Juvenile alligator gar movement patterns in a disconnected floodplain habitat in Southeast Missouri.
Movement is an important part of an organism's life history and has been studied extensively in the field of fisheries including extensive work done on species of conservation concern. However, studies of gar, family Lepisosteidae, are lacking in the literature, particularly work on alligator gar (Atractosteus spatula) that are considered threatened or extirpated in most areas in which they inhabit. Specifically, habitat loss across much of its range [extending from Texas eastward to Florida and Mexico north to central Illinois, (Gilbert, 1992; Garcia de Leon et al., 2001; Ferrara, 2001; Irwin et al., 2001; Sakaris et al., 2003)], coupled with other anthropogenic deleterious effects (overfishing and eradication efforts) has lead to the decline of the species. Historical Missouri records also depict alligator gar populations in the Mississippi River and the tributaries in the vast floodplains of southeast Missouri. Ultimately, these declines across their range have reduced populations making detection of the species difficult. Specific to our study area, alligator gar were considered extirpated in Missouri until recently when two gravid females were taken from the Headwaters Diversion Channel, a tributary of the Mississippi River, near RKM 81 in 2001 and 2007. Conservation efforts (e.g., reintroductions or monitoring of existing population) to ensure native fish community sustainability have increased interest in alligator gar.
Recent studies suggest alligator gar inhabit the lentic portion of large rivers, reservoirs, swamps, brackish areas, and streams (Gilbert, 1992; Pflieger, 1997; Brinkman, 2008; Inebnit, 2009). Knowledge of movement patterns of alligator gar is limited but those that exist have focused on adults, showing highly variable movement patterns and large home ranges. Sakaris et al. (2003) (linear home range 2.73-12.25 kin; mean 6.57 km) and Brinkman (2008) (linear home range 5.77-49.72 km, mean 16.7 km: home range area 493 ha-1713 ha, mean 1170 ha) show that tagged, adult alligator gar exhibit large home ranges and are highly mobile. Sakaris et al. (2003) also showed a positive correlation of movement to fish size. Irwin et al. (2001) suggests that larger alligator gar move more than smaller individuals but found no seasonal effects on movement rates.
While sampling in the Threemile Creek in the Mobile-Tensaw Delta, Alabama, Ferrara (2001) and Irwin et al. (2001) note high catch rates for small alligator gar and Sakaris et al. (2003) sampled smaller individuals multiple times. This suggests site fidelity is more likely for juvenile alligator gar. However, there is no published study to date that focuses on alligator gar movement patterns during early life history. As such, the objective of this study was to determine the feasibility of monitoring movements of juvenile alligator gar and determine if specific movement patterns exist.
MATERIALS AND METHODS
Mingo National Wildlife Refuge (MNWR) is an 8772 ha refuge with a series of drainage channels and 1942 ha of marsh and wetland habitats at normal water levels, with potential for 4451 ha during high water events (Fig. 1). MNWR was created when the Mississippi River shifted its course 18,000 y ago leaving the abandoned river channel to form into a lowland floodplain habitat (Heitmeyer et al., 1985). MNWR consists of diverse habitats including four primary marshes (i.e., Monopoly Marsh, Bee Press Marsh, Rockhouse Marsh, and Gumstump Pool) with a series of connected drainage channels (e.g., Ditch 5, with a permanent connection to Monopoly Marsh) and lowland forest that foods in high water. Across these expansive wetland complexes, the mean depth is 1.5 m with a 2.5 m maximum depth at full pool. Monopoly Marsh has clear water (i.e., secchi disc transparency [greater than or equal to] 35 cm) and is dominated by American Lotus (Nelumbo lutea), watershield (Brasenia schreberi), coontail (Ceratophyllum demersum), bald cypress (Taxodium distichum), yellow and white lily (Nymphea spp.), spatterdock (Nuphar spp.), and milfoils (Myriophyllum spp.) and has a mean depth of 1.5 m with a 2.5 m maximum depth at full pool. The other marshes are shallower (mean depth 1 m) with similar aquatic vegetation, and all marshes contain abundant emergent and submersed woody debris while drainage channels are turbid (secchi disc transparency [less than or equal to] 10 cm) and void of vegetation. Monopoly Marsh and Ditch 5 are also home to 29 documented species of fish, including longnose gar (Leisosteus osseus), spotted gar (L. oculatus), bowfin (Amia calva), and abundant potential prey species (Missouri Department of Conservation, unpubl, data). Aquatic organisms are able to disperse, at high water levels, out of the marsh complexes into major drainage ditches eventually entering the St. Francis River.
