Mammal Tracks Research Articles

The optical passive acoustic adaptive drifter system: A multisensor dynamically drifting mid-water biosurveillance platform

Conducting unobtrusive observations of the physical, acoustic, and biological properties of the mesopelagic zone remains challenging, despite the proliferation of mobile ROV, AUV, and glider platforms. Here, we discuss the Optical Passive Acoustic Adaptive Drifter System (OPAADS), a 2 m tall Lagrangian drifter platform that incorporates a CTD, stereo video cameras, vertical and tetrahedral hydrophone arrays, and acoustic vector sensors. The platform has also suspended a 91-m vertical thermistor array and acoustic doppler current profiler. The OPAADS uses a commercial buoyancy engine to dynamically adjust its target isobar via either a preprogrammed dive sequence or real-time commands relayed by an ultra-short baseline underwater tracking and communication system. Three platforms have been built and deployed over ten times since 2022, off both southern California and off the New England Seamounts, between depths of 100 and 700 m for durations between 24 and 72 h. We discuss the sensors, operations, and observations collected by OPAADS, including data useful for (1) characterizing bioacoustic chorusing, wind-driven surface noise directionality, and turbulence dynamics; (2) conducting species identification in the deep scattering layer; (3) performing marine mammal tracking; and (4) collecting pilot data studying potential approaches for long-range underwater navigation. [Work sponsored by ONR TFO.]

Correlation between mammal track abundance and Forest Landscape Integrity Index validates actual forest ecological integrity

Human disturbance compromises the ecological integrity of forests, negatively affecting associated species. Assessing the impact of forest integrity on biodiversity is complex due to the interplay of various human activities, ecological factors, and their interactions. Current large-scale indices assess forest integrity but often lack a direct connection to the biotic environment. We tested the effectiveness of the global Forest Landscape Integrity Index (FLII) in evaluating aspects of anthropogenic forest degradation on the biotic community. We analyzed the relationship between changes in the ecological integrity of Finnish forests and variations in mammal species abundance, using the number of tracks from 17 different species collected during the winter seasons between 2016 and 2020 in south-central Finland. Beyond the FLII, we analyzed forest and canopy cover to enhance the accuracy of habitat preference assessments. We found that the FLII captures the varying degrees of forest integrity, as reflected by the correlation between the abundance of winter tracks and the FLII for most mammals. Species that were positively associated with forest integrity were all native to the boreal forest, while mammals that adapt well to human-disturbed environments including two invasive species were more common in lower FLII forests. Significant differences in habitat preferences were also observed in relation to forest and canopy cover, revealing additional nuances that the FLII alone did not capture. This study demonstrates that the FLII, when combined with a comprehensive dataset and supplemented with region-specific factors, can assess species' adaptability to human-modified forests, aiding in the development of conservation strategies.

Stepping into Oligocene. A reassessment of the early Oligocene mammal tracks from Saignon (SE France)

ABSTRACT The Saignon ichnosite, located in the Apt syncline, yielded a high density of footprints with hundreds of mammal tracks preserved. It was discovered and first studied in the 1970s, and never re-examined since. Here we present a new analysis of the ichnosite with updates to ichnotaxonomy. The surface of the limestone bed bearing the prints was digitised by aerial photogrammetry (UAV). Best preserved tracks and trackways were digitised by short-range photogrammetric techniques. 3D data served as the basis for all measurements, including precise depth measurements. Of the hundreds of tracks present, this study focuses on the 20 best-preserved perissodactyl trackways. A review of the large perissodactyl morphotype is provided and Rhinoceripeda voconcense comb. nov. is defined. We also present possible evidence of social behaviour in early rhinocerotids. Based on fewer tracks a second smaller perissodactyl ichnotaxon, Lophiopus isp. is identified. Artiodactyl prints are attributed, when possible, to Bifidipes velox. The Saignon tracksite, dated as early Rupelian (MP21), is at an important faunal turnover, following the Grande Coupure. Its ichnofauna is characteristic of a post-Grande Coupure fauna with the presence of newcomer rhinocerotids that reached Europe from Asia and the persistence of endemic pre-Grande Coupure palaeotheriids.

