.  Then, the ants eat the neutralizer.  Like cows that chew and swallow their food repetitively as they predigest their initially indigestible plant-based food with toxin-neutralizing saliva, the ant’s food also gets digested multiple times.  The ant first munches down the leaf into a pulp to feed to the fungus.  The fungus, in turn, synthesizes enzyme-rich clusters called gongylidia designed for the ant to eat, which over evolutionary time, the ant had learned to poop back out onto the leaf mound.

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Figure 5.  from De Fine Licht et al, 2012

Far from insulting table manners, only by passing through the ant’s system can the gongylidia’s embedded enzyme Laccase be chemically free to break down the plant’s toxins, fit enough for the fungus to further enjoy and access more nutrients. The ant then harvests the satiated fungus, now fortified with sugars and proteins, and feeds the fungi to any of the millions of developing larvae in the nest.  Their lives are inextricably linked, co-evolving with one another over time.  Like the Ambrosia Beetle  we highlighted earlier this year with its tight link to fungi nesting in its head, these are all obligate symbionts and  cannot live without each other.

But these symbionts don’t just let themselves be plainly satisfied.  Nay, they demand primo quality experience.  Enhancing the mutualistic partnership is a nitrogen-fixing bacteria that also resides inside in the leaf mound, infusing the medium with supplemental nitrogen.

Similar to the N-fixing bacteria on legume nodules, these bacteria take nitrogen gas amply available from the air and chemically convert it into a form that plants and fungi can absorb for healthy nutrition, a crucial service given that absorbable nitrogen is a severely limiting but necessary chemical for life in the environment.  Rather than hog all the nitrogen, the fungal-ant pair shares some of it with the surrounding soils in the form of compost made from the waste products that the ants discard on the outskirts of their nest.  This compost contains up to 26 times more nitrogen than other leaf litter piles in their habitat.  As a result, they help feed other neighboring plants and build up the local plant biodiversity.

Maintaining a healthy fungal farm is no easy task, as the garden is always susceptible to pathogens. To keep these threats at bay, one more amazing creature is thrown into the mutual symbiont network.  As if three just were not enough! (Mind you, a four-way network is more than any other symbiotic consortium we’ve addressed through BIOTA).

One more bacterial ally is Actinomycete bacteria.  Fully covering the bodies of the worker ants that maintain the fungal farm, they secrete an antibiotic that effectively prevents invaders like the harmful fungus Escovopsis from drowning out the ants’ beneficial Lepiotaceae partner.

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 Figure 6. Bacteria powdered worker ants maintaining the garden

Amazingly, this Actinobacteria is the same bacterial strain notorious for nearly half of all the antibiotics we use in human medicine.  Although humans have only discovered the application of antibiotics for less than a century, Leafcutter ants have been beneficiaries of their services for over ten million years!

Video on Leafcutter ants as hyper-cool masters of mutualism

How have they been able to succeed for so long, especially in the face of very real risks that modern human medicine grapples with like antibiotic resistance?  All over the world, a number of pathogens to humans as well as domesticated agricultural animals have developed genetic resistances to antibacterial drugs, forcing us to develop newer drugs as a counterattack.  Much of the failures of these drugs have stemmed from the over-prescription and improper drug use, creating conditions that are driving the bacteria to build up an extraordinary defense.  Since bacteria reproduce so quickly and in such large numbers, they can develop just the right mutations for getting an edge over whatever drugs we fabricate, making time of the essence.  Being ahead of the game and developing antibiotics fast enough to keep up with the rapidly changing bacteria seems to be precisely what Actinobacteria and the ants have been doing so well for millions of years.

Another more sustainable farming practice is the transplanting of robust fungal farms in areas where the soil is richly nourished and has a rich soil microbial base.  The more biologically active and diverse, the greater the possibilities for resisting attack.

The world of ancient Fungal farmers offers many interesting life lessons as well as possible leads on how we can grow food more sustainably ourselves. Building biologically rich systems, composting, and forging wise, links with other biotic kingdoms may prove fruitful.

The kit and kaboodle about the kit fox.

Thanks to Arjun Roy for his interest on this next symbiotic relationship!

Take our next predator on the arid, grassland, habitat, the kit fox (Vulpes macrotis). Kit foxes are mostly nocturnal, but often active in daytime when it’s cool weather outside.

They call underground dens their homes; their dens are multi-chambered with entrances and secret passage ways. Though kit foxes prefer to dig their own dens, sometimes they take the space of an existing ones; why reinvent the wheel, right? Sometimes kit foxes will find a den created by our unsung hero, the ground squirrel, and then tidy it up by enlarging the hole. Kit foxes will also reuse old dens made by; you think the fox rents month to month? Kit foxes tend to choose dens that are just big enough for them: small enough in diameter to exclude their own predators, the coyote.

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A mother kit fox cleans here pup. Efren Adalem / Oohlookphotography.com

Let’s talk specifically about the San Joaquin kit fox (Vulpes macrotis mutica), commonly found in the San Joaquin Valley and through much of Central California. The numbers for this subspecies are dropping steadily and are considered endangered; it has been on the Endangered Species list for nearly 50 years. Many scientists suspect the culprits to their decline are development- from building farms and houses, to cars and roads; others blame pesticides and outdoor poisons; others say their dwindling numbers are due to an explosive increase in their predators like the coyotes and competition for resources; and others blame climate change. Interestingly, decreases in their  prey abundance caused by circumstances such as drought and too much rainfall result in decreases of reproductive success of kit foxes. Regardless, population numbers for the San Joaquin kit fox are not good.

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The San Joaquin kit fox. Image by  Mark A. Chappell

Learn more about the current status of the San Joaquin kit fox from this scientific paper
Hall, F. and Spiegel, L., 1986. Distribution and habitat requirements of the San Joaquin kit fox in the northern extreme of their range. Transactions of the Western Section of the Wildlife Society, 22, pp.60-70.
http://www.wildlifeprofessional.org/western/transactions/transactions_2007_5.pdf

Bring in our hero, the ground squirrel. Just like the burrow owl, not only does the kit fox relies on ground squirrels for a source of prey but they also rely on them to help create new homes for themselves and their young. Kit foxes occupy soils with a high clay content where they can modify burrow dug by other animals, such as ground squirrels.

However the ground squirrels are in trouble too. The use of pesticides to control rodents and other pests also threatens both the ground squirrel and the kit fox, either by directly through poisoning or indirectly through reduction of prey abundance.

Historically, measures such as hunting and rodenticides have been used to control rodents and reduce conflicts with livestock. This has greatly decreased the populations of these species, reducing prey availability for their predators.

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Photo from https://sites.google.com/site/sanjoaquinkitfoxtp2015/feeding-habits

This relationship demonstrates the message that we all need each other to survive; either friend or enemy. What’s that cliche saying? Keep your friends close, but your enemies closer. Maybe think about this in a science nature sense.