1.         Environmental volunteering can benefit participants and nature through improving physical and mental wellbeing while encouraging environmental stewardship. To enhance achievement of these outcomes, conservation organisations need to reach different groups of people to increase participation in environmental volunteering. This paper explores what engages communities searching online for environmental volunteering.

2.         We conducted a literature review of 1032 papers to determine key factors fostering participation by existing volunteers in environmental projects. We found the most important factor was to tailor projects to the motivations of participants. Also important were:  promoting projects to people with relevant interests; meeting the perceived benefits of volunteers and removing barriers to participation.

3.         We then assessed the composition and factors fostering participation of the NatureVolunteers’s online community (n = 2216) of potential environmental volunteers and compared findings with those from the literature review. We asked whether projects advertised by conservation organisations meet motivations and interests of this online community.

4.         Using Facebook insights and Google Analytics we found that the online community were on average younger than extant communities observed in studies of environmental volunteering. Their motivations were also different as they were more interested in physical activity and using skills and less in social factors. They also exhibited preference for projects which are outdoor based, and which offer close contact with wildlife. Finally, we found that the online community showed a stronger preference for habitat improvement projects over those involving species-survey based citizen science.

5.         Our results demonstrate mis-matches between what our online community are looking for and what is advertised by conservation organisations.  The online community are looking for projects which are more solitary, more physically active and more accessible by organised transport. We discuss how our results may be used by conservation organisations to better engage with more people searching for environmental volunteering opportunities online.

6.         We conclude that there is a pool of young people attracted to environmental volunteering projects whose interests are different to those of current volunteers.  If conservation organisations can develop projects that meet these interests, they can engage larger and more diverse communities in nature volunteering.

The data set consists of separate sheets for each set of results presented in the paper. Each sheet contains the full data, summary descriptive statistics analysis and graphs presented in the paper. The method for collection and processing of the dataset in each sheet is as follows:

The data set for results presented in Figure 1 in the paper - Sheet: "Literature" 

We conducted a review of literature on improving participation within nature conservation projects. This enabled us to determine what the most important factors were for participating in environmental projects, the composition of the populations sampled and the methods by which data were collected. The search terms used were (Environment* OR nature OR conservation) AND (Volunteer* OR “citizen science”) AND (Recruit* OR participat* OR retain* OR interest*).  We reviewed all articles identified in the Web of Science database and the first 50 articles sorted for relevance in Google Scholar on the 22nd October 2019. Articles were first reviewed by title, secondly by abstract and thirdly by full text. They were retained or excluded according to criteria agreed by the authors of this paper. These criteria were as follows - that the paper topic was volunteering in the environment, including citizen science, community-based projects and conservation abroad, and included the study of factors which could improve participation in projects. Papers were excluded for topics irrelevant to this study, the most frequent being the outcomes of volunteering for participants (such as behavioural change and knowledge gain), improving citizen science data and the usefulness of citizen science data. The remaining final set of selected papers was then read to extract information on the factors influencing participation, the population sampled and the data collection methods. In total 1032 papers were reviewed of which 31 comprised the final selected set read in full. Four factors were identified in these papers which improve volunteer recruitment and retention. These were: tailoring projects to the motivations of participants, promoting projects to people with relevant hobbies and interests, meeting the perceived benefits of volunteers and removing barriers to participation.

The data set for results presented in Figure 2 and Figure 3 in the paper  - Sheet "Demographics" 

To determine if the motivations and interests expressed by volunteers in literature were representative of wider society, NatureVolunteers was exhibited at three UK public engagement events during May and June 2019; Hullabaloo Festival (Isle of Wight), The Great Wildlife Exploration (Bournemouth) and Festival of Nature (Bristol). This allowed us to engage with people who may not have ordinarily considered volunteering and encourage people to use the website. A combination of surveys and semi-structured interviews were used to collect information from the public regarding demographics and volunteering. In line with our ethics approval, no personal data were collected that could identify individuals and all participants gave informed consent for their anonymous information to be used for research purposes. The semi-structured interviews consisted of conducting the survey in a conversation with the respondent, rather than the respondent filling in the questionnaire privately and responses were recorded immediately by the interviewer. Hullabaloo Festival was a free discovery and exploration event where NatureVolunteers had a small display and surveys available. The Great Wildlife Exploration was a Bioblitz designed to highlight the importance of urban greenspaces where we had a stall with wildlife crafts promoting NatureVolunteers. The Festival of Nature was the UK’s largest nature-based festival in 2019 where we again had wildlife crafts available promoting NatureVolunteers. The surveys conducted at these events sampled a population of people who already expressed an interest in nature and the environment by attending the events and visiting the NatureVolunteers stand. In total 100 completed surveys were received from the events NatureVolunteers exhibited at; 21 from Hullabaloo Festival, 25 from the Great Wildlife Exploration and 54 from the Festival of Nature. At Hullabaloo Festival information on gender was not recorded for all responses and was consequently entered as “unrecorded”.