Foraging movements of humpback whales relate to the lateral and vertical distribution of capelin in the Barents Sea

Understanding how individual animals modulate their behaviour and movement patterns in response to environmental variability plays a central role in behavioural ecology. Marine mammal tracking studies typically use physical environmental characteristics that vary, and/or proxies of prey distribution, to explain predator movements. Studies linking predator movements and the actual distributions of prey are rare. Here we analysed satellite tag data from ten humpback whales in the Barents Sea (north-east Atlantic) to examine how their spatial movement and dive patterns are influenced by the geographic and vertical distribution of capelin, which is a key prey species for humpback whales. We used capelin density estimates based on direct observations from a trawl-acoustic survey and sun elevation to explore the drivers of changes in movement patterns. We found that the humpback whales’ exhibited characteristic area restricted search movement where capelin density was the highest. While horizontal movements showed both positive and negative individual relationships with sun elevation, humpback whale dive depth was positively correlated with diurnal variations in the vertical distribution of capelin. This suggests that in addition to whales foraging in regions of high capelin density, they also target the densest shoals of capelin at a range of depths, throughout the day and night. Overall, our findings suggest that regions of high capelin density are important foraging grounds for humpback whales, highlighting the central role capelin plays in the Barents Sea marine ecosystem.

Eocene mammal tracks from the southeastern Tibetan Plateau

ABSTRACT Late Eocene artiodactyl and creodont tracks have been reported from the Jianchuan Basin, southeastern Tibetan Plateau, representing the first and the oldest reported mammal tracks in Yunnan Province, China. Sedimentary facies analysis indicates that tracks from the upper Baoxiangsi Formation and the lower Shuanghe Formation occurred in lake shore and flood plain environments, respectively. Based on the morphological analysis, the artiodactyl tracks from the Baoxiangsi Formation are attributed to Anoplotheriipus zeuctus. Combined with fossil records and morphological characteristics, the artiodactyl and creodont tracks were probably produced by entelodonts and mesonychids, respectively. The superimposition of artiodactyl tracks with varying sizes indicates coexistence of juveniles and adults as well as their gregarious behaviour. The co-occurrence of artiodactyl tracks and creodont tracks suggests the predator–prey relationship and ecological chain during the late Eocene. The presence of mammal tracks in the Jianchuan Basin coincides with the climate change from dry to wet in the late Eocene, implying the climatic and ecological effects of the uplift of the Tibetan Plateau.

Mammal tracks record anthropogenic environmental influence in late-Holocene inland dunes of the European Sand Belt, Poland

Structures previously suggested to be footprints or tracks, but which have been little described, were observed within Quaternary inland dunes of the European Sand Belt. Excavation of these in several localities of the eastern part of the belt in Poland reveal that they are hoofprints of various ungulate mammals, both wild and domestic, as well as footprints of humans, ranging from potentially as early as the fifth to sixth century to the 19th century or later. Trample grounds and horizons with high densities of tracks are associated with other signs of intensifying usage of dune habitats for pasture and farming, including constrained movement of livestock, relatively well-developed paleosols, and evidence of ploughing. The presence of such abundant life traces not only reflects the presence of individual animals and people in an area, but sheds light on the potential processes and feedbacks that the tracemakers were involved in, in terms of maintaining and modifying the habitats themselves, which were dynamic and changeable. Footprints and their associated sedimentological records can be integrated with archaeological and historical data to analyse anthropogenic influence through time on physical landscapes and on the wild biota.

Persistent similarities among hoofed mammal tracks across the Cenozoic revealed through Fourier outline shape analysis

Persistent similarities among hoofed mammal tracks across the Cenozoic revealed through Fourier outline shape analysis

Computer-vision object tracking for monitoring bottlenose dolphin habitat use and kinematics.

