Impact of Grazing Systems on Rodent and Cottontail Rabbit Populations in South Texas

Study sites were established at Rob and Bessie Welder Refuge and Encino Division of the King Ranch in south Texas to monitor the impact of Short-duration cell grazing (SDG) and Continuous grazing on small mammal and cottontail rabbit populations. Small mammals were live trapped (With occasional snap trapping) and cottontails were spotlighted. Vertical and horizontal components of vegetative structure were measured in terms of percent cover. There was paucity of rodents on the Welder Refuge – 8 captures for 9705 trap nights. In 1984 127 cottontails/km) and in 1985-1986 64 cottontails were seen along 436.8 km of road transects (.14 cottontails/km). Small mammal and cottontail numbers were small to measure the impact of grazing treatments on small mammals and cottontails. At the Encino study site a total of 9,600 trap nights yielded 1211 unique captures of small mammals in 1985-1986. Nine species of small mammals were captured. There was a significant difference (p\u3c.05) between grazing treatments and most of the small mammal species were capture in greater numbers in SDG treatment. There was no observed deleterious impact due to Short-duration grazing on small mammals, cottontails and vegetative cover on the Welder Refuge, and the Short-duration grazing treatment appeared to positively impact rodents and vegetation at the Encino study site

SATELLITE TRACKING OF A GREATER SANDHILL CRANE

The first satellite transmitter (PTT) to be used on a wild crane was deployed on an isolation-reared greater sandhill crane (Grus canadensis tabida) colt in south Texas on 6 November 1988. The 160-g transmitter required more than 8 hours of direct sunlight for the solar cells to recharge the NiCad battery power supply. Signal repetition rate was once every 60 seconds. National Oceanic and Atmospheric Agency satellites in polar orbits, equipped with Argos instruments, received PIT signals via a doppler shift mechanism. Information included location of PTT (bird), long-term activity, short-term activity, and ambient temperature. The crane colt died on 10 December 1988. The PTT was subsequently deployed on a second year subadult male greater sandhill crane at Paynes Prairie, Florida, on 5 March 1989. This crane was also equipped with a 20-g standard radio transmitter. The crane migrated approximately 1,642 km before PTT transmission failure occurred. The last location was transmitted from near Reed City, Michigan, on 4 April 1989. The last signal was on 7 April, but location had not changed since 4 April. Overcast conditions could have prevented the PTT from recharging, the antenna could have broken and thus cut off transmission, or the bird could have died. Subsequently, we also failed to locate the bird by standard radio telemetry. This study helped identify shortcomings in the design of the PTT; however, based on the encouraging results, PTT\u27s were deployed on common cranes (G. grus) in Siberia in 1990 and may be deployed on Siberian cranes (G. leucogeranus), whose migration routes are as yet unknown

TECHNIQUES FOR REARING AND RELEASING NONMIGRATORY CRANES: LESSONS FROM THE MISSISSIPPI SANDHILL CRANE PROGRAM

Captive-reared Mississippi sandhill cranes (Grus canadensis pulla) reared at the Patuxent Wildlife Research Center (patuxent) have been released at the Mississippi Sandhill Crane National Wildlife Refuge (MSCNWR) since 1981. Of 131 birds released through December 1990, 103 were reared by foster parents. The remaining 28 were experimentally hand-reared in 1989 and 1990. After refining release procedures, parent-reared birds have integrated into the wild flock, many have survived, and some have bred. Releases of hand-reared cranes elsewhere in the 1970\u27s were largely unsuccessful. at least in part due to the lack of a lengthy acclimation period. A new hand-rearing protocol holds promise in producing release-worthy birds. The technique employs some features first used in the 1960\u27s (e.g., a costume for the human caretaker and model crane heads used to train chicks to feed). In the mid-1980\u27s, the following features were added: (1) the costumed caretaker was given a visor and feathers, (2) a taxidermic crane head or a hand puppet was held or suspended from the ceiling for use in stimulating chicks to feed, (3) a taxidermic mount of a brooding crane supplied warmth, (4) a full-sized live crane was maintained in an adjacent pen and in visual contact with neonatal young to provide an imprinting model, and (5) a small group of adult (or subadult) cranes was penned adjacent to the outdoor chick pens to provide socialization models. Recent releases of Mississippi sandhill cranes hand-reared according to this protocol and released in Mississippi have had high first-year survival rates. The now-operational technique holds promise for producing large numbers of release-worthy birds

