Kauai and Maui Lidar derived environmental layers for bird habitat modelling
Gallerani, Erica (2023), Kauai and Maui Lidar derived environmental layers for bird habitat modelling, Dryad, Dataset, https://doi.org/10.5068/D1N682
Translocation, often a management solution reserved for at-risk species, is a highly time-sensitive intervention in the face of a rapidly changing climate. The definition of abiotic and biotic habitat requirements is essential to the selection of appropriate release sites in novel environments. However, field-based approaches to gathering this information are often too time intensive, especially in areas of complex topography where common, coarse-scale climate models lack essential details. We apply a fine-scale remote sensing-based approach to study the 'akikiki (Oreomystis bairdi) and 'akeke'e (Loxops caeruleirostris), Hawaiian honeycreepers endemic to Kaua'i that are experiencing large-scale population declines due to warming-induced spread of invasive disease. We use habitat suitability modeling based on fine-scale lidar-derived habitat structure metrics to refine coarse climate ranges for these species in candidate translocation areas on Maui. We found that canopy density was consistently the most important variable in defining habitat suitability for the two Kaua'i species. Our models also corroborated known habitat preferences and behavioral information for these species that are essential for informing translocation. We estimated a nesting habitat that will persist under future climate conditions on east Maui of 23.43 km2 for 'akikiki, compared to the current Kaua'i range of 13.09 km2. In contrast, the novel nesting range for 'akeke'e in east Maui was smaller than its current range on Kaua'i (26.29 km2 versus 38.48 km2, respectively). We were also able to assess detailed novel competitive interactions at a fine scale using models of three endemic Maui species of conservation concern: 'ākohekohe (Palmeria dolei), Maui 'alauahio (Paroreomyza montana), and kiwikiu (Pseudonestor xanthophrys). Weighted overlap areas between the species from both islands were moderate (<12 km2) and correlations between Maui and Kaua'i bird habitat were generally low, indicating limited potential for competition. Results indicate that translocation to east Maui could be a viable option for 'akikiki but would be more uncertain for 'akeke'e. Our novel multi-faceted approach allows for the timely analysis of both climate and vegetation structure at informative scales for the effective selection of appropriate translocation sites for at-risk species.
An Optech HA-500 dual channel airborne lidar system aboard the Global Airborne Observatory (GAO) was used to collect the lidar point cloud data over east Maui during January 12–14, 2018. During these dates, collection conditions were very good with an absolute positional error of less than 10 cm given previous collections with the same sensor. Flights were performed at an altitude of 2000 m above ground level and a speed of 130 kt. The lidar was configured to have a combined pulse density 200 kHz, scan frequency 34 Hz, and field of view set to 34 degrees. Given these parameters, we computed the point and pulse densities for every 2 m pixel in the coverage. This resulted in 99% of the coverage having point pulse densities between 0.97 and 13.8 pulses m-2 (1.95-37.19 points m-2). Less than 0.03% of the total number of pixels recorded zero pulse returns in the area of interest. Upon visual inspection of these pixels, it was confirmed that most were over water bodies.
These ASCII files can be opened in any GIS software tool (ie QGIS, ArcGIS Pro, etc). Their intended use is in the maximum entropy software (MaxEnt version 3.3.4 k).