5 amazing symbiotic animal relationships you didn't know about | From the Grapevine
Here, we investigate general patterns in such relationships at large spatial and . mainly commensalistic relationships with mammals, and (3) oxpeckers, the . To test whether a nested structure exists for our set of bird–mammal .. plains zebra and African elephant, that occupy mainly open habitats (see. ), but few studies have argued that the relationship may also be Chi- square tests were then used to compare preference index distributions Oxpeckers were also present on Hippopotamus, Plains Zebra and Impala (Figure 1). Impala. One example of a mutualistic relationship is that of the oxpecker (a kind of bird) and the rhinoceros or zebra. Oxpeckers land on rhinos or zebras and eat ticks.
Abstract Birds sitting or feeding on live large African herbivorous mammals are a visible, yet quite neglected, type of commensalistic—mutualistic association.
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Here, we investigate general patterns in such relationships at large spatial and taxonomic scales. To obtain large-scale data, an extensive internet-based search for photos was carried out on Google Images. To characterize patterns of the structural organization of commensalistic—mutualistic associations between African birds and herbivorous mammals, we used a network analysis approach.
We then employed phylogenetically-informed comparative analysis to explore whether features of bird visitation of mammals, i.
We found that the association web structure was only weakly nested for commensalistic as well as for mutualistic birds oxpeckers Buphagus spp.
Moreover, except for oxpeckers, nestedness did not differ significantly from a null model indicating that birds do not prefer mammal species which are visited by a large number of bird species. In oxpeckers, however, a nested structure suggests a non-random assignment of birds to their mammal hosts.
We also identified some new or rare associations between birds and mammals, but we failed to find several previously described associations. Furthermore, we found that mammal body mass positively influenced the number and mass of birds observed sitting on them in the full set of species i. We also found a positive correlation between mammal body mass and mass of non-oxpecker species as well as oxpeckers. Mammal herd size was associated with a higher mass of birds in the full set of species as well as in non-oxpecker species, and mammal species living in larger herds also attracted more bird species in the full set of species.
Habitat openness influenced the mass of birds sitting on mammals as well as the number of species recorded sitting on mammals in the full set of species.
In non-oxpecker species habitat openness was correlated with the bird number, mass and species richness. Our results provide evidence that patterns of bird—mammal associations can be linked to mammal and environmental characteristics and highlight the potential role of information technologies and new media in further studies of ecology and evolution.
However, further study is needed to get a proper insight into the biological and methodological processes underlying the observed patterns. The African herbivorous mammals are composed of many phylogenetic lineages with diverse life strategies, including their body masses and tendency to form herds Smith et al.
The majority of previous studies investigating patterns in commensalistic—mutualistic interactions between African birds and large herbivores have focused only on single or a small number of species Hart et al. Hence, a large-scale and multitaxonomical approach is useful when investigating patterns in bird—mammal interactions to avoid problems with interpretation and generalization of relationships which may be area- or taxa-specific.
Many types of heterospecific relationships, including both commensalism and mutualism, are depicted as complex webs comprising several interacting species, rather than as isolated interactions between species pairs Bascompte et al. As a result, the structure of such community networks exhibit a specific arrangement of interactions rather than random inter-specific interactions.
However, studies involving birds as interactors have had mixed results. For instance, while a highly nested structure was found for cleaning associations between birds and their mammal hosts in Neotropical regions Sazima et al. The number and diversity of birds directly interacting with i. The only examples of African birds exhibiting obligate mutualistic associations with mammals are the small-bodied passerines, oxpeckers Buphagidaebeing two extant species, yellow-billed oxpecker Buphagus africanus and red-billed oxpecker B.
Here, the species association features may differ from other birds since the feeding ecology of oxpeckers and their presence on host species has been found to be strongly correlated with the character of host infestation by ectoparasites Hart et al. To investigate large-scale patterns of bird—mammal associations, extensive data collection from free online sources may be useful. During the last decade, the engagement of volunteers in scientific projects, so-called citizen science, has became an integral part of current ecological and evolutionary research Bonney et al.
Approaches range from the collection of internet data uploaded by the public to active participation and collaboration with scientists e. Rapid technological development and the expanding access of the public to both internet and recording devices, such as cameras or smartphones, around the world have increased the accessibility, immediacy and extent of data sharing.
Online data collected by the public can represent a useful resource for expansion of scientific knowledge on rare or poorly studied phenomena e. Despite the increasing number of such studies, material uploaded on the internet by the public is still an underexploited data source for studies in ecology and evolution. Here, we used photos collected using the web-based search engine Google Images to investigate some aspects of commensalistic—mutualistic associations between African birds and herbivorous mammals.
In contrast to the majority of previous field studies that focused only on spatially and taxonomically restricted systems e.
Firstly, the structure of the association web between African birds and mammals was visualized and analysed to investigate frequencies of association between particular bird and mammal species and whether bird—mammal interactions were arranged in a nested pattern. Then, we employed phylogenetically-informed comparative analysis to explore whether patterns in bird visitation of mammals i.
