Penn Vet Working to Understand Snowy Owls Arriving in U.S. Northern, Mid-Atlantic States


An analysis of competition between barley and white persicaria

“Barley and white persicaria (Polygonum lapathifolium L.) were grown in pure and mixed populations of varying density in sand culture in a glasshouse. The leaf areas and dry weights of leaves, stems and roots were determined at intervals. During the phase of vegetative growth the addition of dry matter by barley was unaffected, although tillering was reduced, by competition from dense stands of white persicaria, whereas the growth of white persicaria was reduced by low densities of barley. The decline in leaf area and reduction in root growth of barley with the onset of flowering was accompanied by increased growth of white persicaria with the production of branches from the upper axillary buds. These flowered and set abundant seed. This behaviour probably accounts for the persistence of this weed in arable rotations.”

Annals of Applied Biology; Volume 47, Issue 1, pages 156–172, March 1959 (paywall)

The death of the Super Hopper

“Picture swirling snow as far as the eye can see — in the middle of summer. Now, imagine this blizzard of flakes transforming into a swarm of locusts. This isn’t just any swarm, but the largest congregation of animal life that the human race has ever known. Picture yourself in Plattsmouth, Neb., in the summer of 1875.

A swarm of Rocky Mountain locusts streams overhead for five days, creating a living eclipse of the sun. It is a superorganism composed of 10 billion individuals, devouring as much vegetation as a massive herd of bison — a metabolic wildfire that races across the Great Plains. Before the year is up, a vast region of pioneer agriculture will be decimated and U.S. troops will be mobilized to distribute food, blankets and clothing to devastated farm families.”

“Today, this is hard to imagine; it sounds like an old Alfred Hitchcock thriller. But if we find it difficult to envision such masses of life, it is even more challenging to grasp that within 30 years of Dr. Child’s account of the largest insect swarm ever recorded anywhere, this species disappeared — forever. The last living specimen of the Rocky Mountain locust was collected in 1902 on the Canadian prairie.”

A dog ‘tail’ of two snails

For two dogs in Hawaii…

“Their job en-“tails” sniffing through some of Oahu’s most beautiful forests looking for the Euglandina rosea (Rosy wolfsnail), a common predator of the endangered Achatinella, commonly known as the Oahu, or kahuli, tree snail.”

“The Rosy wolfsnail is a cannibal snail that was first introduced to Hawaii in 1955 to eradicate the Giant African snail.

However, the Rosy wolfsnail traveled to higher elevations in the mountains of Oahu, where it discovered a new meal, the endangered Oahu tree snail…”