TECHNIQUES FOR REARING AND RELEASING NONMIGRATORY CRANES: LESSONS FROM THE MISSISSIPPI SANDHILL CRANE PROGRAM

Captive-reared Mississippi sandhill cranes (Grus canadensis pulla) reared at the Patuxent Wildlife Research Center (patuxent) have been released at the Mississippi Sandhill Crane National Wildlife Refuge (MSCNWR) since 1981. Of 131 birds released through December 1990, 103 were reared by foster parents. The remaining 28 were experimentally hand-reared in 1989 and 1990. After refining release procedures, parent-reared birds have integrated into the wild flock, many have survived, and some have bred. Releases of hand-reared cranes elsewhere in the 1970\u27s were largely unsuccessful. at least in part due to the lack of a lengthy acclimation period. A new hand-rearing protocol holds promise in producing release-worthy birds. The technique employs some features first used in the 1960\u27s (e.g., a costume for the human caretaker and model crane heads used to train chicks to feed). In the mid-1980\u27s, the following features were added: (1) the costumed caretaker was given a visor and feathers, (2) a taxidermic crane head or a hand puppet was held or suspended from the ceiling for use in stimulating chicks to feed, (3) a taxidermic mount of a brooding crane supplied warmth, (4) a full-sized live crane was maintained in an adjacent pen and in visual contact with neonatal young to provide an imprinting model, and (5) a small group of adult (or subadult) cranes was penned adjacent to the outdoor chick pens to provide socialization models. Recent releases of Mississippi sandhill cranes hand-reared according to this protocol and released in Mississippi have had high first-year survival rates. The now-operational technique holds promise for producing large numbers of release-worthy birds

WINTER RELEASE OF ISOLATION-REARED GREATER SANDHILL CRANES IN SOUTH TEXAS

During the summer of 1988, 7 greater sandhill cranes (Grus canadensis tabida) hatched from 15 eggs collected at Seney National Wildlife Refuge (NWR), Michigan, were isolation-reared at Welder Wildlife Refuge (WWR) near Sinton, Texas, and fitted with radio transmitters prior to fledging. Because of severe drought conditions on WWR. 3 surviving juveniles were moved to Laguna Atascosa NWR (LANWR) in south Texas and released on 27 January 1989. On 12 March 1989 they left LANWR with 3 wild cranes. They were relocated on 4 April in Rosebud, Texas. The 3 cranes were captured and transported to Grand Island, Nebraska. and fe-released on 7 April. They left the Platte River on 21 April with a large flock of wild cranes and migrated at least 160 km north before I lost radio contact with them. They reappeared in Waco, Texas, on 22 May, and in June they were 30 km from WWR. On 11 August, 2 surviving cranes returned to WWR; they were recaptured and transported to LANWR. In the absence of wild migrant cranes, the 2 remaining cranes began associating with domestic animals and humans. On 8 March 1990 they were removed from the wild because they displayed no intention to migrate with wild cranes. These birds showed a strong affinity for their natal area (WWR), suggesting that isolation-reared cranes should be released on breeding grounds rather than on wintering grounds

ISOLATION-REARING OF SIBERIAN CRANE CHICKS AT THE INTERNATIONAL CRANE FOUNDATION

Three Siberian crane (Grus leucogeranus) chicks hatched in the summer of 1987 at the International Crane Foundation (lCF); Baraboo, Wisconsin, were raised in near-complete isolation from humans. The chicks were exposed to species-specific models, vocalizations, a costumed parent and a role-model adult Siberian crane housed in an adjacent pen. Attachment to costumed parent, interchick interaction, and reactions to humans were measured and compared with those aspects of sandhill crane behavior under similar rearing conditions

MINIMUM SURVIVAL RATES FOR MISSISSIPPI SANDHILL CRANES: A COMPARISON OF HAND-REARING AND PARENT-REARING

Hand-reared (56) and parent-reared (76) juvenile Mississippi sandhill cranes (Grus canadensis pulla) were produced at the Patuxent Wildlife Research Center (patuxent), Laurel, Maryland over a 4-year period (1989-92) and released at the Mississippi Sandhill Crane National Wildlife Refuge (Refuge), Gautier, Mississippi in a controlled experiment. Hand-reared survival rates proved higher than for parent-reared survival for each time category: 6 months, 86% versus 75%; 1 year, 77% versus 68%; 2 years, 66% versus 53%; 3 years, 55% versus 43%: partial data for fourth and fifth years were 57% versus 31 % and 48% versus 37%