Total extract from the fruit of Szechuan pepper (Zanthoxylum piperitum DC), the volatile components of the extract and a non-volatile fraction containing alkylamides (NVA fraction) are feeding deterrents for rats. The present study investigated the effectiveness of these natural repellents in prairie voles (Microtus ochrogaster Wagner). Two-choice feeding trials were conducted during which food-deprived voles were offered choices between oat-bran wafers. In Experiment 1, 10 voles were given three sets of feeding trials, each 2 h long. Baseline consumption was established during the first set of two trials by offering a choice between two oat-bran wafers dipped in ethanol, the control solvent. During the second set of two trials the voles were given a choice between an oat-bran wafer dipped in ethanol and a wafer dipped in Zanthoxylum extract. During the third set the voles were given a choice between a wafer served on top of a screened dish containing a sample of ethanol and a wafer served on top of a dish containing a sample of extract. In this manner the voles were exposed to volatile compounds emanating from the extract but could not contact it. Wafers dipped in extract were almost completely avoided. The volatile components of extract also significantly reduced food intake. In Experiment 2, habituation to the volatile constituents of extract was examined in 16 Zanthoxylum-naïve voles. Baseline consumption was established by offering two wafers served on top of screened dishes containing ethanol. This was followed by twelve tests during which a choice between a wafer served above a sample of ethanol and a wafer served above a sample of extract was given. The voles failed to habituate to the volatile components of extract, consistently consuming less of the wafers served above extract. In Experiment 3 a dose-response curve to Zanthoxylum extract was established, using 12 stimulus-naive voles. After baseline consumption was established, the animals were given two tests each, presenting a choice between a control wafer and a wafer dipped in a dilution of extract (0.001-100 g liter(-1)). Only concentrations of 10 and 100 g liter(-1) reduced food intake. In Experiment 4 the effects of the non-volatile fraction of extract were compared to those of whole extract. Vegetable oil was used as solvent. Eight stimulus-naïve voles were given two tests with a choice between an oil-dipped and an extract-dipped wafer. A second group of eight voles received two tests with a choice between an oil-dipped and NVA-dipped wafer. Extract-dipped wafers were avoided, but the NVA fraction had no effect on food consumption.

We investigated the effects of a total extract from Zanthoxylum piperitum fruit, of the volatile components of extract, and of a non-volatile fraction containing the major alkylamides of Zanthoxylum (NVA) on food intake in rats. In Experiment 1, three groups (A, B, C) of mildly food deprived rats were given one hour long feeding trials during which they were offered choices between an oat-bran wafer paired with vegetable oil and a wafer paired with a Zanthoxylum preparation in vegetable oil. Trials were divided into three blocks of two tests each. During Blocks 1 and 3, two wafers coated with vegetable oil were offered to establish baseline consumption. During Block 2, Group A was given choices between wafers coated with oil and wafers coated with total extract. Group B was offered oil coated wafers and wafers coated with the NVA fraction. Group C received two oil coated wafers. One was served on top of a screened dish containing a sample of total extract. In this manner, the rats were exposed to volatile compounds emanating from the extract but could not contact the extract. The second wafer was served on top of a screened sample of oil. Results: In Blocks 1 and 3 trials, the rats fed indiscriminately from both wafers. During Block 2, total extract, the NVA fraction and the volatile compounds from extract all significantly reduced food consumption. In Experiment 2, habituation to the NVA fraction and to the volatile constituents of extract was examined in two additional groups (D, E), using the methods described above. Baseline consumption was tested in Blocks 1 and 3 by offering two oil coated wafers. During Block 2, group D was given 10 trials with oil coated and NVA-fraction coated wafers. Group E was given 10 trials with oil coated wafers paired with the volatile constituents of total extract and with those of oil. Results: Both groups failed to habituate to the Zanthoxylum stimuli. Wafers treated with the NVA fraction and wafers paired with the volatile constituents of extract were avoided throughout the 10 test days.

