Automatic identification of bird targets with radar via patterns produced by wing flapping

Abstract

Bird identification with radar is important for bird migration research, environmental impact assessments (e.g. wind farms), aircraft security and radar meteorology. In a study on bird migration, radar signals from birds, insects and ground clutter were recorded. Signals from birds show a typical pattern due to wing flapping. The data were labelled by experts into the four classes BIRD, INSECT, CLUTTER and UFO (unidentifiable signals). We present a classification algorithm aimed at automatic recognition of bird targets. Variables related to signal intensity and wing flapping pattern were extracted (via continuous wavelet transform). We used support vector classifiers to build predictive models. We estimated classification performance via cross validation on four datasets. When data from the same dataset were used for training and testing the classifier, the classification performance was extremely to moderately high. When data from one dataset were used for training and the three remaining datasets were used as test sets, the performance was lower but still extremely to moderately high. This shows that the method generalizes well across different locations or times. Our method provides a substantial gain of time when birds must be identified in large collections of radar signals and it represents the first substantial step in developing a real time bird identification radar system. We provide some guidelines and ideas for future research.

Adjustments of wingbeat frequency and air speed to air density in free-flying migratory birds

“…In birds, the echo signature mirrors their wingbeat pattern (Bruderer, 1969;Bruderer, 1997) whereas in insects the complicated structure of the echo signature consists probably of a mixture of wing and other body movements (Schmaljohann et al, 2008a;Zaugg et al, 2008). Bird echoes can be assigned to groups of different flight styles according to their wingbeat pattern (Bruderer, 1969;Bruderer, 1997;Schmaljohann et al, 2008a;Zaugg et al, 2008): (a) continuously flapping flyers (waders, waterbirds, gulls, terns, rails, etc.…”

“…With the tracking radar 'Superfledermaus' we recorded the echo signature of birds, i.e. the temporal variation of energy reflected by the bird (Schmaljohann et al, 2008a;Zaugg et al, 2008). This variation in the received signal mirrored the wingbeat pattern of the bird and can, therefore, be used for echo identification (Houghton, 1969;Bruderer and Joss, 1969;Bruderer, 1997;Schmaljohann et al, 2008a;Zaugg et al, 2008).…”

“…the temporal variation of energy reflected by the bird (Schmaljohann et al, 2008a;Zaugg et al, 2008). This variation in the received signal mirrored the wingbeat pattern of the bird and can, therefore, be used for echo identification (Houghton, 1969;Bruderer and Joss, 1969;Bruderer, 1997;Schmaljohann et al, 2008a;Zaugg et al, 2008). In doing so, recorded tracks were assigned to one of the three flight styles: (1) continuously flapping (flapping, such as waders and ducks), (2) irregular flapping and gliding (flap-gliding, such as swifts), and (3) regular flapping and bounding (bounding, such as songbirds).…”

An Objective Prototype-Based Method for Dual-Polarization Radar Clutter Identification

“…For Doppler radar data, insect echoes are a passive tracer for air motion. However, birds/bats have different Doppler velocity characteristics from wind fields [32][33][34]. Zhang et al [35] and Liu et al [36] identified the velocity contamination of migrating birds for WSR-88D radars.…”

Lattitude, Longitude, and Beyond : Mining Mobile Object's Behavior

“…Examples include detection and classification of people when walking [28][29][30], finding the number of people present in the environment from their heartbeat patterns [31], distinguishing human from four legged animals [32], classification of different species by physiological characteristics [33]. Radar has been used to retrieve continuous spatio-temporal data on bird migration [34,35], and to retrieve birds' flying characteristics such as height, velocity, direction, and density regardless of the time of fly.…”