Invasive species are often implicated in population declines of native species
through competition and predation. Red imported fire ant (Solenopsis invicta) predation
of songbird nestlings and eggs has been documented. I conducted a replicated
manipulative experiment to determine the magnitude of the decrease in nest survival
caused by S. invicta in addition to other predators. I conducted mensurative experiments
to quantify the frequency of S. invicta foraging near active songbird nests and factors
that influence the susceptibility of songbird nests to S. invicta predation. I hypothesized
that predation by S. invicta reduced nest survival by 10%, potentially biologically
significant, and that songbird nests would be more susceptible to S. invicta predation that
were located: (1) closer to the ground, (2) closer to an edge, (3) closer to disturbed soils,
and (4) initiated later in the breeding season. I monitored 235 songbird nests including
45 black-capped vireo (Vireo atricapilla), 67 white-eyed vireo (V. griseus), and 123
northern cardinal (Cardinalis cardinalis) nests on 9 patches of 36–103 ha each on
private land in east-central Texas, USA in 2006–2007. I found preventing S. invicta
from preying upon songbird nests increased nest survival 20% for white eyed vireos and
1% for black-capped vireos. I detected S. invicta near songbird nest on 60% of food
lures on the ground and 7% of food lures 1 m high in vegetation (n = 122). Vireo nests <2 m high and <4 m from an edge were more susceptible to S. invicta predation
indicating potential threshold conditions, below which songbird nests may be more
susceptible. If my results are applicable to other areas then songbird populations of
some species nesting below 2 m may have substantially lower nest survival in areas
occupied by S. invicta. I suggest the negative impacts of S. invicta on songbird nest
survival may be reduced by applying integrated pest management methods and
increasing woody vegetation cover in breeding areas of songbird species susceptible to
S. invicta nest predation.
| Identifer | oai:union.ndltd.org:tamu.edu/oai:repository.tamu.edu:1969.1/ETD-TAMU-2843 |
| Date | 15 May 2009 |
| Creators | Campomizzi, Andrew J. |
| Contributors | Morrison, Michael L. |
| Source Sets | Texas A and M University |
| Language | en_US |
| Detected Language | English |
| Type | Book, Thesis, Electronic Thesis, text |
| Format | electronic, application/pdf, born digital |
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