"I come into the peace of wild things who do not tax their lives with forethought of grief.
For a time I rest in the grace of the world, and am free." ~Wendell Berry

Wednesday, June 29, 2016

Purple Martins and The Sounds of Change

“The earth has music for those who listen.”
― George Santayana
This past weekend as I conducted nest checks (now 79 pair), I listened to the efforts of some of the sub-adult males to alert the colony of my intrusions.  It made me laugh at their silliness when they would suddenly launch themselves and try to get the others to flush with them.  Surely, that would serve to frighten and send this frequent intruder running away in terror!  I could tell who were my 'regulars' as they would sit on their perches, beaks stuffed full with some type of food for their broods and roll their eyes at the enthusiastic efforts of the sub-adults.  Ok, maybe they didn't literally roll their eyes, but figuratively speaking anyway.
How about that Green Darner dragonfly? 

As I brushed at the mites, changed out nests and counted nestlings, I heard a group of birds from my colony sound the alarm call to the west and give chase to a Cooper's hawk.  I continued with my nest check after they had evicted the intruder to a safe distance.  Apparently though, the Cooper's wasn't giving up that easily.  Soon I heard the martins chasing her in the field just south of us, then to the west and finally the hapless predator left for good via the northern route.  I knew my martins would soon return to the perches above my head and start bragging and congratulating each other over their victory - at least that's what it sounds like to this happy martin servant.
A short update on my Great Horned Owl situation- in the last 17 nights, I've only experienced 2 GHO visits.  How cool is that?  Bob has some recording doo-hicky machinery and we spent some time recording stuff around the house..doors slamming, Nikki barking, shell loading in a shotgun, shotgun firing, running on my wooden deck, dropping metal pipes on the deck, cough, cough, - you name it, we recorded it.  I also bought a cheap CD player to do repeated, random playing of the cds too.  Along with that, I bought a plethora of night lights and plugged them into a power strip that's on a timer.  Now I have my scarecrow up on the porch, cd playing random "real life" sounds and the lights turning off & on at different times.  Ironically, the only 2 times the owl has visited has been during the timeframes when I had neglected to turn on the cd player.  We're only a little over 2 weeks into testing this, but I am very hopeful.
Anyway, back to this past weekend.  As I continued my work, I thought of all the different calls the purple martins make during their 5-month stay here at Gobbler's Knob and how I can now recognize the various stages of their nesting cycle, just by listening.  Their greetings are loud and raucous when they first arrive in the spring and they sound like excited schoolchildren on their first day back at school, screeching with delight at the sight of old and new friends.  As the season progresses, the loud, persistent mating calls of the males dominate the airwaves.  Eventually, you know when there are eggs in the nests as the colony overall becomes more subdued and they get down to the business of incubation & keeping the eggs warm, except for the evening bathing, and the quiet social gathering and preening on the perches before bedtime.
At some point, the sub-adults arrive and the routines are thrown off kilter as the mated pairs adjust to dealing with the returns of the teenagers from last year.  As eggs start to hatch, I sometimes have to double check that my colony is still around as they become very quiet while fetching and delivering food to the babies.  The only indication they are still here are the black streaks across the yard of approximately 150 adults on cafeteria duty.
An SY Male (left) tries to act cool as the ASY male prepares an attack on him.
When the babies are big enough, they move to the front of the housing and their constant begging for food starts to dominate my backyard.  As my goal is to fledge as many babies as possible, the persistent cries for food are pleasing to my ears.
Mom bringing home the bacon.  Or, in this case, a large dragonfly is what's for dinner.

As of last weekend, we reached the point at my colony where the fun has really started.  As nestlings are preparing for their first flights, the colony is coming alive with the calls of both resident and non-resident martins flying back and forth, screeching to the nestlings at the entrances, providing enthusiastic encouragement for them to spread their wings and take the leap of faith.  As the adults are returning each evening with their newly-fledged broods (of which I have around 25-30 nests fledged to-date), the parents' calls reverberate off my home as they try to direct their reckless entourage of fledges to return to the nest for the night where they will be safe until dawn.  It's a good thing they start at least 45 to 60 minutes before nightfall, as it takes that long for some of them to be successful.
A family unit of martins coming home late in the evening.
One of the youngsters - a protective Dad stands watch as the youngster gets his bearing on which gourd he needs to enter for the night.

All I have to do is listen to them to know where we're at in each phase.  Check out the list below of the multiple vocalizations performed by Purple Martins (via PMCA)

Vocalization Name
Who Uses/Performs It
Description/Purpose of Vocalization
Juvenile Calls
Juvenile martins
•  Given at fledging time
•  Monosyllabic
•  Used when begging for food from parents, or when other martins approach the nest
•  Also used to alert parents that they are being harassed by predators
•  Used on their first flight
Choo Calls
•  Used when escorting fledglings back to the nest
•  Used when taking fledglings out to forage
•  Mainly at dusk
Zwrack Calls
Males and females
•  Used during alarm or highly aggressive situations
•  Given singly
•  Used when predator gets too close to the nest, causing the martin to dive-bomb
Hee-Hee Calls
•  Related to territorial defense; usually given after chasing away an intruder
•  Given in a series of 4 – 10 calls
•  Often given during intraspecific (same species) combat
Zweet Calls
Males and females
•  One-syllable call
•  Indicate alarm
•  Given in flight when martins fly away from a terrestrial predator, causing others to be more vigilant
•  Shows excitement
•  Males use this call if they see another male attempting to copulate with his mate
Cher Calls
Males and females
•  Most common vocalization
•  Used in many situations including during courtship, when showing contentment, when excited, and when approaching housing
•  Sometimes used in conjunction with Zweet and Zwarck calls
•  Given when in flight and when at rest
•  Usually accompanied by wing and body shaking
•  Used mainly during the day but also during pre-dawn hours
Chortle Calls
Males and females
•  Consists of many syllables
•  Sometimes used in conjunction with the Cher call
•  Usually when showing higher excitement levels
•  Both during the day and predawn
•  While sitting
Croak Songs
•  Main courtship song
•  Directed at mate during egg laying
•  Given both before and after copulation
•  Also performed during extra-pair copulations
•  Given in flight and while perched
•  Performed after being rejoined with his mate after being separated for a length of time
Chortle Songs
•  Heard most often during pair formation
•  Mainly during courtship
•  Given towards other females when approaching their territory
•  Only heard near the end of the nesting season, after breeding
•  Performed in a variety of situations
•  Most common after birds began feeding their young
•  Also common during roosting before migration
•  Loudest Purple Martin vocalization
•  During early morning hours to attract other subadult males, and thus females to the colony site
•  Only sung after the male has established a nest

After all we do for our purple martins; the expense, the work, the worry and frustration, peace in nature and connection with them can be found not only in the observation of their antics, but also in the listening.  I truly hope that everyone is listening to their colonies and embracing the joy and energy they share with us with each and every year.  It's not a lot of trouble - one only needs to listen.