No-till agriculture involves the use of pelleted and granular pesticides and chemically treated seeds. Some of these products kill birds. The present experiments were designed to investigate whether four candidate repellents (methyl anthranilate, ortho-aminoacetophenone, d-pulegone, and pine oil) would reduce consumption by European starlings (Sturnus vulgaris) of clay particles similar in size and shape to particles normally used for pesticide delivery. All substances reduced consumption (P < 0.05), although none completely eliminated it. To achieve further reductions in consumption, other particle characteristics might be considered. These include the use of colors that make particles indistinct from the substrate, and a texture or particle size that diminishes the likelihood that particles will be ingested as grit.

Discrimination between male former group members and unrelated males was tested in 13 males. During tests, each subject lived in a cage connected by tunnels to 2 cages, each housing a stimulus male. Subjects used the tunnels to approach and interact with both stimulus animals. Proximity to the stimulus males, aggressive and non-aggressive contacts and exchange of tongue flicks were recorded. Aggressive contacts were rare. The subjects had significantly more non-aggressive contacts with former group members than with unrelated males but exchanged significantly more tongue flicks with unrelated animals. There was no difference in proximity to either class of stimulus male.

Siberian pine needle oil, a mixture of potentially repellent compounds, deters feeding in herbivores. To determine its effectiveness as a general vertebrate repellent, we compared the feeding responses of 2 rodent and an avian species to olfactory and oral cues of Siberian pine needle oil. In 2-choice tests, subjects had access to 2 apple pieces, 1 coated with the vehicle solution (vegetable oil) and the other with the repellent solution (Siberian pine needle oil). Deer mice (Peromyscus maniculatus) ingested 1.9 ? 0.1 g of oil-coated apple compared to 0.7 ? 0.1 g of apple adulterated with 10% pine needle oil (P < 0.05). Prairie voles (Microtus ochrogaster) ingested 2.4 ? 0.3 g of oil-coated apple compared to 1.5 ? 0.2 g of apple treated with 10% pine needle oil (P < 0.05). In contrast, European starlings (Sturnus vulgaris) were insensitive to pine needle oil's aversive effect. Prairie voles increased their avoidance of pine needle oil-adulterated apple in 2-choice tests following repeated exposure to the stimuli. However, in 1-choice tests neither oral contact with pine needle oil nor exposure to its volatile cues decreased apple ingestion by prairie voles. Siberian pine needle oil has promise as a rodent control agent when employed in settings where use of a nonlethal product is desirable and alternative food sources are readily available. J. WILDL. MANAGE. 61(1):235-241

Essential oils from coniferous trees contain secondary metabolites that act as feeding deterrents for a number of herbivorous mammals. We investigated effects of pine needle oil on feeding and other behaviors of herbivorous plains pocket gophers. In experiment l, pocket gophers were offered sweet potato from single feeding stations placed in home cages of individually housed animals. Stations contained either a scent dispenser with pine needle oil or mineral oil. Subjects removed significantly less food from stations scented with pine needle oil. Experiment 2 was performed to investigate neophobic responses to odors.d-Pulegone, presented under conditions identical to those used in experiment l, did not reduce food removal compared to mineral oil. In experiment 3 pocket gophers were observed in a maze consisting of a start box connected to two goal boxes by tunnels. One goal was scented with pine needle oil, the second with mineral oil. Subjects entered goals scented with pine needle oil significantly less frequently than goals scented with mineral oil and spent less time there. They performed all recorded behaviors at lower frequencies while located in pine-scented goals. In experiment 4 animals were introduced into a maze consisting of a start box from which two soil-packed tunnels could be entered. Embedded in the soil of one tunnel was a barrier of electrical cable that had been soaked in pine needle oil, the second tunnel contained a barrier of cable soaked in mineral oil. Pocket gophers gnawed significantly less insulation from cable treated with pine needle oil than from cable treated with mineral oil. Our results show that constituents in pine needle oil are aversive to plains pocket gophers. Under natural conditions they may function as feeding deterrents. Some of the compounds may be suitable repellents for control of pocket gopher damage.

