Wednesday, December 28, 2016

Go Forth

The range of European starlings in North America extends northward to Alaska. We think this range is the result of the 1890 introduction (i.e. invasion) of these birds. The native range of European starlings spreads across Europe and Asia, stretching as far East as Mongolia. Soon we will receive modern birds from Alaska, which made me remember a good question from a student a few years ago. Did starlings arrive in Alaska from their southern invasive range, or from their native range to the west? European starlings are not traditionally regarded as migratory birds. That means they do not fly over long distances seasonally to breed, though some starling populations are exceptions to this. But European starlings have been experts in rapidly and permanently expanding their range. So, some starlings go back and forth, and some just go forth.

The movement of starlings across the Alaskan landscape reminds me of a recent study about early human migrations. Though by feet not flight, humans may (or may not) have traversed a similar path, and with similar rip-roaring gusto. The traditional story is that the first humans arrived in North America across the Bering Straight from Siberia via a now long-gone land bridge. Some scientists have recently suggested that although the land bridge was present 13,000 years ago, the conditions in the region would not have allowed humans to survive (Pederson et. al, 2016). The landscape was barren with no exploitable resources for food or shelter. It was the Ice Age after all, not exactly a time of warmth and abundance. The authors go on to say that perhaps humans arrived via a different, unknown seafaring route. No matter which route they arrived, I always think of those first migrants. Human migrations did not complete themselves within the lifetime of one individual. But that does not mean that brave explorer types did not exist thousands of years ago in the human population. Undoubtedly, these individuals would make Columbus and Darwin look like wimps. The world was wilder then. Imagine going out in the morning and not knowing if continuous land lay ahead? or if you would find familiar food? And you would be a prisoner of the daily cycles of light or dark, and of the unusually long days, or continuous Alaskan nights. It makes my risk-averse body shiver.

A unique quality that humans have, that separates us from other species like birds, is that one individual can have an impact for years to come via the cultural transmission of information for generations. We have key people throughout history who, for better or worse, leave a mark on the population. Then, generations later we remember that person. But was their a starling Elvis Presley, or an Abraham Lincoln starling? The answer is no, but also kind of yes. We do see a few individuals that lead what we call the expanding front of birds. These are the birds on the edge of the group that led the species further into new localities. What was it about those individuals that made them fly farther in a new direction than any starling had before? And maybe the movement wasn’t very far, just a few new miles within their lifetime. They also didn’t know they were explorers. They weren’t leaving a flag in the ground or posing for grainy photographs, they were just eating different caterpillars and living in a new old tree. We can measure their wings, legs, bodies, and learn something about the geographic distribution of genetic diversity to understand more. The answer for why they moved is probably food or safety. This is likely the same reason early humans moved too. No one was running from war or towards religious freedom. Yet. But the new question is how did they adapt to new environments so well? Among hominins, we credit Homo sapiens with the astonishing capability to adapt to new highly varied environments. But the story of European starlings in North America is also one of amazing adaptive flexibility.

In humans, a specific genetic variant of a dopamine receptor gene called DRD4 has been linked to “novelty seeking behavior”. People with the shorter version of this gene are less likely to explore, and those with longer versions are more likely to explore. Some authors have suggested this allele played a role in the behavior of the original human explorers (Matthews and Butler, 2011). In birds, a specific genetic variant of the ADCYAP1 gene has been implicated in seasonal migratory behavior (Mueller et. al., 2011). But we know birds, just like humans, expanded their ranges too. Who were those first starlings that went forth into Alaska and didn’t go back? Why did they go? How did they adapt? They were not what we should call brave, but they were almost certainly, different.

Monday, February 8, 2016

The Nature of Colonialism

When I was reading the chapter on European starlings in Tinkering With Eden: A Natural History of Exotics in America by Kim Todd, there was one thing that kept flashing in my head: colonialism.

Read this section from Todd’s novel:
If starlings have a noteworthy genetically programmed personality characteristic, it is aggression. They wait until other birds have created cavities for nests, then harass the architects until they abandon their site. Sometimes a starling enters a hole while the owner is gone. When the bird returns, the starling leaps onto its back, clinging and pecking it all the way to the ground. Even when it has claimed a nesting cavity, a starling may continue to abuse other birds breeding nearby, plucking their eggs out of the nest and dropping them in the dirt. One ornithologist watched a starling dangle a piece of food in front of the nesting cavity of a downy woodpecker. When the young woodpecker reached out of the hole for the bait, the starling dispatched it with a quick jab of the beak…Two cottonwoods on land hosted fourteen pairs of breeding native birds in 1978, but in early 1979 a starling couple moved in. Then a dozen more joined them…the starlings scared off American kestrels, northern flickers, olive sided flyercatchers, and house wrens in March. In April and May morning doves, tree swallows, and house finches approached the cottonwoods, only to be rebuffed. By June the trees were only offering refuge to nothing but starlings.”

