Olfactory Clues Research Articles

An effective textured Novel Object Recognition Test (tNORT) for repeated measure of whisker sensitivity of rodents

Rodents use their whisker system to discriminate surface texture. Whisker-based texture discrimination tasks are often used to investigate the mechanisms encoding tactile sensation. One such task is the textured Novel Object Recognition Test (tNORT). It takes advantage of a tendency of rodents to explore novel objects more than familiar ones and assesses the sensitivity of whiskers in discriminating different textures of objects. It requires little training of the animals and the equipment involved is a simple arena with typically two objects placed inside. The success of the test relies on rodents spending sufficient time exploring these objects. Animals may lose interests in such tasks when performed repetitively within a limited time frame. However, such repeated tests may be crucial when establishing a sensitivity threshold of the whisker system. Here we present an adapted rodent tNORT protocol designed to maintain sustained interest in the objects even with repeated testing. We constructed complex objects from three simple-shaped objects. Different textures were provided by sandpapers of varying grit sizes. To minimise olfactory clues, we used the sandy and the laminar side of the same sandpaper as the familiar and novel textures assigned at random. We subsequently conducted repeated tNORTs on eight rats in order to identify a critical threshold of the sandpaper grit size below which rats would be unable to discriminate the sandy from the laminar side. With an inter-test-interval of seven days and after five tNORTs, the protocol enabled us to successfully identify the threshold. We suggest that the proposed tNORT is a useful tool for investigating the sensitivity threshold of the whisker system of rodent, and for testing the effectiveness of an intervention by comparing sensitivity threshold pre- and post-intervention.

Aedes aegypti oviposition-sites choice under semi-field conditions.

Vector control is still the recommended approach to avoid arbovirus outbreaks. Herein, we investigate oviposition preferences of Aedes aegypti (Diptera: Culicidae) females under a semi-field structure Rio de Janeiro, Brazil. For that, in Experiment 1, we used two settings: 'Single items', which included as containers drain, beer bottle, bucket, car tyre, water tank, and a potted Peace Lily (Spathiphyllum wallisii) in a saucer with water, or 'Multiple containers', as an urban simulation, in which one drain, two additional beer bottles, and an extra plant pot saucer were added. Experiment 2 (sensory cues) used five variations of potted plant, each one varying in the range of sensory cues known to attract gravid females to oviposition containers. Our results indicate that gravid Ae. aegypti prefer to oviposit close to the ground and in open water containers with organic compounds from plant watering. Domestic large artificial containers containing tap water received significantly fewer eggs, except for the car tyre, which exhibited as many eggs as the potted plant. We also show that visual (potted plant shape) and olfactory clues (odour of the plant or from water containing organic matter) were equally attractive separately as were these stimuli together.

Labellum Features and Chemical Composition of Floral Scent in Bulbophyllum carunculatum Garay, Hamer & Siegrist (Section Lepidorhiza Schltr., Bulbophyllinae Schltr., Orchidaceae Juss.)

The vast majority of fly-pollinated Bulbophyllum species use a combination of visual and olfactory clues to mimic food sources and brood/oviposition sites of pollinators. The aims of the present work were to characterize the floral secretory tissue and the floral scent and compare them with those previously described in B. echinolabium. Based on the histochemical results, the labellar secretion in B. carunculatum is the protein-rich mucilage. The adaxial epidermal cells of the labellum showed typical features of secretory activity. Plastids contained plastoglobuli, which are thought to be the places for scent production in osmophores. Juxtaposed with FeCl3 staining, the presence of dihydroxyphenolic globules in the cytoplasm of the epidermis and sub-epidermis was confirmed. Phenolic derivatives were also described with GC/MS analysis of the floral scent. The number of aromatic compounds and hydrocarbons was indicated in the floral scent of B. carunculatum. Moreover, pregnane-3,20-dione, occurring in the highest percentage in the floral fragrance of B. carunculatum, is a biologically active, 5-alpha-reduced metabolite of plasma progesterone. Progesterone is a mammalian gonadal hormone, but, like other steroid hormones, has been found in plants as intermediates in different biosynthetic pathways. The research on biosynthesis and functions of progesterone and its derivatives in flowers is still lacking.