Predator odors have potential as feeding repellents for mammalian herbivores, including Aplodontia rufa, the mountain beaver. However, the repellency of major chemical constituents of natural predator scents for this species has not been evaluated. In this study, the effects of several synthetic sulfur compounds from predator scents on feeding by mountain beavers were assessed and compared to the effects of coyote (Canis latrans) urine. Retrieval of food by mountain beavers from bowls scented with either coyote urine, diluted with water to different concentrations, synthetic components of predator scents, or control odorants was studied. The following synthetic compounds were tested: δ3‐Isopentenyl methyl sulfide (IMS), a compound present in urine from several canid species; 2,2 dimethylthietane (DMT), a major constituent in anal gland secretion from the mink (Mustela vison); a 1:1 mixture of 2‐propylthietane (PT) and 3‐propyl‐1,2‐dithiolane (PDT), compounds occurring in anal gland secretions from the stoat (Mustela erminea) and the ferret (Mustela putorius). Habituation to PT plus PDT was studied by measuring consumption of dry pellets during continuous exposure to these compounds for 5 d. In two‐choice feeding trials mountain beavers retrieved significantly more food from bowls scented with water than from bowls scented with coyote urine. Dilution of urine had no statistically significant effect on food retrieval, but repellency tended to decrease with decreasing concentration. Mountain beavers retrieved less food scented with a 1:1 mixture of PT and PDT, compared to controls. However, they rapidly habituated to this mixture. None of the other compounds caused an avoidance response. These results show that complex natural predator scents are more effective feeding repellents than some of their major volatile components alone.

For many herbivorous mammals, oils from conifers are feeding repellents. Our study investigated effects of pine needle oil on feeding and other behaviors of northern pocket gophers. In onechoice feeding trials pocket gophers were offered sweet potato from single feeding stations placed into each subject's home cage. Stations contained either a scent dispenser with pine needle oil or with mineral oil. Pine needle oil did not inhibit food retrieval under these conditions. Responses to pine needle oil and to a control odorant, d-pulegone, were also tested in mazes where subjects were offered choices between two goal boxes, each containing food associated with an odorant. To examine the possibility that pocket gophers avoid any unfamiliar odor because of neophobia, freshly caught animals were tested in a maze offering a choice between goals scented with d-pulegone and goals containing mineral oil. The behavior of the animals in the side of the maze containing pulegone did not differ from their behavior in the side containing mineral oil, indicating indifference to this stimulus. Pine needle oil, however, elicited aversive responses. When one goal box contained pine needle oil, the second mineral oil, subjects were less frequently located in the side of the maze containing pine scent and consumed less food there. Responses of northern pocket gophers to pine needle oil in mazes are similar to those of plains pocket gophers studied earlier under comparable conditions. Results obtained with both species suggest that pine needle oil may be an effective repellent for all species of pocket gophers.

Pine-needle oil inhibits feeding in vertebrate species through sensory cues. Prairie voles (Microtus ochrogaster) significantly decreased their ingestion of raw apple pieces when pineneedle oil (10% vol/vol) was applied as a repellent coating. During single-choice tests, voles selected similar amounts of sunflower seeds from pine-needle oil-scented jars and vegetable oiltreated jars. However, when jars containing both stimuli were presented simultaneously, voles retrieved significantly more food from the vegetable oil-treated jars than the pine-needle oil-treated jars. Neonatal administration of capsaicin chronically depletes neurotransmitters in Cand A-a fibers greatly diminishing or abolishing pain transmission in the affected neurons (i.e., trigeminal nerve). Capsaicin-desensitized prairie voles decreased their ingestion of pine-needle oil-treated apples to the same extent as the sham-injected control group of animals, suggesting that pineneedle oil's repellency was not mediated by activation of pain fibers. In settings where alternative foods are available, and where minimal sampling of the product does not represent a hazard, Siberian pine-needle oil may be useful as a rodent repellent.

Predator odors often repel prey species. In the present experiments, we investigated whether changes in the diet of a predator, the coyote (Canis latrans) would affect the repellency of its urine. Furthermore, because predator odors have a high sulfur content, reflecting large amounts of meat in the diet, we investigated the contribution of sulfurous odors to repellency. Our results were consistent with the hypothesis that diet composition and sulfurous metabolites of meat digestion are important for the repellency of predator odors to potential prey.