Materials and Methods Data searching To collect a large dataset of spatially and taxonomically distributed data on bird—mammal associations, we did an extensive internet search for photos on Google Images. Moreover, since results of searches using English and scientific names were highly correlated, we decided to search only for English names of birds and mammals, although this could restrict the geographical coverage and decrease the use of records from non-English-speaking countries.
We also used this searching phrase for species where few interactions had already been found by a word combination search. However, we used only results revealing new, typically rare, bird—mammal associations, hence avoiding significant bias in the search in favour of common or well-recognized associations. The Google searches for photos for each combination of bird and mammal taxa were conducted separately, and for each combination we aimed to collect as many photos as possible until the search produced only a small proportion of photos with relevant content.
For common species it is virtually impossible to collect all available photos, so this solution represented a trade-off between the number of available relevant photos and the time spent searching for new photos; however, we consider that the proportion of available photos sampled was similar in all species.
We only analyzed photos in which birds were in direct contact with the bodies of a mammal, excluding cases where the birds were only feeding or flying near the mammal. We did not include photos of mammals without birds in our data set, even if such individuals were visible in photos.
We focused only on free-living, non-domesticated mammal species in sub-Saharan Africa.Helpful bird eagerly styles zebra's mane
We also excluded photos where birds were observed on captive African mammals outside Africa e. To limit other sources of bias, photos suspected to be shared by multiple sources were briefly checked to see whether they had already been included all photos were collected exclusively by one author, PM, enabling us to do this consistently.
We were particularly careful when working with unusual photos that people might prefer to share, e. This is most likely because of a home range overlap with Yellow-billed Oxpeckers, resulting in interspecific competition Koenig The larger in terms of body size Yellow-billed Oxpecker is territorial and capable of outcompeting the smaller Red-billed Oxpecker Hall-Martinpermitting the former a preferential choice of ungulates.
The study also shows that Red-billed Oxpeckers in the southern regions of KNP utilised the preferred large ungulates in the absence of Yellow-billed Oxpeckers, whereas their preference shifted to smaller ungulates in the presence of Yellow-billed Oxpeckers. This further supports the notion of interspecific competition between Red-billed and Yellow-billed Oxpeckers for access to larger ungulate hosts. Contrary to the results from the present study, Hustler and Koenig in Zimbabwe and Kenya respectively did not find any differences in host ungulate preferences when both species occurred within the same geographic region.
Furthermore, Koenig did not find any marked differences in the host species preferences of Red-billed Oxpeckers when comparing between areas of sympatry and areas of allopatry.
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Perhaps these differences between the Kenya study and the KNP findings could be attributed to differences in ungulate densities between the two sites. One would assume that the Kenya sites Masai Mara Reserve and Lake Nakuru National Park had a high abundance of large ungulates compared to KNP, hence a marked host preference would only be apparent in lower ungulate densities where interspecific competition is unavoidable.
However, that hypothesis cannot be tested without a measure of ungulate densities from all sites. Surprisingly, the PI results in the present study differed from Grobler and Stutterheim and Stutterheim Optimal foraging strategy Pyke will predict that animals will concentrate on the most abundant and profitable food source. For example, there were fewer White Rhinoceros and Hippopotamus in KNP in the s compared to the present-day population It is therefore reasonable to conclude that as White Rhinoceros and Hippopotamus numbers increased, Red-billed Oxpeckers responded by selecting for these new abundant host species with potentially higher tick loads and less hair to hide the ticks.
Giraffe remained the most preferred host species in both the northern and southern regions of the park.
Feeding preferences of Oxpeckers in Kruger National Park, South Africa
This could also be a detection bias, given that it is possibly easier for flying birds to detect Giraffe compared to other shorter species. This is further supported by Oxpeckers' preference for White Rhinoceros and Hippopotamus both large ungulatesrecorded as host species in Skukuza.
Interestingly, Impala, an abundant, small-sized ungulate, was less preferred as a host species across studies. This surprising contradicts what has been reported by GroblerStutterheim and Stutterheim and Hart et al.
Both Red-billed and Yellow-billed Oxpeckers displayed a preference for the back and head regions of their respective host species.
Red-billed Oxpeckers also preferred the necks of Giraffe. Additionally, Oxpeckers prefer feeding on the back regions of a host species since this is easily accessible and provides a stable perch Weeks The head is also preferred since it provides additional food resources other than ticks, i. Exceedingly low occurrences of wound feeding by Red-billed Oxpeckers and the absence of wound feeding in Yellow-billed Oxpeckers suggests that this feeding behaviour is not prevalent in KNP as previously reported in cattle ranches in Zimbabwe Weeks Plantanin her study on both Oxpecker species at Shingwedzi inalso found the prevalence of wound feeding behaviour to be very low 3.
However, she did find that wound feeding was exhibited by Yellow-billed Oxpeckers more than Red-billed Oxpeckers.