Fla. Field Nat. 22(2): 39-47, 1994.
NEST SITES OF FLORIDA SANDHILL CRANES IN
F. CHRIS DEPKIN, LAURA A. BRANDT AND FRANK J. MAZZOTTI
University ofFlorida, : ,. ,: i,'.;' ,*and Range .
118 N.. .... : .. .. . Florida 32611
Abstract.-We located twenty-eight nest sites of the Florida Sandhill Crane in
southwestern Florida during the 1991 breeding season. Similar to other studies, all sites
were classified as palustrine emergent wetlands. Average wetland area and average
maximum depth were 5.96 ha and 0.61 m, respectively. Vegetation assessments at seven
of the sites yielded 82 plant species. Panicum hemilornon,. Poened-
eria cordata and Eleocharis interstincla were the most common species and also contrib-
uted the most cover. vTenty-four of the 28 nests were found in isolated temporary
wetlands of less than 23 ha, which illustrates the i.. : ... ....... relatively small isolated
wetlands. Because of this, the crane population in southwestern Florida may be vulner-
able to pressure from future development. Conservation efforts should recognize the im-
portance of protecting small isolated wetlands within a matrix of uplands.
The Florida ." ...- i- Crane (Grus canadensis pratensis) is one of
three nonmigratory subspecies of the Sandhill Crane. It is estimated
that there are 1-- .......- individuals (Williams 1978, Logan and Nes-
bitt 1987) of this subspecies occurring primarily in central Florida
(Walkinshaw 1976, 1982); however, the range extends from Okefeno-
kee Swamp in southern Georgia (Bennett 1989) to the Everglades
Crane nesting habitat has been described from Loxahatchee Na-
tional '.'. i.' :. Refuge (Thompson 1970) in southeastern Florida, and
from '*'i i River : ..- Park and C. M. Webb Wildlife Management
Area (Bishop 1988, Bishop and Collopy 1987) in west central Florida.
Both of these areas .:i. : to some extent from southwestern Florida.
\11. ... IT. the population in Florida is relatively stable ('. i..:: 1992)
some segments or sub-populations may be declining (Layne 1983).
Probable causes for this decline include direct loss of habitat as well as
drainage of wetlands, which has reduced the ...: -...:: of nest sites
(Layne 1983). Because the i ..... i.. subspecies requires an area with at
least some standing water to initiate nesting (Layne 1981), the re-
maining wetlands in southwestern Florida are of particular concern.
The objective of this study was to determine what was important nest-
ing habitat to cranes in southwestern Florida. Presented here are veg-
etative and topographic descriptions as well as distribution
information on ponds used for nest sites of Florida Sandhill Cranes
found on and around the Immokalee Rise in southwestern Florida.
40 FLORIDA FIELD NATURALIST
The study area, located in southwestern Florida (26 52.5'N to 26 7.5'N and 81
37.5'W, to 800 52.5'W), is 6216 km'and is represented by five physiographic regions (Fer-
nald and Patton 1984) (Fig. 1). The most predominant of the five regions is the Immoka-
lee Rise, which includes most of Hendry county and parts of Lee, Glades and Collier
counties. The central portion of the study area is made up of a mosaic of pine flatwoods
and temporary wetlands, the southern third is primarily cypress forest, and the north-
ern third is agricultural areas.
Historically, before 1940 this area was comprised of marsh and wet prairie (41%/),
pineland systems (29%), cypress stands (18%), and grassy scrub systems (9%) (Univer-
sity of Florida, Center for Wetlands). By 1989 much of this area had been converted to
open range and cattle pasture (28%) and other agricultural uses (18%) (Mazzotti et al.
'. .... -
.'.'..'. ..-. ". -
S A . ATLANTIC
/ -i e -OCEAN
. K "i m"" i l
FL I : 100
0 1cm 100
Figure 1. Study area and physiographic regions of southwestern Florida: l=Ca-
loosahatchee Valley, 2=Immokalee Rise, 3=Southwestern Slope, 4=Big Cypress
DEPKIN ET AL. Florida Sandhill Cranes
Two types of surveys were used between January 1991 and June 1991 to locate crane
nests: 1) aerial surveys and 2) road surveys. Peak nesting at Myakka River State Park
for the years 1984, 1985, 1986 were 9 March, 11 March and 12 March, respectively
ii ; .: 1988); therefore, survey efforts were centered around these dates. A crane nest
site was defined by the presence of a developed platform or the presence of an adult on
the nest. Not all nests were verified as being active.