This research presents a framework to enable computer-automated observation and monitoring of bottlenose dolphins (Tursiops truncatus) in a zoo environment. The resulting approach enables detailed persistent monitoring of the animals that is not possible using manual annotation methods. Fixed overhead cameras were used to opportunistically collect ∼100 hours of observations, recorded over multiple days, including time both during and outside of formal training sessions, to demonstrate the viability of the framework. Animal locations were estimated using convolutional neural network (CNN) object detectors and Kalman filter post-processing. The resulting animal tracks were used to quantify habitat use and animal kinematics. Additionally, Kolmogorov-Smirnov analyses of the swimming kinematics were used in high-level behavioral mode classification. The object detectors achieved a minimum Average Precision of 0.76, and the post-processed results yielded 1.24 × 107 estimated dolphin locations. Animal kinematic diversity was found to be lowest in the morning and peaked immediately before noon. Regions of the zoo habitat displaying the highest activity levels correlated to locations associated with animal care specialists, conspecifics, or enrichment. The work presented here demonstrates that CNN object detection is viable for large-scale marine mammal tracking, and results from the proposed framework will enable future research that will offer new insights into dolphin behavior, biomechanics, and how environmental context affects movement and activity.

Large mammal tracks in 1.8-million-year-old volcanic ash (Tuff IF, Bed I) at Olduvai Gorge, Tanzania

Large animal tracks, unequivocally attributable to terrestrial mammals, are reported for the first time in sediment from uppermost Bed I (Tuff IF; ∼1.803 million years ago) at Olduvai Gorge, Tanzania. One track in particular (attributed to the ichnogenus Pecoripeda) retains an exceptional level of detail, demonstrating the excellent trackway-preserving potential of the volcanic ash fall (tuff) layers at this important hominin archaeological locality. Olduvai Gorge is renowned for its abundant Plio-Pleistocene (zoo)archaeological discoveries and fossiliferous deposits vis-à-vis studies of human evolution. Fossil trackways, and trace fossils more widely, provide an important additional tool for characterizing ancient ecosystems, which remain underexplored at Olduvai. Considered together with fossil hominin remains, information derived from coeval fossil animal tracks provides additional insight into our ancestors’ behaviour and their interactions with the surrounding palaeoenvironment. A range of large herbivore tracks indicates the availability of nearby resources (i.e., freshwater, vegetation preferred by grazers/browsers). These newly-discovered tracks are of archaeological and palaeontological significance because they highlight the potential for future discovery of animal or hominin tracks and trackways preserved in tuff at Olduvai and in other archaeological localities.

Small bird and mammal tracks from a mid-Cenozoic volcanic province in Southern Colorado: implications for palaeobiology

ABSTRACT The surprise discovery of two small assemblages of well-preserved, small bird and small mammal tracks in a thin unit of reworked tuff in the mid-Cenozoic volcanic field of southwestern Colorado represents the first significant report of tetrapod tracks in the region. The bird tracks are represented by a new ichnospecies of Avipeda (A. circumontis ichnosp. nov.), which differs from other Avipeda ichnospecies in representing a trackmaker with a narrower foot and comparatively robust digit traces and digital pads. The mammal tracks which are also well preserved are small (< 1.5 cm long and wide) tetradactyl-pentadactyl and rodent like. They are arguably unique and among the best-preserved small mammal tracks presently known from the Cenozoic, and are here assigned to the new ichnotaxon Musvestigium minutus ichnogen et ichnosp nov. The track-bearing surface represents a very thin unit of reworked tuff sandwiched between massive ignimbrite flows, and therefore represents a localised window into a brief period of biotic activity in local phase of quiescence in a large, active volcanic province.

Limited evidence for negative effects of highway widening on North American large mammals

Roads are one of the most severe threats to wildlife globally because of their pervasive and linear nature. Despite considerable attention afforded to road-effects on animals generally, little information is available concerning the specific impacts of road widening, also known as twinning or highway expansion. To address this gap, we monitored the abundance and distribution of large mammals adjacent to an 18-km section of highway in Ontario, Canada, that underwent expansion from a two-lane to a four-lane, divided highway, over 4 years. We expected to observe an initial decrease in large mammal track abundance and an increased distance from the highway, followed by a period of habituation during which track abundance and proximity to the highway would return to baseline levels. To quantify the effects of highway expansion, we monitored snow-tracks of three ungulates, two felids, and three canids on transects extending perpendicular and parallel to the highway. Our analyses revealed that proximity was species-specific and varied seasonally, but we found little evidence that the new four-lane highway alignment affected the movement ecology of large mammals in our study area. Limited increases in traffic volume could partially explain why we detected no change; however, traffic volume will rise. Although road widening is common for accommodating increased traffic volume, no studies have explicitly investigated its effects on animal movement ecology. Our findings suggest that increasing the footprint of existing roads, rather than building new roads, may be a suitable solution for accommodating increasing traffic with minimal impacts on adjacent large mammal communities.

