Figure 1.
Long Point, Lake Erie, ON, Canada showing tower locations (Points A–E) used in fall 2009.
The directions each antenna were pointing (fall 2009) are shown with red arrows. In fall 2008 and spring 2009 towers A and B were not present and tower D was fitted with 4 antennae and situated approximately 4 km W of the location noted. Banding locations were within 200 m of towers as follows: Mainland (A), Old Cut (C), Tip (E).
Table 1.
Flight and movement data from 322 individuals of 6 species of birds and 1 species of bat tracked during fall 2008, spring 2009, and fall 2009 using radio-telemetry at Long Point, Ontario, Canada.
Figure 2.
A probable migratory departure for a Black-throated Blue Warbler.
Variation in signal strength (arbitrary scale from 0–255) by multiple antennae on three towers (see Figure 1 for locations) is plotted by time. Black vertical lines are sunset; orange dashed lines are sunrise. Left most panel shows all detections in ∼48 h prior to departure; the right panel repeats the last ∼70 minutes of detection (during departure) on an expanded time scale. Reading from left to right (left hand panel), the individual is active up to sunset (high variation in signal strength) and relatively inactive during the night (low variation in signal strength). At sunset on 24 Sept (right hand panel) there is a rapid increase followed by a short period (∼30 min) of low variation in signal strength suggesting the individual moved to a more exposed location just prior to initiating a migratory flight of ∼35 min. The migratory flight is shown by a sharp increase in signal strength at ∼0015 (see peaks on A–S and A–N antennas), followed by detections on tower B and C situated to the South. Final detections show declining signal strength on the C–S antenna suggesting that the individual flew directly south across Lake Erie.
Figure 3.
A stopover flight and probable migratory departure for a Black-throated Blue Warbler.
Figure notation as for Figure 2. The individual was tagged at the Tip (near tower E) on the morning of 24 Sept and remained in the vicinity of the Tip for two days. During the night, signal strength is generally constant, whereas during the day, signal strength varies continuously as the individual moves around. Approximately mid-way through the night of 26 Sept the individual makes a stopover flight – It flies west and settles near tower C. It remains there for two more full days, before departure after sunset on 28 Sept. The middle and right hand panels provide a more detailed view of the detections for the stopover flight and departures, respectively. Note that the stopover flight (middle panel) was ∼30 km over 1.5 h (flight speed of 20 km/h) suggesting that the movement was a single flight. The individual was relocated after the movement. Note that for the departure flight (right panel) the individual was detected leaving the vicinity of tower C to the east (last detections on antenna C–E), then traversed the beam of tower D–W while simultaneously being detected on the west antenna at the Tip (E–W). It was last detected traversing the beam of the south antenna at the Tip (E–S). The pattern suggests a SE departure over Lake Erie.