Most nest sites were classified using National Wetlands Inventory (NWI) maps (Cow-
ardin et al. 1979). Areas were calculated by digitizing wetland outlines from these maps.
Eleven of these nest sites were visited on the ground. Nest diameter and plant species
composition of nest material were recorded when The remaining sites were not
available to us for field inspection; however, aerial surveys suggest they were similar to
those wetlands that were visited in both size and NWI classification.
Wetland topography was determined for the 11 nest sites using a CLS Super Mite la-
ser leveler. Determination of gradient was accomplished by running two transects per-
pendicular to each other through the center of each wetland starting from the outer edge
of the wetland as defined by vegetation type. This was performed on 10 of the 11 sites for
a total of21 transects (at one site only one transect was run). Changes in elevation were
recorded every 9.1, 18.3 or 27.4 meters along the transect depending on the size of the
Plant species cover abundance ratings were determined for seven of the eleven sites
(selection of these sites was based on access) using a cover-abundance scale (Mueller-
Dombois and T'l i 1974) on 29 May, 30 May and 27 June 1991. Vegetation assess-
ments were made from 1-m" plots at intervals of 9.1, 18.3 or 27.4 meters along one
transect through the central portion of the site. Species richness and percent cover-
abundance for each species were determined for each plot using five different vegetation
height classes (submerged, vines, < 1 m, 1 to 2 m, and > 2 m) and 7 different cover
classes: ..... with small cover; few with small cover; numerous but < 5% cover; any
number and 5-25% cover; any number and 25-50% cover; any number and 50-75% cover;
and any number and > 75% cover. Qualitative vegetation assessment for species rich-
ness and relative abundance was conducted at all 11 sites using a meandering survey
S nest platforms were located during aerial :
nests were located in March (14th, 21th, 26th and i. and
six in early May (1st 3rd). One nest was discovered on 8 Feb 1991
during driving surveys. "': 1 was the - active nest found. One addi-
tional nest was reported by a land owner. Of the 28 nest sites 24 were
in temporary wetlands, three were in prairie and one was found in the
confines of an agricultural stormwater detention area. Twenty-eight
percent of the nest sites were located in the northern third of the study
area (N = 8), 64% in the middle third (N = 18) and only 7% in the south-
ern third (N = 2). All nests were in standing water. Fifteen of the nests
were considered to be active by either visually :.: ::: ::::: the presence
of eggs or egg shell fragments or by the persistent presence of an adult
at the platform.
FLORIDA FIELD NATURALIST
Twenty-seven of the 28 nest sites were ::, ..: using NWI maps
and codes. 'i. 28th site was not classified by NWI and was not avail-
able for ground assessment. All 27 sites were classified as palustrine
emergent wetlands with narrow-leaved ... '" ..' vegetation. i- : ..
of those sites (41 ; were narrow-leaved persistent seasonal or sea-
sonal well-drained, 6 sites ( .) were narrow-leaved persistent sea-
sonal, 7 sites (26%) were a combination of narrow and broad-leaved
persistent semipermanent or seasonally well drained. The remaining 3
sites (11 ) were narrow-leaved persistent semipermanent,.
well drained or temporary. All but three of the nests were in isolated
wetlands with well defined boundaries. The three nests not in tempo-
rary wetlands were located in sloughs.
-. width and area of the :...... .. wetlands were deter-
mined from NWI maps. Average length was 328 m 193 SD (N = 23,
range 84-936 m). '.. - width was 194 m + 73 SD (N = 23, : -:: 84-
321 m). Average area was 5.96 ha .. SD (N = 22, range 0.25-22.78
ha). Sixteen nest site wetlands were in or on the edge of pasture while
another nine nests were located in temporary wetlands surrounded by
pine flatwoods adjacent to range or pasture. The remaining three
nests, located in sloughs, also were adjacent to range or pasture.