Review of the early Mammal Brasilichnium and Brasilichnium-like tracks from the Lower Cretaceous of South America

The ichnogenus Brasilichnium Leonardi, 1981 is an early mammal track, presently recognized in several continents, but originally found in the aeolian deposits of Botucatu Formation in the Paraná Basin, Brazil. The sandstones of the Botucatu Formation are generally fine-grained and well-sorted, containing no pebbles; its color can be white, yellowish or reddish, but more commonly it is pinkish. Nearly always, it is silicified and therefore compact and hard, making it a very suitable building material. These sedimentary rocks are interpreted as a Lower Cretaceous desert regarded as the largest paleodesert in the Earth's history. Although the aeolian environment is generally considered inadequate for track preservation, taphonomic events linked to moist dunes and microbial mats foster a good geological context for an early diagenization of the sediments. Brasilichnium is associated with a large ichnofauna of other mammal, theropod and ornithopod tracks, in addition to invertebrate traces. It is today a worldwide ichnogenus that allows an overview of the arid terrestrial ecosystems during Mesozoic. The presence of tritylodontids in the world after the end of the Triassic and up to the Late Cretaceous, and the possibility of attributing Brasilichnium and related ichnogenera to them, has been discussed at great length. It seems preferable, however, to suggest that these tracks can only belong to the Mammalia. Thus, these track-bearing deposits bear witness to small- and medium-size mammaliaform trackmakers; some of them would be remarkably larger than the coeval mammals represented by skeletal remains. This chronological discrepancy between ichnological and bone findings is not a surprising phenomenon: it is also known in other clades. A complete check of these tracks will have to be carried out. It would also be advisable to perform a review of all the tracks recently attributed to Brasilichnium world-wide. The Botucatu and Caiuá ichnofaunas and, globally, the ichnogenus Brasilichnium, should be stressed as an important window into the arid terrestrial ecosystems during the Gondwanic Cretaceous. This study is the result of forty-four years of research in the Botucatu Formation by the first author.

Bison (&lt;i&gt;Bison bison&lt;/i&gt;) activity fragments subnivean tunnels of small mammals

Ecological interactions between ungulates and small mammals are generally not well understood. Here, we report an observation of unusually extensive small mammal (likely Meadow Vole [Microtus pennsylvanicus] or Tundra Vole [Microtus oeconomus]) tracks above the snow, exiting from trails and bed sites created by Bison (Bison bison) in northern Canada. We believe that weather and snow conditions were optimal for this observation. Although alteration of above-snow activity of small mammals in response to snow compaction by ungulates is probably not a rare event, it is not often reported. The effect on voles of exiting their subnivean tunnels as a result of Bison activity is unclear, but may be detrimental to their overwinter survival. Ungulate activity compacts snow, fragmenting small mammal tunnels resulting in loss of their insulative value for voles, and making it harder for them to dig new tunnels. Clearly, determining the effect of snow disturbance by gregarious ungulates on voles or other microtines, particularly regarding their overwinter survival, requires detailed investigation. Nevertheless, this observation provides new information on the ecological interactions between ungulates and small mammals, particularly from the boreal forest, where such information is largely lacking.