OVERALL DESCRIPTION OF METHOD DATA COLLECTION FOR ALL OTHER RESULTS (Figures 4-7 and Tables 1-2)

The remaining data were all collected from the NatureVolunteers website. The NatureVolunteers website https://www.naturevolunteers.uk/ was set up in 2018 with funding support from the Higher Education Innovation Fund to expand the range of people accessing nature volunteering opportunities in the UK. It is designed to particularly appeal to people who are new to nature volunteering including young adults wishing to expand their horizons, families looking for ways connect with nature to enhance well-being and older people wishing to share their time and life experiences to help nature. In addition, it was designed to be helpful to professionals working in the countryside & wildlife conservation sectors who wish to enhance their skills through volunteering.  As part of the website’s development we created and used an online project database, www.naturevolunteers.uk (hereafter referred to as NatureVolunteers), to assess the needs and interests of our online community. Our research work was granted ethical approval by the Bournemouth University Ethics Committee. The website collects entirely anonymous data on our online community of website users that enables us to evaluate what sort of projects and project attributes most appeal to our online community. Visitors using the website to find projects are informed as part of the guidance on using the search function that this fully anonymous information is collected by the website to enhance and share research understanding of how conservation organisations can tailor their future projects to better match the interests of potential volunteers. Our online community was built up over the 2018-2019 through open advertising of the website nationally through the social media channels of our partner conservation organisations, through a range of public engagement in science events and nature-based festivals across southern England and through our extended network of friends and families, their own social media networks and the NatureVolunteers website’s own social network on Facebook and Twitter. There were 2216 searches for projects on NatureVolunteers from January 1^st to October 25^th, 2019.

The data set for results presented in Figure 2 and Figure 3 in the paper  - Sheet "Demographics" 

On the website, users searching for projects were firstly asked to specify their expectations of projects. These expectations encompass the benefits of volunteering by asking whether the project includes social interaction, whether particular skills are required or can be developed, and whether physical activity is involved. The barriers to participation are incorporated by asking whether the project is suitable for families, and whether organised transport is provided. Users were asked to rate the importance of the five project expectations on a Likert scale of 1 to 5 (Not at all = 1, Not really = 2, Neutral = 3, It would be nice = 4, Yes essential = 5). Users were then asked to specify the content of the project. Content relates to the type and attributes of the project. Firstly, users were asked to select the project type(s) that interest them out of three categories; species surveys, improving habitats and other. Users could provide an example of what they meant by other. Secondly, users were asked to select keywords relating to the project out of 12 categories; outdoor based, indoor based, close contact with wildlife, wildlife survey, habitat management, helping other people, plants, mammals, birds, amphibians & reptiles, insects and seashore. For both project type and keywords, users could select as many as they wished. The same questions were asked of conservation organisations when advertising volunteer projects. Online search and project criteria were extracted from the online NatureVolunteers database for the period January 1^st to October 25^th, 2019. All statistical analyses were performed using R Version (3.4.1) (R Core Team, 2017). 

To begin with we used descriptive statistics to explore which project expectations and content were the most appealing for the NatureVolunteers online community. We then examined the link between project expectations and project content. Data was sequentially reduced during analysis to explore all relationships. Firstly, all responses were analysed. Secondly, the project type ‘other’ was removed. Thirdly, responses were aggregated by combining the negative responses (1s and 2s) and the positive responses (4s and 5s), with the addition of a double weight for the extreme values (1s and 5s). This changed project expectation responses to ‘no’, ‘neutral’ and ‘yes’. Finally, we removed all responses which selected more than one project type or keyword and therefore analysed only the response which had only selected one. To better examine relationships between project expectations and keywords selected, the keywords were grouped according to similarities. First, we compared searches which selected indoor based and outdoor based projects. Then we compared searches which selected projects that offered close contact with wildlife and helping people. Finally, we compared responses to the different types of wildlife; plants, mammals, birds, amphibians &reptiles, insects and seashore. The same sequential aggregations of data that is described above were also conducted on these groups. We tested the significance of interactions between the importance of project expectations and project content selected by users at all levels of data aggregation using chi square tests of independence. Chi square tests were also used to determine if the types of projects advertised by organisations met the interests of NatureVolunteers online community.

The data set for results presented in Figures 4 , 5, 6 in the paper  - Sheet  "What are they looking for" 

The individual data from the 2216 searches for projects on NatureVolunteers from January 1^st to October 25^th, 2019 with the Figure 4 graph. We also provide additional supporting exploratory analyses further down on the same sheet.

The data set for results presented in Table 1 in the paper  - Sheet  "Project type Chi-all";  Sheet "Project type Chi-only 1"

The full data are presented togtheer with the Chi square analyses reported in Table 1

The data set for results presented in Table 2 in the paper  -  Sheet  "Keywords Chi- all"; Sheet  "Keywords Chi-only 1"

The full data are presented togtheer with the Chi square analyses reported in Table 2

The data set for results presented in Figure 7 in the paper  - Sheet  "Factors stacked bar chart" 

Conservation organisations advertised 247 projects on NatureVolunteers between January and October 2019. Overall the content and expectations of opportunities advertised differed markedly from what the online community was searching for as is presented in Figure 7. The data supporting the Figure 7 graph are provided in the sheet "Factors stacked bar chart" and the supporting raw data and complete Chi square analysis are presented in the sheet " Supply and demand Chi Square" .