Four nest platforms were assessed for size and plant species com-
position. Average nest diameter was 99.2 cm 11.87 SD (N = 4, range
116 cm). Nest platforms were constructed from the nearest avail-
able material, in these cases Panicum hemitomon and 7. cor-
data. Size and plant species composition of the nests were consistent
with other studies ...... ... 1970).
maximum ...: .- in relief within wetlands containing
nest sites was 0.61 m + 0.16 SD and ranged from -; to 1.00 m (N =
21). On the average, L:. of the change in relief occurred within the
first :: .' of the transect. This zone generally corresponded to an area
of higher plant species diversity. The central deep-water part of these
wetlands often was dominated by a few plant species I. '. hemit-
omon, Pontederia cordata and Eleocharis sp.) which were common in
many of the nest sites.
r'::. i 7-six 1-m' plots at seven sites were assessed for species rich-
ness and cover-abundance. These surveys yielded 82 plant species, .
total number of species per site ranged from 16 to 33. /''... .
plant species were identified, only (N = 2) of the species occurred at
all seven sites compared with (N = 48) of the species occurring
only at a single site. The most common species were Panicum hemito-
mon (76 of 96 plots).- .. ; .. cordata (60 of 96 plots) and * ia
. (53 of 96 plots). .'ii.:. the five ., 1. classes there were 616
plant occurrences. Of these, 84% (N = 518) were less than 1 m in
height, only 13% (N = 80) exceeded 1 m and no plants were greater
DEPKIN ET AL. Florida Sandhill Cranws
than 2 m in height. The most common species exceeding 1 m in height
were Panicum hemitom on, -" ia lancifolia, 7 .- cordata
and Eleocharis interstincta. The remaining of the occurrences were
either :? ... : .. vegetation ( .) or vines (1%).
: .. plant species accounted for 62% (N = 386) of the occur-
rences in the seven cover classes and 68% of the total relative cover
(Table 1). The species contributing the most relative ;. ..... cover at
the most sites were Panicum hemitomon (25%), .. ... spp. (13%),
Sagittaria lancifolia .' and .. . cordata (6%). Most of the
species that occurred at the sites :1 :1.-:. less than 25% cover at a
One hundred and forty-six plant species were encountered at 11
sites in :.. :::., :. : transects. Many of these species also were found
in the cover-abundance survey. The total number of species per site
ranged from 23 to 58. The number of plant species shared among sites
was similar to that observed in the cover-abundance survey. Only 1%
(N = 2) of the species occurred at all 11 sites whereas (N = 56)
were found at only one site.
Twenty-seven of 28 nest sites were located on private land. Owner-
ship status on one site was undetermined.
Florida Sandhill Cranes rarely initiate nesting unless there is at
least some standing water. The species has been known to delay breed-
ing during years when water levels were unfavorable (Walkinshaw
The 1991 breeding season was preceded by a two-year drought
(NOAA 1990). Although heavy rainfalls in the .. ...: ..." of 1991 may
have helped recharge some of the small temporary wetlands, it :..
not have been enough to recharge some of the more extensive sloughs.
Therefore parts of these sloughs may not have been available as nest-
ing habitat in 1991 but may be available in wetter years. That 24 of 28
crane nests were found in isolated temporary wetlands and only three
of the remaining four sites were found in sloughs illustrates the impor-
tance of temporary ponds as crane nesting habitat during the 1991
:: 'i::: season and probably during years of similar hydrological con-
ditions. It may be that sloughs are more important as nest sites in
years when hydrological conditions are .'* .... : and the sloughs are
The concentration of most of the I .. : i nesting habitat (tempo-
rary wetlands within a mosaic of uplands) within the central portion of
the study area probably accounts for the unequal distribution of nest-
ing throughout the study area. The 1. :i r of the public land (and
hence protected areas) is located in the southern portion of the study
Table 1. Most common species within the seven cover classes at seven Florida Sandhill Crane nest sites. Only those species oc-
curring five or more times in a single cover class are included.
Number of occurrences in cover classes
25-49% 5-24% 3%
3 6 7
1 6 0
2 4 8
0 2 1
5 5 5
9 7 5
0 1 1
0 2 6
23 21 16
1 3 5
0 6 4
6 12 18
0 9 6
7 20 17
Se/aria geniculata 0 0 0 0 0 6 0 0.1 3
Selaria geniculata 0
0 0 0 0 6 0
DEPKIN ET AL. Florida Sandhill Cranes
area and consists of relatively large tracts of cypress and pine forest.
