One of the ways scientists learn which species and habitats require conservation measures is by conducting biological surveys or inventories and regularly monitoring populations of plant or animal species over time to detect trends in their numbers. For example, breeding bird surveys conducted in the U.S. each year since the 1960s have identified which bird species are doing well and which are in decline, leading to more focused conservation measures. In addition to national surveys, each state also conducts its own surveys of plant and animal species.
Types of Studies
Several different types of studies are used to assess the health of species and habitats, including:
- Survey or inventory: a point-in-time measurement of the resource to determine location or condition
- Census: a periodic count of the entire population
- Sample: measurement of a small subset of the population, as a representative of the larger population
- Atlas: a comprehensive survey of a large geographical area that maps the occurrence (or occurrence and relative abundance) of species in subdivisions of that area. An atlas is usually based on a grid of fixed intervals of distance or degrees latitude and longitude. It is restricted to a particular season of the year, usually the breeding season.
- Monitoring: the collection and analysis of repeated observations or measurements to evaluate changes in condition. For example, monitoring species typically involves studying their numbers, abundance, distribution, reproduction success, etc. Natural communities are often monitored for plant species composition and associated fauna, habitat quality, threats, etc.
Who Does Surveys and Monitoring?
In the New York metropolitan region, the state agencies involved in survey and monitoring are:
- New York: Department of Environmental Conservation
- New Jersey: Department of Environmental Protection
- Connecticut: Department of Environmental Protection
- Pennsylvania: Pennsylvania Biological Survey
Some conservation organizations also do surveys and monitoring. For example, the International Union for Conservation of Nature (IUCN) compiles the Red List of globally imperiled species. The annual migration of the Monarch butterfly is included as an “endangered biological phenomenon,” but no pollinator species from the region are listed. The Xerces Society publishes Red Lists of imperiled or vulnerable pollinators and butterflies and moths specifically.
Other groups that do survey and monitoring include the Natural Heritage Program in each state, academia, and citizen scientists. Natural history museum collections are important repositories of species information. Currently, American Natural History Museum scientists are databasing the AMNH bee collection, entering information from each specimen label (location, date of collection, species identification) online at discoverlife.org.
Although extensive work has been done on vertebrate species, many plant species, and some invertebrates such as dragonflies and freshwater mussels and snails, we know very little about most insect pollinators in our region. Butterflies may be the best known pollinators in part because there are not too many species and good regional identification guides exist. For example, a new resource, Butterflies and Moths of North America is a user-friendly database that contains the most comprehensive online distribution record of butterfly and moth species available for our region. More than 247,000 records and nearly 4,300 species accounts are accessible via the website through dynamic distribution maps, checklists, and species accounts. Fourth of July butterfly counts are one-day surveys of all butterfly species observed within a defined area. As their name suggests, these are typically held sometime during the 2-week period around July 4th. They provide a snapshot in time of species and numbers and can show general trends over time for local butterflies.
Native bees are especially difficult to identify, requiring collection and specimen preparation, and they can also be challenging to survey. Some bumble bee species are being tracked. Other regional research is being carried out by scientists at Rutgers University, Columbia University, and Long Island University. Along with some native bee surveys ongoing in community gardens, these are the only formal or informal surveys currently underway in New York City for specific insect pollinators in our region.
Guidelines for Survey and Monitoring
To improve our ability to better detect and understand population trends and develop conservation programs, various guidelines have been developed for insect surveys and monitoring.
New, T R. 1998. Invertebrate Surveys for Conservation. Oxford University Press.
Droege, S. 2012. The Very Handy Manual: How to Catch and Identify Bees and Manage a Collection This document contains everything you need to know to collect, survey and monitor bees.
The Bee Monitoring Listserve disseminates information and fosters discussions on the inventory and monitoring of bees as well as their identification.
Butterflies and Moths:
Pollard, Ernest and Tina J. Yates. 1993. Monitoring Butterflies for Ecology and Conservation. Chapman and Hall, Inc. New York, NY. 274 p.
Rzeszotarski, MS and JL Wiedmann. 2008. Long-term Butterfly Monitoring Project – Instructions for Recorders. Publication of The Ohio Lepidopterists.