hello…i live on tybee island in georgia…the low country….the land of wonderful incredible life-sustaining salt marsh….which is one of the truly breath-taking sights on this planet. when the tide is full the view over the marsh is one of green grasses setting atop the blue of the tide-water creeks snaking through the marsh…when the tide is low, the view over the marsh is one of lush green grasses waving in the winds as the blue of the tide-water creeks fall and become more delineated. since the sixteenth of may this year 2007, i have been helping my dear friend who has been so fortunate to live right next to the marsh with an historic creek running past her house, bringing dolphin and great blue heron and white egret seeking food and adventure, clear this vast area of the wrack (wrack is the dead sea grass) that has blanketed the green marsh grasses and is threatening to kill it all. the wrack is a naturally occurring phenomenen which usually finds itself floating back out to sea where it nourishes the vital ocean life….but this year it is different. due to a sorely out-of-date law regarding the building of “long docks,” a neighbor built a 1000′ dock out to “deep water.” this long dock stops the natural flowing of the waters, and causes the wrack build-up on top of the healthy sea grasses. my friend and her husband fought a gallant fight in the courts to stop the building of this long dock, which they knew would bring the destruction that has followed. they lost their court battle. but we are fighting the “freeing of the marsh grass” battle. the process is long…and heart-breaking. since it has been so long, and the area covered so vast, some of the marsh grass has died. we are only so many hands and can only do our work during the high tide time….clearing the creek of the wrack, by helping it move out to deeper water, and then eventually out to sea…so that we can pull more of it off the marsh grass and send it into the creek….we have a 2-2.5 hr window in which to tackle the wrack…when the tide is low, the creek bed is drained and it is impossible to move about in it…there have been many times in which we have been caught further out in the creek and have had to crawl back with just barely enough water to cover our bodies. on sunday while i was out in one of the tide-water creeks, i heard a splashing sound…betsy said, is that you? i said, no. she said it must be a dolphin… i looked up and between me and the pile of wrack that i was moving was a dolphin. splashing and diving and snorting. a most thrilling moment. i know why i am moving this wrack…i am moving it for my friend….i am moving it for the dolphin…i am moving it for the next person who will be able to enjoy the beauty of this eco-system that is the salt marsh….

-Marilyn Fishel

I am a frequent listener to Pulse of the Planet and most often find the information provided to be useful and well presented. However, I must take issue with the logic and conclusions presented in your show of April 13th entitled “American Toads:Crossing the Road”. The naturalist quoted seemed to imply that because the toads tended to cross the road in only one or a few evenings, that put them at greater risk of being killed by automobile traffic than if that were not the case. Now, I am a physicist by profession and not a naturalist, but that assertion is almost certainly untrue. The likelihood of any individual toad being killed crossing the road is determined solely by the ratio of how long it takes to cross the road divided by the average time interval between vehicles. The presence or absence of other toads has no bearing on that ratio, unless they are present in such numbers that they increase the amount of time it takes to cross the road. If the average time it takes a toad to cross the road is the same, and the rate of vehicle traffic is the same, it doesn’t make one bit of difference whether they all cross in one evening or they are spread out equally over the 365 days of the year. This is simple mathematics. What is different, and it is only a difference in perception, is how many dead toads an observer sees in the road before they are removed by scavengers, not what fraction of the toads are actually killed.

This brings me to my second point. The naturalist describes that in a one mile section of road he saw nearly one hundred toads and “out of those hundred toads, sixty of them were killed by cars”. “You can imagine the mortality rate on these toads, and that wasn’t even a busy road.” The implication of the numbers presented is clearly that a large fraction of the toads were killed attempting to cross the road. While I can imagine any number I like, the information provided is not sufficient for either me or the naturalist to compute one. If he had seen only 61 toads, 60 of them would still have been dead - they weren’t going anywhere. If he had seen 1060 toads, the same 60 would still have been dead. The 60 dead toads are the sum of all those that had been killed from the time the migration started (and hadn’t yet been removed by scavengers) until he made his count. There happened to be about 40 other live toads still in the process of crossing. What is missing from the count is the number that had previously crossed successfully and which were now out of sight. Without knowing that number it is impossible to make any sensible estimate of mortality rates.

As I said at the outset, I do enjoy the show, but this particular episode was scientifically misleading at best and serves to give those who don’t care about environmental issues a valid argument in saying that information presented in the name of environmentalism is not scientifically valid.

James Amann Ph.D

Hi Jim -

My boyfriend and his eight year old son and I went to the Minnesota Zoo today. We observed the prairie dogs doing the “yip jumping” and then we observed two prairie dogs in what was either a territorial display or a mating dance - we could not tell which it was. The pair we observed “took turns” turning their bottoms up toward each other and the other prairie dog would approach and appear to sniff the bottom of the other prairie dog. After a few minutes they got into a brief tussle. Was this mating behavior or territorial behavior? Just curious…

Thank you for the info that you have out there on the web. My boyfriend and I are all about educational experiences for his animal loving son and all the stuff on the web is a fantastic tool.

Take care,
Anne