紧急 4月RC GWD原题

是不是这篇？有待求证......

1.        GWD-25-Q13-Q15 songbirds筑巢的成功率

Grassland songbirds often nest in

the same grassland-wetland complexes

as waterfowl, particularly in a certain

Line part of those complexes, namely,

 (5) upland habitats surrounding wetlands.

Although some wildlife management

procedures directed at waterfowl, such

as habitat enhancement or restoration,

may also benefit songbirds , the impact

(10) of others, especially the control of

waterfowl predators, remains difficult to

predict. For example, most predators

of waterfowl nests prey opportunistic-

ally on songbird nests, and removing

(15) these predators could directly increase

songbird nesting success. Alterna-

tively, small mammals such as mice

and ground squirrels are important

in the diet of many waterfowl-nest

(20) predators and can themselves be

important predators of songbird

nets. Thus. Removing waterfowl-nest

predators could affect songbird nesting

success through subsequent increases

(25) in small-mammal populations.

In 1995 and 1996, researchers

trapped and removed certain waterfowl-

nest predators. primary raccoons and

striped skunks, then observed subse-

(30) quent survival rates for songbird nests.

Surprisingly. They observed no sig-

nificant effect on songbird nesting

success. This may be due to several

factors. Neither raccoons nor striped

(35) skunks consume ground squirrels,

which are important predators of song-

bird nests. Thus, their removal may

not have led to significant increases

in populations of smaller predators.

(40) Additionally, both raccoons and striped

skunks prefer wetlands and spend little

time in upland habitats; removing these

species may not have increased the

nesting success of songbirds in the

uplands enough to allow detection.