Vertebrate footprints and a mammal mud-bath trace fossil (Laspichnia) from the Mukdadiya Formation (Late Miocene–Pliocene), Chamchamal Area, Kurdistan Region, Northeast Iraq

The Mukdadiya Formation (Late Miocene–Pliocene) consists of alternations of red to brown sandstone and claystone layers in the Zagros Mountains Belt, northeastern Iraq. Two tracksites preserving bird and mammal tracks were recorded from the base of the formation in the Chamchamal area of the Kurdistan region in northeast Iraq. Avian tracks are large footprints with an average length of 25 cm that belong to Avipeda filiportatis. Mammal footprints imprinted by terrestrial cetartiodactyls belong to Pecoripeda amalphaea and Bifidipes velox, with cervids the most likely track makers. An unfamiliar large trace fossil on the studied slab, has symmetrical to asymmetrical marks, kidney or number-8-shaped and strong wrinkles on the surface. We interpret trace as having been produced by cetartiodactyls wallowing on the soft sediment surface. To accommodate this class of behavioral trace fossils; thus, we introduce a new fossilized behavior class, named “Laspichnia”, which includes a vertebrate mud-bathing imprint on a soft sediment surface.

"Mammal Tracks and Sign: A Guide to North American Species. Second Edition" by Mark Elbroch with contributions by Casey McFarland, 2019. [book review

"Mammal Tracks and Sign: A Guide to North American Species. Second Edition" by Mark Elbroch with contributions by Casey McFarland, 2019. [book review

Lower Eocene Footprints from Northwest Washington, USA. Part 1: Reptile Tracks

Lower Eocene fluvial strata in the Chuckanut Formation preserve abundant bird and mammal tracks. Reptile trace fossils include footprints from a small turtle (ichnogenus Chelonipus), and several Crocodylian trackways that consist of irregularly spaced footprints associated with linear tail drag marks. The latter trackways represent “punting” locomotion, where a submerged Crocodylian used intermittent substrate contacts to provide forward motion of their neutrally buoyant bodies. Two adjacent sandstone blocks preserve Crocodylian trace fossils that are named herein as a new ichnogenus and ichnospecies Anticusuchipes amnis. Two other Crocodylian trackways lack sufficient detail for ichnotaxonomic assignment.

Following the last Neanderthals: Mammal tracks in Late Pleistocene coastal dunes of Gibraltar (S Iberian Peninsula)

The aeolian Pleistocene deposits recorded in the Rock of Gibraltar (S Iberian Peninsula) present a significant sedimentary thickness that fills the wide sea caves and covers its steep slopes. In Catalan Bay these deposits register the development of cliff-foot and rampant dunes that form a 35° sand ramp, 1 km long and up to 300 m in height formed by moderately to well-sorted sands, slightly carbonated and weakly cemented. This morphosedimentary evidence is associated with MIS 5−2 sea level fluctuations. Its internal structure shows lamination sets of 2–3 m in thickness and planar and trough cross-bedding. In these beds, five morphotypes of mammalian footprints have been recognized in vertical cross sections and convex hyporeliefs. Most of them present a moderate degree of conservation due to the poor cementation of the sands. These icnites are related to the activity of terrestrial mammals, possibly belonging to Homininae, Proboscidea, Artiodactila and Carnivora. The affinity between the footprints and their tracemakers has been established in the basis of their physical parameters, the shape of the footprints, their comparison with similar footprints and the correlation with the fossil fauna of vertebrates described for the Late Pleistocene in Gibraltar. These findings represent the first palaeoichnological record in the aeolian sediments of Gibraltar and indirectly corroborate the occupation of the coastal dune landscape by several terrestrial mammals during the Late Pleistocene. In addition, they help reconstructing the animal behaviour and interaction with the extensive dune systems that developed at the foot of the Rock slopes. The age of the tracks has been established within the MIS 2, during the probable Middle-Upper Palaeolithic transition in the climate refuge of Gibraltar.

