Landmark use by Clark’s nutcrackers (Nucifraga columbiana): influence of disorientation and cue rotation on distance and direction estimates

Landmarks, beacons, or panoramic views: What do pigeons attend to for guidance in familiar environments?

Birds and social insects represent excellent systems for understanding visually guided navigation. Both animal groups use surrounding visual cues for homing and foraging. Ants extract sufficient spatial information from panoramic views, which naturally embed all near and far spatial information, for successful homing. Although egocentric panoramic views allow for parsimonious explanations of navigational behaviors, this potential source of spatial information has been mostly neglected during studies of vertebrates. Here we investigate how distinct landmarks, a beacon, and panoramic views influence the reorientation behavior in pigeons (Columba livia). Pigeons were trained to search for a location characterized by a beacon and several distinct landmarks. Transformation tests manipulated aspects of the landmark configuration, allowing for a dissociation among navigational strategies. Quantitative image and path analyses provided support that the panoramic view was used by the pigeons. Although the results from some individuals support the use of beaconing, overall the pigeons relied predominantly on the panoramic view when spatial cues provided conflicting information regarding the goal location. Reorientation based on vector and bearing information derived from distinct landmarks as well as environmental geometry failed to account fully for the results. Thus, the results of our study support that pigeons can use panoramic views for reorientation in familiar environments. Given that the current model for landmark use by pigeons posits the use of different vectors from an object, a global panorama-matching strategy suggests a fundamental change in the theory of how pigeons use surrounding visual cues for localization.

Understanding the role of distance, direction and cue salience in an associative model of landmark learning

Navigation and spatial memory relies on the ability to use and recall environmental landmarks relative to important locations. Such learning is thought to result from the strengthening of associations between the goal location and environmental cues. Factors that contribute to the strength of this association include cue stability, saliency and cue location. Here we combine an autoregressive random walk model, that describes goal-directed swimming behaviour, with an associative learning model to provide an integrated model of landmark learning, using the water maze task. The model allows for the contribution of each cue, the salience and the vector information provided (both distance and directional) to be separately analysed. The model suggests that direction and distance information are independent components and can influence searching patterns. Importantly, the model can also be used to simulate various experimental scenarios to understand what has been learnt in relation to the cues, thereby offering new insights into how animals navigate.

Comparative spatial memory and cue use: The contributions of Marcia L. Spetch to the study of small-scale spatial cognition

Dr. Marcia Spetch is a Canadian experimental psychologist who specializes in the study of comparative cognition. Her research over the past four decades has covered many diverse topics, but focused primarily on the comparative study of small-scale spatial cognition, navigation, decision making, and risky choice. Over the course of her career Dr. Spetch has had a profound influence on the study of these topics, and for her work she was named a Fellow of the Association for Psychological Science in 2012, and a Fellow of the Royal Society of Canada in 2017. In this review, I provide a biographical sketch of Dr. Spetch's academic career, and revisit her contributions to the study of small-scale spatial cognition in two broad areas: the use of environmental geometric cues, and how animals cope with cue conflict. The goal of this review is to highlight the contributions of Dr. Spetch, her students, and her collaborators to the field of comparative cognition and the study of small-scale spatial cognition. As such, this review stands to serve as a tribute and testament to Dr. Spetch's scientific legacy.

Use of medial axis for reorientation by the Clark's nutcracker (Nucifraga columbiana)

Many animals are challenged with the task of reorientation. Considerable research over the years has shown a diversity of species extract geometric information (e.g., distance and direction) from continuous surfaces or boundaries to reorient. How this information is extracted from the environment is less understood. Three encoding strategies that have received the most study are the use of principal axes, medial axis or local geometric cues. We used a modeling approach to investigate which of these three general strategies best fit the spatial search data of a highly-spatial corvid, the Clark's nutcracker (Nucifraga columbiana). Individual nutcrackers were trained in a rectangular-shaped arena, and once accurately locating a hidden goal, received non-reinforced tests in an L-shaped arena. The specific shape of this arena allowed us to dissociate among the three general encoding strategies. Furthermore, we reanalyzed existing data from chicks, pigeons and humans using our modeling approach. Overall, we found the most support for the use of the medial axis, although we additionally found that pigeons and humans may have engaged in random guessing. As with our previous studies, we find no support for the use of principal axes.

Taking an insect-inspired approach to bird navigation

Navigation is an essential skill for many animals, and understanding how animal use environmental information, particularly visual information, to navigate has a long history in both ethology and psychology. In birds, the dominant approach for investigating navigation at small-scales comes from comparative psychology, which emphasizes the cognitive representations underpinning spatial memory. The majority of this work is based in the laboratory and it is unclear whether this context itself affects the information that birds learn and use when they search for a location. Data from hummingbirds suggests that birds in the wild might use visual information in quite a different manner. To reconcile these differences, here we propose a new approach to avian navigation, inspired by the sensory-driven study of navigation in insects. Using methods devised for studying the navigation of insects, it is possible to quantify the visual information available to navigating birds, and then to determine how this information influences those birds' navigation decisions. Focusing on four areas that we consider characteristic of the insect navigation perspective, we discuss how this approach has shone light on the information insects use to navigate, and assess the prospects of taking a similar approach with birds. Although birds and insects differ in many ways, there is nothing in the insect-inspired approach of the kind we describe that means these methods need be restricted to insects. On the contrary, adopting such an approach could provide a fresh perspective on the well-studied question of how birds navigate through a variety of environments.

