Tag: bats

Musings from Austin, TX as our own project gets underway in New Jersey.

By Brian Henderson, GIS Specialist

In April I attended the Anabat Techniques Workshop in Illinois with MacKenzie Hall. The following month I took a brief trip to Austin, TX.

The trip wasn’t work related, and was planned before I knew I would be helping with our bat monitoring work in New Jersey.  But it was appropriate because Austin happens to be home to the largest urban bat colony in North America.

Located near the center of the city, the Congress Avenue Bridge spans Lady Bird Lake, a reservoir on the Colorado River.  Renovations made in 1980 created ideal roosting habitat along the bottom of the bridge and it wasn’t long before migrating bats discovered it.  Now, estimates are that 1-1.5 million Mexican free-tailed bats roost below the bridge between March and November.  Each night around dusk the bats exit the bridge to forage for insects along the river.  When conditions are right the effect is dramatic: a column of bats silhouetted against the setting sun that can last for 45 minutes as the bats exit the bridge.  Although there were petitions to eradicate the bats when they first took up residence, the city has come to embrace them and it isn’t unusual for several hundred people to line up along the bridge on summer nights to watch the bats exit and begin foraging.

Unfortunately, it was cloudy and slightly cool on the evening I visited the bridge and the bats waited until nearly dark before starting to emerge.  It was difficult to observe the bats except in the illumination of the streetlights lining the bridge or when they veered closer to the shore.  Although it wasn’t the spectacle I’d been hoping for, it was still impressive.  Even under less than ideal conditions I saw hundreds (possibly thousands) of bats-more than I observed in the week of training in Illinois, and probably more than in the rest of my life combined.

Here in New Jersey we don’t have Mexican free-tailed bat and we certainly don’t have any bat populations that rival the numbers of the Congress Avenue Bridge Colony.  Even before the arrival of white-nose syndrome populations at our largest hibernacula numbered in the tens of thousands, not millions.  So it was exciting and encouraging to see such a thriving bat population in person.  It was also impressive to see how the city has embraced the colony as a beneficial, unique and interesting attraction.  Similarly, the response to our acoustic monitoring project in New Jersey has been overwhelmingly positive.  Landowners and the general public all seem interested in learning about bats, concerned about white-nose syndrome, and are eager to help however they can.

My experience in Austin was also a reminder that even at the best locations, there are  variables that affect what you observe on any single night.  Rain or cool weather reduce bat activity, and there’s still a lot we don’t know about bat foraging behavior; for instance they may actively forage in an area one night but not the next.  So negative results during one visit isn’t enough evidence to decide bats aren’t in the area.  Ideally we would visit each site multiple times to control for this variability.  However with fifteen sites to monitor, only a few staff members and a fairly short survey period (roughly June 1st to July 31st) we know getting to each site once will keep us busy.  As a result, we may have to survey some sites even though the conditions aren’t ideal.  Unfortunately, these are common problems when surveying for endangered species and are something that many at CWF have had to deal with.

Our acoustic bat monitoring project is just getting underway; we’re taking the lessons learned in Illinois and using that knowledge to monitor for bats in New Jersey.  Expect more updates on our techniques and preliminary results as we have a chance to visit more sites.

CWF visits the “Big Muddy” to learn acoustic bat detection technology

By MacKenzie Hall, Private Lands Biologist

For the past week, fellow CWF’er Brian Henderson and I have been getting familiar with our new toys – two AnaBat acoustic detectors.  We bought the detectors with help from a NJ Landowner Incentive Program (LIP) grant to monitor and learn more about New Jersey’s bats.  The four-day training took place at Western Illinois University’s Kibbe Field Station in Warsaw, Illinois, just a couple thousand feet from the mighty Mississippi River.  We were lucky to have three long-time bat researchers as instructors:  Kim Livengood, Cori Lausen, and AnaBat pioneer Chris Corben.

Acoustic detectors are able to “hear” and record the the echolocation calls that bats give off as they travel and hunt for insects.  Different bat species produce unique call patterns at varying frequencies of sound that can be used to tell them apart (although many calls are very similar and sometimes impossible to distinguish).    Acoustic technology thus allows you to document the diversity and abundance of bats in an area of interest.

The detectors can be used while walking or driving, or they can be set up outside and left to record data for several days, weeks, or even months.  We’ll be doing all of these things, some of them as part of regional/national studies.

At AnaBat training, classroom tutorials were followed each day by nighttime acoustic surveys.  The first night that we went out with our straight-outta-the-box detectors, I can only describe our reaction as bubbly…our “Ooh!”/“Whoa!”/“No way!” squeals were utterly countless as the telltale tick-marks popped up on our PDA screen, indicating nearby bats that we could neither see nor hear on our own.

Back in the classroom, we downloaded the previous night’s bat calls onto our laptops  and practiced identifying the types of bats who had made them –red bats, big brown bats, evening bats, hoary bats, tricolored bats,…and even an endangered Indiana bat or two.  All without having to catch, hold, or even see a thing.

We’re excited to start using this technology in our bat research here in NJ.  Check back for updates about our work with AnaBat!

Students build bat houses and “Adopt a Species” to aid bats in these troubled times

by MacKenzie Hall, CWF Private Lands Biologist

This April, for the second year in a row, I had the happy task of visiting the sixth graders at Valleyview Middle School in Denville, Morris County.  Valleyview  students have taken a great interest in bats lately…partly because their school sits a mere 3 miles from Hibernia Mine, New Jersey’s most important known winter den for resident species like the little brown, northern long-eared, and endangered Indiana bats.

Bats have always been a common neighbor in their town.  And since White-nose Syndrome appeared two winters ago, Denville residents have literally had a front row seat to the toll it has taken.  Many have seen bats flying on cold winter days, searching for food that would not be found, and many have seen the bodies of starved bats on the ground.

Valleyview Middle School has a fantastic science faculty, with teachers like Dan Gross and Chris Bias who aim to give the kids tangible experiences with topics that relate to their own community.   They chose to turn the White-nose Syndrome crisis into a learning opportunity:

Why are bats important?

What happens if we lose them?

What can we do to help?

The school invited us to come in and teach the students about their local bats and talk about the work we’re doing to help study and protect them.  I got to interact with the entire sixth grade, first finding out how much they already knew about bats and then teaching them a whole lot more!

I came back a second day to put the kids to work – we built six bat houses which will be installed in parks and other properties across the region.  Everybody (including me) had a lot of fun with the screw guns, hammers, and caulk…and my “no eyes poked out” success streak continues!

The school also made an “Adopt A Species” donation to the Conserve Wildlife Foundation to support our work.

Thank you, Valleyview Middle School!