Hi recordist of the world:
I am planning to do a short research on diversity, richness, abundance and
seasonality of migrants and resident birds in coffee plantations in the
central region of Veracruz state, Mexico. By this kind of research most
researcher have been used the fixed-radius point count method which is
currently a widely used method for censusing birds in both the understorey
and canopy of forest habitat. That method count all birds seen or heard
within a distance of 25 m for a period of 10 or 15 minutes. As you know the
sound recording is frequently used in conjuntion with playback to attract
birds to the observer so that they may be identified visually or to attract
them to the vicinity of traps. Playback also are used occassionally as aura=
l
sitimuli during point counts to increase the detectability of a given
species or to suerve otherwise secretive or nocturnal species. However,
fewer researcher have used sound recordings as a method of surveying avian
communites. Recently, two researcher made a comparison of point count and
sound recording as bird survey methods in Peru. For the sound recording the=
y
used a Marantz PMD 222 and a Sennheiser ME 66 mic capsule with a K-6 power
supply covered by a foam windshield. They mention that ME 66 is very high
sensitivity (free-field noload transmision factor [1 kHz] =3D 35 mVPa-1 +/-
2.5 dB) such that even very quiet signals are recorded at a good level. The=
y
placed the mic in a clamp attached to a handle that was hand-held by an
assitant at an angle of 20=B0 above the horizontal and they change the
orientation of the mic at regular intervals during the recording period.
Any of you could explain me what does mean that information between
parenthesis?. However, they concluded perhaps the most effective technique
four using sound recording to survey bird populations is to use an
omni-directional microphone capsule, thus eliminating the need for changes
in mic direction.
Recordist, i have three types of mic which i think are omni-directionals:
Sennheisser ME 20 (powering module K3-U), Telinga Digital Stereo and Teling=
a
Twin Science. I think to use a Marantz PMD tape recorder, although is
possible use Walkman Minidisc or Marantz PMD 650 too. I think to do the
recording early in the morning, maybe from 06:00 to 10:00 AM.
I have the following questions?
1) What will be the best mic for my purpose? Record during 10 min and after
try to identificate all species present in that point count.
2). The Telinga Mics must be used without dish?
3) I think to place the mic on a tripod in the center of the point count,
but what will be the best way to aimed the mic?. toward the canopy,,
subcanopy or understorey? Vertical or horizontal?
4) What will be the best height to place the mic from the ground?
5). Is there any way to know which is the detection threshod for each of my
mic?
6). Is there any way to know what sound will be inside a 25 m distance?
7). Must i do stereo or mono recording?
Thanks a lof for your help
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