Results

To What Extent Do Both Species Associate with One Another?

Overall, crowned lemur and Sanford's lemur groups met each other nearly twice daily for nearly 90 minutes. Each study group met at least three groups of the other species per season. Of the 353 encounters throughout the study, 237 were scored as associations, in which activities were coordinated among members of both species (Table 1). On average, associations lasted more than 70 minutes in most seasons. Unlike encounters between groups of the same species, those between different species usually lacked alarm vocalizations (alarm calls, trill-grunts, and raspy calls). Most vocalizations upon meeting groups of other species included contact grunts that group members offered each other during routine feeding and foraging.

Associations seemed to vary seasonally in frequency, average length, and maximum length (Table 1). Wet season values were typically longer than those for other seasons. During the wet season both species associated with one another in 20-30% of daily observations. Crowned lemurs associated significantly more of their typical wet season day than did Sanford's lemurs (A-=9.80, p <0.05). The

Table 1. Frequency of polyspecific encounters and associations among crowned lemurs and Sanford's lemurs at Ampamelonabe

Polyspecific Association time while Association time while encounters observing crowned lemurs observing Sanford's lemurs

Wet season 3.50/day n =140 Dry season 1.69/day n =105 Hot season 1.92/day n =108

214.55 minutes/day n =65 29.80% observations 68.60 minutes/association 71.12 minutes/day n =30 9.88% observations 73.81 minutes/association 70.08 minutes/day n =39 9.73% observations 51.97 minutes/association

143.40 minutes/day n=47 19.92% observations 62.45 minutes/association 83.21 minutes/day n =33 11.56% observations 77.14 minutes/association 38.43 minutes/day n = 23 5.34% observations 48.61 minutes/association two lemurs formed associations in 75% or more of their wet season encounters. In other seasons both lemurs associated in only 5-12% of daily observations, and neither species associated more than did the other. Associations formed in most encounters. For most of the study associations lasted an average of 62-77 minutes, but hot season associations were typically shorter (A- = 48.61-51.97 minutes). Maximum association length varied seasonally as well. The maximum wet season association lasted 305 minutes; the maximum association length was shorter in other seasons (110-288 minutes).

What Is the Context under Which Both Species Associate?

Study groups seemed to have preferred associate groups throughout the year. Each study group usually associated with the group whose home range most overlapped its own. For example, the two southern study groups associated with one another in 43-77% of all polyspecific associations. Likewise, 90% or more of the associations that the northern crowned lemur study group formed usually included the northern Sanford's group. More than half those associations that the Sanford's group formed included the crowned lemur group. Only in the hot season did the crowned lemur group associate with another group nearly as much as it did with the Sanford's group.

Neither species seemed to initiate associations more than did the other (Freed, 1996). Each species initiated associations during similar activities (Figure 2). During the wet season lemurs initiated two-thirds or more associations during feeding and foraging. Otherwise, feeding and foraging accounted for only slightly more of the associate's behavior than did resting and grooming. The initiation of associations seemed to differ seasonally in at least one aspect, the forest level of the initiators. Throughout most of the year, initiators generally began associations from within their own preferred vertical strata. Crowned lemurs initiated associations

Figure 2. Activities of recipient associates when polyspecific associations were initiated.

from the understory 92.5% and 65.1% of the time during the dry season and the hot season, respectively; Sanford's lemurs initiated associations from the middle story 59.5% and 56.6% during the dry season and the hot season. In the wet season, however, association initiators left their preferred forest levels, and sought out their associates elsewhere below the forest canopy. Crowned lemurs initiated associations 56% of the time in the wet season from the middle story. Sanford's lemurs initiated 58.4% of their wet season associations from the understory.

Although both species participated in frequent agonistic displays (i.e., face-offs, fights, and charges) upon meeting conspecific groups, both species displayed little agonism upon meeting one another and associating. Interspecific agonism occurred in 20-25% of encounters in any season. Only 14% (wet season) to 22% (hot season) of encounters ended due to this agonism. Although both lemurs usually tolerated one another, Sanford's lemurs initiated more than 75% of interspecific agonism in any season. Most agonism occurred when both species fed or foraged together. Less than 38% of the agonism took place when Sanford's lemurs chased crowned lemurs from large fruit trees (e.g., Ficus brachyclada, Diospyros sp., and Canarium madagascariensis). In nearly two-thirds of agonistic interactions, crowned lemurs responded by withdrawing from Sanford's lemurs. Although Sanford's lemurs sometimes chased crowned lemurs from large fruit trees, crowned lemurs usually consumed these resources anyway. Crowned lemurs either waited for Sanford's lemurs to finish eating, or returned to the food source when no other groups were present.

Table 2. Average daily percent age of focal observations in which the focal animal was within a polyspecific association"

Season

Average distance between focal animals and associates

Total

Closest distance between focal animals and associates

Bouts

10-20 m

<10 m

10-20 m

<10 m

Wet

39.13%

60.87%

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