The lower Maastrichtian chalk of the Isle of Rügen was deposited in a pelagic setting in the aphotic zone. Its rich fossil content has attracted research attention for centuries, whereas its ichnological characteristics remain poorly understood, even though horizons with intense bioturbation and occurrences of trace fossils in flint are common. The enhanced colour contrast of smooth chalk faces reveals repeated phases of benthic colonisation; larger burrows are commonly subject to silicification, while flint nodules also can preserve burrows in chalk. A total of 37 ichnogenera, including 47 ichnospecies of bioturbation and bioerosion trace fossils have been recognised; these are here briefly described, in addition to indeterminate material. Many ichnotaxa are recorded for the first time from the Rügen chalk. Bioerosion is restricted mainly to local hardgrounds in the form of biogenic components (such as shells and belemnite guards).

Moulting is essential for crustacean growth, but is one of the causes of mortality, because a crustacean cannot move during and just after its ecdysis. In the cases of ectosymbiotic crabs, escape from the host's hostile response may also be a problem during its own ecdysis. In this study, Sestrostoma sp. (Varunidae), an ectosymbiotic crab which clings to the ventral abdomen of upogebiid shrimps with legs that can walk, was studied to clarify how the crab moults and maintains association with the host. Five cases of crab ecdysis were observed, where the crab moulted with its legs clinging to the host abdomen, without detaching from the host body. Time required for moulting was 14–21 min. Shedding of the old exoskeleton (active phase) took only 40–59 s. Sestrostoma sp. detached from the host abdomen and waited in the burrow tube during shrimp ecdysis. The crab then reattached at the same location on the host when shrimp moulting was complete. Our results suggest that Sestrostoma sp. are able to maintain a symbiotic relationship with the same shrimp host after its own ecdysis as well after ecdysis of its host.

Paramya is an enigmatic genus of Myidae (Bivalvia: Heterodonta: Myoidea) that includes three uncommon species: Paramya subovata (Conrad, 1845), Paramya recluzi (A. Adams, 1864) and Paramya africana Cosel, 1995. Paramya subovata is known as a commensal living in the burrow of the spoon worm Thalassema hartmani Fisher, 1947 (Annelida: Echiura: Thalassematidae), in North American coastal waters. However, the biology of the other two species remains unknown. In this study, we found P. recluzi living in the burrows of the two thalassematid echiuran species, Ikedosoma gogoshimense (Ikeda, 1904) and Arhynchite hayaoi Tanaka & Nishikawa, 2013, in intertidal flats in the Seto Inland Sea, Japan. Paramya recluzi was embedded in the burrow wall with its short siphons protruding into the host burrow lumen for respiration and filter feeding. To determine the phylogenetic position of P. recluzi, we performed a molecular phylogenetic analysis using the 18S, 28S, COI and H3 genes. Molecular analysis showed that P. recluzi belongs not to the family Myidae, but to the genus Basterotia (Galeommatoidea: Basterotiidae). Morphological examination of P. recluzi revealed that this species has many similarities with Basterotia (e.g. a single cardinal tooth on each valve and short siphons surrounded by tentacles). Thus, we propose that this species should be transferred from the genus Paramya to Basterotia. In addition, we also suggest that the other two species of Paramya (P. subovata and P. africana) should be transferred to the family Basterotiidae based on their shell morphology, anatomy and ecological characteristics.

Various trace fossils are known from the Upper Triassic (Rhaetian) shale deposits of western Europe, especially from Great Britain. Here we present a unique specimen, unknown from Rhaetian shales in western Europe thus far to our knowledge. The specimen consists of a string of small knobs collected from the dark-coloured Rhaetian shales from the eastern Netherlands, deposited in a marine, near-coastal environment. The specimen represents the first described trace fossil from these shales. The identity of this specimen appears enigmatic. However, SEM-EDS analysis showed that the string of knobs is pyritised and does not contain phosphorus nor did the sediment directly around the specimen, suggesting a non-coprolitic origin of the specimen. Eggs and larvae are also excluded as possibilities. The specimen closely resembles several trace fossils identified as burrows, which is why we favour this interpretation. The rare presence of trace fossils reinforces the hypothesis that the Dutch Rhaetian shales were deposited under a stresses regime with low oxygen conditions.

