Microhabitat and rhythmic behavior of tiger beetle Callytron yuasai okinawense larvae in a mangrove forest in Japan

Mangrove forests are regularly flooded by tides at intervals of approximately 12.4 h (tidal rhythm). Larvae of the tiger beetle Callytron yuasai okinawense in a mangrove forest made shallow burrows in mounds up to 1 m in height constructed by the mud lobster Thalassina anomala. No larval burrows were observed on the forest floor, which was very muddy even during low tide. Some larvae plugged the burrow openings before they were submerged at high tide. The mean interval between consecutive burrow plugging events was 12.37 h, which is similar to the period of tidal cycles. Nine out of 30 larvae plugged the burrow openings even when the burrows did not become submerged. Plugging behavior may be governed by an endogenous biological clock, or may be a response to exogenous information about tidal level (e.g. moisture seeping through the ground).     

The Tactile Communication between Cryptocentrus steinitzi (Pisces,Gobiidae) and Alpheus purpurilenticularis (Crustacea,Alpheidae)

The tactile alarm system between the symbiotic goby Cryptocentrus steinitzi and its burrowing shrimp partner Alpheus purpurilenticularis was investigated by underwater observations in the northern Red Sea. Warning signals by the goby which elicit the retreat of the shrimp into its burrow consist mainly of rapid tail flicks transmitted to the shrimp through its long antenna. No warning signals are given without that contact. The daily rhythm of the antennal contacts was described. Warning signals are emitted by the goby in a selective manner only in response to the approach of certain species of fish to the burrow entrance. The response of the shrimp to warning signals was described. The goby-shrimp communication system was used to study predator recognition in a series of controlled experiments. The sequence of the acts of the goby and shrimp was analyzed.     

Circatidal rhythmic behaviour in the coastal tiger beetle Callytron inspecularis in Japan

Larvae of the coastal tiger beetle Callytron inspecularis (W. Horn) (Coleoptera: Cicindelidae) plug their burrow opening before submergence at high tide. Field observations showed that burrow plugging was a rhythmic behaviour that coincided with the tidal cycle (ca. 12.4 h). On average, larvae plugged their burrows 41.8 min before the tide covered the habitat. The mean interval between consecutive burrow-plugging events in the field was 12.40 h. In the laboratory, in the absence of tidal inundation, the mean interval between consecutive burrow-plugging events was 12.45 h. This suggests that the burrow-plugging rhythm of the coastal tiger beetle is governed by an endogenous circatidal rhythm.     

Passive irrigation and functional morphology of crustacean burrows in a tropical mangrove swamp

Flushing measurements and a resin cast of a burrow inhabited by Sesarma messa and Alpheus cf macklay were taken from a Rhizophoraspp. forest. The burrow had 9 openings and occupied a swamp surface area of 0.64 m². Passive irrigation of the burrow was investigated by recording change in conductivity of burrow water in a chamber 45 cm below the swamp surface during tidal inundation of the swamp. The chamber was completely flushed within approximately one hour, i.e. by a single tidal event. Burrow morphology was determined by means of resin casting. The investigated burrow was of discrete structure, with an overall depth of 1.2 m and a total volume of 68 l, i.e. ca. 9% of the volume of swamp soil. The below ground surface area of chambers and tunnels was 3.8 m². The mean and maximum chamber/tunnel diameter was 7 cm and 11 cm respectively. The soil in the close vicinity of the burrow was extensively penetrated by roots, and any two parts of the burrow were located no further than 20 cm away from each other. By reducing diffusion distances within the soil and by being well flushed, the burrows provide an efficient mechanism for removal of excess salt accumulated in the soil around mangrove roots due to exclusion.     

End-Permian Trace Fossil Dolopichnus and the Stresses of Ash Fall

The fossil burrow Dolopichnus, capped by an ash layer, was collected ～0.6 m below the Permian–Triassic Boundary at the Lung Cam section in North Vietnam. The burrow occurs at the top of Bed 9, directly below the stepped extinction in foraminifera that marks initiation of the global perturbations related to the end-Permian extinction event. Dolopichnus is a plug-shaped burrow, possessing lining and fills. This specimen was found capped by an undisrupted bentonite layer. The main chamber has internal structure throughout indicative of benthic organisms overcoming living pressures of repeated ash falls, which can be applied to paleoenvironmental research across different regions and times, including the recent.     

