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Results for “Ethology, Ecology and Evolution”

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USGS2010

Morning ambush attacks by black-footed ferrets on emerging prairie dogs

Black-footed ferrets ( Mustela nigripes ) often hunt at night, attacking normally diurnal prairie dogs ( Cynomys spp.) in underground burrow systems. While monitoring black-footed ferrets in South Dakota during morning daylight hours, we observed an adult female ferret ambush a black-tailed prairie dog ( C. ludovicianus ) emerging from a burrow. On a neighboring colony, we observed a second adult female ferret engaging in similar ambush behaviors on 12 occasions, although prey was not visible. We retrospectively assessed radio-telemetry data on white-tailed prairie dogs ( C. leucurus ) and a male and a female ferret to evaluate ferret activity in relation to timing of prairie dog emergence. Activity of radio-collared ferrets was high during the hourly period when prairie dogs first emerged and the following 2 hr, relative to later daylight hours. Such behavior is consistent with behaviors observed in South Dakota. Nighttime movements by ferrets might involve hunting but also reconnaissance of prey preparatory to morning ambush attacks.

South Dakota↗

USGS2016

Influence of species, size and relative abundance on the outcomes of competitive interactions between brook trout and juvenile coho salmon

Resource competition between animals is influenced by a number of factors including the species, size and relative abundance of competing individuals. Stream-dwelling animals often experience variably available food resources, and some employ territorial behaviors to increase their access to food. We investigated the factors that affect dominance between resident, non-native brook trout and recolonizing juvenile coho salmon in the Elwha River, WA, USA, to see if brook trout are likely to disrupt coho salmon recolonization via interference competition. During dyadic laboratory feeding trials, we hypothesized that fish size, not species, would determine which individuals consumed the most food items, and that species would have no effect. We found that species, not size, played a significant role in dominance; coho salmon won 95% of trials, even when only 52% the length of their brook trout competitors. As the pairs of competing fish spent more time together during a trial sequence, coho salmon began to consume more food, and brook trout began to lose more, suggesting that the results of early trials influenced fish performance later. In group trials, we hypothesized that group composition and species would not influence fish foraging success. In single species groups, coho salmon consumed more than brook trout, but the ranges overlapped. Brook trout consumption remained constant through all treatments, but coho salmon consumed more food in treatments with fewer coho salmon, suggesting that coho salmon experienced more intra- than inter-specific competition and that brook trout do not pose a substantial challenge. Based on our results, we think it is unlikely that competition from brook trout will disrupt Elwha River recolonization by coho salmon.

Washington↗

USGS2017

Using interviews and biological sign surveys to infer seasonal use of forested and agricultural portions of a human-dominated landscape by Asian elephants in Nepal

Understanding how wide-ranging animals use landscapes in which human use is highly heterogeneous is important for determining patterns of human–wildlife conflict and designing mitigation strategies. Here, we show how biological sign surveys in forested components of a human-dominated landscape can be combined with human interviews in agricultural portions of a landscape to provide a full picture of seasonal use of different landscape components by wide-ranging animals and resulting human–wildlife conflict. We selected Asian elephants ( Elephas maximus ) in Nepal to illustrate this approach. Asian elephants are threatened throughout their geographic range, and there are large gaps in our understanding of their landscape-scale habitat use. We identified all potential elephant habitat in Nepal and divided the potential habitat into sampling units based on a 10 km by 10 km grid. Forested areas within grids were surveyed for signs of elephant use, and local villagers were interviewed regarding elephant use of agricultural areas and instances of conflict. Data were analyzed using single-season and multi-season (dynamic) occupancy models. A single-season occupancy model applied to data from 139 partially or wholly forested grid cells estimated that 0.57 of grid cells were used by elephants. Dynamic occupancy models fit to data from interviews across 158 grid cells estimated that monthly use of non-forested, human-dominated areas over the preceding year varied between 0.43 and 0.82 with a minimum in February and maximum in October. Seasonal patterns of crop raiding by elephants coincided with monthly elephant use of human-dominated areas, and serious instances of human–wildlife conflict were common. Efforts to mitigate human–elephant conflict in Nepal are likely to be most effective if they are concentrated during August through December when elephant use of human-dominated landscapes and human–elephant conflict are most common.

Ethology Ecology and Evolution↗

USGS2021

First documentation of long-distance travel by a Florida manatee to the Mexican Caribbean

West Indian manatees ( Trichechus manatus ) are separated into two allopatric subspecies: the Florida manatee ( T. m. latirostris ) and the Antillean manatee ( T. m. manatus ). In the winter of 2020–2021, an adult manatee was sighted off the coast of Cancun, Quintana Roo, Mexico, in areas where Antillean manatees are not typically seen. The individual had distinct watercraft scars on its body, which were matched using photo-identification to a known male Florida manatee (PE424) that had been repeatedly photographed in Florida since 1998. This is the first record of a Florida manatee visiting the Mexican Caribbean. Previous reports of individuals from this subspecies in Cuba, combined with genetic evidence, suggest some level of connectivity among geographically separated manatee populations. We present the first evidence of along-distance movement by amanatee from Florida to the Yucatan Peninsula (Quintana Roo, Mexican Caribbean). This case, previous reports of Florida manatees in Cuba, and genetic evidence, suggest acertain degree of genetic mixture among the two subspecies.

Yucatan Peninsula↗