During studies of Florida sandhill cranes (Grus canadensis pralensis), greater sandhill cranes (G. c. tabida), and whooping cranes (G. americana) in Florida, we documented cases where these birds were in contact with human-produced objects that resulted in injury or death. We describe \u3e40 instances in which cranes collided with powerlines or fences, became entangled in string or fishing line, or ingested foreign objects. The effect of human-produced objects on crane populations, particularly small populations, may be significant

FOLK, MARTIN J.

NESBITT, STEPHEN A.

SPALDING, MARILYN G.

English

UNL | Libraries

University of Nebraska - Lincoln
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North American Crane Workshop Proceedings North American Crane Working Group
2001
INTERACTIONS OF SANDHILL CRANES
AND WHOOPING CRANES WITH
FOREIGN OBJECTS IN FLORIDA
MARTIN J. FOLK
Florida Fish and Wildlife Conservation Commission
STEPHEN A. NESBITT
Florida Fish and Wildlife Conservation Commission
MARILYN G. SPALDING
University of Florida
Follow this and additional works at: https://digitalcommons.unl.edu/nacwgproc
Part of the Behavior and Ethology Commons, Biodiversity Commons, Ornithology Commons,
Population Biology Commons, and the Terrestrial and Aquatic Ecology Commons
This Article is brought to you for free and open access by the North American Crane Working Group at DigitalCommons@University of Nebraska -
Lincoln. It has been accepted for inclusion in North American Crane Workshop Proceedings by an authorized administrator of
DigitalCommons@University of Nebraska - Lincoln.
FOLK, MARTIN J.; NESBITT, STEPHEN A.; and SPALDING, MARILYN G., "INTERACTIONS OF SANDHILL CRANES AND
WHOOPING CRANES WITH FOREIGN OBJECTS IN FLORIDA" (2001). North American Crane Workshop Proceedings. 91.
https://digitalcommons.unl.edu/nacwgproc/91
INTERACTIONS OF SANDHILL CRANES AND WHOOPING CRANES WITH FOREIGN 
OBJECTS IN FLORIDA 
MARTIN J. FOLK, Florida Fish and Wildlife Conservation Commission, 1475 Regal Court, Kissimmee, FL 34744, USA 
STEPHEN A. NESBITT, Florida Fish and Wildlife Conservation Commission, 4005 South Main Street, Gainesville, FL 32601, USA 
MAR.ll, YN G. SPALDING, Department ofPathobiology, P.O. Box 110880, University of Florida, Gainesville, FL 32611, USA 
Abstract: During studies of Florida sandhill cranes (Grus canadensis pralensis), greater sandhill cranes (G. c. tabida), and 
whooping cranes (G. americana) in Florida, we documented cases where these birds were in contact with human-produced 
objects that resulted in injury or death. We describe >40 instances in which cranes collided with powerlines or fences, became 
entangled in string or fishing line, or ingested foreign objects. The effect of human-produced objects on crane populations, 
particularly small populations, may be significant. 
PROCEEDINGS NORTH AMERICAN CRANE WORKSHOP 8: 195-197 
Key words: entanglement, Florida, ingested foreign body, injuries, mortality, power line collision, sandhill cranes, whooping 
cranes. 
Many wildlife species are impacted by interactions with 
human-related objects in the environment. Brown pelicans 
(Pelecanus occidentalis) are especially susceptible to inges-
tion of and/or entanglement with fish hooks or monofilament 
line (Johnson and Sloan 1975, Schreiber 1978). Collisions 
with powerlines and fences were a major source of mortality 
of whooping cranes in the AransaslWood Buffalo and Rocky 
Mountain populations (Lewis 1995). Few publications are 
available that describe nonhunting mortality of cranes 
(Windingstad 1988). 
METHODS 
In the course of field studies (1980-99) of Florida 
sandhill cranes, eastern greater sandhill cranes, and whoop-
ing cranes, we observed evidence of encounters between these 
cranes and foreign objects. Many of these birds were 
uniquely marked and could be identified individually. In 
some cases the birds were captured and the objects removed. 
Otherwise, the birds were observed in field situations and 
their behavior was documented. 
RESULTS 
Entanglement 
We observed 3 whooping cranes and 1 sandhill crane 
with line wrapped around a leg. The line on 2 of the whoop-
ing cranes and 1 of the sandhill cranes was ~10 lbs test 
monofilament; the line was wrapped around 1 foot and leg. 
