Prothonotary Warbler Project – Continued

Readers:  Thanks so much for reading the previous article about this project and for expressing your desire to know more about what we’re doing and how we’re doing it. Using a series of photos accumulated thus far over the past six weeks of monitoring the nest boxes, I will give you a more in-depth look and a better understanding of those things.

BTNEP’s Prothonotary Warbler Conservation and Monitoring project is done in partnership with the Prothonotary Warbler Working Group, which is a consortium of federal and state agencies, NGOs, and universities to meet the needs of this declining warbler species.  Through this work, we strive to

• Identify and fill knowledge gaps in the breeding, wintering, and migratory ecology of this species.
• Measure vital rates and better understand the full life-cycle dynamics to quantify threats and identify factors that limit population growth
• Develop a conservation plan and implement conservation actions that reverse population declines 

As mentioned in the previous article, we installed 50 nest boxes in two locations:  Lake Palourde area near Morgan City, LA and within the Mandalay National Wildlife Refuge near Houma, LA.   Since that May article, we have banded 61 birds, including many of the mother birds and most of the babies.

That seems so incredible to me, because the timeline is so short in which all of this happens.  After the nest is complete, the female lays one egg per day until the clutch is complete, with the average clutch size being 3-6 eggs.  She then incubates them for about 12-14 days.  Both parents feed the nestlings during the 10-11 days it takes for them to “fledge”, (learn to fly).  Each nesting pair typically has up to two broods in its southern breeding range. (Three broods isn’t typical but can happen in the south). By August, these PW families will be on their way back to their southern wintering grounds.

Now, let’s take a look at the process of this data-gathering journey thus far.

Ideally, we capture the female inside the nest box while she’s either sitting on the eggs or the new-born chicks.  We must approach very quietly and in stealth mode, which isn’t easy on the water. From the front of the boat, Natalie advances using the trolling motor.  Once she’s close to the box, I drop the anchor and use the rope to stop the bow of the boat just in line with the nest box while Natalie places her net over the front opening, taps the box, causing the female to fly into the net; that is, if we’ve been successful in our silent approach. (For the most part this approach has worked very well, but I must admit that there are still a couple of wily females out there that heard us coming and flew out before we got close!)

With equipment at the ready, Natalie takes the next band in the sequence and records its correlating number.  That number is later recorded in an online database which allows for reporting and tracking of each bird if they are caught in the future.  This information is helpful in determining nest site fidelity, survival rate, life-span, and migratory pathways. Using a tool that resembles pliers, Natalie carefully applies the band around the female’s leg and then confirms the number on the band with the written record.

Natalie then starts her assessment of the female bird and data gathering.  The data gathered includes cloacal protuberance (males) or brood patch condition (females), body fat, body molt, flight feather molt, flight feather wear, molt limits, wing chord measurement, age, weight, nest box ID. In addition, she closely observes the feathers for coloring, condition, and color patterns on the tail and wing feathers; all of which indicate whether this is a first-year breeding or older female.  

She then gently places the bird in a cotton draw-string pouch, which she previously weighed, and places it on the digital scale.  After recording the weight, it’s time to check and record the overall health of the bird and gather feathers from the crown, chest, wing, and tail and seal those in an envelope to be later sent to a consortium partner. 

After all the assessments are completed and recorded, Natalie then takes a few quick photos and lets the bird fly away.  Next, we check to see what surprises wait inside the nest box.  

If the nest holds eggs, she counts them and observes the overall condition of the nest and makes note of those things. If there are chicks in the nest, Natalie first determines the age of the chicks by the overall size and the extent of feather development. If they are between five and eights days old, they can be safely banded.

Using a little bowl lined with a cotton cloth, Natalie gently removes all but one of the babies from the nest.  She always leaves one baby on the nest because the mother and father are actively feeding them, and an empty nest might upset them enough to cause them to abandon the nest.  We certainly don’t want that to happen.      

First, the chick is weighed. Next, Natalie uses a leg gauge in order to make sure the band will fit comfortably.  Note that the bands aren’t dangerous, because as the chicks grow, the leg gets thinner, not thicker, which enables the band to be worn comfortably.  She carefully applies the band around the leg, double-checking its ID with her notes, and the chicks are then returned to the nest. Lastly, the one remaining chick receives the same treatment.  Using either the trolling motor or a paddle, we slowly back away from the nest box and continue about 100 meters to the next one, until we’ve checked them all.

With only a few weeks left in this project, we currently have a couple of nests with eggs or babies in them, so we will be checking weekly for hatching, banding, and then fledging.  After all the nestlings have fledged, we will then clean out the boxes and secure them for winter, to be uncovered and readied for the 2018 spring migration.  

The things that have most impressed me during this process include Natalie’s meticulous methods, attention to detail, and her sheer love of and concern for these beautiful winged creatures.  Secondly, I’ve been impressed with the dedication of these PW parents.  My favorite moments have been while anchored within feet of the nest box, both parents continued bringing food to the box to feed the remaining nestling.  Some of PW couples were put off by our presence, making that known by a chip-chip warning sound, but many of them flew right into the box within feet of us. It was, indeed, magical–my own personal “Nat-Geo” moments!  (Yes, Nat, pun intended!)

(Click image for larger view)

It is my hope that this project will reach, and even exceed, all its goals for the prothonotary warbler and its continued existence on this earth.  Further, it has been my privilege to be allowed to take part in this worthwhile project and to share it with you, my readers.

For the birds,

BW