Dear Dr. McDonnell,
Almost every time I let my
horses out of the stalls after feeding them, they roll in the dirt,
dust, or mud. Why?
Mike and Sharon
Rolling associated with turnout after
feeding is a slight variation on the more usual question of rolling
immediately after a good grooming or a bath. Owners often ask why their
horse "hates to be clean," or tries to "ruin his
coat," and seems to deliberately roll to "spite you for
The short answer to rolling when turned
out is that it's normal horse grooming and social behavior to roll
whenever turned out from the stall to an open area. But since rolling is
one of the most interesting equine behaviors, I'll take the opportunity
of your question to explain in greater detail how and why rolling is
In horses living outdoors all of the
time, especially those living under natural herd conditions, rolling
behavior is one of the most conspicuously frequent social and grooming
behaviors. While we don't know precisely what stimulates rolling and
what it means in all circumstances, it likely serves several purposes.
These would include:
Speed drying and refluffing of a wet
or matted coat to restore maximum insulative properties.
Covering the coat with dust that
reflects the sun and possibly helps repel biting insects.
Aiding in shedding.
Increasing comfort by scratching.
There are certain situations that seem
to stimulate rolling, almost as if it is an automatic reflex. In wild
and pastured herds, these could include approaching a common rolling
area. Something about the site stimulates the behavior. Similarly,
horses tend to roll at watering sites, and sometimes the water itself
seems to stimulate the behavior. Also, rolling seems to be what is
called "socially facilitated." Like yawning in people, rolling
of one horse seems to stimulate rolling of a herd mate. This phenomenon
is often quite conspicuous in young foals. Dad rolls, foal rolls,
playmates roll, almost in a playful, mimicking fashion.
Another strong social aspect to rolling
is that it is a part of the ritualized inter-male behavior. This is very
noticeable among bachelor bands. Pairs or small groups of males
investigate one another, posture, stamp, and defecate in a stylized
manner. These ongoing inter-male events often occur near the rolling
site, and include "taking turns" rolling in a fixed order,
either before or after the aggressive tiffs. As with defecating on stud
piles, it often appears as if the top guy gets the last word; in other
words, he goes last in order.
Just like a pecking order for access to
a small watering site, there is a fixed order of access to a dust bowl
among members of a band, or bands within a herd. So when a band passes a
rolling site, the members of the band will roll in the same order day
after day. And if two bands pass by a rolling site at the same time, the
dominant band always gets to use the site first. The two harem stallions
might have a "conversation" over the rolling site.
A very interesting phenomenon in horses
is the "creation" of dust bowls at the rolling sites. Repeated
rolling in the same spot serves to eliminate the vegetation and erodes
the surface, forming a shallow bowl. With time the bowl has a very
compacted base lined with fine powdery soil. The bowl also becomes
"oiled" with body residues. The drier and hotter it gets in
summer, the more rolling occurs, and the deeper and more compact and
oiled the bowl becomes. When it rains, these dust bowls gather water and
become temporary watering sites.
It's tempting to attribute clever
engineering skills to these animals as if they think it through. But
this is a great example of an adaptive behavior-environment interaction
that likely needs no cognitive thought on the part of the horses. Just
one behavior to satisfy one need leads to serving other survival needs.
Is there a relationship between feeding
and rolling? In the environment where horses evolved, feeding is an
ongoing activity day and night, so they don't have "meals" as
we often provide them. Grazing occurs in long bouts of two or three
hours interrupted by resting bouts. There does not appear to be an
association of rolling with feeding. So I would guess that the fact that
your horses roll when they are turned out is coincident with feeding,
not related to feeding.
A less common, but occasional question
about rolling concerns horses which will try to roll under saddle. This
is sometimes when they approach a stream, which is just natural
behavior. Sometimes it seems related to discomfort from the tack.