Thursday, July 24, 2008
Are Hummingbird Numbers Declining, 2008?
Many people have emailed us about their reports of hummingbird population declines in 2007, and this year, notably Ruby-throated Hummingbirds declines. Here are some of their recent comments:
I live in Northern NJ and with the exception of a hummer we spotted in mid-May at the feeder, we haven't seen anything since. I'm hoping once my butterfly bush blossoms, I'll start seeing them again. Also, my Dad lives in Eastern PA and only recently spotted his first hummer of the season. Extremely disappointed this year!
We're in NW New Mexico, and our numbers of Ruby Throats and particularly Rufous are distinctly down. Rubies are 50% off, and Rufous are waaaaay down---we only have one male Rufous this year, whereas we usually get 6-8 Rufous, male and female.
We live in Granville Tennessee and have seen a lot less hummingbirds this year. It seems that only 2 are around the feeder at one time. Last year we had 6. We would sit there laughing at the 1 male that always seemed to guard 2 feeders at once. This year I've only put 1 feeder out since there aren't enough birds to empty them. We've found 2 dead on our deck and aren't sure whether they ran into a window or just died. I was beginning to think that maybe some disease is causing the decline.
Here in Cumming, GA we have not seen any Hummingbirds this year. We've had our feeders up since May.
I live in central PA. We are getting aprox. 50% fewer humming birds at our feeders this year. There seems to be the same number of males to females as usual though.
I live in SW Ohio and from what I have observed, there are at laest 50% fewer humming birds this year in my area; all the people that have feeders here are saying the same thing.
I live in Hendersonville Tennessee and I haven't had any hummers as the last 5 years there normally are 20 to 30 between 3 feeders Does anyone know where they are?
Not everyone is reporting hummer numbers as down, but the vast majority of people we're hearing from are saying they see less hummers than usual. So what's going on? It's hard to know whether the reports we get accurately reflect a widespread population decline in hummingbirds, especially Ruby-throated Hummingbirds. Who is even keeping track of hummingbird numbers?
The Breeding Bird Survey, a long-time study that started in 1966, surveys nesting birds in May and June. Volunteers drive a 25 mile routs and stop every half mile for 3 minutes and record every bird seen or heard at that spot. This is most effective at picking up singing males. Birds that do not sit in one spot and sing (such as hummingbirds) may be under-reported in the BBS. You can look up population trends for any species on the Breeding Bird Survery website.
A check of the population trend for Ruby-throated Hummingbirds in the Eastern BBS region from 2000 to 2007 shows a very, very slight (0.69) population increase.
eBird is another source of bird population data. This recent website was begun in 2002 by Cornell and it allows people to send in their bird reports electronically. You can look up how many reports of each species have been seen in your area on their website. People have been sending in reports of hummingbirds. But this is not a long term scientific study, so it's hard to draw conclusions about overall poplulation trends. The DC Birding Blog tried an analysis based on eBird data and concluded there may possibly be a small decline in Ruby-throat populations.
The Christmas Bird Count is a long running population survery of birds in December and January and you can look up which birds are found where on the website. Many hummingbirds leave the Untied States in the winter months. A few Ruby-throated Hummingbirds do overwinter in southern and Gulf Coast states, see the date for 2007-8 here.
Looking at the presence of Ruby-throated Hummingbirds in Florida from 2000-2007 does show an increase.
Aside from these surveys, there seems little else in the way of widespread collection of hummingbird population data in spring and summer.
Why might some people be seeing less hummingbirds in their areas?
Here is speculation:
- There is lack of food at critical times such as when they first arrive from migration. If colder or more severe weather (due to global warming) delays the flowering of their nectar sources or a delay in insect emergence (Ruby-throats due eat insects) when they need it, they may not survive.
- Or there could be more abundant food and flowers in the wild, so hummers do not come to feeders where they can be seen and counted by people.
- Or there could be higher mortality for Ruby-throated Hummingbirds in their wintering areas (Central and South America, and who is counting them there?) so less return each year.
- Or, there are other unknown factors (disease? severe weather extremes) impacting them that we do not know about.
- Or, their reproductive success rate, due to lack of food when the young are in the nest or other factors, is declining.
How can you help in the short term? Keep your hummingbird feeders clean and free of mold and bacteria, which can harm hummingbirds. That means cleaning your hummer feeders every 2 days in hot weather!! Plant hummingbird flowers that bloom at different times so there is ample wild nectar resources from early spring to fall. Help conserve land so hummingbirds continue to have places to nest.