Metabolic Profiling Reveals That the Olfactory Cues in the Duck Uropygial Gland Potentially Act as Sex Pheromones.

Simple SummaryFor birds, the uropygial gland is a special organ. We believe that its secretion can be used as a pheromone between the sexes to play a role in mate selection and mating. Therefore, we studied the chemical composition of duck uropygial gland secretions and the differences between males and females. After a series of screenings, 24 different volatile metabolites were obtained in our experiment. On this basis, five extremely significant volatile metabolites were screened out—significantly more males than females. The results show that these volatile substances are potential sex pheromone substances, which may be the critical olfactory clues for birds to choose mates. Our results lay the foundation for further research on whether uropygial gland secretion affects duck reproduction and production.The exchange of information between animals is crucial for maintaining social relations, individual survival, and reproduction, etc. The uropygial gland is a particular secretion gland found in birds. We speculated that uropygial gland secretions might act as a chemical signal responsible for sexual communication. We employed non-targeted metabolomic technology through liquid chromatography and mass spectrometry (LC-MS) to identifying duck uropygial gland secretions. We observed 11,311 and 14,321 chemical substances in the uropygial gland secretion for positive and negative ion modes, respectively. Based on their relative contents, principal component analysis (PCA) showed that gender significantly affects the metabolite composition of the duck uropygial gland. A total of 3831 and 4510 differential metabolites were further identified between the two sexes at the positive and negative ion modes, respectively. Of them, 139 differential metabolites were finally annotated. Among the 80 differential metabolites that reached an extremely significant difference (p < 0.01), we identified 24 volatile substances. Moreover, we further demonstrated that five kinds of volatile substances are highly repeatable in all testing ducks, including picolinic acid, 3-Hydroxypicolinic acid, indoleacetaldehyde, 3-hydroxymethylglutaric acid, and 3-methyl-2-oxovaleric acid. All these substances are significantly higher in males than in females, and their functions are involved in the reproduction processes of birds. Our data implied that these volatile substances act as sex pheromones and may be crucial olfactory clues for mate selection between birds. Our findings laid the foundation for future research on whether uropygial gland secretion can affect ducks’ reproduction and production.

How good are clinicians in predicting the presence of Pseudomonas spp. in diabetic foot infections? A prospective clinical evaluation.

IntroductionThe most frequently prescribed empirical antibiotic agents for mild and moderate diabetic foot infections (DFIs) are amino‐penicillins and second‐generation cephalosporins that do not cover Pseudomonas spp. Many clinicians believe they can predict the involvement of Pseudomonas in a DFI by visual and/or olfactory clues, but no data support this assertion.MethodsIn this prospective observational study, we separately asked 13 experienced (median 11 years) healthcare workers whether they thought the Pseudomonas spp. would be implicated in the DFI. Their predictions were compared with the results of cultures of deep/intraoperative specimens and/or the clinical remission of DFI achieved with antibiotic agents that did not cover Pseudomonas.ResultsAmong 221 DFI episodes in 88 individual patients, intraoperative tissue cultures grew Pseudomonas in 22 cases (10%, including six bone samples). The presence of Pseudomonas was correctly predicted with a sensitivity of 0.32, specificity of 0.84, positive predictive value of 0.18 and negative predictive value 0.92. Despite two feedbacks of the interim results and a 2‐year period, the clinicians' predictive performance did not improve.ConclusionThe combined visual and olfactory performance of experienced clinicians in predicting the presence of Pseudomonas in a DFI was moderate, with better specificity than sensitivity, and did not improve over time. Further investigations are needed to determine whether clinicians should use a negative prediction of the presence of Pseudomonas in a DFI, especially in settings with a high prevalence of pseudomonal DFIs.

Do properties and species of weed seeds affect their consumption by carabid beetles?