Microvertebrates preserved in mammal burrows from the Holocene of the Argentine Pampas: a taphonomic and paleoecological approach

Microvertebrates are a major component of many assemblages recovered from the Quaternary of the Argentine Pampas. The main goal of this paper is to analyse the taphonomic history of a Holocene microfossil bonebed, recovered from the infilling of a burrow. Evidences suggest the plains vizcacha Lagostomus maximus as the putative producer of the burrow. The assemblage includes individuals belonging to different taxa of mammals (marsupials and rodents) and reptiles (snakes). Taphonomic features suggest that the accumulation inside the burrow was related to flooding processes in the plain. The burrow was a natural trap that favoured the accumulation and preservation of remains corresponding to individuals from different sources. According to the taphonomic evidence, some individuals (Lagostomus maximus, Lestodelphys halli and Serpentes indet.) died inside the burrow, whereas others (Microcavia australis, Reithrodon auritus and Ctenomys sp.) died outside the burrow, and after a time of being exposed on the surface their remains were transported by surface run-offs into the burrow. The record of Lestodelphys halli and Serpentes indet. in the burrow produced by Lagostomus maximus could be related to a circumstantial use. Mammal burrows are a significant taphonomic mode for the late Cenozoic of the Argentine Pampas.     

The burrow ofDasypus hybridus (Cingulata: Dasypodidae)

Dasypus hybridus (Desmarest, 1804) inhabits open fields in southern South America. Burrows ofD. hybridus were cylindrical with a conical end. They had an entrance and a single tunnel without branches. Three locations of the burrows in the terrain were detected: in banks of dried waterways, near rocks, and in open field. The orientation of 29 burrow mouths was not random and, although they did not point to any cardinal point, in particular there was a strong tendency to avoid the south quadrant. In a sample area of 90 × 140 m, burrow mouths were arranged in a random spatial pattern with a density of 25.4 burrows per ha. Great variation in burrow length was found (118.8 ± 105.69 cm, CV = 89.0%). Tunnels may be used as refuges and/or for thermoregulation. The orientation of burrow mouths can also be related to thermoregulation as tunnels are covered from dominant winds, and, for many hours every day, the temperature at the mouths can be influenced by insolation. The possible existence of shelter-burrows and resting-burrows is discussed.     

Development of an index of abundance for pygmy rabbit populations

The pygmy rabbit (Brachylagus idahoensis) is a cryptic, burrowing lagomorph of conservation concern for which an efficient method to monitor populations is needed for conservation planning. We developed an index of abundance based on density of active burrow systems at 7 sites (57.2–118.5 ha) in east central Idaho. We conducted censuses of burrow systems and used mark-resight surveys of 80 radio-collared individuals to estimate density of rabbits. At 5 sites, we also used a second method to estimate rabbit numbers based on presence of tracks in snow around burrow systems. We evaluated patterns of burrow use by individuals and examined the relationship between vegetation structure and density of rabbits. Density of active burrow systems varied from 0.19 to 3.46 per ha, and density of rabbits ranged from 0.02 to 0.46 per ha. Number of burrow systems used by individuals increased with density of available burrows, which supported a nonlinear relationship between abundance of burrows and rabbits. Population density increased curvilinearly with density of active burrows accounting for >75% of the variation (r² = 0.79) in population estimates across sites. We documented a positive relationship between visual obstruction of vegetation and density of rabbits across 6 of the study sites. Our results suggest that density of burrows can serve as an index for monitoring changes in abundance of pygmy rabbits in east central Idaho and that this index also might be useful for monitoring changes in relative abundance over time at other locations. To assess abundance at larger spatial scales or across different regions, the index should be calibrated under regional conditions and site-level covariates should be evaluated. © 2011 The Wildlife Society.     

Estimating and Correcting for Bias in Population Assessments of Sooty Shearwaters

Abstract: We investigated the precision and accuracy of an infrared burrowscope for detecting sooty shearwater (Pufffinus griseus) chicks at 13 plots from 3 islands in southern New Zealand in 2003. We partially excavated burrows systems to reveal the entire burrow contents after 2 teams of observers had prospected all burrow entrances. Accuracy was similar between islands and observer teams at approximately 85%. The majority of the inaccuracy stemmed from failure to detect some chicks. Logistic regression modeling identified 4 burrow characteristics occurring between the entrance and the nest-site that influenced detection of burrow occupants. Detection was lower at nest-sites further from burrow entrances, in burrows with a high rate of burrow division, and in burrows with a high level of curvature. There was a positive relationship between the interaction of rate of division and curvature and detection of chicks. Distance from the burrow entrance was the only parameter that could be reliably used as a predictor of detection rate, so a reduced model containing only this variable was constructed to correct for burrowscope bias. The correction factor performed well on The Snares and Bench Island where predicted bias was very similar to observed levels (within 5%), but bias was overestimated on Putauhinu by up to 19.1%. Consistent bias, lack of damage to burrows from excavation, and the successful application of a correction factor all indicate the value of further testing burrowscope accuracy on other burrow-nesting seabird species.     