The line on the leg of the third whooping crane was cotton 
string. The monofilament line was difficult to see unless we 
approached unusually close «25 m) and used binoculars or 
195 
a spotting scope. We initially suspected the presence of 
fishing line because of changes in the birds' behavior, 
including limping and reduced activity. We captured all 4 
birds and removed the line. The line was wound tight around 
the lower leg and toes, apparently restricting blood flow. 
There was swelling of the foot and leg distally from the 
constriction. All birds recovered from the line entanglement. 
However, 1 whooping crane lost its hallux and another had 
permanent scarring and swelling on the lower leg. The 
sandhill crane lost the middle toe of its right foot. 
Two whooping cranes were recovered from barbed-wire 
fences. The:first had 1 foot entangled between 2 high strands; 
the bird was able to stand on 1 leg while the other leg was 
behind it and at about a 30° angle above horizontal. The bird 
had a temporarily dislocated hip, laceration of the skin of its 
feathered tibia, and swelling of the foot. It was treated in 
captivity (the hip realigned itself; the skin was sutured and 
observed until it healed) and released after 1 month. The 
second whooping crane that was caught in a barbed-wire 
fence was freed from the fence (by the owner of the ranch) 
and recovered in the wild. 
Woven-wire fences (also known as hog-wire fences) are 
commonly erected with a single strand of barbed-wire 
running across the top. We have found 2 sandhill cranes 
entangled in woven-wire fences; in both cases, a foot was 
trapped between the barbed-wire strand and the top of the 
hog-wire. Apparently the cranes were flying over the fence 
and landed too close, resulting in a leg caught between the 
strands. One sandhill crane was electrocuted when it became 
entangled in an electric fence. 
One whooping crane became entrapped between several 
concrete feed troughs. The bird apparently panicked or was 
attacked by other cranes and in the process of entrapment 
196 CRANES AND FOREIGN OBJECTS' Folk et al. 
suffered a compound fracture of its tarsometatarsus. The bird 
was taken into captivity but died during surgery. It most 
likely would not have been suitable for release had it survived 
the surgery. 
Impalement 
Cranes are curious by nature and will stab at things with 
their bills. As a result, numerous items have become caught 
on the bills of sandhill and whooping cranes. One whooping 
crane spent a day with a shotgun shell jammed on its bill, and 
several whooping cranes were observed for short periods of 
time with flattened aluminum cans on their bills. 
Sandhill cranes have been observed with a plastic wad 
from a shotgun shell, a toy tractor wheel, the core of a golf 
ball, and rubber o-rings on their bills. One with a rubber 
band on its bill visited a home where it was being fed regu-
larly. The band held its bill closed 4 days before the bird 
could be captured and the object removed. An adult male 
sandhill crane that people fed at the Kissimmee Municipal 
Airport had a nickel-sized rubber o-ring jammed midway on 
its upper bill, but the bird was able to eat. After several weeks 
the bird still had the ring stuck on its mandible, which was 
now 2-3 cm shorter than the lower bill. Ultimately the bird 
was captured with a hand net and the ring was removed. The 
bill had not lengthened after several weeks, but the bird was 
eating handouts from the airport personnel. Several months 
later the airport staff reported that the bird was killed by a 
plane on the runway. 
Numerous sandhill cranes on a vegetable farm were 
observed with shreds of "plastic mulch" on their bills. The 
material, similar in thickness and texture to plastic trash bags, 
was used in long rows to conserve moisture and reduce weed 
growth around the vegetables. The cranes probed through the 
material while feeding and often had shreds of plastic stuck 
on their bills. A banded sandhill crane which spent consider-
able time with shreds of mulch on its bill was captured, and 
scar-like markings on the bill were evident. In none of these 
situations did it appear that the cranes were prevented from 
eating or drinking normally. However, in the cases of the 
more finnly affixed items, unless the object fell off spontane-
ously, the birds would have died without human intervention. 