ALLIGATOR GAR TAGGING AND TELEMETRY
Nineteen alligator gar (424-624 mm, mean 470.8 mm; 275-865 g, mean 396.1 g; year 1) were randomly stocked in Monopoly Marsh at three distinct locations, >100 m apart, on 25 May 2007. All individuals were tagged at Tishomingo National Fish Hatchery, OK 30 d prior to stocking (to observe mortality and allow fish to acclimate to tagging) with monofilament t-bar (Floy) tags, passive integrated transponders (PIT) tags, and radio transmitters for individual identification. Radio tags [Advanced Telemetry Systems (Isanti, MN)] were 1.2 X 5 cm, weighed 14 g, had an expected battery life of 12-15 mo, were engineered to fall off after one year and no recapture attempts were made. To attach radio tags, alligator gar were anesthetized using MS 222. Tags were attached 2-3 mm below the dorsal fin, at two points (front and back of tag) by pushing a hollow needle (2.5 mm outside diameter PIT tag needle, BioMark Model N206) through this area and subsequently inserting the radio tag's cables through the needle. A cable stop was crimped on the opposite side of the gar's body to prevent tag loss. Alligator gar were then placed in a recovery tank saturated with dissolved oxygen and then moved to a hatchery pond to acclimate for 30 d prior to stocking.
Alligator gar were tracked daily for the first 30 d after stocking into Monopoly Marsh to determine dispersal into the new environment. Subsequently, telemetry was reduced to locating each fish once per week for 1 y. When a fish was found, a minimum of three directional bearings from different points surrounding the fish's suspected location were collected in the field. Points of origin for directional bearings were obtained using a Global Positioning System (GPS) unit with Universal Transverse Mercator (UTM: NAD83, Zone 15, used throughout) projection coordinates, directional bearings were recorded from a hand held compass, and macrohabitat (i.e., Monopoly Marsh) was recorded. Following data collection, data were analyzed with the GTM v3 Telemetry Program (Sartwell, 2000), the fish's location was triangulated, given a location using UTM coordinates, and associated error ellipses were calculated. Locations were then loaded into ArcMAP 9.2 and obvious outliers (i.e., locations triangulated on land) were omitted from data analysis. Visual location of alligator gar was not possible due to an array of physical factors (submergent vegetation, turbid waters). The date, time, and location (Monopoly Marsh, Bee Press Marsh, Rockhouse Marsh, Ditch 5, and flooded forest areas) were recorded for each point, bearing, and subsequent location.
For data analysis, site fidelity was defined as an individual gar occupying one small area (<25 ha) for an extended period of time (>14 d). The minimum number of locations used to determine an area of site fidelity was six, accomplished during the daily tracking period. Sustained localized movements (SLM) were short-distance movements within an area of site fidelity creating a cluster of locations. When gar exhibited site fidelity, the size of the area was measured using a Minimum Convex Polygon (MCP) in ArcMAP 9.2. Long-distance movements occurred when gar left areas of site fidelity and were significantly greater than any sustained localized movements. Any movement that was significantly greater than the average of 95% of movements within an area of site fidelity was termed a long-distance movement. A minimum long-distance movement was determined for each individual gar by one tailed t-test. Correlation of movement to fish size was tested by using a Pearson correlation analysis.
A total of 19 radio-tagged alligator gar were stocked into Monopoly Marsh, but only 18 were tracked during this study because of one radio tag malfunction. Alligator gar were tracked from 29 May 2007 to 22 May 2008. One transmitter failed in mid Jan. and two more failed in mid April but this did not affect overall results and these individuals were included in data analysis. A mean of 3.9 [+ or -] 1.0 SE (used throughout) directional bearings per location and 34.9 [+ or -] 5.1 locations per individual gar were recorded. When tracking daily, most gar were located every other day. When tracking weekly, every alligator gar was located each week. However, there were many weeks where tracking was not done due to ice cover on Monopoly Marsh or when great numbers of waterfowl were using Monopoly Marsh as a refuge. Tracking was further hindered from late summer through the fall when falling water levels limited accessibility of Monopoly Marsh to airboat; tracking was then done at availability of the refuge's airboat and personnel.
Locations were plotted in ArcMAP 9.2 and obvious outliers were omitted leaving 31.7 [+ or -] 4.4 locations per individual gar for data analysis. The mean error ellipse per individual location was 4.4 [+ or -] 5.1 ha (range: 0.001-20,193.96 ha). Only 2.4% (16 of 658) of locations had an error ellipse above 50 ha. The total mean distance displaced for alligator gar was 6632.8 [+ or -] 3145.6 m with an average displacement between consecutive locations of 201.8 [+ or -] 93.2 m. (Table 1). Alligator gar exhibited three distinct movement patterns, referred to here as groups A, B, and C.
Group A (n = 8) exhibited strong site fidelity characterized by SLM (Fig. 1). Alligator gar in this group occupied a mean area of 12.9 [+ or -] 6.0 ha (range: 0.9-17.8 ha) (Table 1). These gar did not disperse to any other habitats nor did they exhibit long-distance movement away from initial locations. Seven of these alligator gar used Monopoly Marsh while one used Ditch 5. Group B (n = 5) established site fidelity similar to Group A for a mean of 96 [+ or -] 120.9 d (range: 14-306) followed by a long-distance movement to another location to reestablish site fidelity for a mean of 246.6 [+ or -] 121.6 d (range: 44-341) (Fig. 1). The minimum long-distance displacement calculated via t-test were a mean distance of 512 [+ or -] 171 m, however, many far exceeded the minimum. These separate territories were an average of 1200 [+ or -] 500 m apart with a mean size of 4.8 [+ or -] 4.9 ha (range: 0.3-17.5) (Table 1). Group C (n = 5) showed highly variable movement patterns; at times showing site fidelity, then exhibiting long-distance movements. When exhibiting site fidelity, gar occupied a mean area of 11.8 [+ or -] 8.0 ha (range: 1.8-24.8 ha) (Table 1) for a mean time of 120.9 [+ or -] 94.5 d (range: 26-228). Alligator gar exhibited a mean of 4.2 [+ or -] 1.6 long-distance movements per fish with a mean displacement of 1027.3 [+ or -] 482.3 m.
When not showing site fidelity, movement patterns were stochastic with no pattern in distance, direction, or destination. Groups A and B showed no seasonal movement patterns; however, during mid-March, coinciding with flooding and rising water temperatures, Group C began to show consistent long-distance movements with three fish dispersing to new habitats outside Monopoly Marsh. These fish moved to Bee Press (n = 2), Rockhouse Marsh (n = 1), and flooded bottomland hardwood forest areas (n = 1). Overall, 98.6% of locations were in Monopoly Marsh. Sizes of fish were compared to total distance moved using a Pearson correlation analysis and found no apparent trend between movement and size. (r = 0.449, P > 0.05)
This study demonstrates that radio tagging and subsequent monitoring of juvenile alligator gar movement using telemetry is possible. We were able to investigate individual movement patterns of juvenile alligator gar and begin to better understand the complete life history of this species of concern. Specifically, juvenile alligator gar exhibited complex movement patterns over the course of this study; many (n = 13, Groups A and B) exhibited strong site fidelity while some (n = 5, Group C) showed site fidelity at times while also exhibiting highly variable, long-distance (mean > 709 m) movement patterns. These findings coincide with the observations of Irwin et al. (2001) and Sakaris et al. (2003) who also suggest that juvenile alligator gar seem to exhibit site fidelity. However, our study found smaller home ranges/areas of site fidelity for juvenile alligator gar when compared to adults in Brinkman (2008) (juvenile area mean 6.8 ha: adult mean 1170 ha) and Sakaris et al. (2003) (juvenile linear area mean <1 kin: adult linear area mean 6.57 kin). Individual displacements between consecutive locations per juvenile (mean 201 m) were also much smaller than Sakaris et al. (2003) observed in adults (mean 2425 m). Inebnit (2003) and Robertson et at (2008) observed wild juvenile alligator gar inhabiting backwaters, flooded terrestrial areas, and isolated tributaries of major rivers (e.g., Mississippi River, Fourche Lafave River, and Brazos River). Our study, with a vast majority of locations in Monopoly Marsh, supports this as Monopoly Marsh has qualities similar to these other habitats.
Juvenile alligator gar movements also coincide well with adult spotted gar movements in the Lower Atchafalaya River Basin, Louisiana. Nocturnal movements of spotted gar were random with frequent directional changes from summer through winter and spotted gar showed a preference for structurally complex shallow water habitats (Snedden et al., 1999). These results coincide well with our data as alligator gar SLM were also random with frequent directional changes and the majority (98.6%) of alligator gar locations were in the shallow, structurally diverse habitats in Monopoly Marsh. However, since no diel data were taken, we cannot directly compare nocturnal or diurnal movements. Snedden et al. (1999) also showed that during high water events some spotted gar moved out of their previously occupied home ranges (summer-winter) to seasonally flooded backwaters and sloughs (potentially to spawn) while four individuals abandoned a previous home range to reestablish a new one. These movements were also observed by alligator gar in Group C (as these fish moved into flooded terrestrial areas and other marshes that had been dry/ inaccessible) and Group B (deserting an area of site fidelity to establish a new one). These events could not have been spawning behavior (year 1 fish) but could have been an attempt to access new resources. Sizes of home ranges found by Snedden et al. (1999) showed seasonal variability with summer and fall-winter measurements (median 6.6 ha) coinciding well with our findings (mean 6.8 ha) and spring measurements being significantly higher (median 265.1 ha).
Similar patterns have also been observed in other ambush-style piscivorous species. Site fidelity has been observed in juvenile tiger muskellunge [hybrids of northern pike (Esox ludus) and muskellunge (E. masquinongy)] similar to results found in this study (Tipping, 2001). Adult muskellunge show site fidelity to spring spawning sites followed by home range activity (e.g., restricted movements or sedentary habits) in summer months (Miller and Menzel, 1986). Similar to alligator gar in Group B, most of these muskellunge showed two distinct home range areas during summer months (Miller and Menzel, 1986). Other piscivores have shown similar behaviors. Yellow perch (Perca flavescens) and largemouth bass (Micropterus salmoides) show strong homing tendencies to location of original capture, suggesting use of home ranges and site fidelity (Hodgson et al., 1998). Striped bass (Morone saxatilis) exhibit site fidelity to specific tributaries or reservoir basins in an eastern United States reservoir (Jackson and Hightower, 2001). Juvenile lake sturgeon (Acipenser fulvescens) have also been shown to show high site fidelity and small home ranges in large rivers (Barth et al., 2011). In addition, Smith and King (2005) report juvenile lake sturgeon exhibit complex movement patterns with some individuals showing site fidelity while others move great distances.
Our data directly show that backwater and floodplain habitats are suitable for juvenile alligator gar. This adds key information to the very limited literature that discusses juvenile alligator gar. Furthermore, we speculate that the three observed movement patterns may be a result of resource partitioning among individual alligator gar. Alligator gar (groups A and B) occupied distinct territories of Monopoly Marsh for extended periods of time, while not moving into areas occupied by another alligator gar, thus likely partitioning habitat available to limit competition for similar resources. However, major movements did occur and could help to explain alligator gar in groups B or C: moving to new areas within Monopoly Marsh or dispersing to exploit new resources outside Monopoly.
Resource partitioning has been studied extensively with much of the focus being on terrestrial organisms. However, limited studies exist concerning how movement is related to resource partitioning in interspecific or intraspecific interactions in freshwater fishes. In relation to gar species, spotted gar and longnose gar partition resources by occupying different areas of the Brazos River; most longnose gar (84.3%) inhabit the river channel, and most spotted gar (98.1%) inhabit the seasonally connected oxbows (Robertson et al., 2008). Dietary composition (when combined across both years and all habitats) showed high overlap between the two gar species during both the wet year (72.7%) and the dry year (90.1%) (Robertson et al., 2008). In other species, Olsen et al. (1988) suggested lake trout (Salvelinus namaycush) and brown trout (Salmo trutta) in Lake Ontario partition resources by occupying different habitats rather than by prey preference and selection. Matthews et al. (1992) showed that differences in habitat ameliorate effects of diet overlap while investigating interactions between largemouth bass and striped bass in a southern U.S. reservoir. Smith and King (2005), in addition to showing site fidelity and long-distance movements, also demonstrated juvenile lake sturgeon partitioning resources by occupying habitats distinctly separate from adults.
Other potential explanations of alligator gar movement could be resource depletion in an area of site fidelity, forcing the fish to reestablish a new area (Groups B) or disperse out of Monopoly Marsh (Group C). Cannibalism has been observed in isolated, age-0 alligator gar in aquaculture facilities (Inebnit, 2009), suggesting a territorial nature. Territoriality is a concept little studied in gar species but could explain site fidelity patterns and why no alligator gar's area of site fidelity overlapped with another. Territoriality could also potentially explain alligator gar in Group B, perhaps they were displaced by another gar species (longnose and spotted gar) and relocated to reestablish site fidelity at a new location.
Ultimately, juvenile alligator gar can be reintroduced to suitable habitats where their movement patterns can be studied. Fisheries managers can expect future stockings to show site fidelity, similar to the results discussed in this study. We suggest future studies develop a mechanistic understanding of juvenile alligator gar movement patterns. Logging water quality data (temperature, dissolved oxygen, pH, conductivity) could provide additional insight into whether movements were triggered by environmental changes. A study of fish population structure prior to reintroduction or a diet study coinciding with future telemetry could indicate if movement patterns of juvenile alligator gar are influenced based on a specific prey species or abundance. Furthermore, mapping of vegetation (species and density) and bathymetry could provide detailed microhabitat data that could explain individualized gar movement patterns. Finally, as reintroduction programs become successful, we suggest tracking wild alligator gar to determine if the findings uncovered in this study can be corroborated.
Acknowledgments.--We thank K. Burchett, K. Cordell, G. Cwick, R. Hrabik, F. Nelson, J. Sartwell, J. Scheibe, S. Sheriff, and R. Speer along with the Missouri Department of Conservation, U. S. Fish and Wildlife Service and Southeast Missouri State University for support in making this project possible. We thank E. Brothers, J. Crites, T. Cunningham, Z. Fratto, J. Hartleb, R. Holiday, A. Lamb, K, McNabb, S. Mondragon, S. Schell, J. Turner, E. Westhoff, and A. Wright for their assistance with field work. We thank Mammoth Spring National Fish Hatchery, Private John Allen National Fish Hatchery, and Tishomingo National Fish Hatchery for providing alligator gar for this study.
BARTH, C. C., W. G. ANDERSON, L. M. HENDERSON, AND S. J. PEAKE. 2011. Home range size and seasonal movement of juvenile lake sturgeon in a large river in the Hudson Bay drainage basin. Trans. Am. Fish. Soc., 140(6):1629-1641.
BRINKMAN, E. L. 2008. Contribution to the life history of alligator gar, Atractosteus spatula (Lacepede), in Oklahoma. M.S. Thesis. Oklahoma State University, Stillwater, Oklahoma.
FERRARA, A. M. 2001. Life history strategy of Lepisosteidae: implications for the conservation and management of alligator gar. Ph.D. Dissertation. Auburn University, Auburn, Alabama.
GARClA DE LEON, F. J., L. GONZALEZ-GARCIA, j. M. HERRERA-CASTILLO, K. 0. WINEMILLER, AND A. BANDA-VALDES. 2001. Ecology of the alligator gar, Atractosteus spatula, in the Vicente Guerrero Reservoir, Tamaulipas, Mexico. Southwest. Nat., 46(2):151-157.
GILBERT, C. R. 1992. Rare and endangered biota of Florida, Vol. 2. University Press of Florida, Gainesville, Florida.
HEITMEYER, M. E., L. H. FREDRICKSON, AND G. F. KROUSE. 1989. Water and habitat dynamics of the Mingo Swamp in southeastern Missouri. Fish and Wildlife Research 6. United States Department of the Interior, Fish and Wildlife Service, Washington D.C.
HODGSON, J. R., D. E. SCHINDLER, AND H. E. XI. 1998. Homing tendencies of the piscivorous fishes in a north temperate lake. Trans. Am. Fish. Soc., 127:1078-1081.
INEBNIT, T. E. 2009. Aspects of the reproductive and juvenile ecology of alligator gar in the Fourche Lafave River, Arkansas. M.S. Thesis, University of Central Arkansas, Conway, Arkansas.
IRWIN, E. R., A. BELCHER, AND K. KLEINER. 2001. Study 36- Population assessment of alligator gar in Alabama. Alabama Department of Conservation and Natural Resources: Job Performance Final Report Project F-40.
JACKSON, J. R. AND J. E. HIGHTOWER. 2001. Reservoir striped bass movements and site fidelity in relation to seasonal patterns in habitat quality. N. Am. J. Fish. Manage., 21:34-45.
MATTHEWS, W.J., F. P. GELWICK, AND J. J. HOOVER. 1992. Food of and habitat use by juveniles of species of Microoterus and Morone in a southeastern reservoir. Trans. Am. Fish. Soc., 121:54-66.
MILLER, M. L. AND B. W. MENZEL. 1986. Movements, homing, and home range of muskellunge, Esox masquinongy, in West Okoboji Lake, Iowa. Env. Bio. Fish, 16:243-255.
OMEN, R. A., J. D. WINTER, D. C. NETTLES, AND J. M. HAYNES. 1988. Resource partitioning in summer by Salmonids in south-central Lake Ontario. Trans. Am. Fish. Soc., 117:552-559.
PELIEGER, W. L. 1997. The Fishes of Missouri. Missouri Department of Conservation, Jefferson City, Missouri.
ROBERTSON, C. R., S. C. ZUEG, AND K. O. WINEMILLER. 2008. Associations between hydrological connectivity and resource partitioning among sympatric gar species (Lepisosteidae) in a Texas river and associated oxbows. Ecol. Freshw. Fish, 17:119-129.
SARTWELL, J. 2000. The Telemetry Computing Project. Missouri Department of Conservation, Federal Aid in Wildlife Restoration Project W-13-R, Annual Report.
SAKARIS, P. C., A. M. FERRARA, E. R. IRWIN, AND K. KLEINER. 2003. Movements and home ranges of alligator gar in the Mobile-Tensaw Delta, Alabama. Proc. Annu. Conf. Southeast. Assoc. Fish Wildl. Agenc., 57:102-111.
SMITH, K. M. AND D. K. KING. 2005. Movement and habitat use of yearling and juvenile lake Sturgeon in Black Lake, Michigan. Trans. Am. Fish. Sot., 134:1159-1172.
SNEDDEN, G. A., W. E. KELSO, AND D. A. RUTHERFORD 1999. Diel and seasonal patterns of spotted gar movement and habitat use in the lower Atchafalaya River Basin, Louisiana. Trans. Am. Fish. Soc, 128:144-154.
TIPPING, J. M. 2001. Movement of tiger muskellunge in Mayfield Reservoir, Washington. N. Am. J. Fish Manage., 21:683-687.
SUBMITTED 30 JANUARY 2012
ACCEPTED 3 JULY 2012
LEVI E. SOLOMON, (1) QUINTON E. PHELPS AND DAVID P. HERZOG
Open Rivers and Wetlands Field Station, Missouri Department of Conservation, 3815 East Jackson Boulevard, Jackson 63755
CHRISTOPHER J. KENNEDY
Southeast Regional Office, Missouri Department of Conservation, 2302 County Park Drive, Cape Girardeau 63701
MICHAEL S. TAYLOR
Southeast Missouri State University, MS 6200 Rhodes 217, Cape Girardeau 63701
(1) Corresponding author's present address: Illinois River Biological Station, Illinois Natural History
Survey, 704 North Schrader, Havana, Illinois 62644; Telephone: (309) 543-6000; FAX: (309) 543-2105;
TABLE 1.--Fish and telemetry data for alligator gar tracked at Mingo National Wildlife Refuge ID/Group Total length N Locations Area(s) of site (mm) used fidelity (ha) 44/A 472 36 12.1 163/A 469 33 4.1 224/A 460 36 17.5 245/A 437 37 11.8 263/A 540 29 11.7 445/A 428 49 0.9 504/A 450 32 17.8 624/A 424 32 15.1 64/11 533 30 3.7, 1.5 147/11 446 35 8.1, 6.0 385/13 457 36 4.4, 7.0 464/13 431 33 8.7, 17.5 484/13 464 36 2.4, 0.3 302/C 429 35 6 343/C 444 32 14.0, 8.1 362/C 463 25 21.3 422/C 504 36 8.6, 6.1 525/C 624 33 16.1, 19.5 Mean 470.8 34.1 6.8 SE 11.9 4.2 1.6 Mean displacement ID/Group Total observed distance per Date of last displacement (m) relocation (m) location 44/A 6097.7 179.3 4/30/2008 163/A 3255.1 105 5/20/2008 224/A 5956.1 170.1 5/20/2008 245/A 5182 148 5/20/2008 263/A 4386.8 162.4 5/20/2008 445/A 5207.9 118.3 5/20/2008 504/A 4808.2 160.2 5/20/2008 624/A 3797.2 126.5 4/9/2008 64/11 4609.3 177.2 4/16/2008 147/11 4840.7 151.2 5/20/2008 385/13 5371.1 157.9 5/20/2008 464/13 6061.1 195.5 5/20/2008 484/13 5969.8 192.5 5/20/2008 302/C 11944.1 361.9 5/20/2008 343/C 10648.2 354.9 5/5/2008 362/C 5389.6 234.3 1/11/2008 422/C 12393.1 375.5 5/20/2008 525/C 13473.4 434.6 5/22/2008 Mean 6632.8 211.4 SE 741.4 23.4
|Printer friendly Cite/link Email Feedback|
|Author:||Solomon, Levi E.; Phelps, Quinton E.; Herzog, David P.; Kennedy, Christopher J.; Taylor, Michael S.|
|Publication:||The American Midland Naturalist|
|Date:||Apr 1, 2013|
|Previous Article:||Disruptive influences of drought on the activity of a freshwater turtle.|
|Next Article:||Laboratory competition hierarchies between potentially invasive rusty crayfish (Orconectes rusticus) and native crayfishes of conservation concern.|