MOTUS: Serving Arizona Birds

Summary: Now that you know what MOTUS is and what it does, let’s talk about how is helps Arizona birds. Join Cheryl and Kiersten to find out how MOTUS is helping some Arizona birds.

 

For our hearing-impaired listeners, a transcript of this podcast follows the show notes on Podbean.

 

Show Notes:

“Desert Deliverance”, by Margo Rosenbaum, Audubon Magazine Fall 2023, pg 18-19

“Home Away From Home”, by Daniel Grossman, Audubon Magazine Fall 2022, pg 30-35

“The Mysterious Decline of the American Kestrel,” by Jillian Mock, Audubon Magazine Spring 2023, pg 20-27

“Keeping Up with the Grosbeaks,” by Zoe Grueskin, Audubon Magazine Winter 2023, pg 15

Transcript

 

Cheryl-Intro:

            Recently, we posted a podcast about MOTUS.  What it is-radio tracking system-more towers being placed in Arizona, one possibly at the Gilbert Riparian Water Ranch.  I wanted to revisit this because I found actual research studies using MOTUS that has an impact on Arizona birds.  It is exciting to see the impacts of this new technology and how it is advancing research in bird studies.

Keirsten: Purple Martins

            If you have lived on the east coast or in the mid-west of U.S. you have seen Purple Martins, and the colonial-style bird houses that they like to nest in.  A little back story about this bird, Purple Martins are insectivorous (insect eaters) which has made them vulnerable to the pesticides we use on our yards.  So, their numbers were really in decline here in the U.S. until citizen science got involved.  People who enjoyed seeing the birds and understood their importance to local insect control started placing the correct nest boxes these birds like.  These citizen scientists monitored the boxes, eliminated pesticide use on their properties, kept cats indoors etc.

 Over time the populations of Purple Martins bounced back in the Untied States.  So why are we talking about them…because their numbers are still in decline, and scientists don’t really know why.  Purple Martins have been studied extensively In North America; scientific knowledge tapers off when they fly south.  Just where do they go, Wat routes they take, and what critical habitat lies Along the way remain largely a mystery.  The marathon journeys these birds undertake every year compounds the risk to their survival.

Arizona has its own sub-species of Purple Martins that prefer to nest in Saguaro cacti in the southern part of our state.  Arizona’s Purple Martins spend the winter where?  They take a similar marathon journey as those who summer east of the Mississippi River.

Cheryl: Get to the point-Brazil.

            Just off a slice of land sitting mid-stream in Brazil’s Rio Negro, is an island locally known as Ilha do Comaru, every year this island is submerged in March and only the tree tops poke above the surface.  There in those treetops are Purple Martins.  Now, Motus helped to locate this tiny island of 12 acres (slightly larger than Yankee Stadium).  How you ask?  Back in the U.S., scientists with the help of volunteers tagged nesting Purple Martins (adults and fledglings) with radio tags that will ping a receiver, that by chance was placed near this island. 

Scientists looked at the MOTUS network tracking and thought huh?  Where is that?  It turns out that MOTUS revealed to scientists a space that is host to a concentration of roughly 250,000 birds between February and April, it’s one of the largest Purple Martin roost ever discovered.  Its significance isn’t just its size, however, but also the pivotal role the roost may play in the bird’s long-distance migration.  Comaru could be the staging ground, or launch pad, for many of the 9.3 million Purple Martins that funnel through from South to North America. 

Scientists are tagging Purple Martins on this tiny island, so they can trace birds coming and going to see where these birds’ journey to breed.  Some head to Arizona, and some head towards the east coast of the U.S. This is important to Arizona Purple Martins because our sub-species like to nest in Saguaros that are 40 ft high.  It is easier for everyone if the tagging is done on this tiny island.

Scientists are excited to trace the movements of these birds to figure out what they’re eating and analyze whether they’ve been contaminated by pesticides and other pollutants, we can learn something about how they’re doing in Brazil.

Scientists feel that by taking a closer look at the birds onto this small isle, they hope to glean insights that can help secure the future of the entire species, and any discoveries they make will help uncover what’s behind the decline of other songbirds, especially other aerial insectivores.

Keirsten: The American Kestrel

            Arizona hosts the American Kestrel all year long.  It just moves within the state.  This bird is on the decline here due to loss of habitat, pesticide use, and the increase in population of Cooper’s Hawks, to name a few challenges this small falcon must face daily.  Scientists are racing to understand why this bird is continuing to disappear from our skies.

            Let’s move to Texas where there is a project that outfits kestrels with radio trackers to glean how they move on their wintering grounds and where they breed come spring.  The exact paths kestrels take and the ultimate winter destinations for many populations are mysteries.  Their smaller scale movements are also an enigma:  researcher Maddy Kaleta stated in an article for Audubon Society “We know kestrels need open space, but we don’t know enough about where they prefer to hunt, how big their territories are, or what they do when their preferred habitat disappears. Kestrels that spend one winter hunting in a field may return to find it has disappeared under concrete and new shopping attractions the next winter.  MOTUS is helping answer these questions.

            Data from this study indicates sharpest kestrel declines are in the East.   For the birds that show up in the nest boxes placed by citizen scientists, their success rates are very high.  A single kestrel pair fledges three to four chicks on average.  The puzzling problem is that they are not showing up. 

            In the west, kestrels are showing up, but they are breeding weeks earlier than they did in the 1990’s and scientists discovered that farmers are taking advantage of significantly warmer winters by planting crops earlier to avoid the hotter summers.  The change in planting draws insects and rodents which is a bounty for the kestrels, and kestrels are taking advantage of this change. 

            All this data collected will help Arizona protect the American Kestrels that choose Arizona as their home.

Cheryl: Evening Grosbeaks

            This beautiful bird winters here in the lower part of Arizona on occasion but spends most of its time up in Arizona’s boreal forests.  But since 1970, the once common species has sharply declined in the EAST, making irruptions less frequent and grosbeak visits increasingly rare. 

            Scientists started out with a small number of tagged birds aiming to discover where these birds go in spring. Then with numbers declining they scaled up their tagging and tracking to over 200 birds so far.  Using radio and satellite tags, scientists plan to expand across more of the species U.S. Range because Evening Grosbeakshave unpredictable roving patterns and this makes it vital and challenging to understand their movements.  These birds are somewhat secretive and breed in remote areas, so trying to find where they’re nesting isn’t easy.  So once a bird is tagged in winter scientists can follow its journey.   This data collected from MOTUS will help answer questions and could reveal bottlenecks or pressure points for the species and clues about what’s driving the decline.

            Researchers have found evidence of climate change is stressing spruce and fir forests where these birds like to nest, and diseases such as conjunctivitis, West Nile virus, or salmonella infections may all play into Evening Grosbeaks and their decline.  Tagging and tracking birds has highlighted the vulnerability of birds and window strikes.

            All this data, even if it is collected on the East coast will help Arizona fast track efforts to protect our population of Evening Grosbeaks with MOTUS’ help.