Ranger Steve’s Nature Niche By Ranger Steve Mueller

Does the early bird get the worm? I recorded the order bird species arrived at feeders or flew through the sanctuary one morning between 7 a.m. and 8:30. I expected arrival to begin shortly after 7 a.m. in mid-February. Table 1 shows the first arrival time for each species on three dates. 

After observing one morning, I thought it necessary to get additional data because one day’s observation might be quite different from other days. It would be good to gather arrival times and the order species arrived for many days to determine if there is a pattern. I would like to have gathered data for 20 or 30 days so it would be more statistically reliable. 

Each succeeding midwinter day, the sun rises a little earlier so it is expected to change bird wake up and activity times. 

With previous casual observation, I noticed Northern Cardinals are among the first arrivals at daylight and last to depart at dusk. The number of birds at the feeders are most abundant midday. Squirrels impact bird use. It seems like birds and squirrels take turns but I do not think it is by choice. There are 18 squirrels that visit and when they are present, birds tend to stay away. As soon as squirrels leave birds come to feed. 

A factor that affects bird activity is foot-candles of light. That is the amount the light produced by a candle at a distance of one foot. More candles produce more light at one foot. As daylight breaks, the area lightens with increased foot-candles of light. Various species become active at different light levels. Some are late sleepers until it is brighter. 

If the sky is clear there will be more light to produce a higher foot-candle luminance. It is obvious that on cloudy days there are fewer foot-candles of light. I did not measure foot-candles of light to compare with bird arrival times. That would be interesting to see how light levels affected early morning bird activity times. 

Another factor that makes a difference for bird arrival is their location in the time zone. Birds living at the same latitude but at the eastern edge of the time zone experience sunrise an hour early than birds living at the western edge. For convenience, time zones are set for a middle longitude and the time is accepted as the same for the whole zone. Birds do not use our clocks. They use foot-candles of light in the area where they live.

It gets light almost an hour earlier on the east coast of North America than it does at the Lake Michigan shoreline. Birds living on the east coast become active earlier in the day. North-south latitudes affect daylight hours. We are familiar with the land of the midnight sun in the Arctic Circle summer and 24 hours of darkness in winter. Here summer daylight is about 16 hours and winter light about 8 hours. Near equator light and dark remains close to 12 hours all year. 

Table 1 shows first arrival time for each species. The arrival sequence is numbered. It was not the same. If I gathered data for many days, it would provide a more reliable record for determining if species have a consistent sequence for arrival.

Outlier data needs to be ignored. It is possible that an individual for a species could arrive unusually early or late for an abnormal reason. Having many days’ data would allow us to see the abnormal and ignore it. Other outlier data I needed to ignore was first arrivals recorded much later in the day. I did not watch the feeder continuously after 8:30 a.m. Arrival times recorded for bird species later in the day most likely was not a first arrival. They might have come a few minutes after I stopped watching at 8:30. Times later in the day are outlier data that cannot be included when determining nature niche activity.

Natural history questions or topic suggestions can be directed to Ranger Steve (Mueller) at odybrook@chartermi.net – Ody Brook Nature Sanctuary, 13010 Northland Dr. Cedar Springs, MI 49319 or call 616-696-1753.