observed to modify the structure of their pant-hoot based upon the behavioural situations in which they are in. For example, during pant-hoot chorusing behaviour, males will modify the structure of their calls to essentially become more similar to the calls of their affiliative partners, as opposed to the very specific call they produce when pant-hooting individually. Males will also modify the structure of their calls to facilitate this chorusing behaviour and social bonding phenomenon. It has been observed that male chimps will prolong the production of the build-up phase to increase the likelihood of another individual joining in and ultimately forming a chorus. Additionally, once the chorus has been formed, the climax phase of the chorus is extended in length to increase the effectiveness of the display and the strength of the bond between the chorusing partners. The modifications to the duration of the build-up and climax phrases of the pant-hoot structure illustrate a mechanism for increasing the probability and efficient formation and maintenance of social parties and chorusing groups of chimpanzees. Modifications of the structural composition of the pant-hoot between populations may also be explained by genetic differentiation and habitat composition of populations based upon geographical separation. The greater distance there is between populations, there is a reduced possibility of migration and consequently gene flow between populations. Migration in turn causes the genetic makeup of populations to homogenize and converge, increasing similarity between the two groups. With increased geographic separation, and therefore increased distance and reduced gene flow, populations will become genetically divergent from one another and increasingly differentiated, supporting the observation of differences in the duration, and structure of pant-hoot phrases amongst these geographically separated populations. In addition to genetic differentiation between geographically isolated populations, habitat conditions increasingly differ with increasing geographic separation. In turn, structural differences in the pant-hoot are observed based upon habitat differentiation within populations. Pant-hoots are used as a form of long-distance communication between members of chimp parties, therefore, sound attenuation is an important consideration in the production of these calls. Individuals living in forest ecosystems must modify the structure of their pant-hoot to reduce the effects of degradation and attenuation on the transmission of their call due to the high number trees obstructing the pathway of the travelling sound. These obstructions increase the possibility of refraction and scattering of the sound waves, therefore increasing the rate of attenuation and decreasing the effectiveness of