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Palme, R. (2005). Measuring fecal steroids: guidelines for practical application. Ann N Y Acad Sci, 1046, 75–80.
Abstract: During the past 20 years, measuring steroid hormone metabolites in fecal samples has become a widely appreciated technique, because it has proved to be a powerful, noninvasive tool that provides important information about an animal's endocrine status (adrenocortical activity and reproductive status). However, although sampling is relatively easy to perform and free of feedback, a careful consideration of various factors is necessary to achieve proper results that lead to sound conclusions. This article aims to provide guidelines for an adequate application of these techniques. It is meant as a checklist that addresses the main topics of concern, such as sample collection and storage, time delay extraction procedures, assay selection and validation, biological relevance, and some confounding factors. These issues are discussed briefly here and in more detail in other recent articles.
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Touma, C., & Palme, R. (2005). Measuring fecal glucocorticoid metabolites in mammals and birds: the importance of validation. Ann N Y Acad Sci, 1046, 54–74.
Abstract: In recent years, the noninvasive monitoring of steroid hormone metabolites in feces of mammals and droppings of birds has become an increasingly popular technique. It offers several advantages and has been applied to a variety of species under various settings. However, using this technique to reliably assess an animal's adrenocortical activity is not that simple and straightforward to apply. Because clear differences regarding the metabolism and excretion of glucocorticoid metabolites (GCMs) exist, a careful validation for each species and sex investigated is obligatory. In this review, general analytical issues regarding sample storage, extraction procedures, and immunoassays are briefly discussed, but the main focus lies on experiments and recommendations addressing the validation of fecal GCM measurements in mammals and birds. The crucial importance of scrutinizing the physiological and biological validity of fecal GCM analyses in a given species is stressed. In particular, the relevance of the technique to detect biologically meaningful alterations in adrenocortical activity must be shown. Furthermore, significant effects of the animals' sex, the time of day, season, and different life history stages are discussed, bringing about the necessity to seriously consider possible sex differences as well as diurnal and seasonal variations. Thus, comprehensive information on the animals' biology and stress physiology should be carefully taken into account. Together with an extensive physiological and biological validation, this will ensure that the measurement of fecal GCMs can be used as a powerful tool to assess adrenocortical activity in diverse investigations on laboratory, companion, farm, zoo, and wild animals.
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Palme, R., Rettenbacher, S., Touma, C., El-Bahr, S. M., & Mostl, E. (2005). Stress hormones in mammals and birds: comparative aspects regarding metabolism, excretion, and noninvasive measurement in fecal samples. Ann N Y Acad Sci, 1040, 162–171.
Abstract: A multitude of endocrine mechanisms are involved in coping with challenges. Front-line hormones to overcome stressful situations are glucocorticoids (GCs) and catecholamines (CAs). These hormones are usually determined in plasma samples as parameters of adrenal activity and thus of disturbance. GCs (and CAs) are extensively metabolized and excreted afterwards. Therefore, the concentration of GCs (or their metabolites) can be measured in various body fluids or excreta. Above all, fecal samples offer the advantages of easy collection and a feedback-free sampling procedure. However, large differences exist among species regarding the route and time course of excretion, as well as the types of metabolites formed. Based on information gained from radiometabolism studies (reviewed in this paper), we recently developed and successfully validated different enzyme immunoassays that enable the noninvasive measurement of groups of cortisol or corticosterone metabolites in animal feces. The determination of these metabolites in fecal samples can be used as a powerful tool to monitor GC production in various species of domestic, wildlife, and laboratory animals.
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Carroll, J., Murphy, C. J., Neitz, M., Hoeve, J. N., & Neitz, J. (2001). Photopigment basis for dichromatic color vision in the horse. J Vis, 1(2), 80–87.
Abstract: Horses, like other ungulates, are active in the day, at dusk, dawn, and night; and, they have eyes designed to have both high sensitivity for vision in dim light and good visual acuity under higher light levels (Walls, 1942). Typically, daytime activity is associated with the presence of multiple cone classes and color-vision capacity (Jacobs, 1993). Previous studies in other ungulates, such as pigs, goats, cows, sheep and deer, have shown that they have two spectrally different cone types, and hence, at least the photopigment basis for dichromatic color vision (Neitz & Jacobs, 1989; Jacobs, Deegan II, Neitz, Murphy, Miller, & Marchinton, 1994; Jacobs, Deegan II, & Neitz, 1998). Here, electroretinogram flicker photometry was used to measure the spectral sensitivities of the cones in the domestic horse (Equus caballus). Two distinct spectral mechanisms were identified and are consistent with the presence of a short-wavelength-sensitive (S) and a middle-to-long-wavelength-sensitive (M/L) cone. The spectral sensitivity of the S cone was estimated to have a peak of 428 nm, while the M/L cone had a peak of 539 nm. These two cone types would provide the basis for dichromatic color vision consistent with recent results from behavioral testing of horses (Macuda & Timney, 1999; Macuda & Timney, 2000; Timney & Macuda, 2001). The spectral peak of the M/L cone photopigment measured here, in vivo, is similar to that obtained when the gene was sequenced, cloned, and expressed in vitro (Yokoyama & Radlwimmer, 1999). Of the ungulates that have been studied to date, all have the photopigment basis for dichromatic color vision; however, they differ considerably from one another in the spectral tuning of their cone pigments. These differences may represent adaptations to the different visual requirements of different species.
