Describing spatial patterns of phenotypic traits can be important for evolutionary and ecological studies. However, traditional approaches, such as fieldwork, can be time-consuming and expensive. Information technologies, such as Internet search engines, could facilitate the collection of these data. Google Images is one such technology that might offer an opportunity to rapidly collect information on spatial patterns of phenotypic traits.
We investigated the use of Google Images in extracting data on geographical variation in phenotypic traits visible from photographs. We compared the distribution of visual traits obtained from Google Images with four previous studies: colour morphs of black bear (Ursus americanus); colouration and spottiness in barn owl (Tyto alba); colour morphs of black sparrowhawk (Accipiter melanoleucus) and the distribution of hooded (Corvus corone) and carrion crows (Corvus cornix) across their European hybrid zone. Additionally, we develop and present a web application (Morphic), which facilitates the human data capture process of this method.
We found good agreement between fieldwork data and Google Images data across all studies. Indeed, there was strong agreement between the data obtained from the original study and from the Google Images method for the colour morphs of black bear (R2 = 80%) and for two barn owl plumage traits (R2 = 64% and 53%). Our approach also successfully matched the clinal variation of black sparrowhawks morphs across South Africa. Our method also gave a good agreement between the distribution of hooded and carrion crows (with 86% placed on the correct side of the hybrid zone line).
Our results suggest that this method can work well for visible traits of common and widespread species that are objective, binary, and easy to see irrespective of angle. The Google Images method is cost-effective and rapid and can be used with some confidence when investigating patterns of geographical variation, as well as a range of other applications. In many cases, it could therefore supplement or replace fieldwork.
Black bear survey data
Each row represents one image that appeared on a Google Images Search Engine Result Page (SERP). The column headings are as follows: survey_id - unique identifier of the survey result; comments - researcher's comments on the image; subspecies - black bear subspecies; age - black bear age (juvenile or adult); sex - black bear sex (male or female); photographer - name of photographer; colour_morph - black bear colour morph (black or non-black); image_usable - if image of black bear in western North America with colour morph visible (yes/no); state - state in USA where photograph taken; latitude - latitude at which photograph was taken in decimal degrees; longitude - longitude at which photograph was taken in decimal degrees; direct_link - the URL of the image on the internet; visible_link - the website on which the image appeared; search_name - human readable search description; search_query - search phrase entered into Google Images
black-bears-data-for-dryad.csv
Barn owl survey data
Each row represents one image that appeared on a Google Images Search Engine Result Page (SERP). The column headings are as follows: survey_id - unique identifier of the survey result; comments - researcher's comments on the image; age - barn owl age (juvenile/adult); sex - barn owl sex (male/female); photographer - name of photographer; colour_morph - barn owl colour morph score (1-8); spottiness - barn owl spottiness score (1-8); image_usable - if image of barn owl in region of interest with colour morph visible (yes/no); state - state in USA or area where photograph taken; country - country in which photograph taken; bucket - region in which photograph taken used in analyses; latitude - latitude at which photograph was taken in decimal degrees; longitude - longitude at which photograph was taken in decimal degrees; direct_link - the URL of the image on the internet; visible_link - the website on which the image appeared; search_name - human readable search description; search_query - search phrase entered into Google Images
barn-owl-data-for-dryad.csv
Black sparrowhawk survey data
Each row represents one image that appeared on a Google Images Search Engine Result Page (SERP). The column headings are as follows: survey_id - unique identifier of the newer survey result; gce_id - unique identifier of the older survey result; comments - researcher's comments on the image; age - black sparrowhawk age (juvenile/adult); sex - black sparrowhawk sex (male/female); photographer - name of photographer; colour_morph - black sparrowhawk colour morph (dark/light); image_usable - if image of black sparrowhawk in South Africa with colour morph visible; location_name - name of the location where the photograph was taken; latitude - latitude at which photograph was taken in decimal degrees; longitude - longitude at which photograph was taken in decimal degrees; direct_link - the URL of the image on the internet; visible_link - the website on which the image appeared
black-sparrowhawk-data-for-dryad.csv
Crow survey data
Each row represents one image that appeared on a Google Images Search Engine Result Page (SERP). The column headings are as follows: survey_id - unique identifier of the newer survey result; gce_id - unique identifier of the older survey result; comments - researcher's comments on the image; age - crow age (juvenile/adult); sex - crow sex (male/female); photographer - name of photographer; species - crow species (hooded crow/carrion crow); image_usable - if image of crow in Europe with species visible; region - region where the photograph was taken; latitude - latitude at which photograph was taken in decimal degrees; longitude - longitude at which photograph was taken in decimal degrees; direct_link - the URL of the image on the internet; visible_link - the website on which the image appeared; search_name - human readable search description; search_query - search phrase entered into Google Images
crow-data-for-dryad.csv