Alteration of burrow‐related behaviour of the norway lobster,nephrops norvegicus during infection by the parasitic dinoflagellate hematodinium

This study has used time‐lapse video recordings to analyze the burrow‐related behaviour of N. norvegicus under a 12 h light: dark regime in aquarium conditions, and compared this with the behaviour of lobsters infected by the parasitic dinoflagellate Hematodinium. Uninfected lobsters performed a higher number of burrow departures, of longer duration, during the hours of darkness than during the light. Infected lobsters performed a relatively constant number of departures of similar‐duration in the light and the dark periods. However, the mean number of departures per day performed by infected lobsters (70 day^‐1) was more than double that of uninfected lobsters (30.1 day^‐1), while the mean duration of burrow departures performed by infected lobsters (258.5s departure^‐1) was more than six times greater than in uninfected lobsters (38.7s ? departure^‐1). This led to a more than ten‐times increase (from 1.7 to 19.4%) in the percentage of the day spent out of the burrow by infected lobsters. This altered burrow‐related behaviour could be due to the nutritional demands of the parasites on infected lobsters, causing an increased requirement to forage, or alternatively to a ‘functional hypoxia’, due to the additional respiratory demands of the parasite, causing the host to emerge from the burrow onto the sediment surface to seek oxygen. Implications for the increased time spent out of the burrow are discussed in relation to availability of infected lobsters by trawlers and predators, and to the use of infection prevalence data from trawl‐caught samples in stock assessment models for N. norvegicus.     

A versatile laboratory stream with examples of its use in the investigation of invertebrate behaviour

A versatile and simple laboratory stream was designed and used to investigate the burrowing activity of two insects in response to changes in water velocity and substrate type.Aphelocheirus aestivalis adults were unable to burrow into sand, however, a small proportion of juveniles did burrow in this substrate. The presence of sand in gravel reduced the burrowing success of adults. Steady increases in flow stimulated the burrowing response of both adults and juveniles on gravel and sandy gravel.Ephemera danica was unable to burrow in sand alone at the velocities used in the experiment. The presence of particles greater than 2 mm in diameter in the substrate appeared to be essential for successful burrowing under the test conditions. An increase in flow from 3 to 8 cm s^–1 resulted in an increase in burrowing. The time taken for each specimen to burrow varied widely within replicate tests but most specimens had penetrated the substrate within 150 seconds of introduction. The implications of these observations in influencing the microdistribution of these species are discussed.     

Comparative Ecology of the Gobies <Emphasis Type="Italic">Nes longus</Emphasis> and <Emphasis Type="Italic">Ctenogobius saepepallens</Emphasis>, Both Symbiotic with the Snapping Shrimp <Emphasis Type="Italic">Alpheus floridanus</Emphasis>

Synopsis We re-examined the symbiotic association of the western Atlantic gobiid fishes Nes longus and Ctenogobius saepepallens with the snapping shrimp Alpheus floridanus on the basis of a critical literature review and new data. Our research confirms that N. longus interacts closely with the shrimp and is dependent on it for the cover provided by the burrow that the shrimp constructs; the goby serves as the sentinel at the burrow entrance. Ctenogobius saepepallens is often seen occupying a burrow of the alpheid, and the shrimp will leave the burrow to deposit sediment with the goby at the entrance, even pushing the goby aside at times. However, the shrimp does not make contact with the goby with its antennae, nor does the goby communicate with caudal fin fluttering at the approach of danger. We suggest that their relationship is a first step in an evolutionary process that may lead to the very close mutualistic association exhibited by N. longus and the alpheid, as well as Indo-Pacific shrimp gobies of 13 different genera and their alpheid partners. Nes longus remains close to the burrow entrance; it feeds mainly on small gastropods, decapod crustaceans, ostracods, and isopods. By contrast, C. saepepallens makes longer excusions from the shelter of the burrow; its diet is dominated by benthic copepods, followed by ostracods and lesser amounts of foraminiferans, isopods, and decapod crustaceans. By virture of its greater mobility, it can be more selective in its prey.     