Few crane nests were found in this area. The scarceness of temporary
wetlands within this region makes it less suitable for crane nesting.
General NWI classification and :...... 1 .... .:.'. of these nest
site wetlands indicate that there is more similarity than .i
when comparing wetlands with nest sites. Most of the sites were shal-
low depressions with a gradual change in surface 1A i."':' I'. A
change in plant species composition was observed with an increase in
water depth. Sites also were similar in terms of the major plant species
. Three or four species (; -. hemitomon, .. -ia lanci-
" ., ..; .. cordata and Eleocharis interstincta) were important
contributors to total cover at each site as i as being present at all or
most sites. It may be that these species act to attract cranes to a par-
ticular wetland. 7 : the similarity of the major plant .: : seen
:....... the wetlands, these sites were not monotypic. A single site
could display high plant diversity with the majority of the plant spe-
cies occurring only a few times at a site. Not only are the individual
sites diverse but many of the species encountered occurred at only one
site ... :.. each site unique. This pattern also was observed for verte-
brates within temporary wetlands sampled in the proximity of crane
nest sites (Mazzotti et al. 1992). The high degree of diversity is proba-
bly a function of the temporal, dynamic nature of southern i i..
wetlands. Because of the temporal, dynamic nature of these wetlands,
a site used by cranes for nesting in one :: may not be suitable the
next year. if .... .... it will be important to protect a range of wetlands
that are potentially suitable as crane nest sites. Because of the diver-
i' in flora and fauna among wetlands, protecting a range of wetlands
also will help to ensure the continued existence within the region of a
variety of other wetland-dependent plant and animal :..... such as
pine woods tree frogs, sirens, rails, and wading birds i' : .: et al.
1992; Moler and Franz 1987; Kushlan 1 --- :.
Florida Sandhill Cranes require both upland and wetland habitats
for .- .. -. nesting (i and Williams 1990). The '.... i .- --. pro-
ductivity of cranes is '1- i ::' not only on the presence of wetlands
with suitable ]. .1..,. . ..1 (Layne 1 :i but also proximity to suitable
:.- :. -.. habitat, including uplands (range, pasture and pasture-forest
transition) and wetlands (: i. i :.: and Williams 1990).
The findings of this study were consistent with those found at My-
akka :.. .. State Park by i.. ... (1988). In that study most nest sites
were located in ... emergent wetlands where dominant plants
S hemitomon, ... .'. cordata and Sagittaria spp. occurred.
Carex spp., another important species in her study was not an impor-
tant species in this study. In both studies most nest sites were located
FLORIDA FIELD NATURALIST
next to or in open range or pasture which emphasizes the importance
of the relationship of wetlands and uplands to cranes.
The important difference between Myakka River State Park and
this area in southwestern Florida is that of land ownership. Myakka
River State Park is state-owned and most of the area within its bound-
aries are managed to resemble the "original natural Florida." Whereas
the area in southwestern Florida is mostly privately owned and more
vulnerable to pressure from future development. The continued con-
version of pine flatwoods and temporary wetlands to agricultural uses
will ultimately reduce the availability of habitat important for crane
survival. We have described here the characteristics of crane nest sites
from one year. It will be necessary to further address the question of
crane nest site selection under different hydrological regimes, their
population and breeding status, and habitat use in order to make
meaningful decisions concerning the conservation of cranes in south-
We thank the landowners who not only provided us access to their property, but also
were helpful in identifying areas of crane nesting activity. Special thanks go to K. Mont-
gomery and P. Hinchcliff for help with the aerial surveys. M. McMahon provided invalu-
able assistance with the vegetation identification and transects. Thanks also to B. Pace,
D. Rockers, S. Nesbitt and G. Tanner for critical review of this manuscript. This study
was funded by the South Florida Water Management District as part of contract #C89-
0186 with University of Florida, Institute of Food and Agricultural Sciences. University
of Florida Agricultural Experiment Station Journal Series No. R-03785.
BENNETT, A. J. 1989. Population size and distribution of Florida Sandhill Cranes in the
Okefenokee Swamp, Georgia. J. Field Ornithol. 60:60-67.
