Transcript Slide 1

Composition of the Songbird Community
at the DePauw Nature Park and Arboretum
Libby Allard, V. Artman, K. Reed, K. Koehler, Department of Biology, DePauw University, Greencastle, IN 46135
Red-eyed Vireo (REVI)
Acadian Flycatcher (ACFL)
Indigo Bunting (INBU)
Black-and-white warbler
Generally, songbird populations were higher in 2005 than 2004. Populations of all species increased except for the
Indigo Bunting. The Cerulean Warbler, a rare and dangerously declining species in North America, showed higher
populations in 2005 but only occurred in both years at Quarry South. Despite Ohio’s larger sites, the 2005 Cerulean
Warbler population at Quarry South was over double that of Ohio.
Introduction:
DePauw’s Arboretum and Nature Park contain many different habitats. Vegetation and forest
continuity vary, affecting the fauna that inhabit different regions. We collected data on songbird
and plant communities at three forested sites: the Arboretum (ARB, 5 ha), Quarry South (QS, 10
ha), and Quarry Hillside (QH, 10 ha). Until recently there have been little data collected
describing the composition of the songbird community at the three DePauw sites. Comparable
data were collected in Ohio at four 25-30 ha sites from 1995 to 1999. The Ohio forest was used
as a comparison because some species of songbirds that range from Indiana to Ohio are only
present in the Ohio sites. The sites in Ohio also represent relatively undisturbed mature forest,
dominated by a mix of oak and hickory, typical overstory trees in the region. The sites in Ohio are
also situated in a relatively unfragmented landscape. Here, we describe the composition of the
songbird community within these sites, examining the relationship between songbirds and the
habitat characteristics, and comparing our data with data collected in similar conditions in Ohio.
Northern Cardinals were the predominant bird species in both the Arboretum and Quarry Hillside, while Acadian
Flycatchers were the predominant bird species in Quarry South. Wood Thrush levels were much lower at the DePauw
sites than those in Ohio. Red-eyed Vireo levels were highest in the Arboretum, but are comparable to those of Ohio. In
Ohio, however, Acadian Flycatchers were in the minority with Ovenbirds having the dominant population percentage.
Although the Ovenbird range encompasses westcentral Indiana, Ovenbirds were absent from the DePauw sites. Other
breeding species that were present in Ohio but absent in DePauw’s sites were the Black-and-white Warbler, the
Hooded Warbler, and the Worm-eating Warbler.
Songbird populations
(# of territories per 10 hectares)
Differences in songbird communities between Indiana and Ohio sites are related to the age of the
forest and possibly to the extent of forest fragmentation.
Methods:
We collected vegetation data at randomly located plots and nest sites following BBIRD protocol.
We counted shrubs and seedlings by species and size class within a 5 m radius of each random
point and nest and estimated percent cover of understory vegetation. Within an 11.3 m radius we
counted trees and snags (dead trees) by species and size class. We cored one tree at each plot
to estimate the relative age of the forest. We measured height of nests.
2005
2004
2005
2004
2005
1995-99
Acadian flycatcher
9.1
11.0
8.8
12.1
12.0
14.8
3.3
Eastern wood-pewee
1.8
7.3
4.4
6.6
0.9
3.7
1.9
Red-eyed vireo
16.4
14.6
9.9
8.8
9.3
7.4
10.5
Tufted titmouse
3.7
7.3
9.9
5.5
4.6
3.7
0.5
0
0.0
0
0
3.7
5.6
2.6
Northern parula
3.7
3.7
0.0
2.2
1.9
2.8
0
Ovenbird
0.0
0
0
0
0
0
10.2
Black-and-white warbler
0
0
0
0
0
0
0.9
Hooded warbler
0
0
0
0
0
0
2.3
Worm-eating warbler
0
0
0
0
0
0
2.5
Scarlet tanager
1.8
3.7
1.1
3.3
1.9
1.9
3.3
Eastern towhee
5.5
9.1
3.3
2.2
3.7
4.6
0
Northern cardinal
18.3
18.3
9.9
13.2
9.3
11.1
0.5
Indigo bunting
12.8
9.1
3.3
3.3
12.0
9.3
0
Other
40.2
47.5
40.7
39.6
31.5
44.4
17.5
Total
85.8
98.6
68.2
69.3
68.5
83.3
40.4
DePauw sites
2004
1995-1999
2004
2005
2005
# of nests monitored
12
12
95
7
5
# of successful nests
6
7
52
2
2
Observation days
5
5
40
3
3
133
266
1471
85.5
37
5.6
5.4
5.2
5
4.8
4.6
Successful
Failed
120
100
80
60
40
20
0
Shrubs
Trees
Trees
ARB
95.5%
98.1%
97.3%
94.2%
100
random
ACFL nest
80
60
40
The Cerulean Warbler is another species which provokes interest. Population levels for
2004 and 2005 were both larger than that of Ohio, but only in Quarry South. Quarry Hillside
and the Arboretum have no Cerulean Warblers. Why was this species only found in Quarry
South? After analyzing the vegetation data in the CERW territories, they seem to prefer
similar conditions as the ACFL. No CERW nests could be found, so nesting success
couldn’t be calculated. The large population levels in Quarry South may be attributable to
either (a) events during migration or on wintering grounds affecting mortality in the CERW
population* or (b) microscopic parasites negatively affecting population levels in Ohio.