Efficiency: an underlying principle of learning?

Learning is essential. It allows animals to change circumstances, deal with new situations and adapt to environments. Here, we argue that learning, at behavioral and neural levels, involves efficiency, reflected in metabolic cost reductions. Behaviourally, although multiple solutions to a novel problem may be available, all solutions are not learnt – it is too costly. Furthermore, once a strategy has been selected, it is reinforced producing an efficiency that leads to a maximisation of performance and metabolic cost reductions. Learning can be represented in the brain through many mechanisms; however, if learning is truly efficient, then, all such mechanisms should also be accompanied by a reduction in measurable metabolic costs. By thinking about learning in terms of efficiency, not simply as a descriptive term but rather in terms of metabolic costs, it allows learning to be examined more carefully and provides predictions that can be easily tested (and indeed refuted).

Effects of sun compass error on spatial search by Clark's nutcrackers

Animals employ compasses during navigation, but little attention has been paid to how accuracy is maintained in the face of compass error, which is inevitable in biological systems. The use of multiple landmarks may minimize the effect of compass error. We allowed Clark's nutcrackers to cache seeds in an outdoor aviary with either one or four landmarks present, and subsequently subjected them to small clock-shifts mimicking the effects of compass error. As predicted, the results showed a significant decrease in search accuracy following the clock-shift when one landmark was present but not when four landmarks were present. These results support that nutcrackers encode information from the sun as well as terrestrial landmarks, and these spatial cues are used in a flexible manner. Overall, our results are important as they support the hypothesis that multiple landmarks may be used during situations where the sun compass has even a small amount of error.

Wild hummingbirds can use the geometry of a flower array

Animals use cues from their environment to orient in space and to navigate their surroundings. Geometry is a cue whose informational content may originate from the metric properties of a given environment, and its use has been demonstrated in the laboratory in nearly every species of animal tested. However, it is not clear whether geometric information, used by animals typically tested in small, rectangular boxes, is directly relevant to animals in their natural environment. Here we present the first data that confirm the use of geometric cues by a free-living animal in the wild. We trained rufous hummingbirds to visit a rectangular array of four artificial flowers, one of which was rewarded. In some trials a conspicuous landmark cued the reward. Following array translocation and rotation, we presented hummingbirds with three tests. When trained and tested with the landmark, or when trained and tested without it, hummingbirds failed to show geometric learning. However, when trained with a landmark but tested without it, hummingbirds produced the classic geometric response, showing that they had learned the geometric relationships (distance and direction) of several non-reward visual elements of the environment. While it remains that the use of geometry to relocate a reward may be an experimental artefact, its use is not confined to the laboratory.

25 years of research on the use of geometry in spatial reorientation: a current theoretical perspective

The purpose of this article is to review and evaluate the range of theories proposed to explain findings on the use of geometry in reorientation. We consider five key approaches and models associated with them and, in the course of reviewing each approach, five key issues. First, we take up modularity theory itself, as recently revised by Lee and Spelke (Cognitive Psychology, 61, 152-176, 2010a; Experimental Brain Research, 206, 179-188, 2010b). In this context, we discuss issues concerning the basic distinction between geometry and features. Second, we review the view-matching approach (Stürzl, Cheung, Cheng, & Zeil, Journal of Experimental Psychology: Animal Behavior Processes, 34, 1-14, 2008). In this context, we highlight the possibility of cross-species differences, as well as commonalities. Third, we review an associative theory (Miller & Shettleworth, Journal of Experimental Psychology: Animal Behavior Processes, 33, 191-212, 2007; Journal of Experimental Psychology: Animal Behavior Processes, 34, 419-422, 2008). In this context, we focus on phenomena of cue competition. Fourth, we take up adaptive combination theory (Newcombe & Huttenlocher, 2006). In this context, we focus on discussing development and the effects of experience. Fifth, we examine various neurally based approaches, including frameworks proposed by Doeller and Burgess (Proceedings of the National Academy of Sciences of the United States of America, 105, 5909-5914, 2008; Doeller, King, & Burgess, Proceedings of the National Academy of Sciences of the United States of America, 105, 5915-5920, 2008) and by Sheynikhovich, Chavarriaga, Strösslin, Arleo, and Gerstner (Psychological Review, 116, 540-566, 2009). In this context, we examine the issue of the neural substrates of spatial navigation. We conclude that none of these approaches can account for all of the known phenomena concerning the use of geometry in reorientation and clarify what the challenges are for each approach.