The role of chemical communication in the social behavior of most burrowing rodents is largely unknown. We constructed artificial burrow systems to study interactions between mountain beavers (Aplodontia rufa). Though beavers exhibited scent marking behaviors, the marks did not prevent intruders from entering and exploring burrow systems. Encounters were agonistic and resident animals aggressively evicted intruders. We speculate that scent marking enhances the territorial confidence of the established mountain beaver.

Abstract. Behavioural, visual or chemical signalling of the ovulatory period occurs in most mammalian species. In primates, the type of signalling has been linked to mating strategies. It has been suggested that monogamous and polyandrous primates conceal evidence of the periovulatory period. Cotton-top tamarins, Saguinus oedipus, do not display visual or consistent changes in sexual behavioural cues indicating the periovulatory period, although conceptions occur on 84% of all post-partum ovulations in captivity. To examine the possibility that olfactory cues of ovulation are used to signal other tamarins of the female's reproductive status, daily scent marks were collected from a donor female during the ovulatory cycle and transferred to the home cage of eight male-female pairs for testing. Recipient females contacted the platform containing the scent mark significantly more often during the periovulatory period (3 days around the urinary luteinizing hormone peak of the donor female) than the non-periovulatory period (the rest of the cycle: follicular and luteal). Recipient males increased the frequency of mounts of the cagemate female and penile erection rates were significantly higher during the donor female's periovulatory period. These results provide evidence that there is a direct olfactory cue of ovulation in female tamarins and that this cue affects the male's sexual behaviour. This evidence does not support the theory of concealed ovulation since the monogamous cotton-top tamarin appears to signal the timing of ovulation.

Consumption of food by Aplodontia rufa from bowls scented with control odors, secretion from anal glands of minks (Mustela vison), or urine from minks, bobcats (Felis rufus), and coyotes (Canis latrans) was studied. In two-choice control tests, subjects indiscriminately consumed apple from unscented bowls and from bowls scented with urine from an unfamiliar herbivore (Cavia porcellus), or with butyric acid. During two-choice tests offering apple from bowls scented with secretion from anal glands of minks and from bowls scented with butyric acid, significantly less apple was consumed from bowls containing mink scent. In two-choice tests in which apple was offered from bowls scented with urine from either mink, bobcat, coyote, or domestic dog, all predator urines reduced feeding. Habituation was studied by measuring consumption of dry pellets during continuous exposure to coyote urine for 5 days. Significantly less chow was consumed from bowls scented with coyote urine than from control bowls, indicating a lack of habituation to the predator scent. We conclude that predator scents act as natural repellents. The responsiveness to scents from several sympatric predators as well as from domestic dogs suggest an innate reaction to a signal, which is common to carnivores. The utility of predator scents in the control of browsing damage by mountain beavers should be explored.

The aim of this histological study was to investigate the postnatal ontogeny of the ovaries in Saguinus fuscicollis to provide a detailed knowledge of the ovarian morphology for further endocrinological studies. Gonads from 43 animals between one day and 18 years of age were investigated. Based on the available material the ovarian development is characterized by seven distinct stages. 1. Neonatal stage: Folliculogenesis is still in progress. The ovarian medulla is filled with an intraovarian rete system, which forms open connections between the rete tubules and the cords containing oocytes. 2. Infantile stage: One month after birth the ovarian cortex is mainly composed of primordial follicles and a few primary follicles at the corticomedullary border, which are separated from each other by connective tissue. At two months, folliculogenesis is nearly completed. The first secondary follicles are present. 3. Juvenile stage: In six‐month‐old females weighing 184±9.5 g, folliculogenesis has reached the stage of secondary follicles with up to six layers of granulosa cells. In females of the same age weighing 251.5±37 g, antral follicles attain a maximum diameter of 925 μmm. 4. Pubertal stage: At the age of 8–10 months, corpora lutea accessoria (CLA) begin to form from atretic antral follicles. 5. Adult stage: The ovaries of all females older than 1.2 years are filled with large patches of interstitial gland tissue (IGT). In breeding females up to 58.4%of the antral follicles are intact. In non‐breeding daughters living in the family group only 1.8%are intact, the rest are in various stages of atresia and form CLA. 6. Climacterial stage: With increasing age (8–13 years), the number of intact follicles decreases dramatically and IGT fills nearly the whole ovary. 7. Senile stage: In females older than 14 years, nearly all remaining follicles show signs of atresia.