Maternal influence on activity rhythms and reproductive development in Djungarian hamster pups

Photoperiodism and entrainment of the circadian rhythm of locomotor activity were investigated in juvenile Djungarian hamsters. Animals were housed in simulated burrows. Activity was measured as the animal's emergence from a dark nest chamber into an outer box exposed to the room illumination. This burrow emergence activity exhibited marked circadian rhythmicity. Interactions between mother hamsters and their offspring were examined in the simulated burrow system. Male reproductive responses were determined by measuring testicular weights at the time of weaning. It was shown that photoperiodic information received between Days 1 and 15 of life failed to alter the rate of testicular development, but that after Day 15 testicular growth was photoperiod-dependent. The mother, when entrained to a long photoperiod, did not influence the photoperiodic responses of her pups when they were confined to a dark nest box. In contrast, the mother did influence the circadian entrainment patterns of her pups. Pups exhibited a well-developed circadian activity rhythm at weaning with a phase angle roughly similar to that of the mother's activity rhythm. When the maternal rhythms were discrepant with photoperiod information received by the pups directly from the environment, the pups' activity rhythms were synchronized with the light/dark cycle rather than with the rhythm of their mother. Thus, it appears that although pups may first become entrained by maternal cues, they rapidly adjust to the environmental light cycle after leaving the nest.     

Shell-Filled Burrows in the Upper Oligocene Antigua Formation,Antigua, Lesser Antilles

Limestones of the Upper Oligocene Antigua Formation of Antigua contain unusual burrows filled with the densely packed debris of shelly benthos. Unlined burrows (Planolites?) in deep-water biofacies at Half Moon Bay, parish of Saint Philip, are packed with a monospecific assemblage of large benthic foraminiferans (Lepidocyclina canelli Lemoine &; Douvillé) and a single brachiopod valve, Tichosina sp. A similar burrow in shallower-water biofacies at Hughes Point, parish of Saint Philip, is packed with echinoderm debris and, particularly, test fragments of the spatangoid echinoid Lovenia n. sp. Fragments of the same echinoid fill a conical burrow, Bergaueria isp. The latter is probably a physical accumulation, the common fragments of echinoid being washed into an empty burrow. In contrast, the infill of Planolites? isp. is more likely to be an accumulation mediated by the burrower.     

Homing in fiddler crabs (Uca lactea annulipes and Uca vomeris : Ocypodidae)

Fiddler crabs emerge from burrows on intertidal sand- and mudflats to feed during low tide. In the species studied here (Uca lactea annulipes, Uca vomeris) a crab normally wanders no more than about 1 m away from its burrow and, when frightened, dashes back along a straight line to take cover. Feeding crabs tend to move sideways, without changing orientation, along paths radiating from the burrow. When they move along circumferential paths they adjust their orientation so that one side continues to point towards the burrow. The crabs do not need to see the burrow in order to stay aligned with the home vector, and they are not misled by a dummy hole close to their own burrow unless they have come to within about 10 cm of it. The home runs of crabs end within a few centimeters of a burrow that is covered with a sheet of sandpaper and then give way to search runs, centred upon a position slightly short of the burrow location. Feeding crabs can be displaced on sandpapers and their subsequent home runs end at a position where the burrow would be, had there been no displacement. Landmarks close to the burrow do not influence the home runs of displaced crabs. Crabs that are rotated on a sheet of sandpaper, counter-turn to keep their original orientation constant. Fiddler crabs thus employ path integration with external compass information and close range visual guidance for homing. Accepted: 11 May 1998     

What determines the way of deposition of excavated soil

Subterranean rodents continuously extend their burrow systems primarily in search of food, which has an important impact on the ecosystem in which they live. Excavated soil may be pushed either into aboveground mounds or into tunnels underground. Factors affecting the amount of burrowing and the preference of aboveground or underground soil deposition are, nevertheless, little known. We investigated the influence of food supply, soil hardness, and the animal’s body mass on the mode of soil deposition in ten burrow systems of free ranging silvery mole-rats Heliophobius argenteocinereus Peters, 1846. In each burrow system, we estimated the volume of backfilled tunnels and the volume of soil deposited aboveground. The highest amount of variation in these parameters was explained by the interaction of food supply and soil hardness. The ratio of the volume of backfilled tunnels to the volume of mounds was not significantly dependent on any of the explanatory variables. The proportion of backfilled tunnels decreased with the increasing volume of the complete burrow system. We propose that both low food supply and soft soil lead to an increased amount of burrowing, which results in a larger volume of soil deposited both above ground and under ground over a given period of time.     