Seed predators are an integral part of agroecosystems, where they can reduce the populations of weeds. The preference of predators for seeds and the observed predation rate may be affected by the properties of seeds (e.g. taxonomy, chemical composition, physical defence). In this work, we focused on seed consumption of Taraxacum officinale Web. and Stellaria media (L.) Vill., from France and the Czech Republic, by three species of ground beetle that are seed predators (Coleoptera: Carabidae): Poecilus cupreus (Linnaeus), Pterostichus melanarius (Illiger) and Anchomenus dorsalis (Pontoppidan). The seed species were offered in arenas, simultaneously, under three different experimental manipulations of moisture and seed coat conditions: dry and intact, water-imbibed and intact, and water-imbibed with a damaged seed coat. Seed consumption was checked after 0.5, 1, 2, 24, and 48 hours of exposure. Anchomenus dorsalis largely refused to feed on seeds. Taraxacum officinale seeds with damaged coats were most preferred by the remaining two species of carabids. The consumption by P. cupreus of T. officinale seeds with damaged coats increased from 0.18 % after 0.5 hours to 83.83 % after 48 hours, and by P. melanarius from 13.76 % after 0.5 hours to 76.77 % after 48 hours. Seeds of S. media were consumed less. There was a significant difference in consumption rates due to the country of origin of the seeds, but there were no differences between the carabid sexes. That carabids preferred water-imbibed and damaged seeds may suggest an involvement of olfactory clues in the seed selection process, and/or shorter seed-handling times.

The Grueneberg ganglion controls odor-driven food choices in mice under threat

The ability to efficiently search for food is fundamental for animal survival. Olfactory messages are used to find food while being aware of the impending risk of predation. How these different olfactory clues are combined to optimize decision-making concerning food selection remains elusive. Here, we find that chemical danger cues drive the food selection in mice via the activation of a specific olfactory subsystem, the Grueneberg ganglion (GG). We show that a functional GG is required to decipher the threatening quality of an unfamiliar food. We also find that the increase in corticosterone, which is GG-dependent, enhances safe food preference acquired during social transmission. Moreover, we demonstrate that memory retrieval for food preference can be extinguished by activation of the GG circuitry. Our findings reveal a key function played by the GG in controlling contextual food responses and illustrate how mammalian organisms integrate environmental chemical stress to optimize decision-making.

Size of Openings in Water-Holding Containers: Impact on Oviposition by Culex (Culex) Mosquitoes.

To assess how a grate covering a catch basin impacts oviposition by Culex mosquitoes, a field study was conducted in south Florida using containers with two types of covers, with openings of equal area, but different configurations. One opening mimicked a catch basin grate with 16 small openings, while the other cover had just one large opening. The number and presence of egg rafts in six of each container and cover combination was recorded over 18 nights at two field sites, consisting of a wastewater management facility area and residential subdivision. Three mosquito species, all belonging to the subgenus Culex accounted for more than 99% of total egg rafts collected: Culex nigripalpus (n = 1766), Culex quinquefasciatus (n = 754) and Culex coronator (n = 526). Approximately 90% of Cx. nigripalpus and Cx. coronator egg rafts were deposited in the containers with the large opening cover; whereas more Cx. quinquefasciatus egg rafts were laid in the containers with small opening covers than those of Culex nigripalpus and Culex coronator combined. Similar patterns of egg laying activity were noted at each sampling stations. These results suggest that for locating oviposition sites Culex quinquefasciatus may rely more on olfactory clues, while other Culex species depend more on visual clues.

Convergent vomeronasal system reduction in mammals coincides with convergent losses of calcium signalling and odorant-degrading genes.