CollisionslPowerline Strikes 
Five whooping cranes died from contact with powerlines: 
2 died of electrocution/trauma in 2 different years under the 
same set of powerlines across an open field. After the second 
death, we examined the lines and determined that the 
configuration was such that the hot wires were too near the 
neutral/ground wire, resulting in the bird brushing 2 lines and 
shorting out the circuit. The power company was alerted to 
Proc. North Am. Crane Workshop 8:2001 
the problem and corrected it. We have observed cranes 
brushing powerlines in the past; if they do not span 2 conduc-
tors or a conductor and a neutral, the injury, if any, is limited 
to trauma. 
Three whooping cranes from a flock died of electrocu-
tion/trauma when they flew into a powerline in the dark. It 
is possible that the birds had been disturbed from their roost 
and did not see the lines. 
On 19 December 1997, we located a whooping crane's 
radio transmitter attached to a powerline. The leg band was 
of the wrap-around type, and was firmly attached to the lower 
strand of a 2-strand low-voltage line about 8 m above ground 
level. We do not know how the crane (which survived 
unharmed) became entangled in the line and transfer the 
radio from its leg to the wire without serious injury. The 
radio was so securely attached to the powerline that utility 
personnel had to break the band to remove the radio from the 
line. 
Dozens of Florida sandhill cranes are injured or killed 
annually on Florida roads. Of 122 sandhill cranes examined, 
15 were hit by vehicles and another 6 were struck by vehicles 
and/or collided with powerlines. One dead whooping crane 
recovered from a roadside may have struck a powerline and/or 
a vehicle. 
Ingested Items 
For unknown reasons, whooping cranes routinely ingest 
metal fragments and other hard (glass or plastic) items. 
Ingestion of galvanized metal objects may have resulted in 
zinc toxicosis (Spalding et al. 1997) in Florida whooping 
cranes. One bird with lead in its stomach had significantly 
elevated liver lead concentrations when it died. Sandhill 
cranes, by contrast, rarely ingest metal items. Only 3 (1%) of 
212 sandhill crane stomachs contained metal. 
Sharp objects present potential physical hazards to the 
bird's gastrointestinal tract. We observed that a whooping 
crane had roosted away from its group, had not been foraging 
as intently as the others, was rather inactive, and displayed 
peculiar postures suggesting that the bird was straining to 
regurgitate something. We were able to capture it with a 
hand net. The bird had swallowed a fishing lure that became 
lodged in the upper esophagus. The lure, which contained 2 
treble hooks, was surgically removed, and the bird was held 
in captivity several weeks until its weight increased. The bird 
was released back into its cohort and survives to date. 
Miscellaneous 
Two sandhill cranes apparently (based on necropsy) died 
from electrocution associated with lightning. The dead birds 
were recovered near a barbed-wire fence that probably 
Proc. North Am. Crane Workshop 8:2001 
conducted the electricity. Cattlemen in Florida report losing 
livestock to lightning on a regular basis. 
One sandhill crane survived being shot with an arrow. 
The crane was shot as it flew over some boys, and the arrow 
lodged in the skin of the wing close to the body. The arrow 
was about half way through the skin and was in a vertical 
position as the bird stood or walked. The bird could function 
normally, except it probably could not sit. The crane carried 
the arrow for several weeks before the arrow worked its way 
out. People that fed the bird on a routine basis found the 
arrow lying in their yard. 
DISCUSSION 
The importance of injuries and deaths associated with 
foreign objects is not easy to quantify and interpret. Ideally 
a sample from a population will accurately reflect the popula-
tion mortality rate and causes of mortality. However, sam-
pling is often biased because some forms of mortality will be 
over-represented (roadkills) while others will be less detect-
able (predation). Of 122 sandhill cranes carcasses examined, 
39 (32%) probably died from contact with foreign objects. 
Roadkills and powerline collisions constituted another 54% 
(21 of 39 cases), but these are probably over-represented 
because such carcasses are relatively obvious in the environ-
ment. 
Our data for whooping cranes are not directly comparable 
with those from sandhill cranes because the whooping cranes 
were monitored more intensively, and there are inherent 
differences between . the species in their vulnerability to 
certain hazards. Of 116 mortalities of whooping cranes, 6 
died as a result of collisions and entanglements; 6 more might 
have died had they not been "rescued." Another 6 died 
following ingestion of metal. For this small, intensively-
monitored population, perhaps 10-15% have been impacted 
by foreign objects. Predation by bobcats (Lynx rufous) 
remains the primary source of mortality in whooping cranes 
reintroduced in Florida, primarily affecting birds within 1 
year post-release. Injury and mortality associated with 
foreign objects, by contrast, occur in all age classes. Human 
intervention/management can reduce this impact. Prior to 
shipment to the Florida release sites, captive whooping cranes 
CRANES AND FOREIGN OBJECTS· Folk et al. 197 
are routinely radiographed to detect metal in their stomachs. 
