Migratory Pollinators Program
Table 9.
d(%)
VSMOW (Vienna Standard Mean Ocean Water) of saguaro resources and surface water
as a function of date sampled. Means �
SE, and sample sizes (n) are presented. An asterisk denotes the onset of
summer monsoon rains. Note that surface water enriches in dD
slightly as a result of evaporative fractionation before the onset of monsoon
rains. After rains, the composition of surface water approaches that of
rainfall. The temporal variation in isotopic composition in both saguaro
resources and rainwater is small relative to the turnover of the deuterium pool
in doves. However, the use of deuterium as a resource tracer for saguaro
consumption requires monitoring the composition of both sources.
|
|
Nectar |
Fruit |
|
|
5/24/98 | 6/11/98 |
6/20/98 | 7/20/98 |
8/20/98 |
| Saguaro |
19.6 � 3.3 |
26.4 � 3.2 |
47 � 3.1 |
50.5 � 2.3 |
41.3 � 3.5 |
| (9) | (13) |
(17) | (47) |
(19) | |
| Surface Water |
-22.4 | -20.2 |
-18.8 | -34.1 | -36.2 |
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