Tag Archives: biodiversity

Are Insect Populations Declining?

Yellow Scarab Beetle in the Monteverde Cloud Forest, Costa Rica.  Photo by Mark Shepherd

On a recent trip to research insect populations, I visited a small sliver of the Chihuahua desert that runs through the extreme southeast corner of Arizona, I encountered hundreds of eager hover flies.  I say eager, because the flies followed and buzzed around me relentlessly.  While I couldn’t identify any single individual fly, I am certain that a few of them followed me for more than half a mile as I trekked through the dry, rock strewn, dusty desert.  I am not a dancer, but all of the swatting, arm waving, and stumbling probably made me look like I move like Mic Jagger.  Relief came when wind from an approaching thunderstorm forced the flies to land or be blown away.

Of course, the flies were after me because I was a source of water and salt in the middle of a desert.  The flies need both to survive and reproduce.  With a life span measured in weeks, the flies had no time for politeness.  Their tiny biological clocks were ticking.   They were in their golden days, having already lived most of their young lives as larvae and then metamorphosing into the annoying fly stage that zipped just a little too close to my ear canals.  For me it was irritating, but for the swarming flies, it was all-or-nothing; do or die.

Many amazonian insect species were drawn to light.
Many amazonian moths and other insect species can be seen by hanging a sheet and light.  Photo by Mark Shepherd, Peru

Insect Bias

As a group insects get a lot of bad press, when they get any at all.   Biting and stinging insects of course figure prominently in many stories. There are a number of published articles headlining that insects make up a significant number of invasive species, which is partially true.  But the biases against our chitin covered earthmates are largely out of proportion.   Why is large group of caribou called a herd, but a large group of insects is a swarm.  Swarm has a more sinister, negative connotation.  Swarming hover flies are pests.  While many people mourn the loss of the huge buffalo populations that use to wander the western prairies, no one would likely invest in a hover fly reintroduction program if their populations dropped significantly.   Insects are not generally considered a charismatic species, meaning they don’t draw the attention that elephants and polar bears garner.  No one pines for the years when painful, stinging harvester ants were more plentiful in east Texas.  No one has established a non-profit to reintroduce the rocky mountain locust, whose past populations inspired the following letter from E. Snyder of Highland Kansas:

At our place they commenced coming down about 1 O’clock in the afternoon, at first only one at a time, here and there, looking a little like flakes of snow, but acting more like the advance skirmishers of and advancing army; soon they commenced coming thicker and faster, and they again were followed by vast columns, or bodies looking almost like clouds in the atmosphere.  They came rattling and pattering on houses, and against the windows, falling in the feilds, on the prairies and in the waters – everywhere and on everything.  By about 4 o’clock in the afternoon, every tree and bush, buildings fences, fields, roads and everything, except animated beings, was completely covered by grasshoppers. 

The disappearance of the locusts that terrorized the American frontier is noteworthy in that it happened to an insect pest that, at the time, no one believed was vulnerable to extinction.   Why? Because insects appear to be so numerous it is difficult to imagine them being eradicated.  They are described as “R” selected, meaning they have short lifespans and produce enormous numbers of offspring, among other traits.  Such characteristics may seem to make insects invincible, but the truth is many insects are especially vulnerable to habitat loss and invasive species.  Even if insects produce a large number of eggs, they usually have specific habitat requirements necessary to ensure survival.

Researchers have noted insect population declines in many sites across Europe.
Iron clad beetle (Zopherinae sp.) has and extremely tough outer shell, one of the strongest known.  Photo by Mark Shepherd,  Driftwood, Texas.

Declining Populations

A recent article in Science (May 12, 2017) reports that insect biomass captured in traps spread across more than 100 European nature reserves has dropped dramatically since the 1980’s.  Members of the Krefeld Entomological Society, a group of amateur entomologist that have been monitoring insect abundance, raised concern after comparing earlier masses of insects trapped to those in 2013.   Whether similar declines are happening in other locations around the world is difficult to say, because there are too few surveys across multiple years to make anything stronger than a guess.  Also, insect populations can vary significantly from one year to the next, in cycles that may last several years to a decade.  So even if annual surveys were available, for some insect species, it still wouldn’t be enough.  Finally, the lack of public awareness concerning the extinction risk of many insects, other than honey bees and monarch butterflies, means there is likely insufficient funding to conduct surveys.

