Article Spotlight: Carnivore coexistence without competition

by | Apr 30, 2024 | Article Spotlight

"We found that den use by both species overlapped spatially but not concurrently. Contrary to expectations, we also found that giant otters were more active at night than neotropical otters."

Nocturnal activity of tropical otters is rarely reported. To date no studies have documented den use by sympatric giant (Pteronura brasiliensis) and neotropical otters (Lontra longicaudis). We used camera-traps to monitor den use by sympatric otters along an equatorial Amazonian river. Camera-traps provided evidence that giant otters were more nocturnal around dens than sympatric neotropical otters. Nocturnal activity was recorded in 11% of giant otter photos (n = 14 of 125 photos), but was recorded only once for neotropical otters.

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How did researchers monitor den use by giant and neotropical otters in the Amazonian river environment?

The researchers utilized camera-traps to observe and monitor den use by giant and neotropical otters along the equatorial Amazonian river.

What nocturnal activity patterns were observed in giant otters compared to neotropical otters around the dens?

The study found that giant otters exhibited more nocturnal activity around dens, with evidence of nocturnal behavior recorded in 11% of photos. In contrast, neotropical otters were rarely active at night, with only one recorded instance of nocturnal activity.

Was there spatial separation in den use between giant and neotropical otters, and if so, what were the observed patterns?

Yes, the researchers observed spatial separation in den use. Giant otters were predominantly recorded at downstream dens, while neotropical otters were observed at dens located at least 3 km upstream. Despite this spatial overlap, the two species did not use dens concurrently.

Did the researchers find any differences in the timing of den use between giant and neotropical otters?

Yes, the timing of den use differed between the two otter species. Giant otters tended to be more active around dens, with clear peaks in den activity observed throughout the day. In contrast, neotropical otter den activity was less pronounced, with activity concentrated between 8:00 AM and 4:00 PM, declining after 3:00 PM.

What implications do these findings have for understanding the coexistence of giant and neotropical otters in the Amazonian river ecosystem?

The study suggests that despite overlapping spatial and temporal ranges, giant and neotropical otters exhibit distinct den use patterns, with giant otters showing more nocturnal activity around dens. These findings provide insights into how these otter species coexist without direct competition, potentially through niche differentiation in behavior and habitat use.

 

 

 

Carnivore coexistence without competition: giant otters are more nocturnal around dens than sympatric neotropical otters

 

 

Nocturnal activity of tropical otters is rarely reported. To date no studies have documented den use by sympatric giant (Pteronura brasiliensis) and neotropical otters (Lontra longicaudis). We used camera-traps to monitor den use by sympatric otters along an equatorial Amazonian river. Camera-traps provided evidence that giant otters were more nocturnal around dens than sympatric neotropical otters. Nocturnal activity was recorded in 11% of giant otter photos (n = 14 of 125 photos), but was recorded only once for neotropical otters.

 

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