scholarly journals Visual acuity and egg spatial chromatic contrast predict egg rejection behavior of American robins

2020 ◽  
Vol 223 (20) ◽  
pp. jeb229609
Author(s):  
Alec B. Luro ◽  
Esteban Fernández-Juricic ◽  
Patrice Baumhardt ◽  
Mark E. Hauber
Keyword(s):  
Visual Acuity ◽  
Host Species ◽  
Spatial Vision ◽  
Viewing Distance ◽  
Egg Rejection ◽  
Chromatic Contrast ◽  
Brood Parasites ◽  
American Robins ◽  
Avian Visual System ◽  
The Cost

ABSTRACTColor and spatial vision is critical for recognition and discrimination tasks affecting fitness, including finding food and mates, and recognizing offspring. For example, as a counter defense to avoid the cost of raising the unrelated offspring of obligate interspecific avian brood parasites, many host species routinely view, recognize and remove the foreign egg(s) from their nests. Recent research has shown that host species visually attend to both chromatic and spatial pattern features of eggs; yet how hosts simultaneously integrate these features together when recognizing eggs remains an open question. Here, we tested egg rejection responses of American robins (Turdus migratorius) using a range of 3D-printed model eggs covered with blue and yellow checkered patterns differing in relative square sizes. We predicted that robins would reject a model egg if they could visually resolve the blue and yellow squares as separate features, or accept it if the squares blended together and appeared similar in color to the natural blue–green color of robin eggs as perceived by the avian visual system. As predicted, the probability of robins rejecting a model egg increased with greater sizes of its blue and yellow squares. Our results suggest that chromatic visual acuity and viewing distance have the potential to limit the ability of a bird to recognize a foreign egg in its nest, thus providing a limitation to host egg recognition that obligate interspecific avian brood parasites may exploit.

scholarly journals Visual acuity and egg spatial chromatic contrast predict egg rejection behavior of American robins

2020 ◽  
Author(s):  
Alec B. Luro ◽  
Esteban Fernández-Juricic ◽  
Patrice Baumhardt ◽  
Mark E. Hauber
Keyword(s):  
Visual Acuity ◽  
Host Species ◽  
Spatial Vision ◽  
Viewing Distance ◽  
Egg Rejection ◽  
Chromatic Contrast ◽  
Brood Parasites ◽  
American Robins ◽  
Avian Visual System ◽  
The Cost

AbstractColor and spatial vision are critical for recognition and discrimination tasks affecting fitness, including finding food and mates and recognizing offspring. For example, as a counter defense to avoid the cost of raising the unrelated offspring of obligate interspecific avian brood parasites, many host species routinely view, recognize, and remove the foreign egg(s) from their nests. Recent research has shown that host species visually attend to both chromatic and spatial pattern features of eggs; yet how hosts simultaneously integrate these features together when recognizing eggs remains an open question. Here, we tested egg rejection responses of American robins (Turdus migratorius) using a range of 3D-printed model eggs covered with blue and yellow checkered patterns differing in relative square sizes. We predicted that robins would reject a model egg if they could visually resolve the blue and yellow squares as separate features or accept it if the squares blended together and appeared similar in color to the natural blue-green color of robin eggs as perceived by the avian visual system. As predicted, the probability of robins rejecting a model egg increased with greater sizes of its blue and yellow squares. Our results suggest that chromatic visual acuity and viewing distance have the potential to limit the ability of a bird to recognize a foreign egg in its nest, thus providing a limitation to host egg recognition that obligate interspecific avian brood parasites may exploit.

scholarly journals Natural and artificial scents do not increase egg rejection rates of model brood parasitic eggs by American robins (Turdus migratorius)

2020 ◽  
Vol 66 (4) ◽  
Author(s):  
Mark Erno Hauber
Keyword(s):  
Host Species ◽  
Molothrus Ater ◽  
Egg Rejection ◽  
Turdus Migratorius ◽  
Data Set ◽  
Brood Parasites ◽  
American Robins ◽  
Tactile Cues ◽  
Do So ◽  
Rejection Rates

Hosts of obligate avian brood parasites can diminish or eliminate the costs of parasitism by rejecting foreign eggs from the nests. A vast literature demonstrates that visual and/or tactile cues can be used to recognize and reject natural or model eggs from the nests of diverse host species. However, data on olfaction-based potential egg recognition cues are both sparse and equivocal: experimentally-applied, naturally-relevant (heterospecific, including parasitic) scents do not appear to increase egg rejection rates in two host species, whereas unnatural scents (human and tobacco scents) do so in one host species. Here I assessed the predictions that (i) human handling of mimetically-painted model eggs would increase rejection rates, and (ii) applying unnatural or natural scents to mimetically or non-mimetically painted model eggs alters these eggs’ respective rejection rates relative to controls. I studied wild American Robins (Turdus migratorius), a robust rejecter species of the eggs of obligate brood parasitic Brown-headed Cowbirds (Molothrus ater). There was no statistical evidence to support either prediction, whereas poorer color-mimicry was still a predicted cause of greater egg rejection in this data set. Nonetheless, future studies could focus on this and other host species and using these and different methods to apply and maintain the scenting of model eggs to more directly test hosts’ use of potential olfactory cues in the foreign-egg rejection process.