The section reminded me of Edmund Morgan’s recall of history in Early Virginia, American Slavery, and American Freedom: “Since the Indians were better woodsmen than the English and virtually impossible to track down, the method was to feign peaceful intentions, let them settle down and plant their corn wherever they chose, and then, just before harvest, fall upon them, killing as many as possible and burning the corn…”

Humans often pride ourselves with not being animalistic, not acting savagely. However, these British colonists acted in ways that can only be comparable to animalistic ritual behavior. British colonialism is a harsher, crueler, and comparable personification to the spread and destruction caused by European starlings.

The patterns of behavior are so similar that the same language can be used to describe the actions of both the violence caused by European starlings and colonists. For example:

If the British colonists had a noteworthy genetically programmed personality characteristic, it is aggression. They waited until the indigenous communities settled down and planted their corn, then harassed the architects by setting the land on fire and raiding the homes of the indigenous communities until they abandoned their site...Two pieces of land hosted fourteen indigenous families in a tribe in 1808, but in 1809 an American couple moved in. Then a dozen more families joined them…the Americans scared off  the indigenous communities by harassing and pushing them off the land. By June the land only offered refuge to nothing but American colonists.

When the history and behavior of European starlings are studied it is strikingly analogous to the histories and behaviors of European colonists. When looking at the places European starlings have invaded: Argentina, Australia, Brazil, Canada, Falkland Islands, Mexico, Peru, New Zealand, United States, North America, New Zealand, and South Africa—the countries all have one thing in common: they all have been colonized by Europe. Thus, there is a causation relationship between colonialism by European colonists and European starlings; without the colonialism that occurred, starlings would not have been able to be introduced to the lands they now conquer and terrorize.

When we talk about invasive species, we use the same kind of language when we are describing European colonialism. However, our perceptions of the two things are different: we easily perceive invasive species as detrimental, harmful, and something to be prevented at all costs. This is different from our perceptions of colonialism, which were sometimes seen as benevolent and inevitable. Research institutions and scientists work to secure resources to preserve endangered animals and species—the same resources and energy were not used to ensure the prosperity of indigenous communities throughout history. 

Guest Blogger: J. Raihan

map color key: 
light yellow=Introduced European starling summer breeding range
light green=Introduced European starling resident range
dark yellow=Native European starling summer breeding range 
dark green=Native European starling resident range
dark blue=Native European starling winter range

Wednesday, January 20, 2016

Sculptures and Superorganisms

The word murmuration typically refers to a soft, indistinct sound, but in the more rare sense of the word, it refers to a flock of starlings. The first and only time I ever witnessed a starling murmuration was through a laptop screen – yet I was spellbound. The amoeba-like conglomeration of birds seemed to float through space, both fluid and structured at the same time. The dying hues of the setting sun illuminated the gaps between each bird like light through a mesh screen. When I saw this phenomenon, the first thing that came to mind was a term I’d heard about recently: superorganism.
A biologist coined that word for our great African ant colonies, claiming that consciousness and intelligence resided not in the individual ant but in the collective ant mind. Essentially, the superorganism is an organism consisting of many organisms. But I don’t think the concept is reserved solely for animals – I see it in the cars humming by on the highway and the people bustling in the Times Square subway station.

Another biologist – Ian Couzin – has been doing similar work at Princeton University and has found, through computer simulations and mathematical algorithms, that there are indeed many similarities between different levels of organization in nature. It is essentially a biological criticality: when a neighbor moves, so do you. It’s a system that is poised to tip, to be almost instantly and completely transformed.

Something else that surfaced in my mind while watching the murmurations was the work of an artist named Ruth Asawa, whose work I’d recently seen at the Whitney Museum of American Art. Asawa is an artist who learned to draw in an internment camp for Japanese-Americans during World War II and later earned renown weaving wire into intricate, flowing, fanciful abstract sculptures. She started using wire after a trip to Mexico in 1947, and used the craftsmanship she had learned from Mexican basket makers as well as her ambition to extend line drawings into a third dimension. In 1958, The New York Times wrote of her sculptures’ “gossamer lightness” and the way “the circular and oval shapes seem like magic lanterns, one within the other.” In a way, I think these adjectives perfectly describe the starling murmurations as well.

Thus whether we are looking at birds or humans, sculptures or superorganisms, there are some elements which remain undeniably the same – organization, fluctuation, and variability, to name a few. And by viewing Asawa’s hanging mobiles and the starling murmurations side by side, I think it becomes clear that the dichotomy between art and science may not be as rigid as it seems.

Guest blogger: K.S. Mediratta