Size does not matter, but features do: Clark's nutcrackers (Nucifraga columbiana) weigh features more heavily than geometry in large and small enclosures

Two groups of Clark's nutcrackers (Nucifraga columbiana) were trained to locate a hidden goal which was consistently located at one corner of a fully enclosed rectangular environment with distinctive cues available at each corner. One group was trained in a small enclosure, whereas the second group was trained in a large enclosure. Once the birds were showing accurate search behavior, they were presented with non-reinforced tests in either the same sized environment as training or the novel sized environment, as well as in a square-shaped environment. The birds were able to accurately search at the two geometrically correct corners when the four distinctive features were removed showing that they had encoded geometry. Although accuracy was greater when tested in the same sized environment as during training, accuracy was above chance in both environments. Regardless of the size of training enclosure both groups showed primary control by features along with secondary control by geometry. Furthermore, when the features and geometric cues provided conflicting information as to the goal location, both groups weighed featural cues over geometry, and this was independent of whether the size of the testing environment was maintained or manipulated. These results show that for Clark's nutcrackers the size of the environment had little effect on the weighing of featural and geometric cues. Furthermore, although nutcrackers encoded both features and geometry, when spatial cues provided discrepant information as to the goal location, nutcrackers relied primarily on features. This article is part of a Special Issue entitled: CO3 2013.

Clark's nutcracker spatial memory: the importance of large, structural cues

Clark's nutcrackers, Nucifraga columbiana, cache and recover stored seeds in high alpine areas including areas where snowfall, wind, and rockslides may frequently obscure or alter cues near the cache site. Previous work in the laboratory has established that Clark's nutcrackers use spatial memory to relocate cached food. Following from aspects of this work, we performed experiments to test the importance of large, structural cues for Clark's nutcracker spatial memory. Birds were no more accurate in recovering caches when more objects were on the floor of a large experimental room nor when this room was subdivided with a set of panels. However, nutcrackers were consistently less accurate in this large room than in a small experimental room. Clark's nutcrackers probably use structural features of experimental rooms as important landmarks during recovery of cached food. This use of large, extremely stable cues may reflect the imperfect reliability of smaller, closer cues in the natural habitat of Clark's nutcrackers. This article is part of a Special Issue entitled: CO3 2013.

Psychology of spatial cognition

In this overview, focusing on memory and higher cognitive processes, we cover some of the most relevant results that emerged from research on spatial cognition in animals and in humans in the last 3 decades. In particular, we discuss how representations of distance and direction are used to localize oneself with respect to the external world, to determine the position of objects with respect to each other, and to compute the position of invisible goals. The role of landmarks and environmental geometry as cues for extracting spatial information in such abilities is compared, and the reliance upon self-centered and external frames of reference is discussed. Moreover, the contribution of working memory and processing strategies in forming representations of spatial relations in humans is presented. Finally, implications for some neighboring fields of the cognitive sciences will be outlined. WIREs Cogn Sci 2012. doi: 10.1002/wcs.1198 For further resources related to this article, please visit the WIREs website.

What scatter-hoarding animals have taught us about small-scale navigation

Many animals use cues for small-scale navigation, including beacons, landmarks, compasses and geometric properties. Scatter-hoarding animals are a unique system to study small-scale navigation. They have to remember and relocate many individual spatial locations, be fairly accurate in their searching and have to remember these locations for long stretches of time. In this article, we review what is known about cue use in both scatter-hoarding birds and rodents. We discuss the importance of local versus global cues, the encoding of bearings and geometric rules, the use of external compasses such as the Sun and the influence of the shape of experimental enclosures in relocating caches or hidden food. Scatter-hoarding animals are highly flexible in how and what they encode. There also appear to be differences in what scatter-hoarding birds and rodents encode, as well as what scatter-hoarding animals in general encode compared with other animals. Areas for future research with scatter-hoarding animals are discussed in light of what is currently known.

Features enhance the encoding of geometry

Successful navigation within an environment requires that the traveler establish the correct heading--a process referred to as orienting. Many studies have now shown that humans and non-human animals can use the geometric properties of an enclosure to orient. In the present study, two groups of Clark's nutcrackers (Nucifraga columbiana) were trained, in a reference memory task, to find food hidden in one of four containers arranged to form a rectangular array. One group had unique objects placed next to each of the containers, whereas the second group had identical objects placed next to each of the containers. Here, I show for the first time that for the Clark's nutcracker, the distinctive properties of these objects enhanced the encoding of the array's geometry compared to the learning of geometric properties from an array of identical objects, which remained at chance after substantial amounts of training. Subsequent transformation tests showed that an object not associated with reward, but sharing the same geometric properties as the correct object, may have had inhibitory qualities. Furthermore, by systematically removing objects from the array, I show that although nutcrackers encoded the geometry of the array, they did not encode a complete featural representation of the objects within the array.