scholarly journals The Perceptual and Cognitive Processes That Govern Egg Rejection in Hosts of Avian Brood Parasites

2021 ◽  
Vol 9 ◽  
Author(s):  
Daniel Hanley ◽  
Samantha L. Rutledge ◽  
Juliana Villa
Keyword(s):  
Cognitive Processing ◽  
Cognitive Processes ◽  
Selective Pressure ◽  
Null Model ◽  
Egg Rejection ◽  
Egg Recognition ◽  
Brood Parasites ◽  
The Past ◽  
The Cost ◽  
Receptor Noise

Hosts of avian brood parasites are under intense selective pressure to prevent or reduce the cost of parasitism. Many have evolved refined egg discrimination abilities, which can select for eggshell mimicry in their parasite. A classic assumption underlying these coevolutionary dynamics is that host egg recognition depends on the perceivable difference between their own eggs and those of their parasite. Over the past two decades, the receptor noise-limited (RNL) model has contributed to our understanding of these coevolutionary interactions by providing researchers a method to predict a host’s ability to discriminate a parasite’s egg from its own. Recent research has shown that some hosts are more likely to reject brown eggs than blue eggs, regardless of the perceived differences to their own. Such responses suggest that host egg recognition may be due to perceptual or cognitive processes not currently predictable by the RNL model. In this perspective, we discuss the potential value of using the RNL model as a null model to explore alternative perceptual processes and higher-order cognitive processes that could explain how and why some hosts make seemingly counter-intuitive decisions. Further, we outline experiments that should be fruitful for determining the perceptual and cognitive processing used by hosts for egg recognition tasks.

scholarly journals Testing the Interspecific Function of Female Common Cuckoo “Bubbling” Call

2021 ◽  
Vol 9 ◽  
Author(s):  
Yanyi Wang ◽  
Miao Tian ◽  
Jingpeng Liu ◽  
Xingyu Lu ◽  
Anders Pape Møller ◽  
...  
Keyword(s):  
Count Data ◽  
Host Species ◽  
Field Data ◽  
Rejection Rate ◽  
Egg Rejection ◽  
Sufficient Time ◽  
Common Cuckoo ◽  
Field Recordings ◽  
The Cost

Female common cuckoo (Cuculus canorous) predator-like “bubbling” calls distract host parental attention and reduce the egg rejection rate. Such “bubbling” calls are also frequently used to attract males and deter territorial rivals in intraspecies contact, and these calls are an ancestral character in many cuckoo species. Although hosts have had sufficient time to become familiar with this call and evolve anti-parasitic strategies, why are the hosts fooled by this “bubbling” call? We propose two hypotheses. The first hypothesis proposes that call variation reduces the opportunity for host species to correctly assess cuckoo tricks. In contrast, the second hypothesis proposes that the cost of behavior may prevent the antiparasitic strategy from evolving. In the study, we tested the prerequisites of these hypotheses, by investigating whether cuckoo calls vary during the day and testing whether the predator-like calls suppress bird activities. Based on field recordings from three different areas, we found high overlap in the calls generated during different periods. Oriental great reed warblers (Acrocephalus orientalis), a host species, did not show different responses toward the playback of female common cuckoo calls generated before noon or afternoon. Based on bird count data, we found that predator-like call playback is insufficient for suppressing bird activities. Therefore, none of the prerequisites were supported by our field data. We discuss the potential reasons for our findings and hope to inspire more research examining female cuckoo vocalizations.

scholarly journals The costs of avian brood parasitism explain variation in egg rejection behaviour in hosts

2015 ◽  
Vol 11 (7) ◽  
pp. 20150296 ◽  
Author(s):  
Iliana Medina ◽  
Naomi E. Langmore
Keyword(s):  
Comparative Analysis ◽  
Host Species ◽  
Brood Parasitism ◽  
Large Scale ◽  
Bird Species ◽  
Egg Rejection ◽  
Brood Parasites ◽  
Avian Brood Parasitism ◽  
First Time ◽  
Rejection Rates

Many bird species can reject foreign eggs from their nests. This behaviour is thought to have evolved in response to brood parasites, birds that lay their eggs in the nest of other species. However, not all hosts of brood parasites evict parasitic eggs. In this study, we collate data from egg rejection experiments on 198 species, and perform comparative analyses to understand the conditions under which egg rejection evolves. We found evidence, we believe for the first time in a large-scale comparative analysis, that (i) non-current host species have rejection rates as high as current hosts, (ii) egg rejection is more likely to evolve when the parasite is relatively large compared with its host and (iii) egg rejection is more likely to evolve when the parasite chick evicts all the host eggs from the nest, such as in cuckoos. Our results suggest that the interactions between brood parasites and their hosts have driven the evolution of egg rejection and that variation in the costs inflicted by parasites is fundamental to explaining why only some host species evolve egg rejection.

