Changing sunrise, sunset affects animals as well
Posted October 29, 2013
You've probably noticed the sun rising a little later and setting a little earlier lately. Flora, fauna or (Greg) Fishel, we all react to changes in the amount of sunlight.
Keepers at the North Carolina Zoo and North Carolina Aquariums are keenly aware of the animals’ reactions to the day’s length. Lighting is adjusted for some species to keep them on their natural schedule or sometimes encourage specific behaviors.
I talked with Melissa Vindigni, an Alaskan seabird keeper at the zoo’s Rocky Coast exhibit, about their careful control of exhibit lighting to help these birds feel at home.
The zoo’s collection of murres, auklets and puffins comes from near the Arctic Circle and is among the largest in the country. Zoo staff collected about half the animals during an expedition to Savoonga, Alaska, and the remainder hatched at the zoo in the years since. Much of the success of the breeding program comes from the faithful reproduction of the rocky island environment the middle of the Bering Sea, including length of the day.
The birds molt, mate and even migrate according to cues provided by the day length. The shorter winter days cue the birds to head out to sea. A flotilla of puffins spends much of the winter in the zoo's icy 45,000 gallon pool. It's only a few yards away from the rocky ledges where they spend much of the summer, but it's migrating to them.
Lighting timers replicate Savoonga‘s sunrise and sunset times. Currently North Carolina receives nearly 2 hours more sunlight than Alaska, but during summer months, Alaska receives about 5 more hours of sunlight daily. It’s not just the length of the day that differs – day to day changes are more dramatic at that latitude (64°N) than here (36°N). Savoonga loses about 3 minutes of October daylight each day; North Carolina loses about a minute. Zoo staffers adjust the lighting every other week to keep up.
The precision of the timing is working. Zoo staff stay in contact with researchers in the field. Reports are that North Carolina and wild puffins are doing what they do within about a week of each other.
Vindigni recalls a pair of birds who were kept behind the scenes for extra veterinary attention last year and were exposed to local sunlight patterns. “They didn't know when to molt, so they just didn’t that season.”
Brian Dorn, director of operations and husbandry at the North Carolina Aquarium on Roanoke Island, tells of similar lighting controls for their animals. While lighting in most exhibits is timed to each aquarium's operating hours, more sophisticated lighting packages can be used stimulate spawning activity when necessary. Seahorses in particular require 12 hours of light each day to successfully breed.
Lighting control doesn't stop at replicating sun cycles. Coral depend on lunation, the cycle of phases of the moon each month, to trigger spawning. Lights above tanks change nightly to replicate the changing moon. Visitors probably won't notice any of this though.
“These things can be manipulated much easier in back up or holding tanks,” said Dorn. “There lighting parameters can be changed without affecting the visitor experience.”
Tony Rice is a volunteer in the NASA/JPL Solar System Ambassador program and software engineer at Cisco Systems. You can follow him on twitter @rtphokie.