Volunteer Chimney Swift Roost Monitoring – April, 2022

This is a request for volunteers from Emma Dougherty at Fairleigh Dickinson University.


Light pollution is an anthropogenic factor that is increasing more and more every day, posing serious threats to wildlife (Knop et al., 2017; May et al., 2019). Artificial light at night (hereafter, ALAN) has been shown to impact behaviors and population dynamics of wildlife, often with negative consequences

We predict the Chimney swift (Chaetura pelagica) population to be impacted by ALAN. This species is a small aerial insectivore distributed across the Americas which utilizes artificial structures such as chimneys for nesting, breeding, and roosting (Zammuto & Franks, 1981). Once abundant across its range, the Chimney swift population has been steadily declining and is currently listed as Vulnerable by the IUCN (BirdLife International, 2020). Based on the finding that coordinated entry of these swifts into their roosting sites is signaled by the time of sunset (Zammuto & Franks, 1981), we hypothesize that ALAN will affect the roosting behavior of Chimney swifts, specifically that higher levels of ALAN will cause delayed entry into roosting and breeding sites. 

In order to test this hypothesis, we must quantify light intensity and compare this to the coordinated time of entry of the swifts to find possible correlations. Testing this hypothesis will allow us to shed light on the causes of Chimney swift population declines and how best to conserve them, as well as help in understanding the broader effects of ALAN on roosting behaviors in wildlife populations.


In order to gather these data, we are requesting the help of bird watchers and citizen scientists to record the chimney swift behavior when they see them enter a roosting site (a chimney). If you would be willing to help, please read the guidelines below, visit one of the specified sites, and fill out the form detailing your observations here: https://forms.gle/9ZVBNTq2ARaxNmVL7

  1. Locate one of the following roost sites listed in this google form https://forms.gle/9ZVBNTq2ARaxNmVL7, or a different site in your area if you know of one.
  2. On the night of your roost watch, arrive to the site 45 minutes before sunset (find time of sunset at https://sunrise-sunset.org/).  
  3. Observe the chimney swifts entering! 
    1. As the first chimney swift enters…
      1. record the time
      1. record the weather conditions
      1. count the number of birds entering
      1. record the light measurement following the instructions below
  1. Please measure the amount of light using the Light Meter LM-300 app. Available for iPhone: https://apps.apple.com/us/app/light-meter-lm-3000/id1554264761
          1. This app uses the phone’s front facing camera. Hold your phone flat so that the front facing camera aims upward.
          1. Tape a small piece of white printer paper over the phone’s front facing camera as a “diffuser”. The app will instruct you to do this when you open it. 
  • Continue recording light measurements every 10 minutes until the last bird has entered the chimney.
    • When the last bird has entered, record the time again.
  • When you have finished, please record your observations using this google form link https://forms.gle/9ZVBNTq2ARaxNmVL7
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