The metal is removed through endoscopic or conventional 
surgical procedures (Olsen et al. 1996) prior to shipment. 
Two recommendations (Nesbitt 1996) may reduce entangle-
ment with fences. First, construct barbed-wire fences with 3 
rather than 4 or 5 strands and affix the bottom strand 46 em 
above the ground. Second, construct woven-wire fences with 
framed walk-throughs (60 cm high by 46 em wide) spaced 
every 0.5 km. 
ACKNOWLEDGMENTS 
We thank Steve Schwikert, Jim Schmidt, Kathy Sullivan, 
and Tom Miller for assistance collecting data. Thanks to Jeff 
Gore, Glenn Olsen, Don Wood, and an anonymous reviewer 
for comments on the manuscript. 
LITERATURE CITED 
Johnson, R. F., Jr., and N. F. Sloan. 1975. Fishing gear-a deadly 
hazard. Inland Bird Banding News 47:16-17. 
Lewis, J. C. 1995. Whooping crane. N1ll1lber 153 in A. Poole and 
F. Gill, editors. The birds of North America. Academy of 
Natural Sciences, Philadelphia, Pennsylvania, and American 
Ornithologists' Union, Washington, D.C., USA. 
Nesbitt, S. A 1996. Florida sandhill crane. Pages 219-229 in J. A. 
Rodgers, Jr., H. W. Kale IT, and H. T. Smith, editors. Rare and 
endangered biota of Florida. University Presses of Florida, 
Gainesville, Florida, USA. 
Olsen, G. H., J. W. Carpenter, and J. A Langenberg. 1996. 
Medicine and surgery. Pages 137-174 in D. H. Ellis, G. F. 
Gee, and C. M. Mirande, editors. Cranes: their biology, 
husbandry, and conservation. National Biological Service, 
Washington, D.C., and International Crane Foundation, 
Baraboo, Wisconsin, USA. 
Schreiber, R. W. 1978. Eastern brown pelican. Pages 23-25 in H. 
W. Hale II, editor. Rare and endangered biota of Florida. 
University Presses of Florida, Gainesville, Florida, USA. 
Spalding, MG., S. A. Nesbitt, M. J. Folk, L. R. McDowell, and M. 
S. Sepulveda. 1997. Metal cons1ll1lption by whooping cranes 
and possible zinc toxicosis. Proceedings North American 
Crane Workshop 7:237-242. 
Windingstad, R. M 1988. Nonhunting mortality in sandhill cranes. 
Journal of Wildlife Management 52:260-263. 


INTERACTIONS OF SANDHILL CRANES AND WHOOPING CRANES WITH FOREIGN
OBJECTS IN FLORIDA

DigitalCommons@University of Nebraska

University of Nebraska - LincolnDigitalCommons@University of Nebraska - LincolnNorth American Crane Workshop Proceedings North American Crane Working Group2001INTERACTIONS OF SANDHILL CRANESAND WHOOPING CRANES WITHFOREIGN OBJECTS IN FLORIDAMARTIN J. FOLKFlorida Fish and Wildlife Conservation CommissionSTEPHEN A. NESBITTFlorida Fish and Wildlife Conservation CommissionMARILYN G. SPALDINGUniversity of FloridaFollow this and additional works at: https://digitalcommons.unl.edu/nacwgprocPart of the Behavior and Ethology Commons, Biodiversity Commons, Ornithology Commons,Population Biology Commons, and the Terrestrial and Aquatic Ecology CommonsThis Article is brought to you for free and open access by the North American Crane Working Group at DigitalCommons@University of Nebraska -Lincoln. It has been accepted for inclusion in North American Crane Workshop Proceedings by an authorized administrator ofDigitalCommons@University of Nebraska - Lincoln.FOLK, MARTIN J.; NESBITT, STEPHEN A.; and SPALDING, MARILYN G., "INTERACTIONS OF SANDHILL CRANES ANDWHOOPING CRANES WITH FOREIGN OBJECTS IN FLORIDA" (2001). North American Crane Workshop Proceedings. 91.https://digitalcommons.unl.edu/nacwgproc/91INTERACTIONS OF SANDHILL CRANES AND WHOOPING CRANES WITH FOREIGN OBJECTS IN FLORIDA MARTIN J. FOLK, Florida Fish and Wildlife Conservation Commission, 1475 Regal Court, Kissimmee, FL 34744, USA STEPHEN A. NESBITT, Florida Fish and Wildlife Conservation Commission, 4005 South Main Street, Gainesville, FL 32601, USA MAR.ll, YN G. SPALDING, Department ofPathobiology, P.O. Box 110880, University of Florida, Gainesville, FL 32611, USA Abstract: During studies of Florida sandhill cranes (Grus canadensis pralensis), greater sandhill cranes (G. c. tabida), and whooping cranes (G. americana) in Florida, we documented cases where these birds were in contact with human-produced objects that resulted in injury or death. We describe >40 instances in which cranes collided with powerlines or fences, became entangled in string or fishing line, or ingested foreign objects. The effect of human-produced objects on crane populations, particularly small populations, may be significant. PROCEEDINGS NORTH AMERICAN CRANE WORKSHOP 8: 195-197 Key words: entanglement, Florida, ingested foreign body, injuries, mortality, power line collision, sandhill cranes, whooping cranes. Many wildlife species are impacted by interactions with human-related objects in the environment. Brown pelicans (Pelecanus occidentalis) are especially susceptible to inges-tion of and/or entanglement with fish hooks or monofilament line (Johnson and Sloan 1975, Schreiber 1978). Collisions with powerlines and fences were a major source of mortality of whooping cranes in the AransaslWood Buffalo and Rocky Mountain populations (Lewis 1995). Few publications are available that describe nonhunting mortality of cranes (Windingstad 1988). METHODS In the course of field studies (1980-99) of Florida sandhill cranes, eastern greater sandhill cranes, and whoop-ing cranes, we observed evidence of encounters between these cranes and foreign objects. Many of these birds were uniquely marked and could be identified individually. In some cases the birds were captured and the objects removed. Otherwise, the birds were observed in field situations and their behavior was documented. RESULTS Entanglement We observed 3 whooping cranes and 1 sandhill crane with line wrapped around a leg. The line on 2 of the whoop-ing cranes and 1 of the sandhill cranes was ~10 lbs test monofilament; the line was wrapped around 1 foot and leg. The line on the leg of the third whooping crane was cotton string. The monofilament line was difficult to see unless we approached unusually close «25 m) and used binoculars or 195 a spotting scope. We initially suspected the presence of fishing line because of changes in the birds' behavior, including limping and reduced activity. We captured all 4 birds and removed the line. The line was wound tight around the lower leg and toes, apparently restricting blood flow. There was swelling of the foot and leg distally from the constriction. All birds recovered from the line entanglement. However, 1 whooping crane lost its hallux and another had permanent scarring and swelling on the lower leg. The sandhill crane lost the middle toe of its right foot. Two whooping cranes were recovered from barbed-wire fences. The:first had 1 foot entangled between 2 high strands; the bird was able to stand on 1 leg while the other leg was behind it and at about a 30° angle above horizontal. The bird had a temporarily dislocated hip, laceration of the skin of its feathered tibia, and swelling of the foot. It was treated in captivity (the hip realigned itself; the skin was sutured and observed until it healed) and released after 1 month. The second whooping crane that was caught in a barbed-wire fence was freed from the fence (by the owner of the ranch) and recovered in the wild. Woven-wire fences (also known as hog-wire fences) are commonly erected with a single strand of barbed-wire running across the top. We have found 2 sandhill cranes entangled in woven-wire fences; in both cases, a foot was trapped between the barbed-wire strand and the top of the hog-wire. Apparently the cranes were flying over the fence and landed too close, resulting in a leg caught between the strands. One sandhill crane was electrocuted when it became entangled in an electric fence. One whooping crane became entrapped between several concrete feed troughs. The bird apparently panicked or was attacked by other cranes and in the process of entrapment 196 CRANES AND FOREIGN OBJECTS' Folk et al. suffered a compound fracture of its tarsometatarsus. The bird was taken into captivity but died during surgery. It most likely would not have been suitable for release had it survived the surgery. Impalement Cranes are curious by nature and will stab at things with their bills. As a result, numerous items have become caught on the bills of sandhill and whooping cranes. One whooping crane spent a day with a shotgun shell jammed on its bill, and several whooping cranes were observed for short periods of time with flattened aluminum cans on their bills. Sandhill cranes have been observed with a plastic wad from a shotgun shell, a toy tractor wheel, the core of a golf ball, and rubber o-rings on their bills. One with a rubber band on its bill visited a home where it was being fed regu-larly. The band held its bill closed 4 days before the bird could be captured and the object removed. An adult male sandhill crane that people fed at the Kissimmee Municipal Airport had a nickel-sized