Clutch variation and egg rejection in three hosts of the pallid cuckoo, Cuculus pallidus

Behaviour ◽  
2010 ◽  
Vol 147 (1) ◽  
pp. 19-36 ◽  
Author(s):  
Naomi Langmore ◽  
Michelle Landstrom ◽  
Robert Heinsohn
Keyword(s):  
Host Species ◽  
Rejection Rate ◽  
Objective Measures ◽  
Egg Rejection ◽  
Brood Parasite ◽  
Reflectance Spectrophotometry ◽  
Brood Parasites ◽  
Parasitised Host

AbstractIn theory, hosts of avian brood parasites would benefit by modifying their egg appearance in two ways to help identify mimetic foreign eggs: (i) by laying clutches that are more uniform in appearance and (ii) by laying clutches that differ from those of other females in the population. Support for these theories is inconsistent, and few studies have used objective measures of clutch variation. Here we used reflectance spectrophotometry to quantify within-clutch and between-clutch variation of three host species of an Australian brood parasite, the pallid cuckoo (Cuculus pallidus). We used egg-swapping experiments in which subjects were presented with either a conspecific egg or a heterospecific egg to compare the egg rejection responses of a frequently parasitised host, the white-plumed honeyeater (Lichenostomus penicillatus), with two less frequently parasitised hosts, dusky woodswallows (Artamus cyanopterus) and willie wagtails (Rhipidura leucophrys). As predicted, rejection rate increased as contrast between foreign egg and host clutch increased. Further, the major host showed greater between-clutch variation than the occasional hosts, and also rejected more similar-looking eggs. Contrary to predictions however, within-clutch variation was not lower in the major host, nor was it important in predicting the rejection rate of foreign eggs by the three host species.

scholarly journals Glucocorticoids mediate egg rejection in a brood parasite host

2019 ◽  
Author(s):  
Mikus Abolins-Abols ◽  
Mark E. Hauber
Keyword(s):  
Causal Link ◽  
Host Responses ◽  
Egg Rejection ◽  
Brood Parasite ◽  
Ecological Significance ◽  
Turdus Migratorius ◽  
Free Living ◽  
Brood Parasites ◽  
American Robins ◽  
Host Behaviour

AbstractAvian brood parasites and their hosts are engaged in a coevolutionary battle that can result in the evolution of sophisticated trickery by parasites and novel defence behaviours in hosts. Despite the clear evolutionary and ecological significance of host behaviour, however, we know very little about the mechanisms that regulate host defences, which limits our understanding of both inter- and intraspecific variation in host responses to parasitism. Here we tested whether corticosterone, a hormone known to be upregulated in hosts exposed to parasitism, also mediates one of the most frequent host defences – the rejection of foreign eggs. We experimentally reduced corticosterone levels in free-living brood parasite hosts, American robins Turdus migratorius, using mitotane and found that the likelihood of model egg rejection was significantly lower in the mitotane-treated birds relative to the sham-treated birds. These results demonstrate a causal link between glucocorticoids and egg rejection in hosts of avian brood parasites, but the physiological and sensory-cognitive pathways that regulate this effect remain unknown.

scholarly journals Fate of Grackle (Quiscalus SPP.) Defenses in the Absence of Brood Parasitism: Implications for Long-Term Parasite-Host Coevolution

The Auk ◽  
2004 ◽  
Vol 121 (4) ◽  
pp. 1172-1186 ◽  
Author(s):  
Brian D. Peer ◽  
Spencer G. Sealy
Keyword(s):  
Host Species ◽  
Brood Parasitism ◽  
Selection Pressure ◽  
Egg Rejection ◽  
Allopatric Population ◽  
Brood Parasites ◽  
Cowbird Parasitism ◽  
The Common ◽  
Molothrus Aeneus