The vomeronasal system (VNS) serves crucial functions for detecting olfactory clues often related to social and sexual behaviour. Intriguingly, two of the main components of the VNS, the vomeronasal organ (VNO) and the accessory olfactory bulb, are regressed in aquatic mammals, several bats and primates, likely due to adaptations to different ecological niches. To detect genomic changes that are associated with the convergent reduction of the VNS, we performed the first systematic screen for convergently inactivated protein-coding genes associated with convergent VNS reduction, considering 106 mammalian genomes. Extending previous studies, our results support that Trpc2, a cation channel that is important for calcium signalling in the VNO, is a predictive molecular marker for the presence of a VNS. Our screen also detected the convergent inactivation of the calcium-binding protein S100z, the aldehyde oxidase Aox2 that is involved in odorant degradation, and the uncharacterized Mslnl gene that is expressed in the VNO and olfactory epithelium. Furthermore, we found that Trpc2 and S100z or Aox2 are also inactivated in otters and Phocid seals for which no morphological data about the VNS are available yet. This predicts a VNS reduction in these semi-aquatic mammals. By examining the genomes of 115 species in total, our study provides a detailed picture of how the convergent reduction of the VNS coincides with gene inactivation in placental mammals. These inactivated genes provide experimental targets for studying the evolution and biological significance of the olfactory system under different environmental conditions.

Pheromone trapping of brinjal fruit and shoot borer: Male orientation and spatial distribution

Pheromone trapping is an ecofriendly management of the brinjal shoot and fruit borer Leucinodes orbonalis. In the present study on orientation and distribution of male moths to the sticky arenas in a delta trap were evaluated. One-third of moths trapped were oriented towards the lure source, while the remaining two thirds were found oriented either away from or opposite to the pheromone source. This indicates the predominant tendency of the male moths to escape apparently due to overlapping close range visual or olfactory clues. This pest behaviour could be pursued to ascertain the role of olfactory versus visual stimuli in prompting the moth escape behaviour as basis for minimizing the escapes by altering the trap design suitable. The distribution of the moth catches in the length side of the sticky arena (18.0 x11.0 cm) was found to be more (62%) in the inner half section (closer to the lure source) compared to only about 38% in the outer half. This pattern of greater catches closer to lure source was also evident across the width side. The observed lower catches in sections away from lure source could provide directions to alter the dimensions of the sticky arena.

How do migrating birds find their way?

Bird is one of the most abundant and widespread groups in the world. With many specialized structures, such as plumage, air sacs, and hollow bones, most bird species have got flight ability to adapt various niches. Therefore, bird can migrate between wintering and breeding ground, which is usually a long distance, and it’s called migration. Bird navigation is important in migration and is a complex process, which attracts many scientists to dig in how bird finds its way. Since 1873, Charles Darwin has ever mentioned that bird might take the method of dead reckoning on a long-distance migration like human, but at that time no one made further progress. Until 1950s, Kramer firstly found that Common Starling ( Sturnus vulgaris ) can respond to solar azimuth via mirror test. From then on, many experiments revealed that at least four navigation mechanisms are used in bird migration via more than nine external factors. They are: (i) celestial navigation, celestial clues (e.g. solar azimuth, star position, and polarized light) are used during migration period. (ii) Olfactory navigation, odor distributing in the air forms odorous gradient map or mosaic map which can be detected, or can activate directly certain mechanism to navigate. (iii) Auditory navigation, infrasound (0.05 Hz) produced by mountains and rivers generate sonic gradient map. And (iv) magnetic navigation, geomagnetic field can be detected via magnetic materials or chemical magnetoreception to find correct directions. Although many scientists approve that magnetic navigation may be the main mechanism to orientate and navigate, bird has never taken just one mechanism to migrate. Indeed, many species also use the other three mechanisms to calibrate direction, for example, Savannah Sparrow ( Passerculus sandwichensis ) can use polarized light to calibrate the magnetic compass at both sunrise and sunset. Different external clues correspond to different sense organs, so various brain areas should deal with information from different navigation mechanisms. The hippocampus participates in spatial perception and manages anything about celestial navigation via the tectofugal visual pathway and the thalamofugal visual pathway. The piriform cortex (CPi) is the main area to receive stimulation from olfactory bulb and determines how to migrate after receiving olfactory clues. Nervous systems of magnetic navigation include two parts which are trigeminus system and Cluster N. Despite the controversy whether there are some magnetic materials on bird, many experimental evidences have proved that magnetic materials detecting geomagnetic field involve to Trigeminus system. Cluster N, however, is an active area when bird migrates at night and it has an important role in transferring information from chemical magnetoreception to the hippocampus. As illustrated above, navigation mechanisms can get full information from many clues, and then, different brain areas trade off those and co-operate each other to make an elaborate map. Bird navigation involves the receptors to environment and the response of nervous system, so many issues are still maintained. The exact mechanism will be revealed with the new techniques and model animal applied.

