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Your Help is Needed:
Since the 1995 breeding season, landlords many landlords have been participating in a continent-wide, scientific project, known as "Project Martinwatch." Participants monitor their martin nests weekly, record the information on data sheets, then send the data sheets to the PMCA at season's end. Project Martinwatch allow us to obtain information on the range-wide reproductive success of martins and annual population trends.

Participation is Easy:
Just conduct nest checks on your martin housing every 5-7 days, all season long, and record the contents of each nesting cavity on a copy of the Project Martinwatch Nest Data Sheet. There is space to record data from 24 nesting cavities. If you offer more than 24 cavities, please make additional copies of the blank form. We want your data, regardless of the size or success of your site. If some of your martin housing is not accessible during the nesting season, just send us data from those compartments you can check.

Project Martinwatch participants should start monitoring nests when nest building begins at their sites, and continue checking every 5-7 days, all season long, until all the young have fledged. Do your checks at midday or late in the afternoon. Avoid checks during cool or rainy weather, and always work as quickly as possible to minimize the time parents are kept away from their eggs or young. If a period of bad weather threatens to disrupt your regular nest-checking schedule, just postpone the check for a few days, or do it a few days before the predicted storm.

Enter your data directly onto the data sheet as you conduct each check. Be sure to number all of your compartments. Landlords with telescoping poles should draw alignment tabs at each pipe joint to assure that active housing is correctly reoriented after each nest check lowering. For more on drawing alignment tabs, see the booklet, "Enjoying Purple Martins More."

Nest monitoring (including handling nestlings or eggs) will not cause martins to abandon their nests or colony sites; this is an "old wive's tale." In fact, landlords who conduct regular nest checks raise substantially more martins than landlords who don't. Conducting nest checks enables landlords to discover serious problems (e.g., parasites, nest-site competitors, predators, wet nests, chilled nestlings on bare floors, etc.) in time to remedy each of these potentially-lethal situations. Weekly nest monitoring is the best way for landlords to boost the nesting success of their martins.

Nest Check Codes:
The codes to use during your nest checks are listed in the box labeled "Martin Codes" on the data sheet. Please familiarize yourself with these codes and the layout of the entire data sheet. Notice that there is a place at the top of some of the columns for you to record the date of each nest check. Use a separate line to record the contents of each nest cavity. List the housing type and cavity number in the far left column. The second column is for the age of each parent (if known), listing the male first, female second. The third is for the date the first egg is laid, after you determine it through extrapolation. The fourth column is for entering the earliest possible fledging date for each nest. The remaining columns are for entering the results of each nest check, and for recording any actions you may take. Notice that more than one code can be entered in a single box and that codes can be combined, as in 3Y/2DYD, for "3 live young, 2 dead young, discarded." Or, as in 1E/3Y/NR, which means "1 egg, 3 young, nest replaced."

Nest replacement is an optional practice used by many landlords. When the young in each nest are about 10-days old (and again at about 20-days old) landlords remove the nest, and replace it with a 1-2" thick pad of fresh wood shavings, pine straw, or thoroughly-dried lawn clippings. A bowl is fashioned in its center before the young are placed back into the nest. This is the safest way to eliminate nest parasites, without the use of chemical pesticides, which may be harmful the nestlings and parents. As in the sample nest data sheet, landlords should remove dead nestlings from their nests whenever they are encountered.

Calculating Clutch-initiation Date:
Since martins lay just one egg a day, and never skip a nestcheck, it is easy to pinpoint the exact date (or range of dates) the first egg is laid. Please refer to How to Use the Baby Photos and Prognosticator to Determine if Your Martin Nestlings Have Fledged.

Counting Eggs and Nestlings:
Before their clutches are complete, Purple Martins commonly hide their eggs under a layer of green leaves. If landlords don't gently dig through this leaf layer with their fingertips to look for these hidden clutches of eggs, they will miss their opportunity to calculate an accurate clutch-initiation date. After hatching, martin nestlings cuddle with each other in order to reduce heat loss. To count nestlings accurately, this mass of intertwined birds must be separated with a finger or blunt probe. In houses or gourds with access doors, monitoring nests is simple, but in housing lacking these features, landlords may need ladders (please be careful), flashlights, blunt probes, and small mirrors, in order to check nests. Adding porch dividers to all housing with shared porches will prevent older nestlings from walking between compartments and confusing your totals, not to mention causing higher nestling mortality.

