Dr. Daniel T. Blumstein
University of California Los Angeles
What are marmot alarm
Hoary marmots (Marmota
caligata) are sciurid rodents: their nearest relatives are ground squirrels
and prairie dogs. Like all other marmots, hoary marmots may utter one or more
of several types of whistles when alarmed by a variety of predators including
humans. Like their close relative the Olympic marmot, hoary marmots have "ascending
calls", "descending calls", "flat calls" and "trills".
The first three calls are uttered singly; they differ in the relative difference
between their starting and ending frequencies (ascending calls end at a higher
frequency than they start, descending call end a lower frequency, etc.). Trills
are a multi-note call: a series of short ascending calls are packaged together
to form a trill. Collectively, these vocalizations are referred to as "alarm
calls" and marmots who hear them respond by immediately looking around
and returning to their burrows if they are not already at one.
When do marmots call?
Marmots typically alarm
call when they see natural predators, such as coyotes, foxes, and sometimes
when they see eagles and other large birds. Depending upon where marmots live
and how used they are to people, marmots may alarm call when they see a person.
In areas where people are common (e.g., national parks and forests), marmots
may not alarm call and in fact may pay little attention to people (or they
may view people as sources of food!). Both males and females alarm call and
all marmots respond to alarm calls.
What do alarm calls
Some species of animals
produce different types of calls in different situations. Many ground squirrels
"whistle" when they see a hawk and "trill" or "chutter"
when they see a coyote. When there is a strong association between the type
of stimulus and the type of vocalization, such calls function as rudimentary
words: animals hearing them know what type of predator is around and respond
Do hoary marmots have
different words for predators?
In a word, no. Most hoary
marmot alarm calls are 'flatish' and many are long (> 0.5 second). There
is no relationship between the rough type of call a hoary marmot utters and
the type of predator that elicited that call. Hoary marmots tend to call more
and longer to alarming stimuli on the ground when compared to alarming stimuli
in the air. And, terrestrial stimuli tended to elicit longer calls than aerial
stimuli. While calls that ended at a higher frequency than they started seemed
to be more arousing than those calls that ended at a lower frequency, different
length calls did not elicit different sorts of responses.