Differential foraging in presence of predator and conspecific odors in bank voles: a field enclosure study

AbstractBank voles detect and discriminate other organisms, e.g., predators versus conspecifics, based on olfactory clues like urine, feces, or scent marks. The present field enclosure experiment was set up to determine whether scented food is sufficient for inducing such differentiated reactions in bank voles. Fourteen different odors were tested, divided into four categories: (1) terrestrial predators, (2) avian predators, (3) conspecifics, and (4) neutral origin (human, dog, solvent‐treated, and unscented). The odors were extracted with methanol from pellets or feces, or were an artificial substitute. To test the influence of odors on the foraging behavior of voles, artificial food patches containing scented feeders were used. The feeders were cleaned and refilled daily with a calibrated amount of food sprayed with 1 ml of a different odor randomly chosen. The patches were also equipped with monochromatic cameras to monitor the occurrences of voles around the feeders. Both the visits at scented feeders and food consumption were analyzed for each odor. The results show that relative to their foraging activity on unscented food, bank voles significantly reduce it on food scented with odors of terrestrial predators, and increase it in the presence of conspecific odors. Their foraging activity was not affected by neutral scent, nor by scents from avian predators. These results prove that bank voles react to scented food in a way that varies according to the source of odor, even in the semi‐natural conditions of an outdoor enclosure.

Combining Olfactory and Gustatory Clues in the Judgment of Aging Potential of Red Wine by Wine Professionals

The study was aimed at determining the relative importance of olfactory and gustatory information for the <i>vin de garde</i> concept, which refers to wine that is intended for aging. First, the study investigated how olfactory information contributed to the assessment of the aging potential of young wine. Burgundy wine professionals categorized 26 red wines (vintage 2005) according to their aging potential in two experimental conditions: orthonasal evaluation and overall evaluation. Second, the aromatic notes associated with wines perceived with an aging potential were examined. A trained descriptive panel described the odor of the 26 red wines to determine whether the wines judged by wine professionals to have an aging potential (orthonasal evaluation) were characterized by specific aromatic notes. Third, the study investigated how taste and mouthfeel contributed, together with odor, to judgments of aging potential. The trained descriptive panel also assessed taste (sweetness, acidity, and bitterness) and mouthfeel (alcohol and astringency) intensity of the wines. Results showed that odor provides some clues for professional judgment of aging potential. These olfactory clues are sufficient to assess the aging potential for some wines, but not all. Wines judged to have aging potential by orthonasal evaluation tended to have woody, caramel, roasted, and prune notes. Taste and mouthfeel also provided clues for professional judgment of aging potential. Red wines judged to have aging potential by overall evaluation tended to have high astringency and low acidity. Thus, the combination of gustatory and olfactory information allowed professionals to judge the aging potential of wines. The <i>vin de garde</i> concept involves a wide variety of complex perceptual clues (color, odor, taste, and mouthfeel).

DIFFERENCE IN PROBING BEHAVIOUR OF TEA APHID ON VEGETATIVE PARTS OF TEA PLANT AND NON-HOST PLANTS

Abstract Electrical penetration graph (EPG) investigation showed that the secreting (El) and sucking (E2) times of tea aphid stylet in tea phloem were much longer than that on non-host plants such as soybean and wheat. However, non-feeding wave (np) was shorter than that on soybean and wheat. Duration of both El and E2 of stylet in tea phloem of 1st leaf, bud, 4th leaf and tender stem occupied 30.2%, 22.3%, 9.2% and 8.2% of the total experimental time, respectively. E2 wave was accompanied by honeydew secretion, with a time lag. Tea aphid preferred the tender parts, in which amino acids and other nutritional components were very rich. While the stylet of hungry tea aphid was forced to pierce phlom of non-host plant (soybean or wheat), El and E2 waves were also produced, but the action of stylet could be disrupted by tea shoot volatile (10–6 V/V linalool, etc.) emitted near to the antennae. It was considered that before and under probing tea aphid made use of olfactory clues.