The Siberian marmot Marmota sibirica is a social, colonial-living rodent that ranges widely throughout northern Asia. In Mongolia the species has declined substantially in recent years due to overharvesting for fur, meat and body parts, used locally and traded illegally in international markets. The Siberian marmot is often considered a keystone species because its burrows appear to represent an important resource for a variety of taxa, including carnivores. However, few studies have quantified marmot burrow use by other species, although such use may be important for developing conservation strategies. We monitored patterns of burrow use by 10 radio-collared corsac foxes Vulpes corsac during a study in Mongolia during May–November 2006. Corsacs used marmot burrows regularly and at rates greater than expected by chance, suggesting that burrows represent an important resource for foxes and supporting the notion of the Siberian marmot as a keystone species. As corsacs are also declining in Mongolia we contend that targeted patrols of marmot colonies in certain areas would provide a cost-effective means of protecting both species.

This study investigated burrow use and ranging behaviour in the southern hairy-nosed wombat Lasiorhinus latifrons in semi-arid South Australia. Sixteen adult wombats were fitted with radio transmitters and monitored monthly from July 2001 to February 2002. Wombats generally used between one and five warrens, preferred large warrens with a greater number of entrances and showed a preference for one or two warrens. Across the study period there was no apparent change in burrows used within warrens. Radio-tracking indicated that animals spent very little time above ground (26% of 1115 night-time fixes), centred their activity around their preferred warrens, and moved, on average, 99 m/h and 221 m/night. Mean home-range size, estimated using minimum convex polygons and the harmonic mean method from location data, obtained through triangulation, and daytime warren fixes, ranged from 1.3 to 4.8 ha. Home-range size was similar between males and females and home ranges overlapped substantially. The data highlight the importance of burrows to southern hairy-nosed wombats in shaping their home ranges. It seems likely that the use of burrows and a specialized diet are important energy saving strategies for this species in such unpredictable regions of South Australia.

The purpose of this study was to determine whether hibernating European hamsters Cricetus cricetus, L., 1758 stay in their burrows all winter or if they occasionally spent time above ground. If ‘time (spent) above ground’ (TAG) occurred regularly throughout hibernation, the second objective of this work was to categorize and quantify the patterns of TAG during winter. For this purpose, 11 European hamsters were individually housed in wire mesh cages that were buried in the ground of an outdoor enclosure. Each cage was filled with soil up to ground level allowing the animals to construct their own burrows within the cages. Antennae in the bottom and top of the cage were calibrated to receive signals only when the hamsters were in their burrows or above the ground, respectively. This method enabled continuous recordings of the animal's TAG and provided ecologically meaningful results as the animals were housed in a way that closely resembled their natural habitat. About half of the hamsters stayed continuously below ground. Of these hamsters, almost all showed a dense pattern of episodes of reduced body temperature separated by only brief periods of normothermia. In contrast, the other half of the animals moved either episodically or even regularly above ground. For all of these hamsters, TAG was significantly reduced as compared to normothermic values. One hamster did not show any hibernation but did have a significantly reduced normothermic body temperature and did not leave its burrow for periods of up to 3 weeks.

We describe diurnal resting dens (setts) used by Eurasian badgers Meles meles L. in Coto del Rey, Doñana National Park, south-western Spain, and analyse the factors that determine sett location and selection in relation to territory outlines, soil type and vegetation structure. Setts were located by tracking radio-tagged badgers daily. Badger setts were mainly underground burrow systems with, on average, 2.6 badger entrances. Frequently, badgers constructed setts by enlarging existing rabbit warrens. Setts were located almost everywhere, but badgers preferred easily dug, well-drained soils with good vegetation cover within foraging habitats. A logistic regression model showed that badgers select sites with high surrounding shrub density, large shrubs covering the burrow and close to the centre of the territory (in Mediterranean scrubland habitat). The small size of badger setts in Coto del Rey is common to other low density areas, and probably relates to the extent of use (i.e. age of the burrows and number of badgers using them) of the burrow system. The number of setts per badger territory is related positively to territory size. The similarity of sett densities between this low density population and high density populations, points to a minimum number of setts being required to maximize territory use, and to offer easily-available protection. The preservation and improvement of Mediterranean scrubland vegetation, as well as of large and old shrubs, are important for the future conservation of the badger in Mediterranean landscapes. In these areas, and given the impossibility of distinguishing main setts, the estimation of absolute densities in population surveys using main sett numbers should be avoided in favour of relative indices of abundance.