ML645022439

观察细节

These sound like two different call types, but I'm not certain. There is a pretty clear Type 4 call, which is the expected type but the other appears to be slightly lower frequency and a simpler shape in the spectrograph (and perhaps burrier too). It's similar to the shape of Type 3 but not quite the same (which would be really interesting because that is the type most frequently seen in the east). Perhaps it's just a Type 4 calling from further away but not sure that fully explains the lower frequency and apparently different shape.