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Ratcliffe, J. M., Fenton, M. B., & Shettleworth, S. J. (2006). Behavioral flexibility positively correlated with relative brain volume in predatory bats. Brain Behav Evol, 67(3), 165–176.
Abstract: We investigated the potential relationships between foraging strategies and relative brain and brain region volumes in predatory (animal-eating) echolocating bats. The species we considered represent the ancestral state for the order and approximately 70% of living bat species. The two dominant foraging strategies used by echolocating predatory bats are substrate-gleaning (taking prey from surfaces) and aerial hawking (taking airborne prey). We used species-specific behavioral, morphological, and ecological data to classify each of 59 predatory species as one of the following: (1) ground gleaning, (2) behaviorally flexible (i.e., known to both glean and hawk prey), (3) clutter tolerant aerial hawking, or (4) open-space aerial hawking. In analyses using both species level data and phylogenetically independent contrasts, relative brain size was larger in behaviorally flexible species. Further, relative neocortex volume was significantly reduced in bats that aerially hawk prey primarily in open spaces. Conversely, our foraging behavior index did not account for variability in hippocampus and inferior colliculus volume and we discuss these results in the context of past research.
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Shettleworth, S. J. (2003). Memory and hippocampal specialization in food-storing birds: challenges for research on comparative cognition. Brain Behav Evol, 62(2), 108–116.
Abstract: The three-way association among food-storing behavior, spatial memory, and hippocampal enlargement in some species of birds is widely cited as an example of a new 'cognitive ecology' or 'neuroecology.' Whether this relationship is as strong as it first appears and whether it might be evidence for an adaptive specialization of memory and hippocampus in food-storers have recently been the subject of some controversy [Bolhuis and Macphail, 2001; Macphail and Bolhuis, 2001]. These critiques are based on misconceptions about the nature of adaptive specializations in cognition, misconceptions about the uniformity of results to be expected from applying the comparative method to data from a wide range of species, and a narrow view of what kinds of cognitive adaptations are theoretically interesting. New analyses of why food-storers (black-capped chickadees, Poecile Atricapilla) respond preferentially to spatial over color cues when both are relevant in a memory task show that this reflects a relative superiority of spatial memory as compared to memory for color rather than exceptional spatial attention or spatial discrimination ability. New studies of chickadees from more or less harsh winter climates also support the adaptive specialization hypothesis and suggest that within-species comparisons may be especially valuable for unraveling details of the relationships among ecology, memory, and brain in food-storing species.
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Pepperberg, I. M. (2002). In search of king Solomon's ring: cognitive and communicative studies of Grey parrots (Psittacus erithacus). Brain Behav Evol, 59(1-2), 54–67.
Abstract: During the past 24 years, I have used a modeling technique (M/R procedure) to train Grey parrots to use an allospecific code (English speech) referentially; I then use the code to test their cognitive abilities. The oldest bird, Alex, labels more than 50 different objects, 7 colors, 5 shapes, quantities to 6, 3 categories (color, shape, material) and uses 'no', 'come here', wanna go X' and 'want Y' (X and Y are appropriate location or item labels). He combines labels to identify, request, comment upon or refuse more than 100 items and to alter his environment. He processes queries to judge category, relative size, quantity, presence or absence of similarity/difference in attributes, and show label comprehension. He semantically separates labeling from requesting. He thus exhibits capacities once presumed limited to humans or nonhuman primates. Studies on this and other Greys show that parrots given training that lacks some aspect of input present in M/R protocols (reference, functionality, social interaction) fail to acquire referential English speech. Examining how input affects the extent to which parrots acquire an allospecific code may elucidate mechanisms of other forms of exceptional learning: learning unlikely in the normal course of development but that can occur under certain conditions.
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Marino, L. (2002). Convergence of complex cognitive abilities in cetaceans and primates. Brain Behav Evol, 59(1-2), 21–32.
Abstract: What examples of convergence in higher-level complex cognitive characteristics exist in the animal kingdom? In this paper I will provide evidence that convergent intelligence has occurred in two distantly related mammalian taxa. One of these is the order Cetacea (dolphins, whales and porpoises) and the other is our own order Primates, and in particular the suborder anthropoid primates (monkeys, apes, and humans). Despite a deep evolutionary divergence, adaptation to physically dissimilar environments, and very different neuroanatomical organization, some primates and cetaceans show striking convergence in social behavior, artificial 'language' comprehension, and self-recognition ability. Taken together, these findings have important implications for understanding the generality and specificity of those processes that underlie cognition in different species and the nature of the evolution of intelligence.
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Giles, N., & Tupper, J. (2006). Equine interspecies aggression (Vol. 159).
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Cheney, D., Seyfarth, R., & Smuts, B. (1986). Social relationships and social cognition in nonhuman primates. Science, 234(4782), 1361–1366.
Abstract: Complex social relationships among nonhuman primates appear to contribute to individual reproductive success. Experiments with and behavioral observations of natural populations suggest that sophisticated cognitive mechanisms may underlie primate social relationships. Similar capacities are usually less apparent in the nonsocial realm, supporting the view that at least some aspects of primate intelligence evolved to solve the challenges of interacting with conspecifics.
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