Martin Breeding Biology:
Purple Martins lay one egg a day until they've laid anywhere from one to eight eggs, typically four to six eggs. They never skip a day. Incubation begins the day before the last egg is laid and requires 16 days (from the laying of the last egg until the hatching of the last egg). Once hatching begins, it may take 48 hours for all the eggs in a clutch to hatch. Due to this staggered hatch, nestmates may vary in age by as much as two days, causing fledging of most nests to be spread over two or three calendar days. Nestling martins don't fledge until 26-30 days post hatch.

Fledged or Failed?:
Using these parameters, landlords can determine the approximate ages of the young in each nest, and from that, their earliest possible fledging dates. If any nestling disappears before it could possibly be 26 days old (i.e., its earliest possible fledging date), you should assume it did not fledge. To determine the earliest possible fledge date, please refer to How to Use the Baby Photos and Prognosticator to Determine if Your Martin Nestlings Have Fledged.

Summarizing Your Data:
Fill in the three columns on the right-hand side of the data sheet as the season progresses. Once you have determined the clutch size for a nest, enter it in the Egg # column. Likewise, record the maximum number of young that hatched in each nest in the Hatch # column. If you don't wish to calculate earliest possible fledging date (and thus, fledging success), leave the Fledging # column blank - we will do the calculations once we receive your forms. To calculate season totals for each sheet, total all the numbers in each of these 3 columns, and record them in the circles at the bottom of each data sheet. If you allow other species of birds to nest in with your martins, do not include their totals in these summary columns, nor at the bottom of the sheets. Note that nest AG-1 has two entries in each of its three summarization columns, because two nesting attempts were made in this plastic gourd. A renesting attempt is defined as the laying of additional eggs after the first breeding attempt fails or is abandoned.

Criteria For Assigning Parental Ages:
Purple Martins exhibit delayed plumage maturation - they take two years to acquire their adult plumage, but breed as one-year-olds in a subadult plumage. They are also sexually dimorphic, meaning that males and females wear distinctively different plumages. As a result of these two phenomena, landlords will observe four distinct plumages at most colony sites. Landlords that are skilled at distinguishing these four breeding plumages of martins should record the age of each parent at each nest in the second column of the nest data sheet. If you are unsure of the age of a particular individual, just put a questionmark ("?") in its sex/age category on the data form, or refer to our MartinID page or the laminated photo sheets available in the Martin Market Place supplies catalog). Parent martins are best sexed and aged with the aid of binoculars or spotting scopes. Before assigning an age to an individual parent, they should be identified entering their cavity (with nest material, to feed young, or to remove a fecal sac), on at least three different dates. This is because bachelor males frequently sit in front of (and look in) every compartment and could be incorrectly assigned if only one observational period was used.

What Can Be Learned From Project Martinwatch:
Every summer, thousands of landlords conduct weekly nest checks on their martins, recording the breeding success of the birds under their care. Unfortunately, this valuable information isn't collected in a standardized manner, nor is it sent to a centralized location for detailed analysis and eventual publication. Now, with Project Martinwatch, widespread participation will enable the PMCA to obtain data about martins unavailable through any other means and will help answer several important ornithological questions. For instance, we will be able to monitor annual population changes on a continental basis, measure regional and annual differences in reproductive success, and determine the variation in reproductive success (and timing) as affected by parental age. We will also be able to learn how latitude affects clutch size and the timing of breeding in martins, and can compare the relative reproductive success of martins using wooden houses, metal houses, plastic houses, natural gourds, and plastic gourds. Your cooperation with this ongoing project will help us all better understand Purple Martins, and enable us to devise martin housing and management practices best suited to their needs.


If you need additional Project Martinwatch nest data sheets (ruled back version), or have any questions about this project, please contact the Purple Martin Conservation Association via the contact information shown below or at our contact page. Thanks for your help!

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