The Park Service counted 78 horses on the Maryland side of the island in March, up from 73 a year ago, according to a story by WJLA News of Arlington, VA. The findings were released on socialist media.
The fertility control program was shut off in 2016 but the herd has continued to decline, as seen in this history brief by NPS. The chart shows an average growth rate of about 13% per year between 1975 and 1986, before the program was started.
The survey found 27 males and 51 females this year, suggesting that the breakdown by sex may be inching closer to normal.
The expected range of variation from a simple random process centered at 50% males / 50% females, with a herd size of 78, is 25.8 to 52.2. The observed numbers of males and females fall within these limits so the results could be attributed to chance.
Last year’s results were outside of limits.
The increase in herd size this year was due to a larger number of males.
The expected range of variation must be determined by calculation, using basic statistical formulas, where n = 78 and p-bar = .5.