BISHOP, M. A. 1988. Factors affecting productivity and habitat use of Florida Sandhill
Cranes: an evaluation of three areas in central Florida for a nonmigratory population
of whooping cranes. Ph. D. Thesis, Univ. of Florida, Gainesville.
BISnoP, M. A., AND M. W. COLLOPY. 1987. Productivity of Florida Sandhill Cranes on
three sites in central Florida. Pages 257-264 in Proc. 1985 Crane Workshop. (J. C.
Lewis and J. W. Ziewitz, eds.) Platte River Whooping Crane Maint. Trust, Grand Is-
COWARDIN, L. M., V. CARTER, F. C. GOLET, AND E. T. LAROE. 1979. Classification of wet-
lands and deepwater habitats of the United States. United States Fish and Wildlife
Service, FWS/OBS-79/31, Washington, D.C.
FERNALD, E. A., AND D. J. PATTON (editors) 1984. Water Resources Atlas of Florida. Flor-
ida State University. Institute of Science and Public Affairs, Tallahassee.
KUSHLAN, J. A. 1978. Feeding ecology of wading birds. Pages 249-297 in Wading Birds.
(A. Sprunt, J. C. Ogden, and S. Winckler, eds.) Research Rept. No. 7 of the National
Audubon Society, Tavernier.
KUSHLAN, J. A. 1982. The Sandhill Crane in the Everglades. Fla. Field Nat. 4:74-76.
LAYNE, J. N. 1981. Dry ground nest of Florida Sandhill Cranes. Fla Fil:d Nat Il.' 5.5-56
DEPKIN ET AL. Florida Sandhill Cranes
LAYNE, J. N. 1983. Productivity of Sandhill Cranes in south central Florida. J. Wildl.
LOGAN, T, AND S. NESBIT'. 1987. Status of Sandhill and ." :.:. Crane studies in
Florida. : 213-126 in Proc. 1985 Crane Workshop. (J. C. Lewis and J. W. Ziewitz,
eds.) Platte River ..:. .. ...Crane Maint. Trust, Grand Island.
MAZZOTTI, F. J,, L. A. BRANDT, L. G. PEARLSTINE, W M. KITCHENS, F. C. DEPKIN, T. M.
OBREZA, N. MORRIS, AND C. E. ARNOLD. 1992. :. - the short and long-term ef-
fects of citrus development on wildlife in southwest Florida. Final Report contract
C89-0186. South Florida Water Management District, West Palm Beach.
MOLER, P. E., AND R. FRANZ. 1987. Wildlife values of small isolated wetlands in the
southeastern coastal plain. .- 234-238 in Proc. of the third SE Nongame and En-
dangered Wildlife : ., !: of Natural Resources, Athens.
MUELLER-DOMBOIS, D., AND H. ELLENBERG. 1974. Aims and Methods of Vegetation
Ecology. John '":: and Sons, Inc., New York.
NESBITT, S. A. 1992. First reproductive success and individual productivity in Sandhill
Cranes. J. Wildl. Manage. 56:573-577.
NESBITT, S. A., AND K. S. WILLIAMS. 1990. Home range and habitat use of Florida Sand-
hill Cranes. J. Wildl. Manage. 54:92-96.
NATIONAL OCEANOGRAPHIC AND ATMOSPHERIC ADMINISTRATION. 1990.
Data Annual Summary: Florida. Technical Report Vol. 94(13). National Oceano-
graphic and Atmospheric Administration, Ashville.
THOMPSON, R. L. 1970. Florida Sandhill Crane nesting on the Loxahatchee National
Wildlife : Auk 87:492-502.
WALKINSHAW, L. H. 1976. The Sandhill Crane on and near the Kissimmee Prairie, Flor-
ida. Pages 1-18 in Proc. Int. Crane :. .. (J. C. Lewis, ed.). Oklahoma State Uni-
versity Publ. and Print, Stillwater.
WALKINSHAW, L. H. 1982. Nesting of the Florida Sandhill Crane in central Florida.
53-62 in Proc. 1981 Crane Workshop (J. C. Lewis, ed.). Natl. Audubon Soc.,
WILLIAMS, L. E., JR. 1978. Florida Sandhill Crane. Pages 36-37 in Rare and endangered
biota of Florida. Vol. 2: Birds (H. W. Kale. I1. ed.). Univ. Presses Florida, Gainesville.