Northern distributional extensions of Peropteryx leucoptera and Peropteryx pallidoptera (Chiroptera: Emballonuridae) from Vichada, Colombia

The White-winged Dog-like Bat (Peropteryx leucoptera) and the Pale-winged Dog-like Bat (Peropteryx pallidoptera) are distinguished from the other emballonurid bats because they have white or translucent wings. Their distribution and biology are poorly known due to they are no captured in traditional bat inventories using mist nets. In this contribution, we extend the known distribution of P. leucoptera 260 km NE and P. pallidoptera 290 km NE. Our records are from three specimens collected in a mammal assessment at the riparian corridor of the river Meta in the Vichada department. This locality is the northern limit of the distributional range of both species. We highlight the need to continue the fieldwork on mammals inventories with specimen collections through the Colombian Llanos. We call attention to the importance of horizontal rotten logs as roost of P. leucoptera and other little known neotropical bats.

Stream Temperature and Environment Relationships in a Semiarid Riparian Corridor

This study examined the relationship between stream temperature and environmental variables in a semiarid riparian corridor in northcentral Oregon, USA. The relationships between riparian vegetation cover, subsurface flow temperature, and stream temperature were characterized along an 800 m reach. Multiple stream temperature sensors were located along the reach, in open and closed canopy areas, with riparian vegetation cover ranging from 4% to 95%. A support vector regression (SVR) model was developed to assess the relationship between environmental characteristics and stream temperature at the larger valley scale. Results show that air temperature was highly correlated with stream temperature (Pearson’s r = 0.97). Based on the ANOVA, no significant (p < 0.05) differences in stream temperature levels were found among sensor locations at the valley scale, irrespective of percent vegetation cover. Channel subsurface temperature levels from an intermittent flow tributary were generally cooler than those in the perennial stream in the summer and warmer during winter months, indicating that the tributary may have a localized moderating effect on stream temperature. SVR model results showed that air temperature, followed by streamflow, was the strongest variable influencing stream temperature. In general, riparian area land cover showed little effect on stream temperature along the entire riparian corridor. This research indicates that air temperature, subsurface flow, and streamflow are important variables affecting the stream temperature variability observed in the study area.

Historical disturbances to rivers appear to constrain contemporary distribution of a river-dependent frog

Frogs dependent on lotic environments are sensitive to disturbances that alter the hydrology (e.g., water impoundments), substrate (e.g., debris torrents), and riparian vegetation (e.g., wildfires) of river ecosystems. Although rivers are often very dynamic, disturbances can push environmental baselines outside of narrowly defined ecological tolerances under which a species evolved. Short-lived lotic-dependent organisms, restricted to movements within the water or the riparian corridor, are at risk of local extirpations owing to such disturbances if they fragment and isolate affected populations from recolonizing source populations. In Oregon, USA, the foothill yellow-legged frog (Rana boylii) is at its northernmost range margin and has experienced an approximately 41% range contraction compared to their historical distribution. To inform conservation and management, we used species distribution models to identify environmentally suitable watersheds based on intrinsic baseline environmental variables, and then examined potential effects of human-caused alterations to rivers, including splash dams used to ferry timber downstream prior to 1957, large water impoundments, and adjacency to agricultural croplands. We used machine-learning in program Maxent and three different river layers that varied in extent and location of mapped rivers but contained distinct information to produce species distribution models which we then combined into a single ensemble model. Stream order, annual precipitation, and precipitation frequency were the highest ranked baseline environmental variables in most models. Watersheds with highly suitable baseline conditions in our ensemble model were negatively correlated with anthropogenic disturbances to rivers. Foothill yellow-legged frogs appeared to be sensitive to human-caused disturbances to rivers, perhaps indicative of their narrow ecological tolerance to in-river conditions. We do not anticipate variables in our model to change much through time. Rather, for conservation we identified potential legacy (spash dams) and ongoing human-caused disturbances that are more likely to change conditions for the species in the short- and long-term.

Landscape Dynamics in an Iconic Watershed of Northwestern Mexico: Vegetation Condition Insights Using Landsat and PlanetScope Data

Natural vegetation in arid and semi-arid environments of Northwestern Mexico has been subject to transformation due to extensive and intensive human occupation related mostly to primary activities. Keystone habitats such as riparian ecosystems are extremely sensitive to land use changes that occur in their surrounding landscape. In this study, we developed remote sensing-based land cover classifications and post-classification fragmentation analysis, by using data from Landsat’s moderate resolution sensors Thematic Mapper and Operational Land Imager (TM and OLI) to assess land use changes and the shift in landscape configuration in a riparian corridor of a dynamic watershed in central Sonora during the last 30 years. In addition, we derived a high spatial resolution classification (using PlanetScope-PS2 imagery) to assess the “recent state” of the riparian corridor. According to our results, riparian vegetation has increased by 40%, although only 9% of this coverage corresponds to obligate riparian species. Scrub area shows a declining trend, with a loss of more than 17,000 ha due to the expansion of mesquite and buffelgrass-dominated areas. The use of moderate resolution Landsat data was essential to register changes in vegetation cover through time, however, higher resolution PlanetScope data were fundamental for the detection of limited aerial extent classes such as obligate riparian vegetation. The unregulated development of anthropogenic activities is suggested to be the main driver of land cover change processes for arid ecosystems in this region. These results highlight the urgent need for alternative management and restoration projects in an area where there is almost a total lack of protection regulations or conservation efforts.