Northern Cardinal and Indigo Bunting levels were much higher than in Ohio. NOCA is an
edge-dwelling, fragmentation-loving species.* In our sites they only chose territories along
borders (powerlines, streams, or meadows). As the Indiana forest ages, there will be less
clearings and more dense forest—thus, NOCA levels may decline as there will be less
suitable habitat. INBU is an early successional species that is usually found in meadows.*
Surprisingly, they were common in Quarry South and preferred to nest in the low shrubs
growing throughout this site. Their populations may decline in future years as understory
decreases and tree height increases.
0
Shrubs
QH
Further research on the topic of songbirds is important because it relates to the health of the
ecosystem and may provide information that affects forest management decisions. On a
more specific level, further research may address specific species of songbirds, some of
which are of significant conservation concern.
20
Shrubs
Trees
QH
Trees
Ohio
sugar maple
91.9%
ACFL chose nest sites where there was less understory, which is consistent with the
evidence that ACFLs prefer a more mature forest. However, our data show that ACFL
nesting success was actually higher at DePauw’s sites than in the more mature forests in
Ohio. Higher nest placement for ACFL was positively correlated with nesting success in
previous studies.* Thus, a more mature forest would have taller trees and more successful
nests.* Contrary to this evidence, our initial data suggests that lower nests were more
successful. However, our data are inconclusive given small sample sizes. We also found
that smaller diameters of ACFL nesting trees may positively affect nesting success. Some
nest predators may only be able to climb larger trees to consume nest contents, leaving
nests in smaller trees protected.
120
120
100
80
60
40
20
0
slippery elm
Daily nest survival rate
Acadian Flycatcher levels at our sites were surprisingly large, considering the habitat
preference of the species. ACFLs are typically associated with mature forest, along with the
Worm-eating Warbler, Hooded Warbler, Black and White Warbler, Red-eyed Vireo, Wood
Thrush, and Ovenbird.* The three warbler species and Ovenbird were absent from the
Nature Park, while ACFLs were abundant. Why the difference? It is possible that since the
Ohio sites were so large, ACFLs were more spread out, having fewer territories per unit of
area. This does not explain why levels were so high in the Nature Park, though. Even more
surprising is that while the Arboretum is the oldest of the three sites with the typically most
ideal conditions for the ACFL (less understory and more mature trees), QS seemed to
attract the most ACFLs. As an insectivore, ACFLs may possibly be attracted to the greater
number of mosquitoes in QS.
Implications and Future Research:
ARB
# of Stems
Ohio sites
5.8
QS
QH
# of Stems
DePauw sites
# of Stems
The daily nest survival rate of the Acadian Flycatcher increased by roughly 2.5% between 2004
and 2005, and the 2005 rate exceeds that of Ohio. The daily nest survival rate of Indigo Bunting
decreased by 3% from 2004 to 2005.
Indigo Bunting
ACFL nesting success vs nest height
The age of the forest stands in the Arboretum was estimated at 100 years, while both Quarry Hillside and Quarry
South were estimated between 30-60 years. Forests at the Ohio sites were estimated to be slightly more
mature (100-120 years). Understory vegetation in the Arboretum was generally less dense than that of Quarry
Hillside or Quarry South. Acadian Flycatchers typically selected nest sites with less understory vegetation within
the forest.
Results:
Acadian Flycatcher
Ohio
2004
Cerulean warbler
We conducted bird surveys during May and June. We recorded locations of singing and calling
birds. Twelve bird surveys were conducted, four at each site, between the hours of 5am and
10am. We made a map for each bird species and plotted points where each observation
occurred. We used clusters of observations to estimate the relative number and position of
breeding pairs and their territories. Also, we collected nesting success data during the breeding
season. BBIRD protocol (Martin et al. 1995) was used when searching for and monitoring nests.
Nests were revisited every 3-5 days until the nest was no longer active. Daily nest survival rates
were calculated using the Mayfield method.
Quarry
South
Nest Height
Arboretum
Hypothesis:
# of nests failed due to predation
Quarry
Hillside
Discussion:
box elder
hickory
Further research could address important ecological concerns, such as:
 What environmental factors could further increase population levels of the Cerulean
Warbler?
 How could we manage the Nature Park to attract additional species of native songbirds,
such as the Ovenbird and Hooded Warbler?
 How does the composition of invertebrates affect the type of songbirds abiding in the
three study sites?
 Does a correlation exist between levels of leaf litter and abundance and distribution of
songbirds?
 How do we minimize spread of invasive plant species without affecting songbird habitat?
ash
black cherry
walnut
sassafrass
Acknowledgments: A thank you to my group, my professor, and my parents, who made this project possible.
Other
Shrubs
and
Saplings
ARB
ash
QS
QS
Ohio
sugar maple
spicebush
serviceberry
dogwood
coralberry
pawpaw
Cerulean Warbler (CERW)
Scarlet Tanager (SCTA)
Ribes
Hooded Warbler (HOWA)
rose
greenbrier
box elder
grapevine
slippery elm
Other
Ovenbird (Oven)
Wood Thrush (WOTH)
Worm Eating Warbler (WEWA)