rubber o-ring jammed midway on its upper bill, but the bird was able to eat. After several weeks the bird still had the ring stuck on its mandible, which was now 2-3 cm shorter than the lower bill. Ultimately the bird was captured with a hand net and the ring was removed. The bill had not lengthened after several weeks, but the bird was eating handouts from the airport personnel. Several months later the airport staff reported that the bird was killed by a plane on the runway. Numerous sandhill cranes on a vegetable farm were observed with shreds of "plastic mulch" on their bills. The material, similar in thickness and texture to plastic trash bags, was used in long rows to conserve moisture and reduce weed growth around the vegetables. The cranes probed through the material while feeding and often had shreds of plastic stuck on their bills. A banded sandhill crane which spent consider-able time with shreds of mulch on its bill was captured, and scar-like markings on the bill were evident. In none of these situations did it appear that the cranes were prevented from eating or drinking normally. However, in the cases of the more finnly affixed items, unless the object fell off spontane-ously, the birds would have died without human intervention. CollisionslPowerline Strikes Five whooping cranes died from contact with powerlines: 2 died of electrocution/trauma in 2 different years under the same set of powerlines across an open field. After the second death, we examined the lines and determined that the configuration was such that the hot wires were too near the neutral/ground wire, resulting in the bird brushing 2 lines and shorting out the circuit. The power company was alerted to Proc. North Am. Crane Workshop 8:2001 the problem and corrected it. We have observed cranes brushing powerlines in the past; if they do not span 2 conduc-tors or a conductor and a neutral, the injury, if any, is limited to trauma. Three whooping cranes from a flock died of electrocu-tion/trauma when they flew into a powerline in the dark. It is possible that the birds had been disturbed from their roost and did not see the lines. On 19 December 1997, we located a whooping crane's radio transmitter attached to a powerline. The leg band was of the wrap-around type, and was firmly attached to the lower strand of a 2-strand low-voltage line about 8 m above ground level. We do not know how the crane (which survived unharmed) became entangled in the line and transfer the radio from its leg to the wire without serious injury. The radio was so securely attached to the powerline that utility personnel had to break the band to remove the radio from the line. Dozens of Florida sandhill cranes are injured or killed annually on Florida roads. Of 122 sandhill cranes examined, 15 were hit by vehicles and another 6 were struck by vehicles and/or collided with powerlines. One dead whooping crane recovered from a roadside may have struck a powerline and/or a vehicle. Ingested Items For unknown reasons, whooping cranes routinely ingest metal fragments and other hard (glass or plastic) items. Ingestion of galvanized metal objects may have resulted in zinc toxicosis (Spalding et al. 1997) in Florida whooping cranes. One bird with lead in its stomach had significantly elevated liver lead concentrations when it died. Sandhill cranes, by contrast, rarely ingest metal items. Only 3 (1%) of 212 sandhill crane stomachs contained metal. Sharp objects present potential physical hazards to the bird's gastrointestinal tract. We observed that a whooping crane had roosted away from its group, had not been foraging as intently as the others, was rather inactive, and displayed peculiar postures suggesting that the bird was straining to regurgitate something. We were able to capture it with a hand net. The bird had swallowed a fishing lure that became lodged in the upper esophagus. The lure, which contained 2 treble hooks, was surgically removed, and the bird was held in captivity several weeks until its weight increased. The bird was released back into its cohort and survives to date. Miscellaneous Two sandhill cranes apparently (based on necropsy) died from electrocution associated with lightning. The dead birds were recovered near a barbed-wire fence that probably Proc. North Am. Crane Workshop 8:2001 conducted the electricity. Cattlemen in Florida report losing livestock to lightning on a regular