On the Genetic Subversion of an Avian Population by an Introduced Species

A Possible Demonstration of Evolution in an Isolated Population

by Polygon

Compiled by the
Puddlebean Ornithological Society

The Lok' Groton Scavenger Bird  (Larus Slothus) is a well-known creature, found throughout Puddleby Island. Its cries, heard frequently on the beach areas, have always been as much a background as the gentle sound of the waves. It has always been known as a passive, even slightly timid, bird. On rare occasions, a cornered bird has been known to attack, but even then, once the invading exile backed away, it tended to return to its lazy flight seeking small fish and animal carrion. Any large animal or Exile carcass appeared to hold little interest for them.

In recent times, a change has been noted in the behavior of these birds. They now are observed to scavenge for food on the larger corpses they find littered about. They even show an increase in attempts to predate upon living Exiles. In addition, by careful observation from underneath these birds (Figure 1), the author has noted a change with time in the markings on many of the birds (it is quite difficult to see, as the striking black and blue feathers always appear on the north side or underside of the birds; Figure 2).

Figure 1. The Author's Observation technique.
Figure 2. Comparison of ordinary Lok'Groton (left) and Dalnothized Lok'Groton (right) varieties.

By what can we explain this apparent change in behavior and coloration? It is clear that the newly agressive behavior and the markings are due to the introduction of a new genetic component in the population. But this begs the question of the source of the new genetic component.

The changes appeared to be coincident with the appearance in the sea of a dark storm cloud. Could the storms have blown some individuals of a more aggresive strain to these shores? The author rejected this view, as the change in behavior seemed to be so widespread and rapid that a few storm-tossed individuals would not be expected to have such a dramatic effect. However, upon further investigation, it turned out that the cloud concealed a large island within its blustery winds and torrential rains, nearly as large as Puddleby Island itself! Further, the author and others quickly found that the scavenger birds of this island displayed the same aggresive tendencies to a great degree, quickly swarming over any meat carelessly left lying about (Figure 3).

Figure 3. Aggresive tendencies of the Dal'Noth population. This figure was kindly supplied by Microdot. Many /thanks.

To our excitement, all of the birds were found to have blue and black markings on their north sides and undersides! The appetites of these birds were enormous as well, for even abundant food sources exposed for long periods did not seem to satisfy them.

Clearly this seemed to be the source of the new genetic strain. Apparently too, the aggressive tendencies are a dominant trait, though the markings appear not to be. Many of the Puddleby Island birds that lack the distinctive coloration display the same aggressive behavior. The author has named the process by which the new genetic traits become widespread in the local population Dalnothization, after the name of the hidden island.

Are Dalnothized birds a danger to Exiles? It appears that indeed, the loss of small pieces of flesh, eyes, entrails, and other body parts is a hindrance to healing of the fallen. In addition, the new birds seem to make much more of a mess with their droppings. This trait has the effect of total ruination of a picnic on the beach.

In a fascinating parallel, two mammal populations on Puddleby Island seem to have undergone similar genetic invasions. The Puddleby Rat (Rattus Puddliens), well known as an instructive dissection animal for young exiles in their biology studies, has developed an aggresive behavior similar to that of the scavenger birds. Another species, the Puddleby Vermine (small or Verminus Ordinariens variety), apparently shares its ecological niche with, rather than being supplanted by, the Dal'Noth variety. Ironically, unlike the changes in the bird and rat population, Exiles would likely welcome a Dalnothization of the vermines. The Dal'Noth variety is more erratic in its movements and has a much more attractive pelt, some even worth 2 or 3 coins when sold to Zan Bountius.

What ultimately caused these changes in the local populations? As is well known, the Lok'Groton island chain has been isolated for centuries, perhaps millennia, from the large land masses. During this isolation, the local species of scavenger birds developed from a few individuals, perhaps storm-tossed to these islands as mentioned above. The small initial population apparently allowed for a genetic drift of the species from the mainland varieties. The author suggests that because of the enormous populations of large predators on these islands, and because of a relatively larger seacoast to inland ratio than the mainland, the food sources of the birds have always been more abundant than for mainland populations. Therefore, an aggressive, even predatious feeding pattern was easily discarded by the ancestors of the local birds.

With the arrival of Dal'Noth, the inbred local population was quickly genetically invaded by the more various and dominant genes of the new population. We say the "arrival" of Dal'Noth, though perhaps "revelation" would be a better choice; this is unknown. In any case, the new connection between Dal'Noth and the Lok'Grotons appears to be a purposful one. A further question is whether or not sentient creatures actually intended to produce such genetic changes as well as the geographical. There have been hints that there may be someone performing experimental genetic engineering, possibly on this island. Given the well-known humanitarian efforts of the apparent chief of the island, the lizard, pardon, we mean the wizard Qual, this suggestion seems quite likely.

In summation, we have observed a change in the local population of Scavenger Birds. This change appears to be due to the addition of genetic material from a population arriving with Dal'Noth. The near emergence of a new species of birds from the isolated populaton on the Lok'Groton Islands has been ended, perhaps for all time.