Impact of two different flood pulses on planktonic communities of the largest floodplain lakes of the Daugava River (Latvia)

This study investigated whether surface hole counts could be used as a reliable estimate of density of the ghost shrimps Trypaea australiensis Dana 1852 and Biffarius arenosus Poore 1975 (Decapoda, Thalassinidea) in south eastern Australia. The relationship between the number of holes and the number of ghost shrimps was explored in two ways. Resin casts were used to document any changes in the number of burrow openings per shrimp burrow over time. Manual suction pumping (bait pumping) within a given mudflat area was used to directly compare the number of holes on the sediment surface with the number of ghost shrimps occupying the corresponding volume of sediment. Resin casting showed that throughout the year, the burrows of T. australiensis consistently had an average of two openings, whereas the burrows of B. arenosus showed much greater variability over time with two to four openings per burrow. Overall, a significant relationship between the number of holes and the number of ghost shrimps (mixed species populations) was found, with 2.1 burrow openings for each ghost shrimp. However, some temporal and spatial variation was seen in this relationship. We suggest that the hole count method may be reliable in estimating ghost shrimp densities with restricted use and site specific validation based on some limitations found in this study. Handling editor: K. Martens     

Review of “Marine Hard Substrates: Colonization and Evolution,” a Thematic Session at the Geological Society of America Annual Meeting,Denver, USA,November 7–10, 2004

Planolites, although strictly a junior synonym of Palaeophycus, can be retained as a valid ichnotaxon on the basis of stability of nomenclature. As emended by Pemberton and Frey (1982) and consistently adopted by later authors, Planolites is diagnosed primarily on the basis that it is an unlined simple burrow, whereas Palaeophycus is a lined burrow. Other ichnotaxobases and ethological considerations are, without exception, subordinate to this directive.     

An endogenous activity rhythm and the rhythmicity of catches of Nephrops norvegicus (L).

Field and laboratory studies were carried out with Nephrops norvegicus (L.) collected from depths ranging from 10 to 184 m off the west coast of Britain. An endogenous circadian rhythm of locomotor activity was exhibited by prawns from all depths when kept under constant conditions in the laboratory. The rhythm was expressed as nocturnal activity mainly within the burrow, though the prawns repeatedly vacate the experimental burrow during the same period. If, as seems likely, prawns in the field also show burrow-orientated locomotor activity at night this would explain why they are caught in smaller numbers when on commercial fishing grounds attempts are made to trawl them during darkness.Peak catches in trawls occur at differing times of day according to depth, and other workers have suggested that this reflects emergence from burrows at optimal light intensities. Present laboratory experiments show that there is no endogenous basis for a distinct ‘emergence’ rhythm. They suggest that high catches at different times of day at different depths are determined by exogenous factors but not solely by some optimal light intensity. It was not possible to induce emergence from artificial burrows by exposing prawns to light intensities within the presumed optimum range for their depth of capture. Dusk and dawn changes of light intensity may have direct effects upon activity, and light may also have an indirect effect by controlling the availability of suitable food organisms and predators. Light may also have a direct effect by suppressing emergence around midday in intermediate depths, particularly in view of the poor or non-existent light-adapting responses of the retinal shielding pigments.     

Identification versus counting protocols as sources of uncertainty in diatom-based ecological status assessments

The heterogeneity of oxygen distribution in a Hediste diversicolor burrow environment was investigated in a laboratory experiment using a 6-mm thick tank equipped with oxygen planar optodes. The two-dimensional oxygen distribution in a complete burrow was monitored every 2 min for 4 h. Oxygen concentrations fluctuated over a scale of minutes in the burrow lumen and wall (up to 2 mm) reflecting the balance between worm ventilation activity and oxygen consumption. The magnitude of the three surrounding micro-horizons (oxic, oscillating and anoxic) induced by the intermittent worm ventilation was spatially and temporally variable within the structure. Oxygen variations appeared to be controlled by distance from the sediment–water interface and the direction of water circulation. Moreover, there was an apparent ‘buffer effect’, induced by the proximity to the overlying water, which reduced the variations of lumen and wall oxygen in the upper part of the structure. These results highlight the heterogeneous distribution and dynamics of oxygen associated with H. diversicolor burrows and ventilation activity. They also highlight the necessity of integrating this complexity into the current burrow-base models in order to estimate the ecological importance of burrowing species in coastal ecosystems.