Differentiating Footprints of Sympatric Rodents in Coastal Dune Communities: Implications for Imperiled Beach Mice

AbstractIdentifying techniques for conducting frequent, effective, and inexpensive monitoring of small mammals can be challenging. Traditional approaches such as livetrapping can be laborious, expensive, detrimental to animal health, and ineffective. Passive approaches such as tracking (e.g., from tracks on the ground or footprints collected at a tracking station) have been shown to lessen those burdens, but a problem with tracking, particularly for rodents, is the uncertainty in identifying species from footprints. To address the need for a more accurate method of identifying small mammal tracks, we measured footprints from live-captured rodents and developed a classification tree for distinguishing between subspecies and species using footprint widths treated as having known or unknown identification. We captured rodents within or near the coastal dunes of Florida and Alabama with a focus on areas occupied by threatened and endangered beach mice Peromyscus polionotus subspp., whose populations warrant regular monitoring but whose tracks are not easily distinguished from those of some sympatric species. We measured 6,996 front and hind footprints from 540 individuals across eight species. The overall accuracy of our classification tree was 82.6% and we achieved this using only the front footprint width. Footprint width cutoffs for species identification were &amp;lt; 5.5 mm for house mice Mus musculus, 5.5–6.7 mm for beach mice, and 6.7–8.3 mm for cotton mice Peromyscus gossypinus. We were most successful in confirming the identity of beach mice: we correctly classified approximately 94% of beach mice, while we misclassified fewer than 6% as house mice and fewer than 1% as cotton mice. When we input a beach mouse individual into the classification tree as of an unknown species, we correctly identified 78.1% of individuals as beach mice from their tracks, and most incorrect identifications were of house mouse tracks. Our study demonstrates that researchers can identify sympatric rodent species in coastal dune communities from tracks using quantitative classification based on footprint width. Accurate identification of beach mice or other imperiled species from tracks has important management implications. Not only can wildlife managers determine the presence of a species accurately, but they can monitor populations with considerably less effort than livetrapping requires. Although our study was specific to coastal dune communities, our methods could be adapted for the creation of a classification tree for identifying tracks from suites of species in other areas.

Smallest known raptor tracks suggest microraptorine activity in lakeshore setting

Ongoing studies of a multiple track-bearing horizons from massive excavations in the Jinju Formation (Lower Cretaceous) of South Korea have yielded a remarkable diversity of avian, non-avian dinosaur, pterosaur, crocodilian and mammal tracks, many very small and well preserved. Here we report diminutive, didactyl tracks (~1.0 cm long) assigned to a new dromaeosaurid ichnogenus Dromaeosauriformipes, which resembles the larger, but still quite small, ichnogenus Dromaeosauripus, also from the same formation only 30 km away. These diminutive tracks are consistent with the foot size of smaller dromaeosaurid taxa like Early Cretaceous Microraptor from China, and may represent diminutive species or juveniles of larger species. The association of tracks with lakeshore sediments is consistent with the evidence that Microraptor was a fish eater. Two trackways and isolated tracks indicate variable trackmaker gaits and speeds. If oviparous, as assumed for most non-avian dinosaur neonates, the trackmakers must have hatched from tiny eggs. Previous studies of the Korean Cretaceous indicate the presence of other diminutive (~1.0 cm long) theropod tracks (Minisauripus). Such occurrences strongly suggest that small tracks attributed to juveniles, or very small tetrapod species, are more common than previously supposed especially where suitable preservation conditions prevailed.

Crocodylomorph, turtle and mammal tracks in dinosaur-dominated Middle–?Upper Jurassic and mid-Cretaceous ichnoassemblages of Morocco

We report tetrapod traces from two stratigraphic intervals in Morocco, and discuss their palaeoecological implications. In the first interval, crocodylomorph footprints assigned to Crocodylopodus meijidei are described from Middle–?Upper Jurassic continental fluvial red beds of the Isli Formation in the Imilchil region, Central High Atlas, Morocco. These traces are associated with a diverse dinosaur-dominated ichnofauna, including the footprints of theropods, ornithischians, sauropods and pterosaurs, together with numerous invertebrate traces. In the second interval, we report crocodylomorph swim traces assigned to Hatcherichnus isp., turtle trackways assigned to Emydhipus isp. and isolated mammal footprints in the mid-Cretaceous Midelt Formation, in the High Moulouya region, Morocco. These traces are, also, associated with a diverse dinosaur-dominated ichnofauna including theropods and ornithopods as well as pterosaurs and abundant invertebrate traces. Together with plant remains, conchostracans and fishes, findings indicate a diverse community populating a fluvial-brackish environment.