The "sense of being stared at" does not depend on known sensory clues.

The "sense of being stared at" can be investigated by means of simple experiments in which subjects and lookers work in pairs, with the looker sitting behind the subject. In a random sequence of trials, the looker either looks at the back of the subject, or looks away and thinks of something else. More than 15,000 trials have already been conducted, involving more than 700 subjects, with an extremely significant excess of correct over incorrect guesses (Sheldrake [1999]). This effect was still apparent in experiments in which subjects were blindfolded and given no feedback, showing it did not depend on visual clues, nor on the subjects knowing if their guesses were right or wrong (Sheldrake [2000]). In this paper I describe experiments I conducted in schools in England in which the subjects were not only blindfolded and given no feedback, but looked at through closed windows. There was again a very significant excess of correct over incorrect guesses (p < 0.004). At my request, schoolteachers in Canada, Germany and the United States carried out similar experiments and found an even more significant positive effect than in my own experiments (p < 0.0002). The fact that positive results were still obtained when visual clues had been effectively eliminated by blindfolds, and auditory and olfactory clues by closed windows, implies that the sense of being stared at does not depend on the known senses. I conclude that peoples' ability to know when they are being looked at depends on an influence at present unknown to science.

Olfactory clues play a critical role in the estuarine migration of silver-phase American eels

Estuarine migration of anosmic and control silver-phase American eels was examined during the fall spawning migration. Ultrasonic telemetry was used to track seventeen control and eight anosmic silver eels through 32 km of the Penobscot Estuary, Maine, U.S.A.. Twelve of seventeen control eels migrated out of the estuary in 97 h (approximately 4 d) on average. Only two of eight anosmic eels migrated out of the estuary. On average these two anosmic eels migrated out of the estuary within 180 h (approximately 7.5 d) of release and the other six had not left within 9 d. Most control eels progressed rapidly to the mouth of the estuary within a few days. Anosmic eels spent more time in the estuary and demonstrated different behavior from control eels due to their lack of olfaction. Some control eels moved with the appropriate tide, the ebb tide for transport out of the estuary, within one tidal cycle of being released into tidal freshwater. However, anosmic eels either did not move with the appropriate tide or took significantly longer to do so. Olfaction was probably used for orientation by control eels sensing chemical clues (organic and inorganic), which change throughout the tidal cycle. Increased migration times and errors in orientation were likely related to the inability of anosmic eels to use selective tidal stream transport for movement out of the estuary. Chemical clues seem to be one of the most important environmental clues used to guide estuarine migration of silver eels. However, a hierarchy of sensory mechanisms and environmental clues are most likely used for estuarine orientation.

Participation of the olfactory system in the control of approach behavior of the female rat to the male

The amounts of time spent by females in the sector of an open field close to the cage housing a normal male or a castrated male were measured in order to quantitate the tendency of the female to reach physical proximity to a sexually active male (androtropism). Intact proestrous or ovariectomized females primed with 100 μg of estradiol benzoate/kg b.wt. (EB) or EB plus 2 mg progesterone/kg b.wt. (P) spent significantly more time close to the sexually active (intact) male than in the proximity of the orchidectomized male. In order to determine whether olfactory clues were sufficient for female rats to distinguish between intact and castrated males, the males were removed from the stimulus cages, leaving the soiled bedding in place. Ovariectomized rats primed with EB or EB plus P clearly preferred proximity to the cage where the intact male had been living. No preference was evident after transection of olfactory nerves in proestrous rats or in ovariectomized rats primed with EB plus P. Resection of the vomeronasal organ also suppressed preference. These results indicate that olfactory input is necessary and sufficient for androtropism to occur, and suggest that the accesory olfactory system is involved in the analysis of olfactory signals used by female rats to identify the endocrine status of prospective sexual partners. In a different group of animals, it was demonstrated that destruction of the posteromedial cortical amygdaloid nucleus also suppressed preference for the intact male. It is proposed that this structure serves as a relay station for the analysis and integration of olfactory input significant for the motivational control of sexual behavior in the female rat. None of the lesions affected either exploratory activity or sexual receptivity measured as the lordosis score to ten mounts by active males.

