There have been a number of studies in the past few years analyzing the degree to which various species communicate with other species. I expect that many people might assume that little communication occurs between organisms of separate species, but that's just not true. Clearly there are many non-verbal cues that pass from species to species. Consider a bear staring at you while pawing the ground. While I haven't witnessed this myself, I can only assume that the communication from the bear would be crystal clear in my mind. A more interesting aspect than non-verbal communication are the subtleties of vocal or other sounds based communication. Consider the barking dog. Our context and experience enable us to have a pretty good idea of what the dog is trying to communicate.
In 2007, a study was published indicating that Nuthatches eavesdrop on variations in heterospecific chickadee mobbing alarm calls. As these are closely related species that often travel together, I can clearly understand the need and evolutionary benefit of this mechanism.
Recently a new study was publishing analyzing response to the wing whistles of Mourning Doves by other Mourning Doves and other bird species.
Seth W. Coleman (2008). Mourning dove (Zenaida macroura) wing-whistles may contain threat-related information for con- and hetero-specifics Naturwissenschaften, 95 (10), 981-986 DOI: 10.1007/s00114-008-0404-x
Mourning Doves wings make a whistling sound as they take flight. This sounds is most dramatic as they take off from the ground. The researcher recorded these sounds under normal take-offs and again under startled take offs. They then replayed these sounds as birds were eating at a feeding site. When Mourning Doves were present and the startled take-off sound was played, the birds remained more vigilant and stayed away from the feeding site longer than when the non-startled take-off sound was played. The procedure was repeated with other birds including the Northern Cardinal and the House Sparrow. In each case upon hearing the startled Mourning Dove wing whistle the birds in general remained more vigilant and stayed away longer than when they heard the non-startled wing whistle. Its worth noting that the vigilance response rates were higher for Mourning Doves than the other species.
The researcher then repeated the procedure using Northern Cardinal alarm calls and House Sparrow social chatter. Once again, all three species responded to the alarm call with greater vigilance, but the same species response, in this case the Cardinal, was the highest.
I'm interested each time a study like this comes out. The result, while it has some valuable scientific information, is not surprising to me at all. A species in the wild must be vigilant about its surroundings to survive. Cues can come from any direction to alert the presence of danger. Those species which are most in tune with these various cues will likely have a greater chance of survival and thus live to create more offspring. This is not likely just a learned behavior but most possibly an ingrained genetic trait inherited through generations.