MONITORING NESTS

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Active nests must be checked for fate every 3--4 days, and ideally every other day. The longer the interval between checks the more difficult it is to determine the fate of the nest. See Martin and Geupel (1993) for more information on monitoring nests. The information from routine monitoring of nests is used to determine nest fate, productivity, causes of failure and to calculate variables needed for Mayfield nesting success estimates. New participants should request examples of nest cards to help understand the importance of good data reporting. An entire nest visit record line should be filled in each time a nest is visited, even if no activity is observed. Record the number of eggs or young at each visit if you count them even if the number has not changed since the last visit. It is critical to check nests often and to record detailed descriptions of everything you see during each visit.

There are several guidelines that should be followed, in order to minimize disturbance of nests while still providing comprehensive information about a nest and it's fate.

Nest Check Guidelines

1. Check nests from a distance whenever possible, and don't disturb the birds unless a transition from one stage of nesting to the next is expected. Don't go more than 8 days without actually checking nest contents.
2. Check nests more frequently (every 2 days) when transitions (onset of INCUBATION, HATCH, FLEDGING) are expected or when you don't have enough data to estimate when hatch or fledging might occur. The tighter your visits bracket these events the better the data.
3. Don't disturb birds during building or early in egg-laying because they may abandon.
4. Keep careful track of the stage of your nests. Use a table of clutch sizes, and incubation and nestling periods to estimate when incubation, hatch, and fledging may occur so you can plan when more frequent nest visits are needed.
5. Avoid creating dead end paths when checking nests. Approach the nest along one route and leave by another. This makes it more difficult for predators to determine exact nest locations from watching your activity or following scent trails.
6. Never go near an active nest if predators are nearby or watching you.

Determining Nesting Stage -- Useful Cues

Even if you cannot see the contents of a nest, there are still many useful cues that can be used to determine the stage of the nest in the nesting cycle. Be particularly conscious of evidence of nest building or egg-laying and do not approach nests at these times. The following are particularly useful information:

Adults with building material

This almost certainly indicates that birds are still building their nest. Be careful not to get too close to the nest during building -- the birds may abandon.

Mate-feeding

males of some open- and cavity-nesting species will feed the female on the nest during egg laying, incubation, and early brood rearing. A parent going to a nest with food may actually be feeding its mate, not nestlings. Be careful in interpreting feeding when you only observed one parent. Don't jump to conclusions, simply write down what you see. It is particularly difficult to recognize mate-feeding as opposed to nestling feeding in cavity-nesters. Pairs of many species will exchange contact calls during mate-feeding. Sometimes you can see an adult stick its head out of a cavity to get the food. Note: adults will occasionally enter the nest hole to mate feed and nestlings will also stick their heads out for food late in the nestling period.

Fecal Sacs

parents will carry fecal sacs away from the nest during the early and middle parts of the nestling period.

Feeding Young

in cavity-nesters, parents will go into the cavity to feed the young until the end of the brood-rearing period. A parent feeding from outside early in brood-rearing is often an indication that the other parent is in the cavity. Always record whether parents are feeding from the inside or outside of cavities and give a best guess as to whether the one accepting food is an adult or young and why you guess that.

Noisy Babies

Young of many species are very noisy, especially late in the nestling period (e.g. woodpeckers, sapsuckers, orioles). This can be useful in finding nests, and in ageing the young. Listen carefully for noise from nests and record distance at which it is audible. Once noise has been heard, record lack of noise as well.

Filling Out The Nest Card

As in the previous section, UNDERLINED VARIABLES IN LARGE BOLD LETTERS are included in the BBIRD database. The variable codes in parentheses after each variable are the exact names that should be used in data files contributed to the national database. Underlined Variables in italics and mixed case are needed to determine nest fate and/or provide useful information. Italicized variables are not reported directly to the central data repository but some are needed to calculate BBIRD reporting variables. In Arizona we reserve most of the space on the backs of our nest cards for recording information from visits to nests:

FIGURE: NEST VISIT INFORMATION (TOP BACK OF NEST CARD)

At each nest visit the date and time of day are recorded. Then the following information is written on the field nest card:

#Eggs

record a value here only when the nest contents are actually viewed. All nests within 6 m of the ground should be checked by eye or with a mirror pole once during incubation (early is best). Two sections of half inch PVC with a shaving mirror or automobile rear-view mirror on top make a good nest monitoring pole for higher nests. Use binoculars to look at the mirror to check the nest. A short section of larger diameter PVC pipe or a pipe connector fitting can be glued to the end of one of the PVC poles to act as a sleeve that will connect the 2 poles when in use. Extendable light bulb replacement and paint poles can be found at some hardware stores, and window washer poles are very good for high nests. Nest checking poles are a pain to carry around in the field, so given an option, field assistants will tend to forget to use them. Having multiple poles and pushing assistants to get the data will improve your results. The number of eggs is reported once in the BBIRD database as CLUTCH SIZE (CS) or NON-FINAL CLUTCH SIZE (NFCS).

#Yng

number of hatchlings in the nest. Record a number only when actually counted. Check once soon after hatch to get egg hatching success, and once 2-3 days before expected fledging date to get an estimate of number fledged. The closer your check is to fledging the better the estimate of number fledged, but be careful of force fledging by getting too close. Early fledging may reduce survival. Try to check from a distance, particularly late in the nestling period. These data are used to determine NUMBER FLEDGED (NFLDG) which is reported in the BBIRD database.

Elusiveness of parents

How the adult acts around the nest before becoming disturbed. Rate the conspicuousness or elusiveness of the parent around the nest (within a 10 m radius). We are trying to determine if we are just finding nests of the obvious birds, and if nest success differs between obvious and elusive birds. Rate the elusiveness of the more conspicuous parent that is actively involved in the primary activity of that stage of the nest. For example, only females incubate in most passerines, so record female elusiveness during incubation. Both male and female feed the young in most species, so rate the elusiveness of whichever parent is more conspicuous during the nestling period. Report elusiveness only when you are not close to (i.e. within roughly 10 meters of) the nest, and when you are not actively following adults. Elusiveness of parents is a measure of how skittish parent birds are under circumstances in which a potential nest predator (you) has not obviously found a nest, but parental behavior could lead to the nest being detected. The following are the codes used: