Overland Movements Research Articles

Movements of platypuses around and through instream structures and natural barriers in the Jenolan Karst Conservation Reserve, New South Wales

Severe flooding in early 2020 and 2021 necessitated major desedimentation works at the iconic Blue Lake in the Jenolan Karst Conservation Reserve (JKCR). Movements and behaviour of platypuses were monitored before, during and after these works, using direct observations, remote cameras and environmental DNA (eDNA) sampling. Platypuses were observed along a 3 km reach of the Jenolan River, including the areas where works occurred, although in low numbers. In their use of the available waterways, platypuses negotiated artificial barriers, including a 10 m high dam, two smaller weirs and natural waterfalls and cascades. Overland movements were detected through vegetation tunnels, drainage pipes and culverts, and individuals were seen entering the cave system, where eDNA was also detected. Platypuses responded to the works activity by foraging outside the affected areas but also continued to traverse these areas from time to time. We describe movements around and through instream infrastructure and past natural barriers and report on other species detected by remote cameras. These observations could help planning and deployment of bypasses suitable for movement of platypuses around anthropogenic barriers and provide insights into impediments to dispersal and gene flow within stream systems.

Turtle species and ecology drive carapace microbiome diversity in three seasonally interconnected wetland habitats.

Different species of freshwater turtles exhibit primary behaviours ranging from aerial basking to benthic bottom-walking, cycle between wet and dry conditions at different time intervals, and undertake short-distance overland movements between aquatic habitats. These behaviours in turn may impact the accumulation of microbes on external shell surfaces of turtles and provide novel niches for differentiation of microbial communities. We assessed microbial diversity using 16S and 18S rRNA metabarcoding on carapace surfaces of six species of freshwater turtles residing in three adjacent and seasonally interconnected wetland habitats in southeast Oklahoma (United States). Communities were highly diverse, with nearly 4200 prokaryotic and 500 micro-eukaryotic amplicon sequence variants recovered, and included taxa previously reported as common or differentially abundant on turtle shells. The 16S rRNA alpha diversity tended to be highest for two species of benthic turtles, while 18S rRNA alpha diversity was highest for two basking and one shallow-water benthic species. Beta diversity of communities was more strongly differentiated by turtle species than by collection site, and ordination patterns were largely reflective of turtle species' primary habits (i.e. benthic, basking, or benthic-basking). Our data support that freshwater turtles could play a role in microbial ecology and evolution in freshwater habitats and warrant additional exploration including in areas with high native turtle diversity and inter-habitat turtle movements.

The geomagnetic field does not appear to influence navigation in Eastern painted turtles

AbstractGeomagnetic cues provide important information to guide aspects of migration, from the general direction of movement to informing an animal's specific location on the planet. Although such cues are used by many long‐distant migrants, its use for short‐ and moderate‐distance migrations is less clear. We have been studying overland migratory movements in a population of Eastern painted turtles where animals use one of four precise, highly predictable routes to locate water sources during migration. Our previous work suggests a strong role of learning and spatial memory in this precise navigation, but the cues used and the context for their use are unknown. Here, we present a series of controlled field experiments in which we test the hypothesis that geomagnetic cues are utilized when Chrysemys picta engage in these intricate, overland movements. We fitted turtles with 3,309 Gauss magnets (n = 10) or aluminum disk controls (n = 5) and surveyed their ability to locate and navigate their routes during migration; turtles were similarly tested for these abilities outside of the context of migration (magnets, n = 30; control, n = 30). Strong magnets (3,309 Gauss) on their carapaces did not disrupt turtles’ ability to locate the paths or the precision with which they navigated them. Turtles, irrespective of treatment, found their paths and/or navigated their paths with the same high precision that we observed in controls and our previous work, both within and outside of the context of migration. Thus, alternative types of cues must be in use that explain the high precision and high reliability of path location over time. Future studies should examine alternative cues used in migratory navigation and the creation of complex and specific paths.

Overland and oversea migration of white storks through the water barriers of the straits of Gibraltar

Soaring landbirds typically exploit atmospheric uplift as they fly overland, displaying a highly effective energy-saving locomotion. However, large water bodies lack thermal updrafts, potentially becoming ecological barriers that hamper migration. Here we assessed the effects of a sea surface on the migratory performance of GPS-tagged white storks (Ciconia ciconia) before, during and after they crossed the straits of Gibraltar. Oversea movements involved only flapping and gliding and were faster, traversed in straighter, descending trajectories and resulted in higher movement-related energy expenditure levels than overland, supporting the water barrier hypothesis. Overland movements at both sides of the sea straits resulted in tortuous routes and ascending trajectories with pre-crossing flights showing higher elevations and more tortuous routes than post-crossing, thus supporting the barrier negotiation hypothesis. Individual positions at both ends of the sea narrow were predicted by zonal winds and storks´ location at entry in the European hinterland, and birds did not show compensational movements overland in anticipation to subsequent wind displacements oversea. The length of the water narrow at departure shore, the elevation therein and the winds on route affected major components of sea crossing performance (such as distances and times overwater, minimum elevations, climb angles, speeds and energy expenditure), supporting the departure position and oversea winds hypotheses. In summary, our study provides a prime example at high temporal resolution of how birds adjust their behavior and physiology as they interact with the changing conditions of the travelling medium, reallocating resources and modifying their movement to overcome an ecological barrier.

Notes on the Predation of Rough-Footed Mud Turtles (Kinosternon hirtipes) in West Texas, USA

Little is known concerning predation of rough-footed mud turtles (Kinosternon hirtipes), a species of conservation concern in Texas, USA. During field studies conducted from 2007 to 2016, we documented 8 instances (1 juvenile, 2 males, and 5 females) of predation among individuals of one of the few (<10) remaining populations of K. hirtipes in Texas. Predation was attributed to raccoons (Procyon lotor; n = 5) and feral pigs (Sus scrofa; n = 2); the predator responsible for the death of one of the turtles could not be determined. Turtles are vulnerable to predation when exposed by low water levels in ponds, when making overland movements between ponds, and during nesting forays ashore. To reduce the likelihood of predation, we recommend maintaining adequate water levels in wetlands, linking wetlands with ditches, encouraging the growth of aquatic vegetation, and providing experimental raccoon-proof nest mounds.

He leaps, she beats: The role of social interactions on the overland movements of an Amazonian amphibious killifish

AbstractAmphibious habits are present in a variety of fish and are allowed by a set of physiological, morphological and behavioural adaptations. The most intriguing question, however, is what motivates an aquatic organism to venture into the land? Unfavourable abiotic and biotic conditions in the aquatic environment have been reported as main stimuli for fish to emerge from water. However, few attempts have been made to disentangle the effects of different social contexts on the propensity of amphibious fishes to leave the water. Trying to separate the effects of predator threat, intraspecific competition and mate searching on overland movement of amphibious fish, we ran a mesocosm experiment with the Amazonian killifish Anablepsoides micropus. Overland movement was quantified based on fish leaps between artificial pools set in enclosures in a primary forest area. Males moved overland more frequently than females and their movement depended on the social context, being higher in the presence of predators and lower in the presence of females. Females, instead, showed context‐independent movement rates. This suggests that males move between pools searching for mates, stopping when successful in this search. On the other hand, occasional encounters with predators may force males to abandon the pool as a defence mechanism. Female aggressiveness towards the predator may influence its low movement in the presence of the predator. Such differential responses may play important ecological and evolutionary roles, allowing A. micropus to occupy a wide range of environmental conditions under varied ecological and social contexts.

Movement of Imperiled Chiricahua Leopard Frogs during Summer Monsoons

Abstract Habitat fragmentation and subsequent disruption of animal movement are responsible for extinctions in some species, including amphibians. Amphibians that can travel across fragmented landscapes may be at lower risk of extinction. Chiricahua Leopard Frogs are threatened because of fragmentation associated with habitat loss and degradation. We sought to identify cues leading frogs to leave perennial ponds and factors related to movement ability of Chiricahua Leopard Frogs in New Mexico during the summers of 2013 and 2014. Using pitfall traps, we captured frogs leaving ponds and radio-tracked 30 individuals to characterize overland movements. We checked traps and located frogs daily for up to eight weeks. We assessed factors related to the number of frogs leaving ponds using linear models and to distances moved by frogs using linear mixed models. The number of frogs caught was related to rainfall, but not water temperature, and more frogs were found outside ponds at an intermediate level of rainfall...

Small Scale-High Resolution Terrestrial Activity ofTrachemys scripta elegans, Harvest Intensity, and Immediate Movement Responses Following Harvest Events

Overland movement is an important aspect of freshwater turtle ecology. Turtles make overland excursions searching for mates, to find new aquatic habitats, in response to drought, or during nesting. Here, we tested how environmental factors may influence the excursion events of adult Red-eared Sliders (Trachemys scripta elegans). We found that 85% of turtles made overland movements at least once, which is higher than previously reported, and some turtles made multiple movements (2–6) during a single season. Rain and drought events were significant predictors of overland movements. While sex did not appear to be a significant factor, there was an indication that movement may depend on seasonal temperatures. In addition, we showed that turtles immigrated to depopulated ponds in a short period of time after a simulated harvest event. However, after a second harvest simulation, our experimental pond was not repopulated to its original abundance. Our results call for caution when implementing spatially controll...

Overland movement in African clawed frogs (Xenopus laevis): a systematic review.

African clawed frogs (Xenopus laevis) are often referred to as ‘purely aquatic’ but there are many publications which suggest extensive overland movements. Previous reviews which considered the topic have not answered the following questions: (1) is there evidence for overland dispersal in native and invasive ranges; (2) what is the range of distances moved overland; (3) when does overland movement occur; and (4) is there evidence of breeding migratory behaviour? A systematic review was chosen to synthesise and critically analyse all literature on the overland movement in Xenopus laevis. Database searches resulted in 57 documents which revealed a paucity of empirical studies, with 28 containing no data, and 19 having anecdotal content. Overwhelming evidence shows that both native and invasive populations of X. laevis move overland, with well documented examples for several other members of the genus (X. borealis, X. gilli, X. muelleri, X. fraseriand X. tropicalis). Reports of distances moved overland were from 40 m to 2 km, with no apparent difference between native and invasive ranges. Overland movements are not confined to wet seasons or conditions, but the literature suggests that moving overland does not occur in the middle of the day. Migrations to temporary water-bodies for breeding have been suggested, but without any corroborating data.

Pharmacological evidence is consistent with a prominent role of spatial memory in complex navigation.

The ability to learn about the spatial environment plays an important role in navigation, migration, dispersal, and foraging. However, our understanding of both the role of cognition in the development of navigation strategies and the mechanisms underlying these strategies is limited. We tested the hypothesis that complex navigation is facilitated by spatial memory in a population of Chrysemys picta that navigate with extreme precision (±3.5 m) using specific routes that must be learned prior to age three. We used scopolamine, a muscarinic acetylcholine receptor antagonist, to manipulate the cognitive spatial abilities of free-living turtles during naturally occurring overland movements. Experienced adults treated with scopolamine diverted markedly from their precise navigation routes. Naive juveniles lacking experience (and memory) were not affected by scopolamine, and thereby served as controls for perceptual or non-spatial cognitive processes associated with navigation. Further, neither adult nor juvenile movement was affected by methylscopolamine, a form of scopolamine that does not cross the blood-brain barrier, a control for the peripheral effects of scopolamine. Together, these results are consistent with a role of spatial cognition in complex navigation and highlight a cellular mechanism that might underlie spatial cognition. Overall, our findings expand our understanding of the development of complex cognitive abilities of vertebrates and the neurological mechanisms of navigation.

The importance of terrestrial dispersal for connectivity among headwater salamander populations

Many organisms are primarily constrained to the channels of the upstream terminus of river networks with limited capacities for both in‐stream and overland dispersal. Dispersal is believed to contribute to gene flow and the demographic stability of headwater populations. While assumed, the importance of overland dispersal to gene flow is largely unexplored in headwater salamanders. Six microsatellite markers were used to assess patterns of genetic population structure for a headwater salamander, Desmognathus fuscus. Tissue samples were collected using a nested hierarchical study design, which specifically addressed the contribution of overland movements to the genetic connectivity of headwater populations. Genetic divergence was significant among all populations (Fst = 0.027–0.405) and at all hierarchical spatial scales. However, lower degrees of genetic population structure were observed among proximal streams that shared no downstream hydrologic connections. Mantel tests indicated a significant relationship between genetic divergence and overland distance, suggesting that D. fuscus populations conform to an isolation‐by‐distance model of gene flow. Estimated dispersal among headwater streams was limited, with an average of less than one effective migrant per generation moving between paired headwater streams. These results indicate that regional patterns of genetic population structure are influenced by overland dispersal and suggest the importance of terrestrial movements in maintaining population connectivity among D. fuscus populations.

Overwater Movement of Raccoons (Procyon lotor) in a Naturally Fragmented Coastal Landscape

Procyon lotor (Raccoon) is a major predator of beach-nesting and colonial waterbirds on the Virginia barrier islands. An understanding of water as a barrier to inter-island movement by Raccoons will be essential to effective management of these predators in this naturally fragmented coastal environment. We examined 4 independent lines of direct evidence for Raccoon movement between 1999 and 2007: 1) locations of recaptured, ear-tagged Raccoons on both the islands and the adjacent mainland, 2) overland movements of radio-collared Raccoons, 3) inter-island movements of radio-collared resident Raccoons, and 4) movements of translocated Raccoons. We recaptured 78 of 177 ear-tagged island Raccoons, all on the same island as the initial capture. We also tagged and released 65 mainland Raccoons, none of which was ever recaptured on an island. We often observed overland movements >1 km per day by radio-collared animals on both the islands and the mainland. Nevertheless, only 3 of 51 (6%) collared animals (2 males and 1 female) moved overwater from the location where they were captured. None of the 4 Raccoons radio-collared on the mainland moved to an island. Although Raccoons in this system are highly mobile, overwater movements seem to be infrequent events; only 3 of 234 tagged/ collared island individuals moved between islands, and none of the 69 tagged/collared mainland individuals moved to an island. Finally, we observed return movements by 22 of the 32 (69%) animals (11 males and 11 females) that were translocated either from the mainland to a nearby island or between adjacent islands. Translocated animals exhibited a much greater tendency than resident animals to make overwater crossings. In all cases of overwater movement, the water channels were relatively shallow and relatively slow moving. None of the 335 marked animals in this study crossed a tidal inlet. The mobility observed here is consistent with the idea that the distribution of Raccoons on the islands has expanded in recent decades. Predation management on these islands will require a strategic approach that takes into account both island isolation and Raccoon mobility.

Eurasian watermilfoil fitness loss and invasion potential following desiccation during simulated overland transport

Abstract Vegetative reproduction promotes human-mediated dispersal of aquatic invasive plants as fragments “hitchhike” between water bodies on boats and trailers. However, desiccation of plant fragments may also reduce fitness, decreasing the likelihood of fragment survival as transport distances increase. Current inter-lake invasive species spread models do not directly consider fitness loss due to desiccation and mechanical damage of the transport pathway. Here, we estimate survival as a function of desiccation exposure for Eurasian watermilfoil ( Myriophyllum spicatum ). Following desiccation treatments, we monitored survival and root formation of individual fragments and assessed the differences between treatments. Highest survival rates occurred for short (< one hour) air exposures and coiled fragments with root production for the coiled treatment occurring in less than two weeks, irrespective of fragment length. In contrast, fragments that experienced desiccation for more than 24 hours had little risk of surviving. Our results emphasize the threat posed by same-day overland movements of boats from invaded to uninvaded waterways, and provide managers with a surveillance radius to inform delimitation surveys arising from the discovery of a new invasion.

U.S. import/export container flow modeling and disruption analysis

International containerized freight movement is a vital part of the supply chain for many companies, and a critical element of moving consumer goods to points of retail sale within the U.S. Containerized imports also present a clear security concern ( e.g., terrorists attempting to ship “dirty bombs,” chemical, biological or even nuclear weapons, into the U.S. in a shipping container). The goal of the research presented here is to create a modeling tool for analyzing flows of U.S. imports and exports of containerized freight, and the potential changes in those flows under a variety of conditions ( e.g., port disruptions, extensive security-related delays, etc.). Our focus is on movements through maritime container ports, and not overland movements between the U.S. and Canada or Mexico. The network model, referred to as the System for Import/Export Routing and Recovery Analysis (SIERRA), represents container movements between the U.S. and 46 other countries that account for the vast majority of U.S. imports and exports. The SIERRA model is a network equilibrium model that predicts flows between foreign countries and North American ports, the total volumes handled (import and export) by each port, the modal volumes (truck and rail) moving domestically into and out of each port, and volumes between each port and a set of transportation analysis zones within the U.S.

Seed Dispersal by Red-Eared Sliders (Trachemys scripta elegans) and Common Snapping Turtles (Chelydra serpentina)

Abstract Seed dispersal capabilities by red-eared sliders (Trachemys scripta elegans) and common snapping turtles (Chelydra serpentina) in southwestern Missouri were investigated for mulberry (Morus spp.), barnyardgrass (Echinochloa crus-galli), and curly dock (Rumex crispus). Feeding trials conducted on these seeds demonstrated that seed damage was low and percentage of germination of turtle-passed seeds did not exceed controls for any seed species tested. These turtle species are capable of dispersing mulberry, barnyardgrass, and curly dock seeds to areas near pond margins and to more distant locations during overland movements.

Interpond Movements of Western Painted Turtles (Chrysemys picta) in East-Central Kansas

The general paradigm associated with overland movements of semi-aquatic turtles between aquatic habitats predicts that males move more frequently and for greater distances than females and juveniles, and that larger individuals move more frequently than smaller individuals. We used capture-mark-recapture techniques to examine interpond movement patterns of western painted turtles (Chrysemys picta) among a complex of eight ponds in east-central Kansas in 2007. We assessed the broad applicability of predictions of the general paradigm by testing the following hypotheses: 1) males make interpond movements more frequently than females, 2) larger adult-sized individuals make interpond movements more frequently than juveniles, 3) propensity for pond-to-pond movement varies as a function of size within categories (i.e., males, females, and juveniles), and 4) mean minimum distance traveled between ponds is greatest for males. The proportion of males that moved between ponds was not significantly different from that of females, and we did not observe a significant difference in proportion of adults and juveniles categorized as movers. Mean length of plastron of individuals classified as movers and non-movers was not significantly different within either females or juveniles. Males categorized as non-movers were significantly larger than those that made interpond movements. Mean minimum distance traveled between ponds was not significantly different among males, females, and juveniles. Thus, our results were not consistent with any of the predictions of the general paradigm. Costs and benefits associated with overland movements of turtles are likely to vary both spatially and temporally. We suggest that as cost-benefit ratios vary, so should predictions about the propensity for interpond movements among turtles of different sexes, sizes, and ontogenetic stages.

Movements, Habitat Use, and Thermal Ecology of an Isolated Population of Bog Turtles (Glyptemys muhlenbergii)

Because many species of semi-aquatic turtles have specific habitat requirements and unique life history characteristics, they are particularly vulnerable to anthropogenic habitat modification. The federally threatened Bog Turtle (Glyptemys muhlenbergii) requires specialized wetland habitats, such as bogs and fens, in the eastern United States and often occurs in isolated populations. To develop a more a detailed understanding of the habitat use, movement, and thermal biology of Bog Turtles, we radiotracked and monitored the temperatures of 11 adult Bog Turtles at an isolated Piedmont meadow bog in North Carolina from May 2007 to March 2008. We found that turtles used soft, shallow mud habitat in the bog, but moved to a streambed when the bog became dry. While in the bog, turtles were often found within or underneath woody debris. Although most turtles resided exclusively in the southern part of the bog and the stream, two male turtles made substantial over-land movements away from the bog exceeding 130 m. All but one turtle overwintered in a streambed adjacent to the bog. Turtles overwintering within stream habitat were not exposed to temperatures below 0°C, but one turtle that overwintered in the bog did reach below-freezing temperatures. This study suggests that high-quality bog habitat and habitat heterogeneity are critical for populations living in isolated and dynamic habitats. However, maintenance of corridors between suitable habitats may be necessary for the long-term survival of Bog Turtle populations.

An Assessment of the Asian Swamp Eel (Monopterus albus) in Florida

The Asian swamp eel (Monopterus albus) is an air-breathing, sex-reversing, eel-like exotic fish that was first reported from Florida waters in 1997. This illegally introduced fish is now abundant in four major southeastern Florida canal systems, and it continues to slowly spread into nearby areas, including the Everglades. Swamp eel feed on a wide variety of organisms, the most common of which are small fishes, crustaceans (mostly crayfish), and insects. In a laboratory study, swamp eel died at temperatures ≤8°C. No deleterious ecological effects associated with the swamp eel's presence were detected during the 11 years we studied this species, nor was there any evidence that it makes overland movements. Based on these data and observations, the swamp eel in Florida is best described as an illegally introduced, opportunistic and successful predator that feeds on a variety of small prey; fortunately, however, it is unlikely to perpetrate major ecological or economic disturbances.

Vagrancy of Brünnich’s Guillemot Uria lomvia in Europe

We review the occurrence of vagrant Brünnich’s Guillemots Uria lomvia in Europe. The 104 records of 109 individual birds that could be traced showed a distinct seasonal pattern. There were no September records, but a small autumn peak was apparent in late October and early November. Numbers increased again in early December, peaked in late January and early February, and declined through spring, with only seven records in summer. Autumn records were mostly of first-winter birds, whereas relatively more adults were recorded in winter, in line with expectations based on timing of migration for these different age classes. We speculate that vagrant birds to western Europe have strayed from the wintering grounds and migration routes south of Iceland and along the Norwegian coast, while overland movements from the Barents Sea may explain inland records from northern Scandinavia, and some from the Baltic Sea. Two spatial clusters of records were evident, one in Scotland and the other in the Skagerrak, Kattegat and southern Baltic Sea. Between 1975/76 and 2005/06, the number of records declined in the former region but increased in the latter, which may represent a real decrease in occurrence, and increased observer effort, respectively.

Gosling Growth and Survival in Relation to Brood Movements in Greater Snow Geese (Chen Caerulescens Atlantica)

AbstractPost-hatch brood movements to high-quality foraging sites are common in precocial birds but may entail costs for young. We assessed effects of overland movements of broods between the nesting and rearing areas in Greater Snow Geese (Chen caerulescens atlantica) breeding on Bylot Island, Nunavut, Canada, to determine whether these movements affected gosling survival and growth. We monitored 51 radiomarked females over five years to quantify movement distance, movement duration, and gosling survival. Gosling growth was compared over four years using a sample of web-tagged broods recaptured shortly before fledging among adults that (1) nested and reared their young in a dense colony, (2) left the colony and moved ≈30 km to reach the main brood-rearing area, or (3) nested and reared their young in the main brood-rearing area. Brood movements by radio-marked birds were highly variable (2.6-52.5 km, depending on rearing areas used) and fairly rapid (≤6 days after hatch for 72% of the females). Gosling survival was not related to distance moved between nesting and brood-rearing areas. However, gosling growth was influenced by areas used and whether or not they had to move to reach their brood-rearing area. Geese nesting at the main brood-rearing area generally reared heavier and larger goslings than those that moved ≈30 km from the main nesting colony to rear their brood at the main brood-rearing area. On the other hand, goslings leaving the nesting colony after hatch were heavier and larger than those that stayed there throughout brood rearing in one of two years. Although brood movements allow goslings access to high-quality habitats, they entail some costs. Thus, minimizing such movements through nest-site selection should provide a selective advantage by allowing goslings to maximize their growth.Croissance et Survie des Oisons en Relation avec les Déplacements des Familles chez Chen caerulescens atlantica