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* Specific Microclimate Conditions for Ground Nesting Warblers Taylor Naiman Young1, Tami Ransom1, Eric Liebgold2, Jacob O’Neil1, and Ravyn Saunders2
1Environmental Studies Department and 2Department of Biological Sciences, Salisbury University
Introduction • Worm-eating Warblers (Helmintheros
vermivorum) and Ovenbirds (Seiurus aurocapilla) are migratory, forest interior-dwelling songbirds
• Both are small ground nesting birds that compile nests out of leaf litter
• As ground-nesters, these warblers face many threats such as:
-Predators including raccoons, opossums, snakes, and squirrels
- Brown-headed Cowbirds (Molothrus ater),which are nest parasites
- Invasive earthworms, which may reduce leaf litter depth
• Nest success is low at 50% and fledglings often do not make it through their first migration
• Given this, it is important to understand where these warblers choose to nest and why
Hypothesis Because these birds nest on the ground, and are at risk of predation, I predicted that there must
be certain sought out conditions at the nest sites that differ from control sites.
Methods and Processes • From mid May to early July we were in the field
early to find nests while birds were active till around noon at either Nanticoke River Wildlife Management Area or Hazel Outdoor Discovery Center sites.
• Found nests by following the males to the female, then to the nest or by flushing a female off of her nest while incubating.
• Collected nests when empty. • Tagged and mist netted to keep track of
territories (Far Controls). • Placed camera traps at nests to monitor
predation and fledging. • Placed iButtons at nests and close controls (10m
away from nest) to monitor temperature. • Looked at camera trap photos to see if or what
predated the nest. • Collected invertebrates to record bird feeding
conditions. • Took vegetation recordings to determine nesting
site preferences. • Added findings and recordings to previous two
years of data.
Conclusions Results
Fig. 1 Average % of pine in leaf litter at nest sites, near controls, and far controls. On average, nest sites had significantly more pine in the leaf litter than near controls (F3,53=3.36, p=0.043).
Fig. 2 Average number of pine trees in a 5m radius around nest site, near controls, and far controls. Though not significant, both nest sites tended to have more more pine trees than near or far controls (F3,53=2.02, p= 0.143).
Fig. 3 Total number of trees in a 5m radius around nest sites, near controls, and far controls. There was no difference in the number of trees among the three types of sampling sites ( F3,53=1.35, p=0.263).
Fig. 4 Average percent cover at 30cm height at nest sites, near controls, and far controls. Though not significant, both nest sites and near controls tended to have more direct cover than far controls (F3,53= 2.00, p= 0.146)
Future Research
Fig. 6 Average leaf litter depth (mm). There was no difference in leaf litter depth among nest sites, near controls, and far controls (F3,53=0.85, p=0.433).
Acknowledgments
• In the Fall we will measure and record invertebrates we collected in late June to early July.
• We will sample earthworms as they may influence leaf litter, soil, and understory vegetation
• We will continue the same research next year to increase our nest and iButton data.
• Additional data (e.g., invertebrate data) will be analyzed in the Fall.
• The Guerrieri Summer Research Program and Dr. Stoner • Environmental Studies Department and the Fulton School • Dr. Ransom and Dr. Liebgold for all their advisement • Jake O’Neil, Ravyn Saunders, Dylan Ferris and Ryan Tant
for all their help in and out of the field
Fig. 5 Average temperature (oC) from iButton data. There was no difference in average temperature (oC) between nest locations and near controls (F3,53=0.01, p=0.922).
• The warblers preferred places with more pine trees and pine in the leaf litter rather than large leafy trees (Fig. 1 and Fig. 2).
• Both species of warblers built their nests in wooded areas (Fig. 3), but the tree density at nest sites didn’t differ from the surrounding forest.
• Warblers tended to build nests in places with small shrubs or vegetation near the ground (Fig. 4), likely as a means of concealment.
• We did not find a difference in the iButton data in temperature between nests and near controls (Fig. 5). This implies either that warblers are not choosing nest sites with a particular microhabitat in terms of temperature or that the microhabitat temperature is similar at least as far as 10 m away from nests (at the site of near controls).
• Surprisingly, we did not find greater leaf litter depth at nest sites compared to the two controls (Fig. 6).
Personal Information: Taylor Naiman Young Major- Environmental Studies Minor- Chemistry [email protected]
• We found 14 nests in 2015, each with a control site. • 50% of nests in 2015 were predated. • The following analyses combine data from 2014 and 2015. • N=21,16 for near controls (~10m from nest), and 16 for far controls (>10m from nest sites)
throughout.
16 21 21
0
2
4
6
8
10
12
Nest Near Control
Far Control
Num
ber
of T
rees
Sites Where Data was Collected
Nest
0
5
10
15
20
25
30
35
40
45
50
Nest Near Control
Far Control
Avg.
Lea
f Li
tter
Pin
e (%
)
Sites Where Data was Taken
Nest
0
0.5
1
1.5
2
2.5
3
3.5
4
4.5
Nest Near Control
Far Control
Num
ber
of P
ine
Tree
s
Sites Where Data was Collected
0
5
10
15
20
25
30
Nest Near Control
Far Control
Avg.
Per
cent
Cov
er
Sites Where Data was Collected
Nest
17
17.5
18
18.5
19
19.5
20
20.5
21
Nest Near Control
Avg.
Tem
pera
ture
(oC
)
Sites Where Data was Collected
N=7 N=7
0
5
10
15
20
25
30
35
Nest Near Control
Far Control
Leaf
Lit
ter
Dep
th (
mm
)
Sites Where Data was Collected
Nest Nest
Nest