So why be concerned about declining insect populations?  Because they pollinate most of our food crops, aerate the soil, control other pests, and feed those bat, bird, and fish species we humans so love to photograph.


Vaquita: The World’s Rarest Marine Mammal Is In Trouble

Vaquita (Phocoena sinus), a small porpoise endemic to the northern Gulf of Mexico, Illustration by Justin Shepherd www.markshepherdjournal.com
Vaquita (Phocoena sinus), a small porpoise endemic to the northern Gulf of Mexico. Illustration by Justin Shepherd

Another species of marine mammal is on the verge of extinction.  The Vaquita (Phocoena sinus), a small porpoise endemic to the northern Gulf of Mexico, is reportedly just 30 individuals away from being lost forever.  The name vaquita is Spanish for “little cow,” and it looks somewhat like a panda mixed with a dolphin.   Because individuals suffer high mortality when trapped in illegal gill nets used by fishermen, the vaquita populations have plummeted since 1997.  Mexico has spent millions trying to stop the illegal practice of using gill nets, but to date has not been able to prevent it completely.

Faced with the imminent loss of the vaquita, the Mexican government approved a conservation plan in April, 2017.  The plan, however, may not be implemented until October, 2017, as there are many logistical hurdles, including building enclosures to house the captive breeding program.  There are also many unknowns, such as whether the vaquita will breed in captivity, how long they live, what age they mature sexually, and the minimum number of individuals necessary to keep the species from going extinct.  It will be tricky to get all of the things needed to save the vaquita by October.  Let’s hope the efforts that the Mexican government is taking, and the recent awareness brought to the issue by Leonardo De Caprio and several wildlife conservation organizations, will help turn things around.   Otherwise, like the Chinese river dolphin, we will lose another unique aquatic species.

Monk Parakeet Populations Growing


Three Monk Parakeets perched and interacting in a tangle of branches (Buenos Aires); markshepherdjournal.com
Three Monk Parakeets perched and interacting in a tangle of branches (Buenos Aires).
Photo by Rich Lindie

In 1939, nearly 77 years ago, the Carolina Parakeet (Conuropsis carolinensis) was declared extinct.  At the time, it was United States’ only known native parrot.  The cause for its extinction is not certain, but is frequently reported to be the result of deforestation.  Some experts, however, believe deforestation and hunting may have reduced the

populations sufficiently to allow other factors, such as disease, to be the proximate cause of extinction.  Whatever the cause, the species’ population decline appears to have been rapid, occurring sometime between 1896 and 1904.   The last one died in captivity in 1918 at the Cincinnati Zoo (Click on the book cover to the right to get a copy of an excellent book Errol Fuller discussing the Carolina Parakeet and other extinct species titled, “Lost Animals”).

Since 1968, a new parakeet is taking up residence in some habitats formerly occupied by the Carolina Parakeet.  Also known as the Quaker parakeet, the monk parakeet is native to South America, occurring from central Bolivia and southern Brazil, south to central Argentina.  Monk parakeets (Myiopsitta monachus), believed to have been accidentally or intentionally released, are now found in several states of the U.S., and can also be found in Canada, Puerto Rico, Bahamas, West Indies, England, Belgium, Italy, Spain, and Israel.  In the United States breeding populations occur in Texas, Louisiana, Florida, Illinois, New York and as far north as Connecticut.

Here in Austin, as in all major Texas cities, there is an established population of monk parakeets.  They are almost always found in groups, frequently searching the ground for seeds and any fallen fruit, which is reported to be their main diet.  They are also frequently found on electric transmission lines crisscrossing the city.

Monk Parakeets are unique among the psittacines (parrots) in that rather than making their home in cavities, they build large communal nests using sticks, often among those same transmission lines, which is the only potential problem with any increase in their numbers.

Populations of monk parakeets are thought to be growing exponentially, and while they do not seem to pose the same pest problem in United States that they do in their native South America, there is still concern that could change.   One study reports that parakeet populations will likely continue to expand and grow for the foreseeable future (Pruett-Jones et al., 2007).

Click the link below to see a short video of monk parakeets in Austin, Texas

monk parakeets short 2

Pruett-Jones S, Newman JR, Newman CM, Avery ML, Lindsay JR: Population viability analysis of monk parakeets in the United States and examination of alternative management strategies. Human-Wildlife Conflicts. 2007, 1:35-44.