Various methods were used to collect and analyze data in this investigation

Various methods were used to collect and analyze data in this investigation. Several studies were collected as a way of surveying the existing literature. Other secondary sources of information that were used included the searching of the web and the citations in most of the written articles. Direct contacts with the researchers were also an invaluable way of collecting information. The team also had access to additional unpublished studies which focused on three bird species. The three cases indicated that helpers have a negligible effect on parental fitness, and there is no proof for a sex ratio bias in favor of the helping sex (Griffin et al., 2005). The inclusion of these data served to further strengthen the relationship presented in this context. When the helping sex is absent or rare, there is a tendency for parents to produce the helping sex in large numbers depending on the benefit that these helpers provide. In general, it can be predicted that the sex ratio adjustment ought to be positively correlated with the benefit that the helping sexes can provide.