Series consists of records pertaining to the history of the Hamilton Naturalists’ Club and its daily operations. This series includes a copy of the Club Constitution and by-laws, meeting minutes, financial statements such as receipts, revenue and expenditure sheets, investment income and bank account slips, a membership card, as well as President’s reports, an organizational report, and reports from various Club committees.

Series consists of letters written by Hamilton Naturalists’ Club members to specific organizations and individuals, raising concerns over issues such as environmental conservation, the welfare and protection of wildlife, and the hunting, trafficking and killing of birds. Correspondence also pertains to inquiries about donations, memberships, publications and programs. This series also includes correspondence from a few notable Hamiltonians such as a letter from the Club to Reverend Calvin McQuesten of Whitehern asking him to be the Honourary President of the Club for the 1961-62 season, and McQuesten’s acceptance of this position. There is also a letter addressed to His Worship Mayor Victor K. Copps regarding the Club’s disapproval of a proposed commercial development of LaSalle Park in Burlington, Ontario (December 9, 1969).

Series consists of detailed observations and daily journal records of birds and their nesting patterns in Hamilton, Ontario. The data was predominantly collected and recorded by Hamilton ornithologists Thomas McIlwraith (1824-1903), and George W. North, who was a member of the Hamilton Naturalists’ Club. Also included in this series are bird records from Kenneth C. McIlwraith and J. Harvey Williams, as well as Christmas Bird Count Censuses, and a report on the Ontario Nest Records Scheme.

Series consists of documentation and reports on several environmental conservation projects initiated by the Hamilton Naturalists’ Club out of concern for the protection of the environment and the local community. Projects include but are not limited to, a water quality study of Cootes Paradise, the use of Dombind (a dust suppressant) on roadways, legislation to protect endangered species, land evaluations and inventories of natural areas such as the Eramosa Karst, Friends of the Red Hill Valley group, the Nature Counts Project, the construction of the Red Hill Creek Expressway, the concern over leachate at the Rennie and Brampton Streets Landfill Sites, Save Our Ravines, Save the Oak Ridges Moraine, tree cutting and the West Harbour Trails. This series also includes photographs of the Falcon Watch project from a peregrine falcon observation session at the Sheraton Hotel in Hamilton.

Series consists of programs and events hosted by the Hamilton Naturalists’ Club and Junior Audubon Club. Programs include bald eagle hacking to stimulate eagle nesting and population recovery, as well as bird study groups and regular nature walks and outings. Former programs included the Wonders of Nature Show as well as the Nature in your Neighbourhood program, which featured Club members and community group speakers, discussing topics such as wildlife preservation and protection, nature photography and bird watching. This series also includes events such as the 85th anniversary of the Club, which unveiled the organization’s historic plaque at Princess Point, a lecture by Dr. Norman Pearson on the Bruce Trail, Hamilton NatureFest, and the Robert Bateman fundraiser dinner. This series contains photographs of the bald eagle hacking program and the Dr. Norman Pearson lecture.

Subseries consists of records of the Junior Audubon Club, which was a club for children interested in nature and wildlife preservation. The material includes a record book consisting of the lists of schools and teachers involved in the Club, meeting minutes and bird club statistical records. In 1986, this club partnered with the Royal Botanical Gardens to form the Hamilton Junior Naturalists’ Club to instill in children a life-long appreciation and respect for the environment and the natural world. This subserie also includes photographs from the Junior Club program Worm Watch that took place at the Royal Botanical Gardens Nature Centre in 2000.

Series consists of records pertaining to the purchase of land by the Hamilton Naturalists’ Club for the use as a nature and wildlife sanctuary. The land became known as the Short Hills Wilderness Area. Records in this series also document the legal correspondence between the former land owner, a hydro electric company and pipeline company regarding the expropriation of a portion of land, as well as debris being left on the property causing damage to the farmland.

Series consists of material related to raising funds for the Club,such as donation and legacy brochures, as well as documentation regarding the Townsend Bequest, and draft policy statements governing future bequests, endowments and funds. This series also includes a file on R. Owen Merriman, the founder and first president of the Hamilton Bird Protection Society. The file contains correspondence pertaining to the raising of funds to erect a memorial sculpture in honour of the founder, as well as a portrait of Merriman. This file also contains photographs and a postcard image of the memorial sculpture, which was created by Elizabeth Holbrook, and located in the Rock Gardens of the Royal Botanical Gardens.

Series consists of letter correspondence and a certificate congratulating the Hamilton Naturalists’ Club on receiving the Corporate Partner of the Year Award, Tourism Award of Excellence from the City of Hamilton (June 18, 2001). The Club was awarded this honour for their publication Naturally, Hamilton!, which encourages people to think of Hamilton as a place to visit for its natural areas and wildlife viewing opportunities. There is also letter correspondence congratulating the Club on receiving the Federation of Ontario Naturalists’ Award (June 26, 2001), as well as some biographical information on volunteer Hazel Broker for Volunteer Corner. The file contains three photographs pertaining to the award recognition.

Series consists of the Club’s promotional materials such as pamphlets, program guides, flyers, and information guides, as well as radio and news media releases. There are also newspaper clippings written mostly by former Club members George W. North and R. H. Westmore, as well as clippings pertaining to the publication of Birds of Hamilton and Surrounding Areas. The series also includes publication materials such as correspondence regarding articles for publication in The Wood Duck (the Club’s newsletter), as well as correspondence and documentation about the Club’s Naturally, Hamilton! publication. The series also contains manuscript copies of published articles written by various members, some of which were published in various newspapers such as the Dundas Banner, the Hamilton Spectator and the Club's newsletter, The Wood Duck. There is also a manuscript of bird songs compiled by long-time member Anna McLoghlin.

Series consists of photographs taken by various members of the Hamilton Naturalists' Club.

Series consists of 4 scrapbooks. The two earlier scrapbooks contain information from when the Club was called the Hamilton Bird Protection Society and include newspaper articles, correspondence, photographs, meeting announcements, and programs for lectures and events. The third scrapbook contains information on the sanctuaries held by the Club, and photographs of the Spooky Hollow and Short Hills Wilderness Sanctuaries. The fourth scrapbook contains mostly newspaper articles of press coverage on the Hamilton Naturalists’ Club.