Abstract We tested grackles (Quiscalus spp.) to determine whether they retain egg rejection behavior in the absence of the selection pressure of brood parasitism. Neither Bronzed Cowbird (Molothrus aeneus) nor Brown-headed Cowbird (M. ater) parasitism was recorded in 797 Great-tailed Grackle (Q. mexicanus) nests. Cross-fostered Bronzed Cowbird nestlings, but not Brown-headed Cowbird nestlings, fledged from Great-tailed Grackle nests, indicating that Brown-headed Cowbird parasitism does not select for rejection in these grackles. Great-tailed Grackle populations sympatric and allopatric with Bronzed Cowbirds rejected 100% of model cowbird eggs. An allopatric population of Boat-tailed Grackle (Q. major), a sister species of the Great-tailed Grackle, also rejected 100% of model eggs. Egg rejection in the Boat-tailed Grackle has apparently been retained in the absence of parasitism for as long as 800,000 years since it split from the Great-tailed Grackle. The Common Grackle (Q. quiscula), which lays the most variable eggs among the grackles, also has the lowest level of egg rejection—which is consistent with the argument that it may have lost most of its rejection behavior in the absence of parasitism. With extreme intraclutch egg-variation, Common Grackles may be more likely to reject their own oddly colored eggs, which would select against rejection behavior in the absence of parasitism. Those results have significant implications for long-term parasite-host coevolution, because they suggest that egg rejection has been retained in most species of Quiscalus in the absence of parasitism. If typical of the world's avifauna, such retention may force brood parasites to specialize on a few host species and to rarely return to using old hosts, which would readily reject their eggs.

scholarly journals Collective defence portfolios of ant hosts shift with social parasite pressure

2014 ◽  
Vol 281 (1791) ◽  
pp. 20140225 ◽  
Author(s):  
Evelien Jongepier ◽  
Isabelle Kleeberg ◽  
Sylwester Job ◽  
Susanne Foitzik
Keyword(s):  
Host Species ◽  
Nest Site ◽  
Host Defence ◽  
Nest Defence ◽  
Social Parasite ◽  
Arms Races ◽  
Ant Colonies ◽  
Brood Parasites ◽  
Protomognathus Americanus ◽  
The Cost

Host defences become increasingly costly as parasites breach successive lines of defence. Because selection favours hosts that successfully resist parasitism at the lowest possible cost, escalating coevolutionary arms races are likely to drive host defence portfolios towards ever more expensive strategies. We investigated the interplay between host defence portfolios and social parasite pressure by comparing 17 populations of two Temnothorax ant species. When successful, collective aggression not only prevents parasitation but also spares host colonies the cost of searching for and moving to a new nest site. However, once parasites breach the host's nest defence, host colonies should resort to flight as the more beneficial resistance strategy. We show that under low parasite pressure, host colonies more likely responded to an intruding Protomognathus americanus slavemaker with collective aggression, which prevented the slavemaker from escaping and potentially recruiting nest-mates. However, as parasite pressure increased, ant colonies of both host species became more likely to flee rather than to fight. We conclude that host defence portfolios shift consistently with social parasite pressure, which is in accordance with the degeneration of frontline defences and the evolution of subsequent anti-parasite strategies often invoked in hosts of brood parasites.

scholarly journals Inter-Individual Variation in Anti-Parasitic Egg Rejection Behavior: A Test of the Maternal Investment Hypothesis

2020 ◽  
Vol 2 (1) ◽  
Author(s):  
M E Hauber ◽  
M Abolins-Abols ◽  
C R Kim ◽  
R T Paitz
Keyword(s):  
Host Species ◽  
Maternal Investment ◽  
Egg Yolk ◽  
Laying Date ◽  
Egg Rejection ◽  
Brood Parasites ◽  
Egg Yolks ◽  
3D Printed ◽  
Future Work ◽  
Investment Hypothesis

Synopsis Hosts of avian brood parasites may reduce or forego the costs of caring for foreign young by rejecting parasitic eggs from the nest. Yet, many host species accept parasitic eggs and, even among rejecter species, some individuals go on to incubate and hatch them. The factors explaining the variation in egg rejection between species have received much theoretical and empirical attention, but the causes of intraspecific variation in different individuals’ propensity for accepting parasitic eggs are less well understood. Here we tested the maternal investment hypothesis, which predicts that hosts with costlier clutches will be more likely to reject parasitic eggs from their nest. We studied variation in the egg rejection responses of American robins (Turdus migratorius), a robust egg-rejecter host of the brood parasitic brown-headed cowbird (Molothrus ater), to 3D-printed cowbird-sized eggs which were painted dark blue, a color known to induce variable and repeatable egg rejection responses in individual robins. Costlier clutch investment was estimated by earlier laying date, larger clutch size, heavier unincubated yolk mass, and variable yolk steroid hormone concentrations. There was no statistical support for most of our predictions. However, we detected more concentrated and greater overall amount of deoxycorticosterone deposited in egg yolks of rejecters relative to acceptors, although this accounted for no more than 14% of variance in the data. Future work should test experimentally the potential physiological linkage between maternal egg yolk steroid investment and egg rejection propensity in this and other host species of avian brood parasites.

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