Hydrolysis, extraction, and radioimmunoassay techniques for the estimation of excreted testosterone metabolites in the urine of saddle-back tamarins have been validated and are described. The steroids measured with the testosterone antiserum used are mostly present as glucuronides and sulfates. Immunoreactivity in high-performance liquid chromatography (HPLC) fractions of urinary extracts and in a standard mixture of cortisol, testosterone, and dihydrotestosterone (DHT) were compared. The fractions with the same retention data as testosterone accounted for the major part of the immunoreactivity. Several other immunoreactive compounds of unknown identity were present in low concentrations. These results suggest that testosterone conjugates are the major steroid metabolites measured with this method in Saguinus fuscicollis. Urinary testosterone levels of castrated males were much lower than those of intact males. Testosterone treatment of castrated males resulted in a temporary superphysiological increase in the levels of urinary testosterone and in an individually variable increase in the levels of the minor immunoreactive compounds. These results suggest that estimation of testosterone metabolite levels in urine is a valid method for the assessment of testicular activity in Saguinus fuscicollis.

The sexual interactions of Saguinus fuscicollis males castrated as neonates, at 37 days of age, or prepubertally with adult intact females were studied. Prepubertally castrated males were observed while receiving testosterone, and while being treated with saline. Males castrated neonatally or at 37 days of age were observed while receiving testosterone. Neonatal castrates had previously been studied without hormone treatment and therefore no control condition was included for these animals. Prepubertally castrated males showed Mounts, Mounts with Thrusts, and Sexual Tongue Flicking when treated with saline only. In three of the four males, all measures of sexual behavior increased with testosterone treatment. Neonatally castrated males had failed to display any mounting or thrusting without testosterone treatment during a previous study. During the present study, three of the four males did not respond to testosterone treatment with sexual behavior. The fourth male and one male castrated at 37 days of age displayed some sexual behavior. These results suggest that most neonatally castrated males are not able to respond to testosterone with the activation of copulatory behavior. The findings are consistent with the hypothesis that in callitrichids the sensitive period for behavioral differentiation is shifted into neonatal life. However, some neonatally castrated males show a weak response to testosterone. This may reflect an extended and perhaps partially prenatal period of sensitivity.

The attraction of permanently cohabiting males and females to their pair mate was assessed in a preference situation in which a subject was given a choice between its pair mate and a stranger of the mate's sex. Animals were tested in a choice apparatus, consisting of 1 cage housing the subject, 1 cage housing its pair mate, and 1 cage housing the strange stimulus animal. Wire mesh tunnels connected the subject's cage with that of each stimulus animal. Each tunnel was divided into 5 sections of equal length. During a series of 30-min choice tests, the subjects' location was scored every 10 sec as being in the home cage or in one of the sections of the tunnels leading to the cages of the other animals. In addition to these location scores, being at Zero Distance from a stimulus animal, as well as a number of behaviors directed at both stimulus animals, were recorded. Males were in closer proximity to their females than to strange females (Fig. 2), approached their females more frequently and directed more Tongue Displays and Sniffs at their mates (Figs. 3–5). Females did not prefer their males in terms of these behaviors (Figs. 2–5). Moreover, they directed a higher number of Gazes at strange males (Fig. 6). Both males and females were more frequently at Zero Distance from their pair mates than from strange stimulus animals and had more Nonaggressive Contacts with their pair mates (Figs. 7–8). These results suggest that males show a strong attachment to their female pair mates while females are attracted to their mates as well as to strange males.