basis. One sandhill crane survived being shot with an arrow. The crane was shot as it flew over some boys, and the arrow lodged in the skin of the wing close to the body. The arrow was about half way through the skin and was in a vertical position as the bird stood or walked. The bird could function normally, except it probably could not sit. The crane carried the arrow for several weeks before the arrow worked its way out. People that fed the bird on a routine basis found the arrow lying in their yard. DISCUSSION The importance of injuries and deaths associated with foreign objects is not easy to quantify and interpret. Ideally a sample from a population will accurately reflect the popula-tion mortality rate and causes of mortality. However, sam-pling is often biased because some forms of mortality will be over-represented (roadkills) while others will be less detect-able (predation). Of 122 sandhill cranes carcasses examined, 39 (32%) probably died from contact with foreign objects. Roadkills and powerline collisions constituted another 54% (21 of 39 cases), but these are probably over-represented because such carcasses are relatively obvious in the environ-ment. Our data for whooping cranes are not directly comparable with those from sandhill cranes because the whooping cranes were monitored more intensively, and there are inherent differences between . the species in their vulnerability to certain hazards. Of 116 mortalities of whooping cranes, 6 died as a result of collisions and entanglements; 6 more might have died had they not been "rescued." Another 6 died following ingestion of metal. For this small, intensively-monitored population, perhaps 10-15% have been impacted by foreign objects. Predation by bobcats (Lynx rufous) remains the primary source of mortality in whooping cranes reintroduced in Florida, primarily affecting birds within 1 year post-release. Injury and mortality associated with foreign objects, by contrast, occur in all age classes. Human intervention/management can reduce this impact. Prior to shipment to the Florida release sites, captive whooping cranes CRANES AND FOREIGN OBJECTS· Folk et al. 197 are routinely radiographed to detect metal in their stomachs. The metal is removed through endoscopic or conventional surgical procedures (Olsen et al. 1996) prior to shipment. Two recommendations (Nesbitt 1996) may reduce entangle-ment with fences. First, construct barbed-wire fences with 3 rather than 4 or 5 strands and affix the bottom strand 46 em above the ground. Second, construct woven-wire fences with framed walk-throughs (60 cm high by 46 em wide) spaced every 0.5 km. ACKNOWLEDGMENTS We thank Steve Schwikert, Jim Schmidt, Kathy Sullivan, and Tom Miller for assistance collecting data. Thanks to Jeff Gore, Glenn Olsen, Don Wood, and an anonymous reviewer for comments on the manuscript. LITERATURE CITED Johnson, R. F., Jr., and N. F. Sloan. 1975. Fishing gear-a deadly hazard. Inland Bird Banding News 47:16-17. Lewis, J. C. 1995. Whooping crane. N1ll1lber 153 in A. Poole and F. Gill, editors. The birds of North America. Academy of Natural Sciences, Philadelphia, Pennsylvania, and American Ornithologists' Union, Washington, D.C., USA. Nesbitt, S. A 1996. Florida sandhill crane. Pages 219-229 in J. A. Rodgers, Jr., H. W. Kale IT, and H. T. Smith, editors. Rare and endangered biota of Florida. University Presses of Florida, Gainesville, Florida, USA. Olsen, G. H., J. W. Carpenter, and J. A Langenberg. 1996. Medicine and surgery. Pages 137-174 in D. H. Ellis, G. F. Gee, and C. M. Mirande, editors. Cranes: their biology, husbandry, and conservation. National Biological Service, Washington, D.C., and International Crane Foundation, Baraboo, Wisconsin, USA. Schreiber, R. W. 1978. Eastern brown pelican. Pages 23-25 in H. W. Hale II, editor. Rare and endangered biota of Florida. University Presses of Florida, Gainesville, Florida, USA. Spalding, MG., S. A. Nesbitt, M. J. Folk, L. R. McDowell, and M. S. Sepulveda. 1997. Metal cons1ll1lption by whooping cranes and possible zinc toxicosis. Proceedings North American Crane Workshop 7:237-242. Windingstad, R. M 1988. Nonhunting mortality in sandhill cranes. Journal of Wildlife Management 52:260-263. 

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INTERACTIONS OF SANDHILL CRANES AND WHOOPING CRANES WITH FOREIGN OBJECTS IN FLORIDA

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