Mating Behavior of the Terrestrial Isopod, Venezillo evergladensis (Oniscoidea, Armadillidae)

This report describes mating behavior in the terrestrial isopod, Venezillo evergladensis, relating female receptivity and molting cycle. A brief review of molting and mating in isopods precedes the data and a description of the observational method appears in sufficient detail to permit duplication. Males orient to receptive females using olfactory clues. Visual recognition appears absent. The male initiates mating by actively tapping the female's cephalon with his antennae. The female's two gonopores are inseminated by separate acts of copula, each preceded by a nuptial ride. Virgin females mate during the intermolt period or just prior to a growth molt. Their first parturial molt is the second molt following the mating. Females no longer elicit male attention shortly after a mating. They again elicit male mating behavior (1) shortly after birth of a brood of young before loss of the brood pouch by a molt, and (2) just prior to the subsequent parturial molt. In the former case, females were not receptive to the males. A single mating likely occurs for each brood of young. The large older males dominate small younger males in competition for mates. Young virgin females most likely mate with older males of a preceding generation, constituting a mating system adding stability to genetic variation.

Observations on Mammalian Prediation of Snapping Turtle Nests (Reptilia, Testudines, Chelydridae)

An investigation of the ecology of the common snapping turtle within the Great Swamp National Wildlife Refuge, Basking Ridge, New Jersey, was initiated in 1975. Observations made during three turtle nesting seasons indicated that a large number of nests fell victim to mammalian predation pressure. The study reported here was undertaken in an attempt to determine how predators locate turtle nests and to ascertain which factors may either promote or inhibit predation efficiency. Location of turtle nests may be facilitated by the predator's sighting of the female turtle during nesting or by olfactory clues associated with: (1) secretions of the nesting female; (2) the egg; or (3) disturbance of soil layers during nest digging. We were also concerned with: (1) whether predation will occur during periods other than the regular turtle nesting season; (2) whether established turtle nesting areas along watercourses experience greater predation pressure than locations not normally used for nesting; and (3) precipitation levels have any effect on predation efficiency. An informal study was conducted 8-19 April 1977 using decoy nests stocked with chicken and/or dove eggs buried to an approximate depth of 10 cm, an average derived from measurements of opened turtle nests. Results suggested that: (1) predators would readily open these nests in the absence of visual or olfactory clues associated with nesting turtles; (2) established nesting areas adjacent to watercourses were no more vulnerable to predation than areas where nests were not normally found; (3) predation pressure appeared to be as intense in mid-April as during May-June, the regular turtle nesting period; and (4) live trapping at the location of the decoy nests resulted in the capture of raccoons exclusively. As a result of this work, further studies were undertaken to confirm these findings and to elucidate the other possible parameters of predation already mentioned.

Location and recognition of pups by adult female harp seals

Harp seal ( Pagophilus groenlandicus) cows use visual, auditory and olfactory clues to locate and/or identify their pups. Identification is made at a close range and the pups are approached from a distance in a random manner. The topography of the ice supporting the pups changes frequently. These changes probably preclude or reduce the use of spatial memory by the adults. Because the pups cannot be identified at a distance, and because of the absence of stable landmarks, the adult must probably remain relatively close to her pup at all times. The large number of pups in the area suggests that random searching will not be efficient. The ability of various mammalian species to utilize spatial memory may well influence their modes of locating and identifying their young.