Seabirds At-Sea Surveys: The Line-Transect Method Outperforms the Point-Transect Alternative

Seabirds At-Sea Surveys: The Line-Transect Method Outperforms the Point-Transect Alternative

Methods: We tested whether modeling of detection probabilities, and density estimates with their coefficients of variation obtained from the point-transect method provided more robust and precise results than the more commonly used line-transect method. We subdivided our data by species groups (alcids, and aerialist species), and into two behavior categories (flying vs. swimming). We also compu...

Line transect methods for plant surveys.

Interest in surveys for monitoring plant abundance is increasing, due in part to the need to quantify the rate of loss of biodiversity. Line transect sampling offers an efficient way to monitor many species. However, the method does not work well in some circumstances, for example on small survey plots, when the plant species has a strongly aggregated distribution, or when plants that are on th...

Point Transect Surveys for Songbirds: Robust Methodologies

Parametric models for line transect surveys

With data from line transeot surveys, the pattern of distances at which animals are detected provides the information for estimating the area which the observer effectively surveys. This paper suggests a parametric structure for the problem wherein this area is characterized by an effective half-width parameter which appears as a scale parameter in the distributions of detection distances. Seve...

Point process models in line transect studies

In visual line transecting, whales are observed when surfacing to breath. Surfacings are short. Point process models for surfacing times are combined with a model for the hazard probability of initial sighting to obtain a likelihood for the observed encounters. Point processes are also useful for describing the clustering of encounters along the track line due to spatial clustering of whales.